NASA
Autonomous Tritium Micropowered Sensors
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Autonomous Tritium Micropowered Sensors concept.NASA/Peter CabauyPeter Cabauy
City Labs, Inc.
The NIAC Phase I study confirmed the feasibility of nuclear-micropowered probes (NMPs) using tritium betavoltaic power technology for autonomous exploration of the Moon’s permanently shadowed regions (PSRs). This work advanced the technology’s readiness level (TRL) from TRL 1 to TRL 2, validating theoretical models and feasibility assessments. Phase II will refine the technology, address challenges, and elevate the TRL to 3, with a roadmap for further maturation toward TRL 4 and beyond, supporting NASA’s mission for lunar and planetary exploration. A key innovation is tritium betavoltaic power sources, providing long-duration energy in extreme environments. The proposed 5cm x 5cm gram-scale device supports lunar spectroscopy and other applications. In-situ analyses at the Moon’s south pole are challenging due to cold, limited solar power, and prolonged darkness. Tritium betavoltaics harvest energy from radioactive decay, enabling autonomous sensing in environments unsuitable for conventional photovoltaics and chemical-based batteries.
The proposal focuses on designing an ultrathin light weight tritium betavoltaic into an NMP for integrating various scientific instruments. Tritium-powered NMPs support diverse applications, from planetary science to scouting missions for human exploration. This approach enables large-scale deployment for high-resolution remote sensing. For instance, a distributed NMP array could map lunar water resources, aiding Artemis missions. Beyond the Moon, tritium-powered platforms enable a class of missions to Mars, Europa, Enceladus, and asteroids, where alternative power sources are impractical.
Phase II objectives focus on improving energy conversion efficiency and resilience of tritium betavoltaic power sources, targeting 1-10 μW continuous electrical power with higher thermal output. The project will optimize NMP integration with sensor platforms, enhancing power management, data transmission, and environmental survivability in PSR conditions. Environmental testing will assess survivability under lunar landing conditions, including decelerations of 27,000-270,000g and interactions with lunar regolith. The goal is to advance TRL from 2 to 3 by demonstrating proof-of-concept prototypes and preparing for TRL 4. Pathways for NASA mission integration will be explored, assessing scalability, applicability, and cost-effectiveness compared to alternative technologies.
A key discovery in Phase I was the thermal-survivability benefit of the betavoltaic’s tritium metal hydride, which generates enough heat to keep electronic components operational. This dual functionality–as both a power source and thermal stabilizer–allows NMP components to function within temperature specifications, a breakthrough for autonomous sensing in extreme environments. Beyond lunar applications, this technology could revolutionize planetary science, deep-space exploration, and terrestrial use cases. It could aid Mars missions, where dust storms and long nights challenge solar power, and Europa landers, which need persistent low-power operation. Earth-based applications such as biomedical implants and environmental monitoring could benefit from the proposed advancements in betavoltaic energy storage and micro-scale sensors. The Phase II study supports NASA’s Artemis objectives by enabling sustainable lunar exploration through enhanced resource characterization and autonomous monitoring. Tritium-powered sensing has strategic value for PSR scouting, planetary-surface mapping, and deep-space monitoring. By positioning tritium betavoltaic NMPs as a power solution for extreme environments, this study lays the foundation for transitioning the technology from concept to implementation, advancing space exploration and scientific discovery.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
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About NIAC
Autonomous Tritium Micropowered Sensors
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Autonomous Tritium Micropowered Sensors concept.NASA/Peter CabauyPeter Cabauy
City Labs, Inc.
The NIAC Phase I study confirmed the feasibility of nuclear-micropowered probes (NMPs) using tritium betavoltaic power technology for autonomous exploration of the Moon’s permanently shadowed regions (PSRs). This work advanced the technology’s readiness level (TRL) from TRL 1 to TRL 2, validating theoretical models and feasibility assessments. Phase II will refine the technology, address challenges, and elevate the TRL to 3, with a roadmap for further maturation toward TRL 4 and beyond, supporting NASA’s mission for lunar and planetary exploration. A key innovation is tritium betavoltaic power sources, providing long-duration energy in extreme environments. The proposed 5cm x 5cm gram-scale device supports lunar spectroscopy and other applications. In-situ analyses at the Moon’s south pole are challenging due to cold, limited solar power, and prolonged darkness. Tritium betavoltaics harvest energy from radioactive decay, enabling autonomous sensing in environments unsuitable for conventional photovoltaics and chemical-based batteries.
The proposal focuses on designing an ultrathin light weight tritium betavoltaic into an NMP for integrating various scientific instruments. Tritium-powered NMPs support diverse applications, from planetary science to scouting missions for human exploration. This approach enables large-scale deployment for high-resolution remote sensing. For instance, a distributed NMP array could map lunar water resources, aiding Artemis missions. Beyond the Moon, tritium-powered platforms enable a class of missions to Mars, Europa, Enceladus, and asteroids, where alternative power sources are impractical.
Phase II objectives focus on improving energy conversion efficiency and resilience of tritium betavoltaic power sources, targeting 1-10 μW continuous electrical power with higher thermal output. The project will optimize NMP integration with sensor platforms, enhancing power management, data transmission, and environmental survivability in PSR conditions. Environmental testing will assess survivability under lunar landing conditions, including decelerations of 27,000-270,000g and interactions with lunar regolith. The goal is to advance TRL from 2 to 3 by demonstrating proof-of-concept prototypes and preparing for TRL 4. Pathways for NASA mission integration will be explored, assessing scalability, applicability, and cost-effectiveness compared to alternative technologies.
A key discovery in Phase I was the thermal-survivability benefit of the betavoltaic’s tritium metal hydride, which generates enough heat to keep electronic components operational. This dual functionality–as both a power source and thermal stabilizer–allows NMP components to function within temperature specifications, a breakthrough for autonomous sensing in extreme environments. Beyond lunar applications, this technology could revolutionize planetary science, deep-space exploration, and terrestrial use cases. It could aid Mars missions, where dust storms and long nights challenge solar power, and Europa landers, which need persistent low-power operation. Earth-based applications such as biomedical implants and environmental monitoring could benefit from the proposed advancements in betavoltaic energy storage and micro-scale sensors. The Phase II study supports NASA’s Artemis objectives by enabling sustainable lunar exploration through enhanced resource characterization and autonomous monitoring. Tritium-powered sensing has strategic value for PSR scouting, planetary-surface mapping, and deep-space monitoring. By positioning tritium betavoltaic NMPs as a power solution for extreme environments, this study lays the foundation for transitioning the technology from concept to implementation, advancing space exploration and scientific discovery.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
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About NIAC
Addressing Key Challenges To Mapping Sub-cm Orbital Debris in LEO via Plasma Soliton Detection
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the Mapping Sub-cm Orbital Debris in LEO concept.NASA/Christine HartzellChristine Hartzell
University of Maryland, College Park
The proposed investigation will address key technological challenges associated with a previously funded NIAC Phase I award titled “On-Orbit, Collision-Free Mapping of Small Orbital Debris”. Sub-cm orbital debris in LEO is not detectable or trackable using conventional technologies and poses a major hazard to crewed and un-crewed spacecraft. Orbital debris is a concern to NASA, as well as commercial and DoD satellite providers. In recent years, beginning with our NIAC Phase I award, we have been developing the idea that the sub-cm orbital debris environment may be monitored by detecting the plasma signature of the debris, rather than optical or radar observations of the debris itself. Our prior work has shown that sub-cm orbital debris may produce plasma solitons, which are a type of wave in the ionosphere plasma that do not disperse as readily as traditional waves. Debris may produce solitons that are co-located with the debris (called pinned solitons) or that travel ahead of the debris (called precursor solitons). We have developed computational models to predict the characteristics of the plasma solitons generated by a given piece of debris. These solitons may be detectable by 12U smallsats outfitted with multi-needle Langmuir probes.
In this Phase II NIAC award, we will address two key technical challenges that significantly effect the value of soliton-based debris detection: 1. Develop an algorithm to constrain debris size and speed based on observed soliton characteristics. Our prior investigations have produced predictions of soliton characteristics as a function of debris characteristics. However, the inverse problem is not analytically solvable. We will develop machine learning algorithms to address this challenge. 2. Evaluate the feasibility and value of detecting soliton velocity. Multiple observations of the same soliton may allow us to constrain the distance that the soliton has traveled from the debris. When combined with the other characteristics of the soliton and knowledge of the local plasma environment, back propagation of the soliton in plasma simulations may allow us to extract the position and velocity vectors of the debris. If it is possible to determine debris size, position and velocity from soliton observations, this would provide a breakthrough in space situational awareness for debris that is currently undetectable using conventional technology. However, even if only debris size and speed can be inferred from soliton detections, this technology is still a revolutionary improvement on existing methods of characterizing the debris flux, which provide data only on a multi-year cadence. This proposed investigation will answer key technological questions about how much information can be extracted from observed soliton signals and trade mission architectures for complexity and returned data value. Additionally, we will develop a roadmap to continue to advance this technology.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
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About NIAC
Addressing Key Challenges To Mapping Sub-cm Orbital Debris in LEO via Plasma Soliton Detection
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the Mapping Sub-cm Orbital Debris in LEO concept.NASA/Christine HartzellChristine Hartzell
University of Maryland, College Park
The proposed investigation will address key technological challenges associated with a previously funded NIAC Phase I award titled “On-Orbit, Collision-Free Mapping of Small Orbital Debris”. Sub-cm orbital debris in LEO is not detectable or trackable using conventional technologies and poses a major hazard to crewed and un-crewed spacecraft. Orbital debris is a concern to NASA, as well as commercial and DoD satellite providers. In recent years, beginning with our NIAC Phase I award, we have been developing the idea that the sub-cm orbital debris environment may be monitored by detecting the plasma signature of the debris, rather than optical or radar observations of the debris itself. Our prior work has shown that sub-cm orbital debris may produce plasma solitons, which are a type of wave in the ionosphere plasma that do not disperse as readily as traditional waves. Debris may produce solitons that are co-located with the debris (called pinned solitons) or that travel ahead of the debris (called precursor solitons). We have developed computational models to predict the characteristics of the plasma solitons generated by a given piece of debris. These solitons may be detectable by 12U smallsats outfitted with multi-needle Langmuir probes.
In this Phase II NIAC award, we will address two key technical challenges that significantly effect the value of soliton-based debris detection: 1. Develop an algorithm to constrain debris size and speed based on observed soliton characteristics. Our prior investigations have produced predictions of soliton characteristics as a function of debris characteristics. However, the inverse problem is not analytically solvable. We will develop machine learning algorithms to address this challenge. 2. Evaluate the feasibility and value of detecting soliton velocity. Multiple observations of the same soliton may allow us to constrain the distance that the soliton has traveled from the debris. When combined with the other characteristics of the soliton and knowledge of the local plasma environment, back propagation of the soliton in plasma simulations may allow us to extract the position and velocity vectors of the debris. If it is possible to determine debris size, position and velocity from soliton observations, this would provide a breakthrough in space situational awareness for debris that is currently undetectable using conventional technology. However, even if only debris size and speed can be inferred from soliton detections, this technology is still a revolutionary improvement on existing methods of characterizing the debris flux, which provide data only on a multi-year cadence. This proposed investigation will answer key technological questions about how much information can be extracted from observed soliton signals and trade mission architectures for complexity and returned data value. Additionally, we will develop a roadmap to continue to advance this technology.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
NIAC Funded Studies
About NIAC
Breathing Beyond Earth: A Reliable Oxygen Production Architecture for Human Space Exploration
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the Breathing Beyond Earth concept.NASA/Alvaro Romero-CalvoAlvaro Romero-Calvo
Georgia Tech Research Corporation
The reliable and efficient operation of spacecraft life support systems is challenged in microgravity by the near absence of buoyancy. This impacts the electrolytic production of oxygen and hydrogen from water by forcing the adoption of complex multiphase flow management technologies. Still, water splitting plays an essential role in human spaceflight, closing the regenerative environmental control and life support loop and connecting the water and atmosphere management subsystems. Existing oxygen generation systems, although successful for short-term crewed missions, lack the reliability and efficiency required for long-duration spaceflight and, in particular, for Mars exploration.
During our Phase I NIAC effort, we demonstrated the basic feasibility of a novel water-splitting architecture that leverages contactless magnetohydrodynamic (MHD) forces to produce and separate oxygen and hydrogen gas bubbles in microgravity. The system, known as the Magnetohydrodynamic Oxygen Generation Assembly (MOGA), avoids the use of forced water recirculation loops or moving parts such as pumps or centrifuges for phase separation. This fundamental paradigm shift results in multiple operational advantages with respect to the state-of-the-art: increased robustness to over- and under-voltages in the cell stack, minimal risk of electrolyte leaching, wider operational temperature and humidity levels, simpler transient operation, increased material durability, enhanced system stability during dormant periods, modest water purity requirements, reduced microbial growth, and better component-level swap-ability, all of which result in an exceptionally robust system. Overall, these architectural features lead to a 32.9% mass reduction and 20.4% astronaut maintenance time savings with respect to the Oxygen Generation Assembly at the ISS for a four-crew Mars transfer, making the system ideally suited for long-duration missions. In Phase II, we seek to answer some of the key remaining unknowns surrounding this architecture, particularly regarding (i) the long-term electrochemical and multiphase flow behavior of the system in microgravity and its impact on power consumption and liquid interface stability, (ii) the transient operational modes of the MHD drive during start-up, shutdown, and dormancy, and (iii) architectural improvements for manufacturability and ease of repair. Toward that end, we will leverage our combined expertise in microgravity research by partnering with the ZARM Institute in Bremen and the German Aerospace Center to fly, free of charge to NASA, a large-scale magnetohydrodynamic drive system and demonstrate critical processes and components. An external review board composed of industry experts will assess the evolution of the project and inform commercial infusion. This effort will result in a TRL-4 system that will also benefit additional technologies of interest to NASA and the general public, such as water-based SmallSat propulsion and in-situ resource utilization.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
NIAC Funded Studies
About NIAC
Breathing Beyond Earth: A Reliable Oxygen Production Architecture for Human Space Exploration
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the Breathing Beyond Earth concept.NASA/Alvaro Romero-CalvoAlvaro Romero-Calvo
Georgia Tech Research Corporation
The reliable and efficient operation of spacecraft life support systems is challenged in microgravity by the near absence of buoyancy. This impacts the electrolytic production of oxygen and hydrogen from water by forcing the adoption of complex multiphase flow management technologies. Still, water splitting plays an essential role in human spaceflight, closing the regenerative environmental control and life support loop and connecting the water and atmosphere management subsystems. Existing oxygen generation systems, although successful for short-term crewed missions, lack the reliability and efficiency required for long-duration spaceflight and, in particular, for Mars exploration.
During our Phase I NIAC effort, we demonstrated the basic feasibility of a novel water-splitting architecture that leverages contactless magnetohydrodynamic (MHD) forces to produce and separate oxygen and hydrogen gas bubbles in microgravity. The system, known as the Magnetohydrodynamic Oxygen Generation Assembly (MOGA), avoids the use of forced water recirculation loops or moving parts such as pumps or centrifuges for phase separation. This fundamental paradigm shift results in multiple operational advantages with respect to the state-of-the-art: increased robustness to over- and under-voltages in the cell stack, minimal risk of electrolyte leaching, wider operational temperature and humidity levels, simpler transient operation, increased material durability, enhanced system stability during dormant periods, modest water purity requirements, reduced microbial growth, and better component-level swap-ability, all of which result in an exceptionally robust system. Overall, these architectural features lead to a 32.9% mass reduction and 20.4% astronaut maintenance time savings with respect to the Oxygen Generation Assembly at the ISS for a four-crew Mars transfer, making the system ideally suited for long-duration missions. In Phase II, we seek to answer some of the key remaining unknowns surrounding this architecture, particularly regarding (i) the long-term electrochemical and multiphase flow behavior of the system in microgravity and its impact on power consumption and liquid interface stability, (ii) the transient operational modes of the MHD drive during start-up, shutdown, and dormancy, and (iii) architectural improvements for manufacturability and ease of repair. Toward that end, we will leverage our combined expertise in microgravity research by partnering with the ZARM Institute in Bremen and the German Aerospace Center to fly, free of charge to NASA, a large-scale magnetohydrodynamic drive system and demonstrate critical processes and components. An external review board composed of industry experts will assess the evolution of the project and inform commercial infusion. This effort will result in a TRL-4 system that will also benefit additional technologies of interest to NASA and the general public, such as water-based SmallSat propulsion and in-situ resource utilization.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
NIAC Funded Studies
About NIAC
TFINER – Thin Film Isotope Nuclear Engine Rocket
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the TFINER concept.NASA/James BickfordJames Bickford
Charles Stark Draper Laboratory, Inc.
The Thin-Film Nuclear Engine Rocket (TFINER) is a novel space propulsion technology that enables aggressive space exploration for missions that are impossible with existing approaches. The concept uses thin layers of energetic radioisotopes to directly generate thrust. The emission direction of its natural decay products is biased by a substrate to accelerate the spacecraft. A single stage design is very simple and can generate velocity changes of ~100 km/s using a few kilograms of fuel and potentially more than 150 km/s for more advanced architectures.
The propulsion system enables a rendezvous with intriguing interstellar objects such as ‘Oumuamua that are on hyperbolic orbits through our solar system. A particular advantage is the ability to maneuver in deep space to find objects with uncertainty in their location. The same capabilities also enable a fast trip to the solar gravitational focus to image multiple potentially habitable exoplanets. Both types of missions require propulsion outside the solar system that is an order of magnitude beyond the performance of existing technology. The phase 2 effort will continue to mature TFINER and the mission design. The program will work towards small scale thruster experiments in the near term. In parallel, isotope production paths that can also be leveraged for other space exploration and medical applications will be pursued. Finally, advanced architectures such as an Oberth solar dive maneuver and hybrid approaches that leverage solar sails near the Sun, will be explored to enhance mission performance.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
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About NIAC
TFINER – Thin Film Isotope Nuclear Engine Rocket
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the TFINER concept.NASA/James BickfordJames Bickford
Charles Stark Draper Laboratory, Inc.
The Thin-Film Nuclear Engine Rocket (TFINER) is a novel space propulsion technology that enables aggressive space exploration for missions that are impossible with existing approaches. The concept uses thin layers of energetic radioisotopes to directly generate thrust. The emission direction of its natural decay products is biased by a substrate to accelerate the spacecraft. A single stage design is very simple and can generate velocity changes of ~100 km/s using a few kilograms of fuel and potentially more than 150 km/s for more advanced architectures.
The propulsion system enables a rendezvous with intriguing interstellar objects such as ‘Oumuamua that are on hyperbolic orbits through our solar system. A particular advantage is the ability to maneuver in deep space to find objects with uncertainty in their location. The same capabilities also enable a fast trip to the solar gravitational focus to image multiple potentially habitable exoplanets. Both types of missions require propulsion outside the solar system that is an order of magnitude beyond the performance of existing technology. The phase 2 effort will continue to mature TFINER and the mission design. The program will work towards small scale thruster experiments in the near term. In parallel, isotope production paths that can also be leveraged for other space exploration and medical applications will be pursued. Finally, advanced architectures such as an Oberth solar dive maneuver and hybrid approaches that leverage solar sails near the Sun, will be explored to enhance mission performance.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
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About NIAC
Photophoretic Propulsion Enabling Mesosphere Exploration
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Photophoretic Propulsion Enabling Mesosphere Exploration concept.NASA/Igor BargatinIgor Bargatin
University of Pennsylvania
We propose to use the photophoretic levitation and propulsion mechanism to create no-moving-parts flying vehicles that can be used to explore Earth’s upper atmosphere. The photophoretic force arises when a solid is heated relative to the ambient gas through illumination, inducing momentum exchange between the solid and the gas. The force creates lift in structures that absorb light on the bottom yet stay cool on the top, and we engineered our plate mechanical metamaterials to maximize this lift force and payload. The levitation and payload capabilities of our plates typically peak at ambient pressures in the 0.1-1000 Pa range, ideal for applications in Earth’s mesosphere and Mars’s low gravity and thin atmosphere. For example, in the Earth’s mesosphere (i.e., at altitudes from ~50 to ~80 km), the air is too thin for conventional airplanes or balloons but too thick for satellites, such that measurements can be performed for only a few minutes at a time during the short flight of a research rocket. However, the range of ambient pressures in the mesosphere (1-100 Pa) is nearly optimal for our plates’ payload capabilities. Phase 2 of the proposal focuses on the scalable fabrication of Knudsen pump structures that will enable missions with kg-scale payloads in the mesosphere as well as trajectory control with 1 m/s velocity control in existing stratospheric balloon vehicles.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
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About NIAC
Photophoretic Propulsion Enabling Mesosphere Exploration
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Photophoretic Propulsion Enabling Mesosphere Exploration concept.NASA/Igor BargatinIgor Bargatin
University of Pennsylvania
We propose to use the photophoretic levitation and propulsion mechanism to create no-moving-parts flying vehicles that can be used to explore Earth’s upper atmosphere. The photophoretic force arises when a solid is heated relative to the ambient gas through illumination, inducing momentum exchange between the solid and the gas. The force creates lift in structures that absorb light on the bottom yet stay cool on the top, and we engineered our plate mechanical metamaterials to maximize this lift force and payload. The levitation and payload capabilities of our plates typically peak at ambient pressures in the 0.1-1000 Pa range, ideal for applications in Earth’s mesosphere and Mars’s low gravity and thin atmosphere. For example, in the Earth’s mesosphere (i.e., at altitudes from ~50 to ~80 km), the air is too thin for conventional airplanes or balloons but too thick for satellites, such that measurements can be performed for only a few minutes at a time during the short flight of a research rocket. However, the range of ambient pressures in the mesosphere (1-100 Pa) is nearly optimal for our plates’ payload capabilities. Phase 2 of the proposal focuses on the scalable fabrication of Knudsen pump structures that will enable missions with kg-scale payloads in the mesosphere as well as trajectory control with 1 m/s velocity control in existing stratospheric balloon vehicles.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
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About NIAC
Mars Roundtrip Success Enabled by Integrated Cooling through Inductively Coupled LED Emission (MaRS ICICLE)
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of MaRS ICICLE concept.NASA/Aaswath Pattabhi RamanAaswath Pattabhi Raman
University of California, Los Angeles
Exploration of Mars has captivated the public in recent decades with high-profile robotic missions and the images they have acquired seeding our collective imagination. NASA is actively planning for human exploration of Mars and laid out some of the key capabilities that must be developed to execute successful, cost-effective programs that would put human beings on the surface of another planet and bring them home safely. Efficient, flexible and productive round-trip missions will be key to further human exploration of Mars. New round-trip mission concepts however need substantially improved long-duration storage of cryogenic propellants in various space environments; relevant propellants include liquid Hydrogen (LH2) for high specific impulse Nuclear Thermal Propulsion (NTP) which can be deployed in strategic locations in advance of a mission. If enabled, such LH2 storage tanks could be used to refill a crewed Mars Transfer Vehicle (MTV) to send and bring astronauts home quickly, safely, and cost-effectively. A well-designed cryogenic propellant storage tank can reflect the vast majority of photons incident on the spacecraft, but not all. In thermal environments like Low Earth Orbit (LEO), there is residual heating due to light directly from the Sun, sunlight reflected off Earth, and blackbody thermal radiation from Earth. Over time, this leads to some of the propellant molecules absorbing the requisite latent heat of vaporization, entering the gas phase, and ultimately being released into space to prevent an unsustainable build-up of pressure in the tank. This slow “boil-off” process leads to significant losses of the cryogenic liquid into space, potentially leaving it with insufficient mass and greatly limiting Mars missions. We propose a breakthrough mission concept: an ultra-efficient round-trip Mars mission with zero boil off of propellants. This will be enabled by low-cost, efficient cryogenic liquid storage capable of storing LH2 and LOx with ZBO even in the severe and fluctuating thermal environment of LEO. To enable this capability, the propellant tanks in our mission will employs thin, lightweight, all-solid-state panels attached to the tank’s deep-space-facing surfaces that utilize a long-understood but as-yet-unrealized cooling technology known as Electro-Luminescent Cooling (ELC) to reject heat from cold solid surfaces as non-equilibrium thermal radiation with significantly more power density than Planck’s Law permits for equilibrium thermal radiation. Such a propellant tank would drastically lower the cost and complexity of propulsion systems for crewed Mars missions and other deep space exploration by allowing spacecraft to refill propellant tanks after reaching orbit rather than launching on the much larger rocket required to lift the spacecraft in a single-use stage. To achieve ZBO, a storage spacecraft must keep the storage tank’s temperature below the boiling point of the cryogen (e.g., < 90 K for LOx and < 20 K for liquid H2). Achieving this in LEO-like thermal environments requires both excellent reflectivity toward sunlight and thermal radiation from the Earth, Mars and other nearby bodies as well as a power-efficient cooling mechanism to remove what little heat inevitably does leak in, a pair of conditions ideally suited to the ELC cooling systems that will makes our full return-trip mission to Mars a success.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
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Mars Roundtrip Success Enabled by Integrated Cooling through Inductively Coupled LED Emission (MaRS ICICLE)
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of MaRS ICICLE concept.NASA/Aaswath Pattabhi RamanAaswath Pattabhi Raman
University of California, Los Angeles
Exploration of Mars has captivated the public in recent decades with high-profile robotic missions and the images they have acquired seeding our collective imagination. NASA is actively planning for human exploration of Mars and laid out some of the key capabilities that must be developed to execute successful, cost-effective programs that would put human beings on the surface of another planet and bring them home safely. Efficient, flexible and productive round-trip missions will be key to further human exploration of Mars. New round-trip mission concepts however need substantially improved long-duration storage of cryogenic propellants in various space environments; relevant propellants include liquid Hydrogen (LH2) for high specific impulse Nuclear Thermal Propulsion (NTP) which can be deployed in strategic locations in advance of a mission. If enabled, such LH2 storage tanks could be used to refill a crewed Mars Transfer Vehicle (MTV) to send and bring astronauts home quickly, safely, and cost-effectively. A well-designed cryogenic propellant storage tank can reflect the vast majority of photons incident on the spacecraft, but not all. In thermal environments like Low Earth Orbit (LEO), there is residual heating due to light directly from the Sun, sunlight reflected off Earth, and blackbody thermal radiation from Earth. Over time, this leads to some of the propellant molecules absorbing the requisite latent heat of vaporization, entering the gas phase, and ultimately being released into space to prevent an unsustainable build-up of pressure in the tank. This slow “boil-off” process leads to significant losses of the cryogenic liquid into space, potentially leaving it with insufficient mass and greatly limiting Mars missions. We propose a breakthrough mission concept: an ultra-efficient round-trip Mars mission with zero boil off of propellants. This will be enabled by low-cost, efficient cryogenic liquid storage capable of storing LH2 and LOx with ZBO even in the severe and fluctuating thermal environment of LEO. To enable this capability, the propellant tanks in our mission will employs thin, lightweight, all-solid-state panels attached to the tank’s deep-space-facing surfaces that utilize a long-understood but as-yet-unrealized cooling technology known as Electro-Luminescent Cooling (ELC) to reject heat from cold solid surfaces as non-equilibrium thermal radiation with significantly more power density than Planck’s Law permits for equilibrium thermal radiation. Such a propellant tank would drastically lower the cost and complexity of propulsion systems for crewed Mars missions and other deep space exploration by allowing spacecraft to refill propellant tanks after reaching orbit rather than launching on the much larger rocket required to lift the spacecraft in a single-use stage. To achieve ZBO, a storage spacecraft must keep the storage tank’s temperature below the boiling point of the cryogen (e.g., < 90 K for LOx and < 20 K for liquid H2). Achieving this in LEO-like thermal environments requires both excellent reflectivity toward sunlight and thermal radiation from the Earth, Mars and other nearby bodies as well as a power-efficient cooling mechanism to remove what little heat inevitably does leak in, a pair of conditions ideally suited to the ELC cooling systems that will makes our full return-trip mission to Mars a success.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
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About NIAC
Gravity Poppers: Hopping Probes for the Interior Mapping of Small Solar System Bodies
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Gravity Poppers: Hopping Probes for the Interior Mapping of Small Solar System Bodies concept.NASA/Benjamin HockmanBenjamin Hockman
NASA Jet Propulsion Laboratory
The goal of this effort is to develop a robust and affordable mission architecture that enables the gravimetric density reconstruction of small body interiors to unprecedented precision. Our architecture relies on the novel concept of “Gravity Poppers,” which are small, minimalistic probes that are deployed to the surface of a small body and periodically “pop” so as to perpetuate a random hopping motion around the body. By tracking a large swarm of poppers from orbit, a mother spacecraft can precisely estimate their trajectories and continuously refine a high-resolution map of the body’s gravity field, and thus, its internal mass distribution. Hopping probes are also equipped with minimalistic in-situ sensors to measure the surface temperature (when landed) and strength (when bouncing) in order to complement the gravity field and build a more accurate picture of the interior. The Phase I study focused on feasibility assessment of three core technologies that enable such a mission: (1) the mechanical design of hopping probes to be small, simple, robust, and “visible” to a distant spacecraft, (2) the tracking strategy for detecting and estimating the trajectories of a large number of ballistic probes, and (3) the algorithmic framework by which such measurements can be used to iteratively refine a gravity model of the body. The key finding was that the concept is feasible, and demonstrated to have the potential to resolve extremely accurate gravity models, allowing scientists to localize density anomalies such as “weighing” large boulders on the surface. This Phase II Proposal aims to further develop these three core technologies through continued mission trade studies and sensitivity analysis, case studies for simulated missions, and hardware prototypes demonstrating both hopping behavior and tracking performance.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
NIAC Funded Studies
About NIAC
Gravity Poppers: Hopping Probes for the Interior Mapping of Small Solar System Bodies
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Gravity Poppers: Hopping Probes for the Interior Mapping of Small Solar System Bodies concept.NASA/Benjamin HockmanBenjamin Hockman
NASA Jet Propulsion Laboratory
The goal of this effort is to develop a robust and affordable mission architecture that enables the gravimetric density reconstruction of small body interiors to unprecedented precision. Our architecture relies on the novel concept of “Gravity Poppers,” which are small, minimalistic probes that are deployed to the surface of a small body and periodically “pop” so as to perpetuate a random hopping motion around the body. By tracking a large swarm of poppers from orbit, a mother spacecraft can precisely estimate their trajectories and continuously refine a high-resolution map of the body’s gravity field, and thus, its internal mass distribution. Hopping probes are also equipped with minimalistic in-situ sensors to measure the surface temperature (when landed) and strength (when bouncing) in order to complement the gravity field and build a more accurate picture of the interior. The Phase I study focused on feasibility assessment of three core technologies that enable such a mission: (1) the mechanical design of hopping probes to be small, simple, robust, and “visible” to a distant spacecraft, (2) the tracking strategy for detecting and estimating the trajectories of a large number of ballistic probes, and (3) the algorithmic framework by which such measurements can be used to iteratively refine a gravity model of the body. The key finding was that the concept is feasible, and demonstrated to have the potential to resolve extremely accurate gravity models, allowing scientists to localize density anomalies such as “weighing” large boulders on the surface. This Phase II Proposal aims to further develop these three core technologies through continued mission trade studies and sensitivity analysis, case studies for simulated missions, and hardware prototypes demonstrating both hopping behavior and tracking performance.
Facebook logo @NASATechnology @NASA_Technology Share Details Last Updated May 27, 2025 EditorLoura Hall Related Terms Keep Exploring Discover More NIAC TopicsSpace Technology Mission Directorate
NASA Innovative Advanced Concepts
NIAC Funded Studies
About NIAC
Johnson’s Paige Whittington Builds a Symphony of Simulations
What do music ensembles and human spaceflight have in common? They require the harmonization of different elements to create an inspiring opus.
NASA’s Paige Whittington has experience with both.
As a principal flutist for Purdue University’s Wind Ensemble, Whittington helped fellow flutists play beautiful music together while pursuing her graduate degree. Now, as a space exploration simulation architect at Johnson Space Center in Houston, she strives for a cross-team harmony that can inform the agency’s Moon to Mars exploration approach.
“Simulation often sits at the intersection of several teams because we integrate various designs and mission requirements,” she said. “We have to learn how to best fit those teams and their priorities together to enable cutting-edge human exploration.”
Official NASA portrait of Paige Whittington.NASA/Josh ValcarcelWhittington is part of the NASA Exploration Systems Simulations (NExSyS) team, which develops physics-based simulations to evaluate various vehicles and mission concepts. Her role includes working with lunar and Mars architecture teams within NASA’s Strategy and Architecture Office to assess current and potential future elements of vehicle design, logistics, and planning.
“Our simulations help inform engineers, astronauts, and managers about the new, challenging environments that await us on the Moon and Mars,” she said.
One of the most challenging and rewarding projects she is working on is the Artemis Distributed Simulation. “NExSyS develops and maintains several individual simulations such as rovers, landers, and habitats. However, human exploration on other planetary bodies requires careful integration and coordination of these individual pieces,” she explained.
The distributed simulation brings those pieces together to enable agency teams to envision a complete Artemis mission to the lunar surface. Different elements can be added or removed to create a wide variety of scenarios. The simulation can run automatically with predetermined settings or be responsive to real-time and randomized changes. Participants can operate the team’s video walls, mock-up mission control console, virtual reality platforms, and lander piloting facility to interact together within the chosen Artemis mission scenario.
Paige Whittington standing in front of the Video Wall used for human-in-the-loop simulations located inside the Systems Engineering Simulator facility at NASA’s Johnson Space Center. Image courtesy of Paige Whittington“I am very proud to know that the simulations I help develop have impacted some of the decisions being made by NASA’s architecture teams,” she said.
She is excited to take on a new responsibility, as well. Whittington recently became project manager of the JSC Engineering Orbital Dynamics software package. Also known as JEOD, this open-source tool was created by NASA to model spacecraft trajectories, such as proposed flight paths for a lunar lander. JEOD calculates gravitational and other environmental forces acting on spacecraft to simulate the position and orientation of those vehicles over time, whether they are orbiting a cosmic body or traveling between planets.
Whittington’s family moved frequently during her childhood, calling five different states home as she grew up. Their time in Florida would have a life-long impact.
“My parents drove me and my sister across the state to visit NASA’s Kennedy Space Center. It was mesmerizing, awe-inspiring, and seemingly a whole different world from where my 8-year-old self thought I was living,” she said. Her love of space never waned, and a high school physics teacher encouraged her to study aerospace engineering in college. “That was the turning point when I realized space exploration didn’t have to stay in my dreams – it was a career field I could actually work in.”
Whittington took her teacher’s advice, earning a bachelor’s degree in aerospace engineering from the University of Texas at Austin. She also completed two internships at Johnson through the Universities Space Research Association and interned with a NASA contractor after graduation. While pursuing a master’s degree in Aeronautics and Astronautics at Purdue, Whittington was accepted to NASA’s Pathways Program and did two rotations with the Simulation and Graphics Branch before joining the team as a full-time employee in June 2022.
Paige Whittington celebrating the launch of Artemis I at Johnson Space Center in 2022. Image courtesy of Paige WhittingtonWhittington has learned several key lessons during her five years with NASA, including the essential part open, regular communication plays in understanding an individual’s or team’s core needs and limitations. She also stressed the importance of adaptability.
“The path that you planned for may not be the path you end up choosing. But that planning enabled you to be who you are now and to make different choices,” she said. “I did not anticipate working in simulations when I started my aerospace engineering degree, but I took the opportunity when it was presented, and I am so happy that I did.”
Explore More 9 min read Station Nation: Meet Megan Harvey, Utilization Flight Lead and Capsule Communicator Article 6 days ago 4 min read Andrea Harrington’s Vision Paves the Way for Lunar Missions Article 1 week ago 4 min read Aubrie Henspeter: Leading Commercial Lunar Missions Article 2 weeks agoJohnson’s Paige Whittington Builds a Symphony of Simulations
What do music ensembles and human spaceflight have in common? They require the harmonization of different elements to create an inspiring opus.
NASA’s Paige Whittington has experience with both.
As a principal flutist for Purdue University’s Wind Ensemble, Whittington helped fellow flutists play beautiful music together while pursuing her graduate degree. Now, as a space exploration simulation architect at Johnson Space Center in Houston, she strives for a cross-team harmony that can inform the agency’s Moon to Mars exploration approach.
“Simulation often sits at the intersection of several teams because we integrate various designs and mission requirements,” she said. “We have to learn how to best fit those teams and their priorities together to enable cutting-edge human exploration.”
Official NASA portrait of Paige Whittington.NASA/Josh ValcarcelWhittington is part of the NASA Exploration Systems Simulations (NExSyS) team, which develops physics-based simulations to evaluate various vehicles and mission concepts. Her role includes working with lunar and Mars architecture teams within NASA’s Strategy and Architecture Office to assess current and potential future elements of vehicle design, logistics, and planning.
“Our simulations help inform engineers, astronauts, and managers about the new, challenging environments that await us on the Moon and Mars,” she said.
One of the most challenging and rewarding projects she is working on is the Artemis Distributed Simulation. “NExSyS develops and maintains several individual simulations such as rovers, landers, and habitats. However, human exploration on other planetary bodies requires careful integration and coordination of these individual pieces,” she explained.
The distributed simulation brings those pieces together to enable agency teams to envision a complete Artemis mission to the lunar surface. Different elements can be added or removed to create a wide variety of scenarios. The simulation can run automatically with predetermined settings or be responsive to real-time and randomized changes. Participants can operate the team’s video walls, mock-up mission control console, virtual reality platforms, and lander piloting facility to interact together within the chosen Artemis mission scenario.
Paige Whittington standing in front of the Video Wall used for human-in-the-loop simulations located inside the Systems Engineering Simulator facility at NASA’s Johnson Space Center. Image courtesy of Paige Whittington“I am very proud to know that the simulations I help develop have impacted some of the decisions being made by NASA’s architecture teams,” she said.
She is excited to take on a new responsibility, as well. Whittington recently became project manager of the JSC Engineering Orbital Dynamics software package. Also known as JEOD, this open-source tool was created by NASA to model spacecraft trajectories, such as proposed flight paths for a lunar lander. JEOD calculates gravitational and other environmental forces acting on spacecraft to simulate the position and orientation of those vehicles over time, whether they are orbiting a cosmic body or traveling between planets.
Whittington’s family moved frequently during her childhood, calling five different states home as she grew up. Their time in Florida would have a life-long impact.
“My parents drove me and my sister across the state to visit NASA’s Kennedy Space Center. It was mesmerizing, awe-inspiring, and seemingly a whole different world from where my 8-year-old self thought I was living,” she said. Her love of space never waned, and a high school physics teacher encouraged her to study aerospace engineering in college. “That was the turning point when I realized space exploration didn’t have to stay in my dreams – it was a career field I could actually work in.”
Whittington took her teacher’s advice, earning a bachelor’s degree in aerospace engineering from the University of Texas at Austin. She also completed two internships at Johnson through the Universities Space Research Association and interned with a NASA contractor after graduation. While pursuing a master’s degree in Aeronautics and Astronautics at Purdue, Whittington was accepted to NASA’s Pathways Program and did two rotations with the Simulation and Graphics Branch before joining the team as a full-time employee in June 2022.
Paige Whittington celebrating the launch of Artemis I at Johnson Space Center in 2022. Image courtesy of Paige WhittingtonWhittington has learned several key lessons during her five years with NASA, including the essential part open, regular communication plays in understanding an individual’s or team’s core needs and limitations. She also stressed the importance of adaptability.
“The path that you planned for may not be the path you end up choosing. But that planning enabled you to be who you are now and to make different choices,” she said. “I did not anticipate working in simulations when I started my aerospace engineering degree, but I took the opportunity when it was presented, and I am so happy that I did.”
Explore More 9 min read Station Nation: Meet Megan Harvey, Utilization Flight Lead and Capsule Communicator Article 6 days ago 4 min read Andrea Harrington’s Vision Paves the Way for Lunar Missions Article 1 week ago 4 min read Aubrie Henspeter: Leading Commercial Lunar Missions Article 2 weeks agoSummary of the 2024 SAGE III/ISS Meeting
19 min read
Summary of the 2024 SAGE III/ISS MeetingIntroduction
The Stratospheric Aerosol and Gas Experiment (SAGE) III/International Space Station [SAGEIII/ISS] Science Team Meeting (STM) took place on October 22–23, 2024, in a hybrid format. Approximately 50 scientists attended in person at NASA’s Langley Research Center (LaRC) – see Photo. Participants included researchers from U.S. universities, NASA LaRC, NASA’s Goddard Space Flight Center (GSFC), the NASA/Jet Propulsion Laboratory (JPL), and National Oceanic and Atmospheric Administration (NOAA) laboratories. Speakers from Canada and Germany also attended.
The history of the SAGE missions, the development and accomplishments of the SAGE III/ISS mission, and a summary of the 2022 STM appear in a previous article – see “Summary of the SAGE III/ISS Science Team Meeting,” in The Earth Observer, May–June 2023, 35:3, 11–18.
This article will summarize the content and key outcomes from the 2024 STM. The full agenda and presentations can be viewed at the SAGE III/ISS website. To access the presentations, use the link provided, then click on the Science Team tab and scroll about halfway down the page to find the 2024 meeting where they are listed.
Photo. Group photo of the in-person attendees of the SAGE III/ISS science team meeting, which took place at NASA’s Langley Research Center October 22–23, 2024. Photo Credit: NASADAY ONE
Jun Wang [University of Iowa—SAGE III/ISS Science Team Leader] and David Flittner [LaRC—SAGE III/ISS Project Scientist] kicked off the STM. The pair welcomed all participants and invited Richard Eckman [NASA Headquarters (HQ)—SAGE III/ISS Program Scientist, now emeritus (as of January 1, 2025)] to deliver opening remarks. Allison McMahon [LaRC/Science Systems and Applications, Inc. (SSAI)—SAGE III/ISS Communications Lead] then spoke and provided logistical details for the meeting.
The morning sessions focused on project updates and the synergy between SAGE III/ISS and future missions currently in the planning phase, with potential launches in the early 2030s. The afternoon sessions were dedicated to aerosol research and the calibration/validation of SAGE III/ISS data products.
Project Operation and Data Product Briefing
David Flittner presented an update of the mission status, with over seven years and counting of data collection/analysis/release. SAGE III/ISS went through the 2023 Earth Science Senior Review (see page 15 of linked document for specific summary of the SAGE III/ISS results), and NASA HQ approved the proposal for continued operations for 2024–2026, with partial, overguide (i.e., above baseline request) funding approved to support community validation efforts, e.g., developing online quick look tools – see Figure 1 – and timely algorithm and product improvements. However, some reduction in mission staff and reorganization of work assignments have had to occur to stay within the allotted budget.
Overall, Flittner described 2024 as “a year of growth” for many on the SAGE III/ISS Team. He referenced important mission activities planned during the current three-year tenure of the new Science Team cohort. This work includes supporting the 2026 World Meteorological Organization (WMO) International Ozone assessment with a release of improved solar/lunar product in early 2025, examination of product sensitivities to variable aerosol loadings, introduction of a research product with retrieved temperature and pressure profiles, and continuing a much sought-after summer internship program.
Figure 1. An example of an enhanced tool for the community to visualize SAGE III/ISS data validation. Figure Credit: Mary Cate McKee [LaRC]Robbie Manion [LaRC] presented version 6.0 (V6) of the SAGE III/ISS data products, which were released in April 2025. Owing to a change in source ozone (O3) cross sections, this version will resolve the longstanding low bias in retrieved aerosol extinction around 600 nm. As a result, some changes in the downstream data products for inferred particle size distribution and aerosol/cloud categorization are expected. In addition, V6 will allow for recovery of hundreds of profiles previously impeded by the recent proliferation of sunspots.
Jamie Nehrir [LaRC] stated that SAGE III celebrated its seventh year onboard the ISS on February 19, 2024. [UPDATE: As of this publication, SAGE III/ISS has now passed eight years in orbit.] The payload continues to operate nominally surpassing 70,000 occultation events successfully acquired. Nehrir reported that SAGE III was not affected by the October 9, 2023, external leak from the Russian Nauka (or Multipurpose Laboratory) Module. However, the Disturbance Monitoring Package (DMP) lasers for the y- and z-axes on the instrument have been degrading. The operations team has been in a healthy dialog with the science and processing teams and external partners to determine the potential impact of these degradations on payload performance and on any ISS activities that could affect the science.
Invited Presentations on Synergy with New Limb Missions in Formulation
Lyatt Jaeglé [University of Washington] presented the mission concept for the Stratosphere Troposphere Response using Infrared Vertically-resolved light Explorer (STRIVE), which was recently selected for a competitive Phase A Concept Study within NASA’s 2023 Earth System Explorers Program (an element of the 2017–2027 Earth Science Decadal Survey). STRIVE fills a critical need for high vertical [1 km (0.6 mi)] resolution profiles of temperature, O3, trace gases, aerosols, and clouds in the upper troposphere–stratosphere (UTS). The system will provide near-global coverage and unparalleled horizontal sampling, producing 400,000 profiles each day. STRIVE will carry two synergistic instruments: a limb-scanning, infrared-imaging Dyson spectrometer to retrieve profiles of temperature, water vapor, trace gas concentrations, aerosol extinction, and cloud properties during day and night; and a dual-spectral, multi-directional, limb-profiling radiometer that retrieves detailed aerosol properties during day.
Björn-Martin Sinnhuber [Karlsruhe Institute of Technology, Germany] gave an overview of the Changing-Atmosphere Infrared Tomography Explorer (CAIRT), a candidate mission for the upcoming European Space Agency (ESA) Earth Explorer 11 satellite. If selected, CAIRT would provide passive infrared limb imaging of atmospheric temperature and trace constituents from the upper troposphere at about 5 km (3 mi) altitude up to the lower thermosphere at 115 km (71 mi) altitude. The presentation highlighted how these observations can provide information on how atmospheric gravity waves drive middle atmosphere circulation, age-of-air in the middle atmosphere, the descent of nitrogen oxides (Nox) from the thermosphere into the stratosphere, as well as the detection of sulfur species and sulfate (SO42-) aerosols in the stratosphere.
Aerosols
Mahesh Mundakkara [LaRC] presented the research used to generate the Global Space-based Stratospheric Aerosol Climatology (GloSSAC) product, a critical resource for analyzing and modeling the climatic effects of stratospheric aerosols. His presentation focused on assessing the Ozone Mapping and Profiler Suite (OMPS) limb profiler (LP) by comparing its data with other datasets, particularly SAGE III/ISS. (NOTE: While OMPS currently flies on the NASA–NOAA Suomi National Polar-orbiting Partnership (Suomi NPP), NOAA-20, and NOAA-21 platforms; LP is only part of OMPS on NOAA–21.) The evaluation aims to identify discrepancies and assess the suitability of OMPS-LP data for integration into the GloSSAC framework.
Jianglong Zhang [University of North Dakota] discussed the research plans of a newly funded SAGE project to investigate effective methods for improving stratospheric aerosol analyses and forecasts from aerosol models that can be used for future air quality and visibility forecasts and climate applications. Zhang also presented preliminary comparisons of collocated SAGE aerosol extinction and Cloud Aerosol Transport System (CATS) lidar aerosol extinction values in the stratosphere. [NOTE: CATS operated on ISS from 2015–2017.]
Sara Lu [The State University of New York, Albany] discussed efforts to examine smoke aerosol radiative effects in the upper troposphere and lower stratosphere using SAGE III/ISS observations. Lu explained that this project aims to produce multiyear analysis of aerosol radiative effects from all known pyrocumulonimbus cloud (pyroCb) events worldwide over a range of pyroCb intensities and various injection altitudes, geographic locations, and backgrounds. He presented findings from a pyroCb inventory compiled by the Naval Research Lab (NRL).
Xi Chen and Jun Wang [both University of Iowa] presented their new project on retrieving aerosol properties using SAGE III/ISS lunar measurements. They noted the challenges in normalizing lunar measurements caused by the Moon’s non-uniform surface. To address this, the team is developing a local normalization method to derive atmospheric transmissions from signals detected within each lunar event, enabling accurate aerosol retrieval. They reported that preliminary results are promising as evidenced by comparison with transmission product from collocated solar events – see Figure 2. This new processing will enrich the spatial and temporal coverage of SAGE III/ISS aerosol product by involving lunar events.
Figure 2. Preliminary results of the transmission derived from SAGE III/ISS lunar measurements (y-axis) and its comparison with collocated SAGE III/ISS solar measurements (x-axis). The comparisons are presented in two ways, one for the same wavelength color-coded by altitude [left] and another at the same altitude color-coded for the different wavelengths [right]. The results are for June 2017 through Novembe 2022, and the collocation criteria requires latitude separation smaller than 1˚ and observation times within 10 days. Note that if the transmission at any wavelength or altitude is smaller than 0.005, it is removed from the comparison for quality assurance purpose. Figure Credit: Xi Chen, University of IowaAdam Pastorek and Peter Bernath [both Old Dominion University] discussed the properties of stratospheric SO42- aerosols from the infrared transmission spectra of Atmospheric Chemistry Experiment (ACE) – flying on the Canadian SCISAT satellite since 2003 – and optical extinction from SAGE III/ISS. Based on ACE infrared measurements, the researchers derived an empirical formula to determine the composition (weight % H2SO4) of volcanic plumes. They combined coincident ACE and SAGE III/ISS measurements, using bimodal, log-normal size distributions to reproduce the observations – see Figure 3. They used ACE observations of sulfur dioxide (SO2) to study the creation and destruction of stratospheric SO42- aerosols.
Figure 3. Combined transmittance fitting results from Atmospheric Chemistry Experiment– Fourier Transform Spectrometer (ACE-FTS), and SAGE III/ISS measurements demonstrate an improved characterization of sulfate particle size distribution using bi-lognormal (mode) distributions compared to a single lognormal distribution. The panels on the left show the transmittance fitting [top] and residuals [bottom] for the mono-mode distribution model, while the center panels show the transmittance fitting [top] and residuals [bottom] for the bi-mode distribution. The right panel illustrates the contributions of fine and coarse mode components to the total transmittance. The measurements for this figure were taken approximately four months after the January 2022 Hunga Tonga–Hunga Haʻapai eruption at a tangent height of 23.6 km (14.5 mi) in ACE occultation (ss100628), with coincident SAGE measurements from that same period (2022041609). Figure Credit: Adam Pastorek, adapted from a Figure in a paper published in Journal of Quantitative Spectroscopy and Radiative Transfer in January 2024.Sean Davis [NOAA, Chemistry Science Lab] presented on his research aimed at constraining decadal variability and assessing trends in stratospheric composition and tropospheric circulation using SAGE III/ISS and complementary satellite data sets. The team continues to include the SAGE water vapor and O3 products in the Stratospheric Water and OzOne Satellite Homogenized (SWOOSH) dataset. Davis also highlighted preliminary work evaluating V6 data in comparison to the former V5.3. He discussed line-of-sight, transmission-based filtering for O3 profiles and O3 diurnal variability corrections.
Lars Kalnaajs [University of Colorado, Boulder] presented results from two studies of particle size distributions from SAGE aerosol extinction data. Kalnaajs summarized results from two papers in review. His team paired the Optical Particle Counter collected from balloon platforms with SAGE II data to derive the parameters for bi-mode aerosol size distribution. They also presented the work of using SAGE III extinction ratios, 448/756 versus 1544/756, to derive monomodal lognormal size distribution, which allows them to compute distribution moments and compare these to in situ measurements taken over Sweden in the winters of 2002 and 2004.
Anne Thompson [GSFC, emeritus] presented on the Southern Hemisphere Additional Ozonesondes (SHADOZ) network and how that SHADOZ data are a satellite validation standard and can also be used to assess ozone trends in the upper troposphere and lower stratosphere. Thompson emphasized that SHADOZ O3 profiles are the only standard process to obtain measurements from surface to mid-stratosphere at 100–150 m (328–492 ft) resolution. Such measurements are essential to validate O3 measurements from SAGE-derived products. She also presented an update on the free tropospheric and lowermost stratospheric (LMS) O3 trends from eight equatorial SHADOZ sites. Newer calculations confirm that an apparent LMS seasonal decline (July–September) is associated with a roughly 100 m (328 ft) upward trend in tropopause height.
DAY TWO
The second day started with Jack Kaye [NASA Earth Science Division—Associate Director for Research for the Earth Science Division, emeritus as of April 30, 2025] providing a historic perspective on SAGE and comments on its context within NASA’s overall Earth science program. A technical session was held with three invited presentations, followed by three additional sessions where science team members presented their research on trace gas studies, including data product calibration and validation. The meeting concluded with updates from the SAGE project team on the SAGE III/ISS website and ongoing operations aboard the ISS. In his presentation, Kaye shared about his past involvement with the SAGE program and his perspective on its future in the context of flight missions for Earth observations.
Invited Presentations on Advanced Modeling and New Satellite Mission For UTS
Steven Pawson [GSFC] presented on the comprehensive modeling and analysis capabilities of
Upper troposphere and lower stratosphere (UTLS) dynamics and composition in the Goddard Earth Observing System (GEOS) model Pawson discussed the Global Modeling and Assimilation Office’s (GMAO) recent support for the Asian summer monsoon Chemical and CLimate Impact Project (ACCLIP) mission and the trend analysis of stratospheric O3. He also discussed future plans for GMAO, including improving the representation of water vapor in UTS through data assimilation and increasing horizontal and vertical resolution in the GEOS model.
Kostas Tsigaridis [Columbia University] presented recent research on the composition and climate impacts of increasing launches to Low Earth Orbit (LEO). Assuming that there are 10,000 launches per year and all launches use liquefied natural gas (LNG) as a propellant, the team compiled launch-related emission inventories and highlighted key uncertainties that could significantly affect climate predictions – particularly the impact black carbon has on the radiative balance and heterogeneous chemistry of the UTS. In addition, water vapor was found to contribute to the heating of the stratosphere and to a nontrivial amount of O3 depletion – 13 Dobson units (DU) on the global mean.
Adam Bourassa [University of Saskatchewan, Canada] introduced the satellite mission for High-altitude Aerosol, Water vapor, and Clouds (HAWC), planned as the Canadian contribution to the NASA Atmosphere Observing System (AOS) for launch in 2031 – a key component in NASA’s next generation Earth System Observatory. Bourassa highlighted the three Canadian instruments, which include limb profilers for water vapor and aerosol in the UTS and a far infrared imaging radiometer for ice cloud microphysics and radiative budget closure. He discussed instrument requirements and development progress as well as results from recent sub-orbital testing of prototypes on the NASA Earth Resources (ER)-2 and stratospheric balloons.
Trace Gases
Brian Soden [University of Miami] presented a new project that will use SAGE data to constrain climate sensitivity in climate models. Climate models differ substantially in their calculation of the radiative forcing from carbon dioxide (CO2), and these intermodel differences have remained largely unchanged for several decades. Soden highlighted the role of stratospheric temperature in modulating the radiative forcing from CO2. He explained that models that simulate a cooler stratosphere simulate a larger radiative forcing for the same change in CO2 compared to models that posit a warmer stratosphere. He added that determining the cause of the model biases in stratospheric temperature – particularly the role of water vapor in driving this intermodel spread – is an area of active research.
Ray Wang [Georgia Institute of Technology] compared the uncertainty analysis of SAGE III retrieved O3 and water vapor data in V5.3 to the same parameters in V6.0. He then compared the SAGE III data to the correlative measurements from other platforms. For O3, the differences between SAGE and measurements from the Microwave Limb Sounder (MLS) on NASA’s Aura platform are less than 5% in the stratosphere. SAGE V6.0 ozone values are systematically about 1–2% higher than those from V5.3 O3 – due to changes in how the O3 cross-section is represented in each version. For water vapor, SAGE data agree with MLS and Frost Point Hygrometer (FPH) data within 5%. Wang showed some differences between SAGE water vapor data retrievals using V5.3 and the same data obtained using version 6.0. He also said that a two-dimensional (i.e., spatial and temporal) regression model can be used to minimize sampling bias in climatology derived from non-uniform satellite measurements – ensuring more accurate representation of long-term trends.
Emma Knowland [GSFC/Morgan State University, Goddard Earth Sciences Technology and Research II (GESTAR II), now NASA HQ—SAGE III/ISS Program Scientist] discussed the progress of assimilating SAGE III water vapor data product into NASA’s GEOS re-analysis. Her team’s work demonstrated that while the number of solar occultation observations a day from SAGE III/ISS is about 1% of the total number of profiles observed globally by MLS, the chemical timescales of water vapor in the lower stratosphere are long enough that the SAGE III/ISS data can provide a valuable constraint on GEOS re-analysis, especially in the absence of MLS data – see Figure 4.
Figure 4. Hovmöller diagrams of the vertical distribution of 15°S–15°N average water vapor anomalies in upper troposphere–stratosphere with water vapor relaxed to a climatology [top left] and from data assimilation of SAGE III/ISS water vapor into the Goddard Earth Observing System (GEOS) model [bottom left]. Scatter plots show water vapor mixing ratios (y-axis) with [top right] and without [bottom right] data assimilation compared independent observations from the Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) data (x-axis). The ACE–FTS data were not used in data assimilation. This shows that data assimilation of SAGE data improves the agreement with ACE-FTS – especially in the lower stratosphere (400 to 500 K). Figure Credit: Emma Knowland [NASA]Melody Avery [University of Colorado, Boulder] discussed using SAGE data and data from the Cloud–Aerosol Lidar with Orthogonal Projection (CALIOP) instrument (on the former Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission) to study thin clouds and aerosol distributions in the tropical tropopause region (TTL). Avery explained that these distributions from V5.3 of SAGE-III/ISS and V5.41 of CALIOP are shown to agree well, and CALIOP observations of cloud frequency are shown to be a sensitive metric for defining the width of the Hadley Cell near the tropical tropopause. Combining SAGE and CALIOP data produced a longer timescale to constrain and evaluate climate models that currently do not agree on how the tropical width at this altitude varies. They found that results derived using SAGE V6.0 versus V5.3 differ on the order of 2% in the TTL region.
Pamela Wales [GESTAR II] introduced a new project that leverages SAGE III/ISS measurements to explore diurnal characteristics of O3 and nitrogen dioxide (NO2) in GEOS model products. Her team is exploring potentially using a GEOS reanalysis of stratospheric trace gases collected by MLS as a transfer standard to evaluate the consistency between the SAGE III/ISS solar and the less frequently measured lunar retrieval. They are also assessing uncertainties in stratospheric NO2 in the GEOS Composition Forecast (GEOS-CF) model using SAGE III/ISS and complementary satellite instruments. This work will inform how effectively GEOS-CF can be used in air quality studies to remove the stratospheric signal from column retrievals of NO2.
Luis Millán [JPL] presented work on the change of stratospheric water vapor mass after the Hunga Tonga–Hunga Haʻapai (Hunga) volcano eruption in 2022. Millán found an increase (~10%) of total stratospheric water vapor – a potent greenhouse gas. Given their advanced age, MLS, ACE-FTS, and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on NASA’s Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) mission (Heliosphere Division), are nearing the end of their missions, leaving SAGE III/ISS as the primary instrument for monitoring the plume’s evolution. Millán discussed how the SAGE III/ISS measurements might be sufficient to observe the dispersion of the excess Hunga water vapor from stratosphere in coming years. He also discussed a 39-year plus record of stratospheric water vapor mass using the overlapping periods between SAGE II, MLS, and SAGE III/ISS.
Ryan Stauffer [GSFC] presented the operation and outcomes of the Ticosonde balloon-borne O3 and water vapor sonde project in San Jose, Costa Rica. Ongoing since July 2005, Ticosonde has collected over 700 O3 profiles and 270 water vapor profiles for climate and pollution studies and satellite validation. Because Ticosonde is the only long-term water vapor sonde station in the tropics, the stratospheric water vapor data is vital for validation of SAGE-III/ISS and MLS profiles. Ticosonde has been used to verify the success of updated water vapor retrieval algorithms for both instruments – which now agree within a few percent up to 25 km (15 mi) altitude.
Natalya Kramarova [GSFC] showed the comparison of O3 profile retrieved from SAGE III with those derived from the OMPS-LP sensor – which is part of OMPS on NOAA-21 – from February 2023–June 2024. Diurnal corrections using the Goddard Diurnal Ozone Climatology (which is described in a 2020 article in Atmospheric Measurement Techniques) is applied to account for differences in measurement times between SAGE III’s sunrise or sunset observations and NOAA-21 LP’s midday measurements. Once the time correction is made, results show good agreement between the two instruments in depicting vertical ozone distribution across different geographical regions (e.g., tropics and mid-latitudes) and under various conditions (e.g., near the edge of the Antarctic O3 hole in October 2023). The mean biases between NOAA-21 LP and SAGE III are typically within ±5% between ~18–45 km (11–28 mi).
Project Team and Operations Highlights
Michael Heitz [LaRC] showed that V5.3 and previous versions of the SAGE III/ISS data product had a noticeable – and unphysical – dip in the retrieved aerosol extinction between 520–676 nm. This dip has been referred to as the aerosol “seagull.” However, adoption of a new absorption cross-section database into the V6.0 algorithm reduced the aerosol seagull effect significantly. Kevin Leavor [LaRC] presented new developments for the SAGE III/ISS quick look website. Mary Cate McKee [LaRC] introduced a new feature of the quick look website that showcases comparisons of O3 and water vapor sonde data at over 40 stations. Sonde data is sourced from the Network for the Detection of Atmospheric Composition Change (NDACC), GSFC’s SHADOZ, and the World Ozone and Ultraviolet Radiation Data Centre (WOUDC). Heitz explained that the comparison plots are updated continuously as new coincidences occur, providing the community with valuable insight to the quality of SAGE III/ISS data relative to this external network of ground stations. Future additions to the website include aerosol and lidar comparisons, additional plot statistics, and comparisons with novel homogenized datasets.
Returning to a topic discussed in Jamie Nehrir’s presentation, Charles Hill [LaRC] showed that the SAGE III Disturbance Monitoring Package (DMP) correction to the data product – which was implemented beginning with V5.3 – has significantly reduced the product uncertainties caused by ISS vibrations. Approximately 7% of SAGE III occultation events are highly disturbed by mechanical vibrations, and the DMP correction has improved pointing registrations in these events significantly. The DMP’s x-axis gyroscope failed on August 8, 2023 – but this loss did not significantly affect the DMP correction to scan plane elevation. Future possible losses of either the y- or z-axes will end active correction of ISS disturbances.
Conclusion
Jun Wang, David Flittner, and Richard Eckman led the closing discussion that highlighted the growing interest in atmospheric composition change – particularly due to emissions from large wildfires and volcanic eruptions in recent years. This increasing interest contrasts with the declining availability of observational data from the upper troposphere, following the retirement of CALIPSO in late 2023 and the planned decommissioning of Aura’s aging limb instruments in 2026. This gap underscores the critical importance of SAGE III/ISS data – not only for current UTS research but also for the next 5–7 years, during which no new limb measurements are planned.
SAGE III/ISS remains essential for profiling key atmospheric constituents, including water vapor, aerosols, O₃, and NO₂. The long-term, consistent data record provided by the SAGE series of instruments since the late 1970s – including SAGE III/ISS since 2017 – has been invaluable for studying past and future changes in atmospheric composition within the UTS. To further support research and applications of SAGE data products, participants discussed the possibility of proposing a special collection of articles in AGU journals.
Overall, the 2024 SAGE III/ISS meeting was a success. Participants received valuable updates on the status of SAGE III/ISS operations, data product calibration and validation, and new developments. The meeting also showcased the collective expertise and excellence in driving advancements in UTS research, from climate change studies to data assimilation for chemistry transport models and contributions to multi-sensor data fusion.
Jun Wang
University of Iowa
jun-wang-1@uiowa.edu
David Flittner
Langley Research Center
david.e.flittner@nasa.gov
Richard Eckman
NASA Langley Research Center
richard.s.eckman@nasa.gov
Emma Knowland
NASA Headquarters
k.e.knowland@nasa.gov
Summary of the 2024 SAGE III/ISS Meeting
19 min read
Summary of the 2024 SAGE III/ISS MeetingIntroduction
The Stratospheric Aerosol and Gas Experiment (SAGE) III/International Space Station [SAGEIII/ISS] Science Team Meeting (STM) took place on October 22–23, 2024, in a hybrid format. Approximately 50 scientists attended in person at NASA’s Langley Research Center (LaRC) – see Photo. Participants included researchers from U.S. universities, NASA LaRC, NASA’s Goddard Space Flight Center (GSFC), the NASA/Jet Propulsion Laboratory (JPL), and National Oceanic and Atmospheric Administration (NOAA) laboratories. Speakers from Canada and Germany also attended.
The history of the SAGE missions, the development and accomplishments of the SAGE III/ISS mission, and a summary of the 2022 STM appear in a previous article – see “Summary of the SAGE III/ISS Science Team Meeting,” in The Earth Observer, May–June 2023, 35:3, 11–18.
This article will summarize the content and key outcomes from the 2024 STM. The full agenda and presentations can be viewed at the SAGE III/ISS website. To access the presentations, use the link provided, then click on the Science Team tab and scroll about halfway down the page to find the 2024 meeting where they are listed.
Photo. Group photo of the in-person attendees of the SAGE III/ISS science team meeting, which took place at NASA’s Langley Research Center October 22–23, 2024. Photo Credit: NASADAY ONE
Jun Wang [University of Iowa—SAGE III/ISS Science Team Leader] and David Flittner [LaRC—SAGE III/ISS Project Scientist] kicked off the STM. The pair welcomed all participants and invited Richard Eckman [NASA Headquarters (HQ)—SAGE III/ISS Program Scientist, now emeritus (as of January 1, 2025)] to deliver opening remarks. Allison McMahon [LaRC/Science Systems and Applications, Inc. (SSAI)—SAGE III/ISS Communications Lead] then spoke and provided logistical details for the meeting.
The morning sessions focused on project updates and the synergy between SAGE III/ISS and future missions currently in the planning phase, with potential launches in the early 2030s. The afternoon sessions were dedicated to aerosol research and the calibration/validation of SAGE III/ISS data products.
Project Operation and Data Product Briefing
David Flittner presented an update of the mission status, with over seven years and counting of data collection/analysis/release. SAGE III/ISS went through the 2023 Earth Science Senior Review (see page 15 of linked document for specific summary of the SAGE III/ISS results), and NASA HQ approved the proposal for continued operations for 2024–2026, with partial, overguide (i.e., above baseline request) funding approved to support community validation efforts, e.g., developing online quick look tools – see Figure 1 – and timely algorithm and product improvements. However, some reduction in mission staff and reorganization of work assignments have had to occur to stay within the allotted budget.
Overall, Flittner described 2024 as “a year of growth” for many on the SAGE III/ISS Team. He referenced important mission activities planned during the current three-year tenure of the new Science Team cohort. This work includes supporting the 2026 World Meteorological Organization (WMO) International Ozone assessment with a release of improved solar/lunar product in early 2025, examination of product sensitivities to variable aerosol loadings, introduction of a research product with retrieved temperature and pressure profiles, and continuing a much sought-after summer internship program.
Figure 1. An example of an enhanced tool for the community to visualize SAGE III/ISS data validation. Figure Credit: Mary Cate McKee [LaRC]Robbie Manion [LaRC] presented version 6.0 (V6) of the SAGE III/ISS data products, which were released in April 2025. Owing to a change in source ozone (O3) cross sections, this version will resolve the longstanding low bias in retrieved aerosol extinction around 600 nm. As a result, some changes in the downstream data products for inferred particle size distribution and aerosol/cloud categorization are expected. In addition, V6 will allow for recovery of hundreds of profiles previously impeded by the recent proliferation of sunspots.
Jamie Nehrir [LaRC] stated that SAGE III celebrated its seventh year onboard the ISS on February 19, 2024. [UPDATE: As of this publication, SAGE III/ISS has now passed eight years in orbit.] The payload continues to operate nominally surpassing 70,000 occultation events successfully acquired. Nehrir reported that SAGE III was not affected by the October 9, 2023, external leak from the Russian Nauka (or Multipurpose Laboratory) Module. However, the Disturbance Monitoring Package (DMP) lasers for the y- and z-axes on the instrument have been degrading. The operations team has been in a healthy dialog with the science and processing teams and external partners to determine the potential impact of these degradations on payload performance and on any ISS activities that could affect the science.
Invited Presentations on Synergy with New Limb Missions in Formulation
Lyatt Jaeglé [University of Washington] presented the mission concept for the Stratosphere Troposphere Response using Infrared Vertically-resolved light Explorer (STRIVE), which was recently selected for a competitive Phase A Concept Study within NASA’s 2023 Earth System Explorers Program (an element of the 2017–2027 Earth Science Decadal Survey). STRIVE fills a critical need for high vertical [1 km (0.6 mi)] resolution profiles of temperature, O3, trace gases, aerosols, and clouds in the upper troposphere–stratosphere (UTS). The system will provide near-global coverage and unparalleled horizontal sampling, producing 400,000 profiles each day. STRIVE will carry two synergistic instruments: a limb-scanning, infrared-imaging Dyson spectrometer to retrieve profiles of temperature, water vapor, trace gas concentrations, aerosol extinction, and cloud properties during day and night; and a dual-spectral, multi-directional, limb-profiling radiometer that retrieves detailed aerosol properties during day.
Björn-Martin Sinnhuber [Karlsruhe Institute of Technology, Germany] gave an overview of the Changing-Atmosphere Infrared Tomography Explorer (CAIRT), a candidate mission for the upcoming European Space Agency (ESA) Earth Explorer 11 satellite. If selected, CAIRT would provide passive infrared limb imaging of atmospheric temperature and trace constituents from the upper troposphere at about 5 km (3 mi) altitude up to the lower thermosphere at 115 km (71 mi) altitude. The presentation highlighted how these observations can provide information on how atmospheric gravity waves drive middle atmosphere circulation, age-of-air in the middle atmosphere, the descent of nitrogen oxides (Nox) from the thermosphere into the stratosphere, as well as the detection of sulfur species and sulfate (SO42-) aerosols in the stratosphere.
Aerosols
Mahesh Mundakkara [LaRC] presented the research used to generate the Global Space-based Stratospheric Aerosol Climatology (GloSSAC) product, a critical resource for analyzing and modeling the climatic effects of stratospheric aerosols. His presentation focused on assessing the Ozone Mapping and Profiler Suite (OMPS) limb profiler (LP) by comparing its data with other datasets, particularly SAGE III/ISS. (NOTE: While OMPS currently flies on the NASA–NOAA Suomi National Polar-orbiting Partnership (Suomi NPP), NOAA-20, and NOAA-21 platforms; LP is only part of OMPS on NOAA–21.) The evaluation aims to identify discrepancies and assess the suitability of OMPS-LP data for integration into the GloSSAC framework.
Jianglong Zhang [University of North Dakota] discussed the research plans of a newly funded SAGE project to investigate effective methods for improving stratospheric aerosol analyses and forecasts from aerosol models that can be used for future air quality and visibility forecasts and climate applications. Zhang also presented preliminary comparisons of collocated SAGE aerosol extinction and Cloud Aerosol Transport System (CATS) lidar aerosol extinction values in the stratosphere. [NOTE: CATS operated on ISS from 2015–2017.]
Sara Lu [The State University of New York, Albany] discussed efforts to examine smoke aerosol radiative effects in the upper troposphere and lower stratosphere using SAGE III/ISS observations. Lu explained that this project aims to produce multiyear analysis of aerosol radiative effects from all known pyrocumulonimbus cloud (pyroCb) events worldwide over a range of pyroCb intensities and various injection altitudes, geographic locations, and backgrounds. He presented findings from a pyroCb inventory compiled by the Naval Research Lab (NRL).
Xi Chen and Jun Wang [both University of Iowa] presented their new project on retrieving aerosol properties using SAGE III/ISS lunar measurements. They noted the challenges in normalizing lunar measurements caused by the Moon’s non-uniform surface. To address this, the team is developing a local normalization method to derive atmospheric transmissions from signals detected within each lunar event, enabling accurate aerosol retrieval. They reported that preliminary results are promising as evidenced by comparison with transmission product from collocated solar events – see Figure 2. This new processing will enrich the spatial and temporal coverage of SAGE III/ISS aerosol product by involving lunar events.
Figure 2. Preliminary results of the transmission derived from SAGE III/ISS lunar measurements (y-axis) and its comparison with collocated SAGE III/ISS solar measurements (x-axis). The comparisons are presented in two ways, one for the same wavelength color-coded by altitude [left] and another at the same altitude color-coded for the different wavelengths [right]. The results are for June 2017 through Novembe 2022, and the collocation criteria requires latitude separation smaller than 1˚ and observation times within 10 days. Note that if the transmission at any wavelength or altitude is smaller than 0.005, it is removed from the comparison for quality assurance purpose. Figure Credit: Xi Chen, University of IowaAdam Pastorek and Peter Bernath [both Old Dominion University] discussed the properties of stratospheric SO42- aerosols from the infrared transmission spectra of Atmospheric Chemistry Experiment (ACE) – flying on the Canadian SCISAT satellite since 2003 – and optical extinction from SAGE III/ISS. Based on ACE infrared measurements, the researchers derived an empirical formula to determine the composition (weight % H2SO4) of volcanic plumes. They combined coincident ACE and SAGE III/ISS measurements, using bimodal, log-normal size distributions to reproduce the observations – see Figure 3. They used ACE observations of sulfur dioxide (SO2) to study the creation and destruction of stratospheric SO42- aerosols.
Figure 3. Combined transmittance fitting results from Atmospheric Chemistry Experiment– Fourier Transform Spectrometer (ACE-FTS), and SAGE III/ISS measurements demonstrate an improved characterization of sulfate particle size distribution using bi-lognormal (mode) distributions compared to a single lognormal distribution. The panels on the left show the transmittance fitting [top] and residuals [bottom] for the mono-mode distribution model, while the center panels show the transmittance fitting [top] and residuals [bottom] for the bi-mode distribution. The right panel illustrates the contributions of fine and coarse mode components to the total transmittance. The measurements for this figure were taken approximately four months after the January 2022 Hunga Tonga–Hunga Haʻapai eruption at a tangent height of 23.6 km (14.5 mi) in ACE occultation (ss100628), with coincident SAGE measurements from that same period (2022041609). Figure Credit: Adam Pastorek, adapted from a Figure in a paper published in Journal of Quantitative Spectroscopy and Radiative Transfer in January 2024.Sean Davis [NOAA, Chemistry Science Lab] presented on his research aimed at constraining decadal variability and assessing trends in stratospheric composition and tropospheric circulation using SAGE III/ISS and complementary satellite data sets. The team continues to include the SAGE water vapor and O3 products in the Stratospheric Water and OzOne Satellite Homogenized (SWOOSH) dataset. Davis also highlighted preliminary work evaluating V6 data in comparison to the former V5.3. He discussed line-of-sight, transmission-based filtering for O3 profiles and O3 diurnal variability corrections.
Lars Kalnaajs [University of Colorado, Boulder] presented results from two studies of particle size distributions from SAGE aerosol extinction data. Kalnaajs summarized results from two papers in review. His team paired the Optical Particle Counter collected from balloon platforms with SAGE II data to derive the parameters for bi-mode aerosol size distribution. They also presented the work of using SAGE III extinction ratios, 448/756 versus 1544/756, to derive monomodal lognormal size distribution, which allows them to compute distribution moments and compare these to in situ measurements taken over Sweden in the winters of 2002 and 2004.
Anne Thompson [GSFC, emeritus] presented on the Southern Hemisphere Additional Ozonesondes (SHADOZ) network and how that SHADOZ data are a satellite validation standard and can also be used to assess ozone trends in the upper troposphere and lower stratosphere. Thompson emphasized that SHADOZ O3 profiles are the only standard process to obtain measurements from surface to mid-stratosphere at 100–150 m (328–492 ft) resolution. Such measurements are essential to validate O3 measurements from SAGE-derived products. She also presented an update on the free tropospheric and lowermost stratospheric (LMS) O3 trends from eight equatorial SHADOZ sites. Newer calculations confirm that an apparent LMS seasonal decline (July–September) is associated with a roughly 100 m (328 ft) upward trend in tropopause height.
DAY TWO
The second day started with Jack Kaye [NASA Earth Science Division—Associate Director for Research for the Earth Science Division, emeritus as of April 30, 2025] providing a historic perspective on SAGE and comments on its context within NASA’s overall Earth science program. A technical session was held with three invited presentations, followed by three additional sessions where science team members presented their research on trace gas studies, including data product calibration and validation. The meeting concluded with updates from the SAGE project team on the SAGE III/ISS website and ongoing operations aboard the ISS. In his presentation, Kaye shared about his past involvement with the SAGE program and his perspective on its future in the context of flight missions for Earth observations.
Invited Presentations on Advanced Modeling and New Satellite Mission For UTS
Steven Pawson [GSFC] presented on the comprehensive modeling and analysis capabilities of
Upper troposphere and lower stratosphere (UTLS) dynamics and composition in the Goddard Earth Observing System (GEOS) model Pawson discussed the Global Modeling and Assimilation Office’s (GMAO) recent support for the Asian summer monsoon Chemical and CLimate Impact Project (ACCLIP) mission and the trend analysis of stratospheric O3. He also discussed future plans for GMAO, including improving the representation of water vapor in UTS through data assimilation and increasing horizontal and vertical resolution in the GEOS model.
Kostas Tsigaridis [Columbia University] presented recent research on the composition and climate impacts of increasing launches to Low Earth Orbit (LEO). Assuming that there are 10,000 launches per year and all launches use liquefied natural gas (LNG) as a propellant, the team compiled launch-related emission inventories and highlighted key uncertainties that could significantly affect climate predictions – particularly the impact black carbon has on the radiative balance and heterogeneous chemistry of the UTS. In addition, water vapor was found to contribute to the heating of the stratosphere and to a nontrivial amount of O3 depletion – 13 Dobson units (DU) on the global mean.
Adam Bourassa [University of Saskatchewan, Canada] introduced the satellite mission for High-altitude Aerosol, Water vapor, and Clouds (HAWC), planned as the Canadian contribution to the NASA Atmosphere Observing System (AOS) for launch in 2031 – a key component in NASA’s next generation Earth System Observatory. Bourassa highlighted the three Canadian instruments, which include limb profilers for water vapor and aerosol in the UTS and a far infrared imaging radiometer for ice cloud microphysics and radiative budget closure. He discussed instrument requirements and development progress as well as results from recent sub-orbital testing of prototypes on the NASA Earth Resources (ER)-2 and stratospheric balloons.
Trace Gases
Brian Soden [University of Miami] presented a new project that will use SAGE data to constrain climate sensitivity in climate models. Climate models differ substantially in their calculation of the radiative forcing from carbon dioxide (CO2), and these intermodel differences have remained largely unchanged for several decades. Soden highlighted the role of stratospheric temperature in modulating the radiative forcing from CO2. He explained that models that simulate a cooler stratosphere simulate a larger radiative forcing for the same change in CO2 compared to models that posit a warmer stratosphere. He added that determining the cause of the model biases in stratospheric temperature – particularly the role of water vapor in driving this intermodel spread – is an area of active research.
Ray Wang [Georgia Institute of Technology] compared the uncertainty analysis of SAGE III retrieved O3 and water vapor data in V5.3 to the same parameters in V6.0. He then compared the SAGE III data to the correlative measurements from other platforms. For O3, the differences between SAGE and measurements from the Microwave Limb Sounder (MLS) on NASA’s Aura platform are less than 5% in the stratosphere. SAGE V6.0 ozone values are systematically about 1–2% higher than those from V5.3 O3 – due to changes in how the O3 cross-section is represented in each version. For water vapor, SAGE data agree with MLS and Frost Point Hygrometer (FPH) data within 5%. Wang showed some differences between SAGE water vapor data retrievals using V5.3 and the same data obtained using version 6.0. He also said that a two-dimensional (i.e., spatial and temporal) regression model can be used to minimize sampling bias in climatology derived from non-uniform satellite measurements – ensuring more accurate representation of long-term trends.
Emma Knowland [GSFC/Morgan State University, Goddard Earth Sciences Technology and Research II (GESTAR II), now NASA HQ—SAGE III/ISS Program Scientist] discussed the progress of assimilating SAGE III water vapor data product into NASA’s GEOS re-analysis. Her team’s work demonstrated that while the number of solar occultation observations a day from SAGE III/ISS is about 1% of the total number of profiles observed globally by MLS, the chemical timescales of water vapor in the lower stratosphere are long enough that the SAGE III/ISS data can provide a valuable constraint on GEOS re-analysis, especially in the absence of MLS data – see Figure 4.
Figure 4. Hovmöller diagrams of the vertical distribution of 15°S–15°N average water vapor anomalies in upper troposphere–stratosphere with water vapor relaxed to a climatology [top left] and from data assimilation of SAGE III/ISS water vapor into the Goddard Earth Observing System (GEOS) model [bottom left]. Scatter plots show water vapor mixing ratios (y-axis) with [top right] and without [bottom right] data assimilation compared independent observations from the Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) data (x-axis). The ACE–FTS data were not used in data assimilation. This shows that data assimilation of SAGE data improves the agreement with ACE-FTS – especially in the lower stratosphere (400 to 500 K). Figure Credit: Emma Knowland [NASA]Melody Avery [University of Colorado, Boulder] discussed using SAGE data and data from the Cloud–Aerosol Lidar with Orthogonal Projection (CALIOP) instrument (on the former Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission) to study thin clouds and aerosol distributions in the tropical tropopause region (TTL). Avery explained that these distributions from V5.3 of SAGE-III/ISS and V5.41 of CALIOP are shown to agree well, and CALIOP observations of cloud frequency are shown to be a sensitive metric for defining the width of the Hadley Cell near the tropical tropopause. Combining SAGE and CALIOP data produced a longer timescale to constrain and evaluate climate models that currently do not agree on how the tropical width at this altitude varies. They found that results derived using SAGE V6.0 versus V5.3 differ on the order of 2% in the TTL region.
Pamela Wales [GESTAR II] introduced a new project that leverages SAGE III/ISS measurements to explore diurnal characteristics of O3 and nitrogen dioxide (NO2) in GEOS model products. Her team is exploring potentially using a GEOS reanalysis of stratospheric trace gases collected by MLS as a transfer standard to evaluate the consistency between the SAGE III/ISS solar and the less frequently measured lunar retrieval. They are also assessing uncertainties in stratospheric NO2 in the GEOS Composition Forecast (GEOS-CF) model using SAGE III/ISS and complementary satellite instruments. This work will inform how effectively GEOS-CF can be used in air quality studies to remove the stratospheric signal from column retrievals of NO2.
Luis Millán [JPL] presented work on the change of stratospheric water vapor mass after the Hunga Tonga–Hunga Haʻapai (Hunga) volcano eruption in 2022. Millán found an increase (~10%) of total stratospheric water vapor – a potent greenhouse gas. Given their advanced age, MLS, ACE-FTS, and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on NASA’s Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) mission (Heliosphere Division), are nearing the end of their missions, leaving SAGE III/ISS as the primary instrument for monitoring the plume’s evolution. Millán discussed how the SAGE III/ISS measurements might be sufficient to observe the dispersion of the excess Hunga water vapor from stratosphere in coming years. He also discussed a 39-year plus record of stratospheric water vapor mass using the overlapping periods between SAGE II, MLS, and SAGE III/ISS.
Ryan Stauffer [GSFC] presented the operation and outcomes of the Ticosonde balloon-borne O3 and water vapor sonde project in San Jose, Costa Rica. Ongoing since July 2005, Ticosonde has collected over 700 O3 profiles and 270 water vapor profiles for climate and pollution studies and satellite validation. Because Ticosonde is the only long-term water vapor sonde station in the tropics, the stratospheric water vapor data is vital for validation of SAGE-III/ISS and MLS profiles. Ticosonde has been used to verify the success of updated water vapor retrieval algorithms for both instruments – which now agree within a few percent up to 25 km (15 mi) altitude.
Natalya Kramarova [GSFC] showed the comparison of O3 profile retrieved from SAGE III with those derived from the OMPS-LP sensor – which is part of OMPS on NOAA-21 – from February 2023–June 2024. Diurnal corrections using the Goddard Diurnal Ozone Climatology (which is described in a 2020 article in Atmospheric Measurement Techniques) is applied to account for differences in measurement times between SAGE III’s sunrise or sunset observations and NOAA-21 LP’s midday measurements. Once the time correction is made, results show good agreement between the two instruments in depicting vertical ozone distribution across different geographical regions (e.g., tropics and mid-latitudes) and under various conditions (e.g., near the edge of the Antarctic O3 hole in October 2023). The mean biases between NOAA-21 LP and SAGE III are typically within ±5% between ~18–45 km (11–28 mi).
Project Team and Operations Highlights
Michael Heitz [LaRC] showed that V5.3 and previous versions of the SAGE III/ISS data product had a noticeable – and unphysical – dip in the retrieved aerosol extinction between 520–676 nm. This dip has been referred to as the aerosol “seagull.” However, adoption of a new absorption cross-section database into the V6.0 algorithm reduced the aerosol seagull effect significantly. Kevin Leavor [LaRC] presented new developments for the SAGE III/ISS quick look website. Mary Cate McKee [LaRC] introduced a new feature of the quick look website that showcases comparisons of O3 and water vapor sonde data at over 40 stations. Sonde data is sourced from the Network for the Detection of Atmospheric Composition Change (NDACC), GSFC’s SHADOZ, and the World Ozone and Ultraviolet Radiation Data Centre (WOUDC). Heitz explained that the comparison plots are updated continuously as new coincidences occur, providing the community with valuable insight to the quality of SAGE III/ISS data relative to this external network of ground stations. Future additions to the website include aerosol and lidar comparisons, additional plot statistics, and comparisons with novel homogenized datasets.
Returning to a topic discussed in Jamie Nehrir’s presentation, Charles Hill [LaRC] showed that the SAGE III Disturbance Monitoring Package (DMP) correction to the data product – which was implemented beginning with V5.3 – has significantly reduced the product uncertainties caused by ISS vibrations. Approximately 7% of SAGE III occultation events are highly disturbed by mechanical vibrations, and the DMP correction has improved pointing registrations in these events significantly. The DMP’s x-axis gyroscope failed on August 8, 2023 – but this loss did not significantly affect the DMP correction to scan plane elevation. Future possible losses of either the y- or z-axes will end active correction of ISS disturbances.
Conclusion
Jun Wang, David Flittner, and Richard Eckman led the closing discussion that highlighted the growing interest in atmospheric composition change – particularly due to emissions from large wildfires and volcanic eruptions in recent years. This increasing interest contrasts with the declining availability of observational data from the upper troposphere, following the retirement of CALIPSO in late 2023 and the planned decommissioning of Aura’s aging limb instruments in 2026. This gap underscores the critical importance of SAGE III/ISS data – not only for current UTS research but also for the next 5–7 years, during which no new limb measurements are planned.
SAGE III/ISS remains essential for profiling key atmospheric constituents, including water vapor, aerosols, O₃, and NO₂. The long-term, consistent data record provided by the SAGE series of instruments since the late 1970s – including SAGE III/ISS since 2017 – has been invaluable for studying past and future changes in atmospheric composition within the UTS. To further support research and applications of SAGE data products, participants discussed the possibility of proposing a special collection of articles in AGU journals.
Overall, the 2024 SAGE III/ISS meeting was a success. Participants received valuable updates on the status of SAGE III/ISS operations, data product calibration and validation, and new developments. The meeting also showcased the collective expertise and excellence in driving advancements in UTS research, from climate change studies to data assimilation for chemistry transport models and contributions to multi-sensor data fusion.
Jun Wang
University of Iowa
jun-wang-1@uiowa.edu
David Flittner
Langley Research Center
david.e.flittner@nasa.gov
Richard Eckman
NASA Langley Research Center
richard.s.eckman@nasa.gov
Emma Knowland
NASA Headquarters
k.e.knowland@nasa.gov
