Astronomy

Between 2011 and 2018, NASA’s Dawn mission conducted extended observations of Ceres and Vesta, the largest bodies in the Main Asteroid Belt. The mission’s purpose was to address questions about the formation of the Solar System since asteroids are leftover material from the process, which began roughly 4.5 billion years ago. Ceres and Vesta were chosen because Ceres is largely composed of ice, while Vesta is largely composed of rock. During the years it orbited these bodies, Dawn revealed several interesting features on their surfaces.

This included mysterious flow features similar to those observed on other airless bodies like Jupiter’s moon Europa. In a recent study, Michael J. Poston, a researcher from the Southwest Research Institute (SWRI), recently collaborated with a team at NASA’s Jet Propulsion Laboratory to attempt to explain the presence of these features. In the paper detailing their findings, they outlined how post-impact conditions could temporarily produce liquid brines that flow along the surface, creating curved gullies and depositing debris fans along the impact craters’ walls.

Michael J. Poston, the lead author of the study, is the Group Leader of Laboratory Studies (Space Science) at the SwRI. He was joined by a team of researchers from NASA JPL at the California Institute of Technology (Caltech) and the Airborne Snow Observatories, including Jennifer Scully – a NASA JPL planetary geologist and an Associate on the Dawn science mission team. The paper that describes their findings, “Experimental Examination of Brine and Water Lifetimes after Impact on Airless Worlds,” was published on October 21st in The Planetary Science Journal.

The planetoid Vesta, which was studied by the Dawn probe between July 2011 and September 2012. Credit: NASA

Airless bodies are frequently struck by asteroids, meteorites, and other debris that form impact craters and cause temporary atmospheres to form above them. On icy bodies or those with sufficient amounts of volatile elements (possibly beneath the surface), this will trigger temporary outflows of liquid water. However, water and other volatiles (like ammonia, carbon dioxide, methane, etc.) will lose stability in strong vacuum conditions. For their study, the team sought to examine how long liquid could potentially flow on the surfaces of airless bodies (such as Ceres and Vesta) before refreezing.

To this end, they simulated the pressures that ice on Vesta experiences after a meteoroid impact and how long it would take the liquid released from the subsurface to refreeze. “We wanted to investigate our previously proposed idea that ice underneath the surface of an airless world could be excavated and melted by an impact and then flow along the walls of the impact crater to form distinct surface features,” said Scully in a recent SwRI press release.

To this end, the team placed liquid-filled sample containers in a modified test chamber at NASA JPL to simulate the rapid pressure decreases that occur after an impact on airless bodies. In so doing, they were able to simulate how liquid behaves as the temporary atmosphere created by an impact dissipates. According to their results, the pressure drop was so fast that test liquids immediately and dramatically expanded, ejecting material from the sample containers. As Poston explained:

“Through our simulated impacts, we found that the pure water froze too quickly in a vacuum to effect meaningful change, but salt and water mixtures, or brines, stayed liquid and flowing for a minimum of one hour. This is sufficient for the brine to destabilize slopes on crater walls on rocky bodies, cause erosion and landslides, and potentially form other unique geological features found on icy moons.”

This image of the Cornelia Crater on Vesta shows lobate deposits (right) and curvilinear gullies (indicated by white arrows, left). Credit: SwRI/NASA JPL-Caltech/Poston et al. (2024)

These findings could help explain the origins of similar features on other airless bodies, like Europa’s smooth plains and the spider-like feature in its Manannán impact crater (which is due to “dirty ice” existing alongside “pure” water ice). They could also shed light on post-impact processes on bodies with very thin atmospheres, like Mars. This includes its gullies, which have dark features that flow downhill, and fan-shaped debris deposits that form in the presence of flowing water. Last, the study could support the existence of subsurface water in other inhospitable environments throughout the Solar System.

“If the findings are consistent across these dry and airless or thin-atmosphere bodies, it demonstrates that water existed on these worlds in the recent past, indicating water might still be expelled from impacts,” said Poston. “There may still be water out there to be found.” This could have profound implications for future missions to these bodies, including NASA’s Europa Clipper mission. This mission launched on October 14th, 2024, and will establish orbit around Europa by April 2030.

Further Reading: SwRI, The Planetary Science Journal

The post New Research Reveals Provides Insight into Mysterious Features on Airless Worlds appeared first on Universe Today.

SpaceX plans to launch 23 more of its Starlink internet satellites from Florida's Space Coast on Wednesday evening (Oct. 23).

A recent SpaceX Starlink launch featured an extra video treat: a view of the Internet satellites being revealed for future Internet service. But Starlink's effects on astronomy still causes concern.

A climate-cooling La Niña pattern was expected to develop in the Pacific Ocean months ago, but forecasters now say it won't appear until November

A climate-cooling La Niña pattern was expected to develop in the Pacific Ocean months ago, but forecasters now say it won't appear until November

Testing is one of the unsung steps in the engineering process. Talk to any product development engineer, and they will tell you how big of a milestone passing “V&V” – or verification and validation – testing is. Testing is even more critical when you work on equipment meant for the harsh space environment. It is also more challenging to mimic those harsh environments on Earth. Luckily for some of NASA’s more critical upcoming missions, another government agency has a unique test lab to help V&V with some of its most critical components – their heat shields.

That other government agency is the US Department of Energy (DoE), specifically its Sandia National Laboratory. The US’s national labs were initially developed to coordinate nuclear weapons research, but they have since taken on a broader role in the country’s fundamental scientific research efforts. That includes providing test equipment unavailable anywhere else in the world.

One unique test setup at Sandia is known as the solar testing facility. It’s a field with over 200 “heliostats” – giant mirrors that can focus the light from the Sun that they reflect on a particular point. With all of them focused on the same point, it can get as hot as 3,500 times the typical sunlight on an area.

The setup at Sandia isn’t just for testing material – it can also be used for power generation, as show in this video.
Credit – Sandia National Labs YouTube Channel

That area is also one of the selling points of the solar testing facility. It can test pieces of material up to 1 m (3 ft) in diameter. This makes it superior to other test facilities that intend to test the same types of materials, such as those that use arc jets or lasers. Cost is also a consideration, with arc jet or laser testing costing more than $100,000 daily. Comparatively, solar testing costs only $25,000 per day, mainly due to the lower energy costs of operating the heliostats. 

NASA has used all of that testing technology over the last year to test the heat shields of some of its most important missions – the Mars Sample Return (MSR) mission and Dragonfly, the helicopter mission to Titan. Each mission has its challenges, but the materials for their heat shields are the same. Known as a Phenolic impregnated Carbon Ablator, this material has already been successfully used for missions such as Stardust, OSIRIS-REx, and Mar Science Laboratory.

MSR and Dragonfly each have unique challenges that other missions didn’t face. MSR will be carrying a significant payload of samples back to Earth, meaning it will be heavier than the OSIRIS-REx asteroid sample return mission. It will be so heavy that some NASA engineers intentionally bent the test material at Sandia’s test lab to model what happens to material undergoing the force of reentry.

NASA’s reentry testing program is intensive, as discussed in this video.
Credit – BPS.space YouTube Channel

For its part, Dragonfly has to deal with a world with a much thicker atmosphere than Earth itself. Titan’s atmosphere is four times denser than Earth’s. Given the interplanetary speeds at which the mission will be traveling when it reaches orbital insertion, Dragonfly’s accompanying lander will be subjected to both high heat and pressure as it descends onto the Moon’s surface.

Sandia’s lab technicians made a number of improvements to the test setup for the tests, including running gas lines to the sample from the base of the tower to better mimic the atmosphere the heat shields will be encountering. They were also on hand to help with troubleshooting, which included multiple instances where some fiber surrounding the sample caught fire before the test could be completed.

V&V testing rarely completes without some adjustments and occasionally without any fires. Testing on this type of setup is just part of NASA’s test plan for the heat shield use case, with other tests happening elsewhere. Given the importance of this particular material to the overall success of these critical missions, the more testing they are able to undergo here on Earth, the better.

Learn More:
Sandia National Laboratory – Sandia tests heat shields for space
UT – NASA is Continuing to Build the Titan Dragonfly Helicopter. Here are its Rotors
UT – NASA and ULA Successfully Test a Giant Inflatable Heat Shield That Could Land Heavier Payloads on Mars
UT – An Innovative Heat Shield That Doesn’t Need to Be Replaced Between Missions

Lead Image:
Smoke billowing off NASA’s heat shield material during a recent test at Sandia National Laboratories’ National Solar Thermal Test Facility.
Credit – Photo by Craig Fritz

The post Testing Heat Shields for Different Atmospheres appeared first on Universe Today.

Most of us know about the impact that wiped out the dinosaurs about 66 million years ago. It’s a scientific fact that’s entered mainstream knowledge, maybe because so many of us shared a fascination with dinosaurs as children. However, it’s not the only catastrophic impact that shaped life on Earth.

There was an even more ancient one about 3.26 billion years ago, and its repercussions shaped early life in a unique way.

The impact event is called S2, and it took place during Earth’s Archean Eon. The Archean is the second of Earth’s four geological eons, spanning from 4,031 to 2,500 Mya (million years ago). A series of significant changes took place during the Archean, including the formation of Earth’s crust, the emergence of the first continents, and the development of a reducing atmosphere suitable for the first simple lifeforms.

When the S2 impactor struck, Earth life was simple and microbial. The impact had a powerful effect on our planet’s early living things, and new research examines what happened. It’s titled “Effect of a giant meteorite impact on Paleoarchean surface environments and life,” and it’s published in The Proceedings of the National Academy of Sciences. The lead author is Nadja Drabon, an assistant professor in the Department of Earth and Planetary Sciences at Harvard University.

“We think of impact events as being disastrous for life,” Drabon said. “But what this study is highlighting is that these impacts would have had benefits to life, especially early on … these impacts might have actually allowed life to flourish.”

Nadja Drabon, Dept. of Earth and Planetary Sciences, Harvard.

Drabon and her fellow researchers performed painstaking, detailed work to get their results. They travelled to the Barberton Greenstone Belt in South Africa to do their fieldwork. The Belt contains some of the oldest exposed rocks on Earth, and those rocks hold some of the oldest traces of life on Earth. Barberton also holds evidence of at least eight ancient impacts, including S2. Drabon and her team examined rock samples centimetres apart and analyzed their geochemistry, sedimentology, and carbon isotope compositions.

This figure from the research shows some of the rocks the team worked with. (A) is an overview of the Umbaumba section showing, from base to top, black-and-white banded chert (BWBC), S2, fallback layer, and BWBC. (B) shows the S2 spherule bed, (C) shows fine laminations in the fallback layer, (D) shows the BWBC below S2, and (E) shows alternating siliciclastic and siderite-rich chert beds. (F) shows laminated carbonaceous chert below S2 in the Umbaumba section. Red arrows indicate fractures filled by chert. (G) shows clots of carbonaceous matter and other siliciclastic debris from the fallback later in the Umbaumba section. Image Credit: Drabon et al. 2024.

They were able to paint a picture of the momentous day over three billion years ago when an extremely large carbonaceous chondrite 37-58 km in diameter, or 200 times larger than the dinosaur-killing Chicxulub impactor, struck Earth.

It started with a tsunami.

“Picture yourself standing off the coast of Cape Cod, in a shelf of shallow water. It’s a low-energy environment without strong currents. Then all of a sudden, you have a giant tsunami, sweeping by and ripping up the sea floor,” said Drabon.

The ocean was mixed up, and the tsunami carried debris from the land into the oceans. The catastrophic impact generated an enormous amount of heat, boiling away the uppermost layer of the ocean and heating the atmosphere. Next came a thick cloud of dust that prohibited any photosynthesis.

This was a dismal yet brief period in Earth’s history. But life has repeatedly shown how resilient it is. Earth’s primitive bacteria quickly bounced back from the cataclysm.

The impact stirred up iron and mixed deep Fe²+-rich waters with shallow Fe²+-poor waters. Fe²+ is an essential nutrient, and along with phosphorous released from the vaporized meteorite and increased weathering from the tsunami, these two nutrients fuelled life’s rebound.

According to the researchers’ analysis, all of this iron triggered a great flourishing of iron-metabolizing bacteria. This bias toward iron-loving life didn’t last, however, and equilibrium eventually returned. But the event is still a key piece in the puzzle of life on Earth. Despite the cataclysmic effect of giant impacts, they can provide some benefits. (There’s some evidence that meteorites delivered the building blocks of life to Earth.)

This figure from the research shows the stratigraphic layers of the Bruce’s Hill and Umbaumba locations. The inset shows the top of the fallback layer. Image Credit: Drabon et al. 2024.

“The recovery of life would have been fueled by an increase in ferrous iron in the photic zone and enhanced nutrient (especially phosphorous) availability, both indicated by geochemical data,” the authors explain in their research.

“We think of impact events as being disastrous for life,” Drabon said. “But what this study is highlighting is that these impacts would have had benefits to life, especially early on … these impacts might have actually allowed life to flourish.”

The researchers say that events immediately following the impact followed a tight timeline. The heat melted rock into spherules, and they were deposited just before or concurrent with the tsunami deposit. After the spherules and tsunami debris settled, the fallback layer quickly formed. That layer consists of rock lofted into the air by the impact.

“Altogether, the spherule beds and fallback deposits (1.3 to 5 m of strata) were likely deposited within no more than a few days—a geological instant,” the authors write in their research. “In this limited time period, the impact-initiated tsunami ripped up the sea floor, disturbed coastal benthic biosystems, mixed the water column, washed debris from coastal areas into the sea, and caused turbid conditions.”

S2, and probably other large impacts during the early Archean, seem to have had mixed effects on life. For some, the increased nutrients were a boon; for others, the thick dust cloud inhibited photosynthesis. “The tsunami, ocean evaporation, and darkness most severely affected phototrophs in surface waters, but chemoautotrophs in the lower water column and hyperthermophiles would likely have been less influenced,” the authors explain.

Other research into S2 suggests that the impact had other effects. Several studies suggest that it triggered volcanic activity. It may have also generated hydrothermal fields at the impact site, which could have added additional Fe²+ to the environment. It may even have generated tectonic activity.

S2 is just one example of the impacts that shaped life’s trajectory on Earth. Archean rocks contain evidence of at least 16 ancient impacts with bolides larger than 10 km. All of these likely generated severe though short-lived effects.

“Our work suggests that on a global scale, early life may have benefitted from an influx of nutrients and electron donors, as well as new environments, as a result of major impact events,” the researchers conclude.

The post This Early Impact Devastated Life then Gave it a Boost appeared first on Universe Today.

Comet A3 Tsuchinshan-ATLAS proved to be photogenic as it lit up the early autumn skies of the Northern Hemisphere this month.

Nearly four decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years. The titanic supernova, called Supernova 1987A (SN 1987A), blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987.

A researcher who underwent dozens of brain scans discovered that the volume of her cerebral cortex was 1 per cent lower when she took hormonal contraceptives

A researcher who underwent dozens of brain scans discovered that the volume of her cerebral cortex was 1 per cent lower when she took hormonal contraceptives

A neuroscientist underwent dozens of brain scans over three months to better understand the neurological effects of hormonal contraceptives

A neuroscientist underwent dozens of brain scans over three months to better understand the neurological effects of hormonal contraceptives

The supergiant star Betelgeuse may have a companion star that pushes light-blocking dust out of the way, causing the irregular changes observed in the star's brightness.

The moon has been bombarded by asteroids and comets for more than 4.32 billion years.

In Absolution, the fourth novel in Jeff VanderMeer’s Southern Reach saga, scientists try to know the unknowable

With ‘Thousand Sails,’ China joins the race to fill up Low Earth Orbit with mega-satellite constellations.

It’s getting crowded up there in Low Earth orbit (LEO). By now, flocks of Starlinks have become a familiar sight, and the bane of astrophotographers as the ‘vermin of the skies.’ Now, several new competitors have joined the fray, with more waiting in the wings.

Perhaps, you’ve seen one of these curious-looking ‘satellite trains,’ and wondered what they were. Certainly, the advent of satellite trains courtesy of Starlink have added to the annals of purported UFO videos shot via smartphone across YouTube. Now, more agencies worldwide are getting into the game in 2024, assuring that the next ‘star’ you wish on at dusk may, in fact, be an artificial satellite.

Approaching An Artificial Sky

Streaks and trails due to the increasing number of Starlinks in orbit have also become a standard feature in modern deep sky images. While techniques to remove these have been pioneered by astrophotographers, these will continue to impact deep sky astronomy. This impact extends to sky surveys soon set to come online such as the Vera Rubin Observatory, set to see first light early next year in 2025.

The first batch of Thousand Sails satellites in orbit, shortly after launch. Credit: Nick James.

SpaceX has implemented mitigation plans in response, including use of sun visors on first generation satellites, diffuse ‘dielectric mirror’ material on newer Version 2 (V2) platforms, and angling solar arrays. These have seen some success. Certainly, spotters have noted that the new Version 2’s have a bluer tint, and seem to shine at magnitude +7 once they’re boosted into their respective orbital slots. This is near the +7 magnitude threshold called for by the National Science Foundation (NSF) and the International Astronomical Union (IAU).

Radio noise from these new communications satellite constellations is also an issue that astronomers now have to contend with. LOFAR (The Netherlands Institute for Astronomy’s Low Frequency Array) notes that “new observations with the LOFAR radio telescope…have shown that the second generation ‘V2-mini’ Starlink satellites emit up to 32 brighter unintended radio waves than satellites from the previous generation.”

Enter China’s ‘Thousand Sails’ Initiative

China also recently joined the competition in LEO, with the launch of a Long March-6 rocket from Taiyuan Satellite Launch Center with 18 satellites for Shanghai Spacecom Satellite Technology (SSST). This is part of the company’s ‘Thousand Sails’ initiative.

The first batch of Thousand Sails satellites head to orbit. Credit: CNSA.

Dubbed China’s answer to Starlink, This will see an initial 1,296 satellites for the constellation placed in orbit by 2027. The company also has plans to expand the network to 12,000 satellites into the 2030s. This first batch went into a polar (sun-synchronous) orbit, and the resulting satellite train was spotted in orbit shortly after launch.

The Long March 6A booster fuel dump from the first Thousand Sails deployment, shortly after launch. Credit: Dan Bush/Missouri Skies.

And there’s more in store. China also launched a Long March 6 rocket on September 5th, with 10 new satellites for Geely Group Automotive. These are part of the company’s effort to build a communication network for autonomous vehicles.

An artist’s impression of Geely Group satellites in orbit. Credit: Geely Group.

As a follow-on this month, China also launched a Long March-6 rocket on October 15th with another batch of 18 satellites headed into a polar orbit. This group is also part of the Thousand Sails constellation. Satellite spotters have already tracked these in orbit, with an estimated brightness of up the +4th magnitude when near the zenith on a visible pass. Keep in mind, China isn’t beholden to any obligations to mitigate the impact that satellite constellations might have on the night sky…nor do any formal international standards exist.

More Mega Satellite Constellations to Come

Not to be outdone, SpaceX is putting up more than just Starlink. Last month, SpaceX launched a Falcon 9 rocket on September 12th, with the first five Bluebird satellites. These are ASTMobile’s follow-on to the BlueWalker-3 test satellite, still in orbit. With a phased-array antenna 10-meters across when deployed, BlueWalker-3 reaches magnitude 0. The company plans to put 110 of these potentially brilliant Bluebirds in orbit over the next few years.

A Bluewalker antenna unfolded on Earth. Credit: ASTMobile.

OneWeb is also still putting satellites in orbit. The ongoing Russia-Ukraine War has forced the company to forego Soyuz launches. Instead, OneWeb now relies on competitor SpaceX to get into orbit.

The OneWeb satellite constellation currently hosts 660 satellites in orbit, right around the initial target number set by the company Eutelsat-OneWeb for nominal operation. The company began offering services through residential providers last year, including Hughesnet, Viasat and ironically, Starlink.

Starlink’s current status is 7,125 satellites in orbit, with 23 more planned tonight with the launch of Starlink Group 6-61 from the Cape. 12,000 satellites in orbit are planned for in the coming years, and the constellation could extend to a total of 34,400 satellites in future years.

Not to be outdone, the Unites States’ Department of Defense is putting its own dedicated satellite constellation in space. Dubbed Starshield, the network already has 73 satellites in orbit, and a total of more than a 100 are planned. As expected, the DoD is already shaping up to be Starlink’s (and SpaceX’s) biggest customer.

Hunting Satellite Trains

Other bright reflectors are making themselves seen in the night sky as well. ACS-3 (the Advanced Composite Solar Sail System) was launched this past April on a Rocket Lab Electron rocket. The mission successfully unfurled this summer on August 29th. ACS-3 is the latest in a batch of satellites to attempt to test solar sail technologies in orbit. Mission planners could use this tech on future missions for maneuvering, propulsion or reentry disposal. Previous missions, including NanoSail-D2 and Planetary Society’s Light Sail have struggled with this tech, demonstrating just how difficult it’s turning out to be.

ACS-3 is definitely tumbling: we’ve seen it flare up to 0 magnitude (as bright as Vega) on a good pass. This seems to be very angle dependent.

You can track these missions and more on Heavens-Above. The leaders for the first two batches of respective Thousand Sail groups are 2024-140A and 2024-145A. Plus, Heavens-Above tracks Starlink batches (which are once again going up at a furious rate) on a dedicated page. We saw the most recently launched Starlink Group Batch 8-19 this past weekend… and that was from under the bright lights of downtown Bristol, Tennessee.

The Promise and Peril of Mega-Sat Constellations

To be sure, we’re a huge consumer of roaming WiFi. If we can continue our career and online exploits from a remote basecamp, then that’s a good thing… but there also needs to be oversight when it comes to what we’re collectively doing to our night sky as a resource.

Are we headed towards a future where artificial stars in the night sky outnumber real ones? Perhaps, the best thing that amateur satellite trackers can do now, is to chronicle what’s happening, as the Anthropocene era leaves its mark on a brave new night sky.

The post China’s ‘Thousand Sails’ Joins Starlink as the Latest Mega-Satellite Constellation in Orbit appeared first on Universe Today.

A map of gravity wells or "basins of attraction" in the local universe may resemble a Taylor Swift outfit, but they define the largest structure in the universe, the last line of your cosmic address.

ESA Impact Council Edition: Your update on space achievements

An interactive publication covering captivating stories and stunning images since the last Council meeting.

A type of mathematical problem that was previously impossible to solve can now be successfully analysed with artificial intelligence