Astronomy

On opposite sides of the Atlantic Ocean, Central Europe and North Carolina have both been drenched by torrential rains

A SpaceX Falcon 9 rocket launched two European navigation satellites tonight (Sept. 17) and then landed safely, acing its 22nd mission.

Americans are famously fond of their guns. So it should come as no surprise that a team of NASA scientists has devised a way to “shoot” a modified type of sensor into the soil of an otherworldly body and determine what it is made out of. That is precisely what Sang Choi and Robert Moses from NASA’s Langley Research Center did, though their bullets are miniaturized spectrometers rather than hollow metal casings. 

First, let’s look at the miniaturized spectrometers. Spectrometers have been a workhorse of space exploration for decades. They analyze everything from the surface of Enceladus to stars. However, they almost all use a type of spectroscopy known as Fraunhofer diffraction. Drs. Choi and Moses decided to use a different physical phenomenon in their invention, known as Fresnel’s diffraction.

In Fresnel diffraction, a spectral graph becomes very clear at much smaller distances than those created by Fraunhofer diffraction. Since the necessary distance between a “grating” and the sensor required by a spectrometer using Fraunhofer diffraction is one of the system’s design constraints, most spectrometers in use today are prohibitively large.

Fraser discusses the importance of the lunar south pole – which includes many permanently shadowed craters

Fresnel diffraction, however, allows for the creation of much smaller spectrometers. In the case of Dr. Choi and Moses’s invention, all of the necessary power, signaling, and analysis electronics can fit into a small cylindrical tube only slightly larger than a traditional bullet.

That was likely where the idea for shooting these sensors into the ground came from. If the “micro-spectrometers” were surrounded by regolith, whether the Moon, an asteroid’s, or Mars’, it would allow quick analysis of the composition of the soil wherever it is embedded. Since these sensors are easily deployed, if multiple of them were spread throughout a lunar crater, a single astronaut (or rover) could characterize the soil makeup of an entire area without hand-digging a space for each sample area.

This is where the “gun” comes in—a rover, or even an astronaut, could be fitted with a tube that “fires” the cylindrical micro-spectrometer into the ground, embedding it where it can do the best science. A single rover or astronaut could then distribute enough of these to collect data on an entire area, such as the permanently shadowed regions of a lunar crater.

Image of a prototype micro-spectrometer
Credit – Choi and Moses

Such a system could also be used on asteroids from an orbiter or even Mars. It could use telemetry back to a central connection point—potentially also carried by the astronaut or rover. Unfortunately, at least in the current iteration, it couldn’t be reused, though that could change in new designs.

This invention, which NASA has patented, could also be used on Earth if a mining or petroleum company wants to quickly sample an area’s geological makeup. But it is also useful in space—so much so that we might someday find astronauts shooting what look to be bullets but are actually miniaturized sensors directly into the ground.

Learn More:
Sang H Choi – Lunar, Mars, and Asteroid Exploration for Space Resources
Choi & Moses – Micro-Spectrometer for Resource Mapping in Extreme Environments
UT – The Darkest Parts of the Moon are Revealed with NASA’s New Camera
UT – Absorption Spectroscopy

Lead Image:
Depiction of the “bullets” being deployed in a lunar crater.
Credit – NASA

The post Could You Find What A Lunar Crater Is Made Of By Shooting It? appeared first on Universe Today.

Is it time for space lasers yet? Almost.

As time passes, ideas that were once confined to the realm of science fiction become more realistic. It’s true of things like using robots to explore other worlds. Space lasers are a well-used element in science fiction, and we’re approaching the time when they could become a reality.

Where would we put them, and what could we use them for?

In science fiction, lasers are predominantly used as powerful weapons. While some countries have investigated the idea of using lasers as space weapons, an international treaty limits their use.

A more realistic use for lasers is for deflecting incoming asteroids or as propulsion systems for spacecraft. In a new paper, a researcher examines where a giant laser array could be positioned in space to be of most use to humanity while at the same time minimizing risk.

The research is “Minimum Safe Distances for DE-STAR Space Lasers.” The paper is in pre-print, and Adam Hibberd from the Initiative for Interstellar Studies in London, UK, is the sole author.

While space lasers could also be used to utilize resources or in satellite laser ranging systems to control space traffic, Hibberd’s focus is on using them to protect Earth from impacts.

DE-STAR stands for Directed Energy Systems for Targeting of Asteroids and exploRation. Of all the space laser ideas that have been discussed, DE-STAR is probably the most well-studied and developed. It would consist of a modular phased array of lasers powered by solar cells. It could heat the surface of potentially hazardous objects (PHO) to approximately 3,000 Kelvin. That’s hot enough to melt all known constituents of PHOs. DE-STAR could also be used to propel spacecraft.

The idea originated in 2013 when a group of researchers published a paper titled “DE-STAR: Phased-Array Laser Technology for Planetary Defense and Other Scientific Purposes.” In their paper, they outlined the idea for DE-STAR, a stand-off laser array. In 2016, some of the same authors published another paper titled “Directed Energy Missions for Planetary Defense.” It expanded on DE-STAR and added DE-STARLITE, a stand-on system that would be sent to the vicinity of an approaching object to ward it off with lasers.

This artist’s illustration shows DE-STARLITE firing its lasers at a hazardous object. Image Credit: Lubin et al. 2016.

In either case, the system would be based on the Sun’s energy. “DE-STAR is a square modular design which exploits the energy created by banks of solar cells in space to generate and amplify the power of a laser beam,” Hibberd explains in his new paper. In literature, DE-STAR is typically referred to as DE-STAR n, where n is usually between 0 and 4 and denotes the size of the bank of lasers. The larger the array, the more powerful it is. The more powerful DE-STAR is, the more effective it will be at deflecting asteroids from greater distances.

While the merit of this idea is immediately clear, the problems follow soon after. A bank of powerful space lasers is every supervillain’s dream. Its destructive power could be immense. “With a DE-STAR 4
structure (10 km × 10 km square) capable of generating a laser beam on the order of tens of gigawatts,
clearly, there is the potential for such an asset to be deployed as a weapon by targeting locations on Earth,” Hibberd writes.

How can this risk be mitigated so that the system can be used to protect Earth rather than as a weapon?

The simple solution is to not deploy them in Earth’s orbit. The lasers lose energy with range, so they could be deployed at distances where they pose no threat. “Results indicate that given they should lie 1 au from
the Sun, there are feasible locations for DE-STAR 0-2 arrays where there is no danger to Earth,” Hibberd writes.

This table from the paper shows the specs adopted in this paper for different-sized DE-STAR arrays. The clip ratio affects beam quality, energy efficiency, how well it propagates through space, and how well it handles heat generation. Smaller is generally better, and 0.9 is the ratio adopted by other researchers. Optimizing the clip ratio is an important part of designing an effective array. Image Credit: Hibberd 2024.

Of course, the more lasers there are in the array, the greater the safe minimum distance.

For DE-STAR 4 or even 5, that distance wouldn’t be enough. Instead, these lasers would need to be much further away or at positions in the Solar System with no direct line of sight to Earth. These systems would need to correct their positions regularly with an on-board propulsion system “or preferably using push-back from the laser itself,” Hibberd explains.

The minimum safe distance also changes depending on the wavelength of the DE-STAR system. Hibberd defines minimum safe distance as a single laser with a maximum intensity on Earth’s surface of 100 Wm-2. “Or on the order 10 % of the Solar Constant at Earth (1 au from the Sun),” Hibberd writes. For an infrared system, the minimum safe distance is just beyond geosynchronous Earth orbit (GEO). At the more powerful end of the scale, a UV laser would need to be beyond cis-lunar space.

This figure from the research shows the Dependence of the Minimum Safe Distance of any Unphased DE-STAR Array with the Wavelength of the Laser. Image Credit: Hibberd 2024.

There’s another factor to consider. Since DE-STAR gets its energy from the Sun, its power decreases the further away from the Sun it is. “This reduction is a consequence of the decrease in solar flux intensity on the photovoltaic cells, where an inverse square law is followed,” Hibberd explains.

This figure shows how the laser’s power diminishes with distance from the Sun for four different array sizes. “We find that a DE-STAR n at 90 au from the Sun is approximately equivalent to a DE-STAR n-1 at 10 au and a DE-STAR n-2 at 1 au,” Hibberd writes. Image Credit: Hibberd 2024.

For DE-STAR 1 and 2 Arrays, the minimum safe distances are not that great. Hibberd points out that for a DE-STAR 2 Array, Sun/Earth Lagrange 4 and 5 points would be suitable and require no propulsion. L4 and L5 are about 400,000 km from Earth.

These figures show the minimum safe distance for DE-STAR 1 and 2 Arrays by wavelength. Image Credit: Hibberd 2024.

However, as the arrays become larger, the minimum safe distance quickly increases. Conversely, the available solar energy decreases.

A DE-STAR 3 would have to be placed somewhere beyond the asteroid belt. If it were ultraviolet, it would have to be beyond Jupiter.

A DE-STAR 4 phased array would have to be much further away. It would have to be about 30 ? 40 au away, and even further for an ultraviolet system, about 70 au from the Sun.

These figures show the minimum safe distance for DE-STAR 3 and 4 Arrays by wavelength. Image Credit: Hibberd 2024.

The tables above assume a direct line of sight to Earth. But there are locations where there is no direct line, and they could be used as locations for powerful arrays. Hibberd explains that the Earth/Moon Lagrange 2 point and the Sun/Earth Lagrange 3 point both lack direct lines of sight but, unfortunately, are unstable. “In both cases, the instability of these points will result in the DE-STAR wandering away and potentially becoming visible from Earth, so an on-board propulsion would be needed to prevent this,” Hibberd writes. It’s possible that an array could be built that is physically prevented from pointing at Earth, but the author doesn’t tackle that aspect of the problem.

Sun-Earth Lagrange Points. Credit: Xander89/Wikimedia Commons

Nobody’s building a DE-STAR phased array, but that doesn’t mean it’s too soon to think about it. This type of technology is on the horizon, and it’s difficult to predict which nation or nations might be the first to build one. Treaties are in place to prevent the weaponization of space, but not everybody signed them. Some nations are known to sign treaties and then break them, in any case. Also, an argument could be made that this isn’t a weapon.

It likely won’t be long before serious talk about such a system begins to surface in wider public discussions. That will surely generate a lot of political difficulty and wrangling as nations argue over what constitutes a weapon and what doesn’t.

If civilization is to survive, we will eventually need a way to protect the entire globe from asteroid strikes, whether it’s phased laser arrays or some other system.

The post There are Plenty of Uses for Powerful Lasers in Space. But Where Should We Put Them? appeared first on Universe Today.

Even though the strange behaviour we observe in the quantum realm isn’t part of our daily lives, simulations suggest it is likely our reality could be one of the many worlds in a quantum multiverse

Even though the strange behaviour we observe in the quantum realm isn’t part of our daily lives, simulations suggest it is likely our reality could be one of the many worlds in a quantum multiverse

If microscopic black holes born a fraction of a second after the Big Bang exist, then at least one may fly through the solar system per decade, generating tiny gravitational distortions that scientists can detect.

The FAA has proposed fining SpaceX more than $630,000 for allegedly failing to comply with regulations on two launches in 2023.

"I would say family and part of that 'first-gen experience' [shaped me]...It shaped me to be a hard worker and to aspire to large things because not only was it my goal at this point, but it was also my parents' aspiration." – Zaida Hernandez, Engineer, Lunar Architecture Team, NASA's Johnson Space Center

Comet Tsuchinshan-ATLAS will sweep around the sun on Sept. 27 to make a brief foray into the morning sky. Will it be a bright naked-eye object with a significant tail? Here's where and when you might be able to see it.

Billions of dollars of observatory spacecraft orbit around Earth or in the same orbit as our planet. When something wears out or goes wrong, it would be good to be able to fix those missions “in situ”. So far, only the Hubble Space Telescope (HST) has enjoyed regular visits for servicing. What if we could work on other telescopes “on orbit”? Such “fixit” missions to other facilities are the subject of a new NASA paper investigating optimal orbits and trajectories for making service calls on telescopes far beyond Earth.

Some of the most productive orbiting telescopes operate at the Sun-Earth Lagrange points L1 and L2. Currently, those positions afford us some very incredible science. What they can’t afford is easy access for repairs and servicing. That limits the expected lifetime of facilities such as JWST to about 10-15 years. In the future, more missions will be deployed a Lagrange points. These include the Nancy Grace Roman Telescope, ESA’s PLATO and ARIEL missions, and the Large Ultraviolet Optical Infrared Surveyor (LUVOIR).

Artist’s impression of the Nancy Grace Roman Space Telescope, named after NASA’s first Chief of Astronomy. This spacecraft will orbit at SEL2, far from Earth. Credits: NASA

These observatories need propellants for attitude thrusters to help them stay ‘in place’ during their observations. There’s only so much “gas” you can send along with these observatories. In addition, components wear out, as they did with HST. So, people are looking at ways to extend their lifetimes through servicing missions. If failing components can be replaced and propellant delivered, the lifetimes of these observatories should be extended quite a bit, giving astronomers more bang for the observational buck.

Planning Future Spacecraft Servicing Missions

Researchers at the Satellite Servicing Capability Office (SSCO) at the Goddard Space Flight Center (GSFC) investigated the possibilities for servicing missions to distant space telescopes. In a recently released paper, they focus on the feasibility of on-orbit refueling missions for space telescopes orbiting at Sun-Earth Lagrange 2 (SEL2).

There are many challenges. For one thing, present-day launch technologies are (at this writing) inadequate to do that kind of mission at such distances. Clearly, the technology has to advance for servicing visits to take place. In addition, it’s important to remember that current telescopes, such as Gaia and JWST, weren’t designed for such access. However, future telescopes can be fitted with servicing ports, etc. to enable servicing. Finally, there are the challenges of actually getting the servicing missions to the observatories.

Illustration of OSAM-1 (bottom) grappling Landsat 7. This servicing mission concept was discontinued by NASA, but remains a good example of what’s needed to perform repairs and refueling to orbiting spacecraft. Credits: NASA

The Goddard team focused on this final issue by computing models of various launch and orbital solutions for such missions. Not only did they take into account the launch trajectories themselves, but also Sun-Earth-Lagrange point dynamics, plus the relative positions of observatories at SEL2. In addition, the team considered the stability of the observatories during and after rendezvous and attachment. All of these factors count when planning whether or not a servicing vehicle can be launched at a reasonable cost to extend the lifetime of the observatory enough to make the effort worth the time and expense.

Getting a Spacecraft Refuelling Mission Underway

The team created models for a theoretical mission for on-orbit fuelling at SEL2. That’s where JWST and Gaia are sitting, for example, along with WMAP, Planck, and others. The paper examines robotic refueling missions out to SEL2 for modeling purposes.

To do that, however, there must be an optimal trajectory for the robotic spacecraft to take out to SEL2. They need to be able to perform autonomous navigation to the correct point in space. Once at the target observatory, the refueling robot would then need to make a careful approach for its docking maneuvers. That requires on-orbit assessment of the target’s motion in space with respect to the Sun as well as its position in its SEL2 orbit. Docking itself can affect the observatory’s position and motion and the robot needs to take that into account, as well. The idea is to keep the observatory in the same position after docking.

However, the big question is: how do we get it out there inexpensively, fast, and safe?

The Goddard team primarily investigated the best and most efficient trajectories to get to SEL2. In particular, they looked at the best approaches to get to the Gaia spacecraft, which will run out of its propellant sometime in the next year. They also examined JWST as a possible target for such a mission. If such a mission was possible today, those observatories would gain years of “point and shoot” access to the Universe.

How to Get There

In their paper, the team looks at two approaches to the SEL2 refueling mission. One is a direct launch trajectory from Earth and the other is a spacecraft leaving from a geostationary transfer orbit (GTO). They assumed that the point of the mission was the fastest possible restoration of telescope operation. That dictates the shortest and safest possible trajectory along which the spacecraft can maintain constant thrust.

The Goddard team created a “forward design” approach for computing low-energy and low-thrust transfers from an Earth departure orbit to a space telescope orbiting the SEL2 point. Then they did the same for a servicing spacecraft leaving from a point in geostationary space. Essentially, either an Earth-departure or GTO-centric departure will work. Once the robotic servicing mission leaves Earth orbit, it travels at low thrust during a spiraling transit to SEL2. Once there, it does a rendezvous with the target, matches its motion in space, and then “locks on” to perform its delivery mission.

It’s important to remember that a launch from Earth or GTO is part of several solutions to SEL2 servicing missions. The team’s analysis resulted in a simplified process of generating possible orbits and trajectories for such activities. You can read the full text of their detailed analysis of the different trajectory solutions at the link below.

For More Information

Mission Design for Space Telescope Servicing at Sun-Earth L2
JWST Home Page
Gaia Telescope

The post There Could be a Way to Fix Spacecraft at L2, Like Webb and Gaia appeared first on Universe Today.

Maternity services need to educate parents-to-be on how pregnancy will affect their brain - their life could depend on it, says Helen Thomson

Maternity services need to educate parents-to-be on how pregnancy will affect their brain - their life could depend on it, says Helen Thomson

Echolocating bats can more easily find and pollinate long-stemmed flowers that stand out from the surrounding foliage, which may be why this floral trait evolved

Echolocating bats can more easily find and pollinate long-stemmed flowers that stand out from the surrounding foliage, which may be why this floral trait evolved

Snoring is often viewed as harmless, at least to the snorer, but we are now uncovering its potentially serious effects on cardiovascular health. And finding ways to stop is surprisingly challenging

Snoring is often viewed as harmless, at least to the snorer, but we are now uncovering its potentially serious effects on cardiovascular health. And finding ways to stop is surprisingly challenging

Four private astronauts are back on Earth after a five-day mission that set firsts and broke records in an effort to advance human spaceflight.

Rather than building an obsolescent, obscenely-over-budget jumbo rocket, NASA should turn to building truly innovative space technologies and plan a realistic lunar landing program

Astronomers have observed three types of black holes in the Universe. Stellar-mass black holes formed from the collapse of a massive star, intermediate mass black holes found in some star clusters, and supermassive black holes that lurk in the centers of galaxies. But there is a fourth type that remains hypothetical an unobserved. Known as primordial black holes, they are thought to have formed from tiny fluctuations in the hot and dense early cosmos. Since they wouldn’t have formed from stars or mergers, they could have a much smaller mass. And with small masses, primordial black holes would be tiny. Their event horizons would be smaller than an apple, perhaps as small as a grain of sand. You can see why they would be hard to find.

If they exist, these dustmote singularities would be a perfect candidate for dark matter. This is not a new idea. Observations of dark matter have ruled out stellar-mass black holes and even planet-mass ones, but they haven’t quite ruled out primordial black holes. So they are a possible explanation for dark matter, but how would we prove it? A new study on the arXiv tries to find out.

Observational constraints on primordial black holes over various mass ranges. Credit: M. Cirelli (2016)

The authors begin by noting that if dark matter really is composed of primordial black holes, then they must be clustered around regular matter in the way dark matter does. There must be a halo of tiny black holes surrounding the Milky Way, and there must be primordial black holes scattered throughout our solar system. The gravitational pull of these tiny black holes should therefore affect the motion of planets, asteroids, and comets in detectable ways. Previous searches turned up nothing, but the authors wanted to know whether the effect would be significant enough to observe with our current technology.

So they ran several computer simulations to calculate the size of the effect. Since the gravitational pull of a single black hole would be tiny, the team looked at how nearby encounters would shift the orbits of solar system bodies. We describe orbital motion by ephemerides tables, so they used simulations to determine how the ephemerides would change over time. What they found was that even if we took a decade’s worth of ephemerides observations, the effect of primordial black holes would be an order of magnitude smaller than the limits of observation. In other words, even if primordial black holes exist their effect is way too tiny to observe in our solar system.

While the result is a bit disappointing, it does contradict a few studies that argue current observations rule out primordial black holes as dark matter. Though they are an unlikely solution to this cosmic mystery, they are still in the game.

Reference: Thoss, Valentin, and Andreas Burkert. “Primordial Black Holes in the Solar System.” arXiv preprint arXiv:2409.04518 (2024).

The post Could We Find Primordial Black Holes in the Solar System? appeared first on Universe Today.