Astronauts are Going to Check if There are Microbes on the Outside of the Station

On Thursday January 30th, astronauts Suni Williams and Butch Wilmore are doing a 6.5-hour spacewalk outside the International Space Station. Among other goals, they’ll be collecting surface samples from the station to analyze for the presence of microbes.

The ISS “surface swab” is part of the ISS External Microorganisms project. It was developed to understand how microorganisms are transported by crew members to space. It also seeks to understand what happens to those “mini-critters” in the space environment.

The “bugs” that the two astronauts bring back in for analysis will come from areas on the space station near life-support system vents. The idea is to figure out if the station releases those microbes through the vents. Scientists also want to know the size of the release population, and where else they show up on the station.

The Microbes Experiment

Researchers seek to understand how microbes exist and thrive in space and planetary environments. At the moment, the best analog for those is on the ISS, particularly its exterior. So, when microbes find their way out, people want to know how long they survive the radiation. Do quick temperature changes affect them? What else happens to them? Also, scientists want to know if microbes manage to reproduce and how the environment changes that.

Samples from the ISS surface get frozen in special containers and eventually get returned to Earth. Once in the lab, they’re analyzed using culture-independent techniques such as next-generation deoxyribonucleic acid (DNA) sequencing to measure microbial community. Functional pathways in these microbial communities are characterized by targeting multi-gene analysis. This approach allows for a comprehensive assessment of the microbial diversity and metabolic function without cultivation. The samples collected at different locations or during different EVA opportunities allow investigators to map the microbial diversity of ISS external surfaces.

A member of the ISS External Microorganisms payload development team demonstrates removing a swab from the sampling caddy that is used by an astronaut during a spacewalk. A crew member uses the swabbing tool to collect microbes in samples from the exterior surface of the International Space Station at various locations. Results could inform preparations for future human exploration missions to the Moon and Mars. Credit: NASA.

Why Test for Microbes?

While people have been flying to and from space for decades now, the scientific community still has significant gaps in knowledge about understanding how microbes get released, how they thrive, and what their life cycles are in space. In particular, the ISS sees many visiting vehicles each year, and astronauts move around freely inside. Those activities likely increase the microbe population both inside and out.

Collecting microbes and analyzing them allows scientists to assess the types and numbers of microorganisms living on the outer shell of a spacecraft. The larger goal is to supply more information under the guidelines of NASA’s policy on Planetary Protection Requirements for Human Extraterrestrial missions. There are still many questions to be answered, including: what are the acceptable levels of microbial life? Which ones make it out through the vents? What are acceptable contamination rates? While NASA has designed this mission to answer those and other questions, the Russian space agency Roscosmos is also making similar investigations to sample the Russian side of the station. That resulted in the discovery of non-spore-forming bacteria growing on the outer skin of the station.

The results of microbe analysis from this and other microorganism collections could affect spacecraft design and spacesuit changes. This becomes doubly important when people venture out onto the surface of Mars, for example. While we see no direct evidence of life there now, it could be there and likely existed in the past. Not only do we want to avoid contaminating astronauts with that life, we also want to avoid (as much as possible) bringing Earth life to Mars. This same research has applications in other fields, such as agriculture and pharmaceuticals.

Info on the Space Walk

This isn’t the first time the ISS has been tested for exterior microbial life, and the long-term study is necessary. The planned sampling to be mission undertaken by Williams and Wilmore is officially called Spacewalk 92 and should start at 8 a.m. on January 30th. NASA will provide live coverage of the walk (check here for more information), which will also conduct some other maintenance on the station along with the sampling activities.

For More Information

Astronauts Set to Swab the Exterior of Station for Microbial Life
Space Station Research Explorer

The post Astronauts are Going to Check if There are Microbes on the Outside of the Station appeared first on Universe Today.

It’s Time to Start Classifying Exoplanetary Systems

When an exoplanet is discovered, scientists are quick to describe it and explain its properties. Now, we know of thousands of them, many of which are members of a planetary system, like the well-known TRAPPIST-1 family of planets.

Patterns are starting to emerge in these exoplanetary systems, and in new research, a team of scientists says it’s time to start classifying exoplanet systems rather than just individual planets.

The paper is “Architecture Classification for Extrasolar Planetary Systems,” and it’s available on the pre-print site arxiv.org. The lead author is Alex Howe from NASA’s Goddard Space Flight Center. The authors say it’s time to develop and implement a classification framework for exoplanet systems based on our entire catalogue of exoplanets.

“With nearly 6000 confirmed exoplanets discovered, including more than 300 multiplanet systems with three or more planets, the current observational sample has reached the point where it is both feasible and useful to build a classification system that divides the observed population into meaningful categories,” they write.

The authors explain that it’s time for a systemic approach to identifying patterns in exoplanet systems. With almost 6,000 exoplanets discovered, scientists now have the data to make this proposition worthwhile.

Artist’s rendition of a variety of exoplanets featured in the new NASA TESS-Keck Survey Mass Catalog, the largest, single, homogenous analysis of TESS planets released by any survey thus far. Credit: W. M. Keck Observatory/Adam Makarenko

What categories do the authors propose?

The first step is necessarily broad. “The core of our classification system comes down to three questions for any given system (although, in several cases, we add additional subcategories). Does the system have distinct inner and outer planets?” the authors write.

Next comes the question of Jupiters. “Do the inner planets include one or more Jupiters?” After that, they ask if the inner planets contain any gaps with a period ratio greater than 5. That means if within the gaps between the inner planets, are there any instances where the ratio of the orbital periods of two hypothetical planets occupying those gaps would exceed 5? Basically, that boils down to asking if the absence of planets in specific regions in the inner solar system is related to unstable orbits.

These three questions are sufficient to classify nearly all of the exoplanet systems we’ve discovered.

“We find that these three questions are sufficient to classify ~97% of multiplanet systems with N ?3 planets with minimal ambiguity, to which we then add useful subcategories, such as where any large gaps occur and whether or not a hot Jupiter is present,” the authors write.

The result is a classification scheme that divides exoplanet systems into inner and outer regimes and then divides the inner regimes into dynamical classes. Those classes are:

• Peas-in-a-pod systems where the planets are uniformly small
• Warm Jupiter systems containing a mix of large and small planets
• Closely-space systems
• Gapped systems

There are further subdivisions based on gap locations and other features.

“This framework allows us to make a partial classification of one- and two-planet systems and a nearly complete classification of known systems with three or more planets, with a very few exceptions with unusual dynamical structures,” the authors explain.

In summary, the classification scheme first divides systems into inner and outer planets (if both are detected). Systems with more than three inner planets are then classified based on whether their inner planets include any Jupiters and whether (and if so, where) their inner planets include large gaps with a period ratio >5. Some systems have other dynamical features that are addressed separately from the overall classification system.

This is a quick reference chart for the new system of classifying planetary system architectures, with representative model systems for each category. Each row is one planetary system, where the horizontal spacing corresponds to the orbital period, and the point sizes correspond to planet sizes. Colours correspond to planet type: Jupiters (>6 Earth radii, red), Neptunes (3.5-6 Earth radii, gold), Sub-Neptunes (1.75-3.5 Earth radii, blue), and Earths (<1.75 Earth radii, green). Image Credit: Howe et al. 2025.

The classification system is based on NASA’s Exoplanet Archive, which listed 5,759 exoplanets as of September 2024. It’s a comprehensive archive, but it also contains some questionable exoplanets drawn from papers that can sometimes be inaccurate, poorly constrained, or even contradicted by subsequent papers. The researchers filtered their catalogue to remove data they considered unusable. As a result, they removed 2% of the exoplanets in their archive.

They also filtered out some of the stars because of incomplete data, which meant that planets around those stars were removed, too. Planets orbiting white dwarfs and pulsars were removed, as were planets orbiting brown dwarfs. The idea was to “represent the population of planets orbiting main sequence stars,” as the authors explain.

This table from the research shows the number of confirmed planetary systems by multiplicity after the researchers applied all of their filters. Image Credit: Howe et al. 2025.

As the table above makes clear, most exoplanet systems contain only a single detected planet. 78% of them host only one planet, often a hot Jupiter, though selection effects play a role in the data. Jupiters are a key planet type in nature and in the classification scheme.

“As expected, Jupiter-sized planets are far less likely to occur in multiplanet systems at periods of <10 days and virtually none do at <5 days, as indicated by the near-coincidence of the two Jupiter distributions at those periods. Meanwhile, roughly half of all other planet types and even a third of Jupiters at periods >10 days occur in multiplanet systems,” the authors explain.

This figure shows the cumulative distributions of confirmed exoplanets with orbital periods. It compares the total numbers of planets (dashed) to those in single-planet systems (solid). “Hot Jupiters show far fewer companions than other planet types, as illustrated by the near-coincidence of the two Jupiter distributions at <10 days,” the authors explain.

The classification system does a good job of capturing the large majority of exoplanet system architectures. However, there are some oddballs, including the WASP-148 system, the only known system with a hot Jupiter and a nearby Jupiter companion. “Given the high detection probability of such a companion and the fact that 10 hot Jupiters are known to have smaller nearby companions, this points to an especially rare subtype of system and potential unusual migration processes,” the authors write.

This table presents the seven oddballs in NASA’s Exoplanet Archive according to the classification scheme. Image Credit: Howe et al. 2025.

Though exoplanet systems seem to be very diverse, this classification scheme shows that there’s a lot of uniformity in the patterns. Even though there’s a large diversity of planet types, most inner systems are either peas-in-a-pod systems or warm Jupiter systems. “Only a tiny minority of N ?3 systems (9 out of 314) prove difficult to classify into one of these two categories,” the authors write.

Like much exoplanet science, this system is hampered by detection biases. We struggle to detect small planets like Mars with our current capabilities. There could be more of them hiding in observed exoplanet systems. There are more detection problems, too, like planets on long orbits. However, the scheme is still valuable and interesting.

“This classification scheme provides a largely qualitative description of the architectures of currently observed multiplanet systems,” the authors explain. “The next step is to understand how such systems are formed, and, perhaps equally important, why other dynamically plausible systems are not present in the database.”

One outcome concerns the peas-in-a-pod systems. Since they’re so prevalent, scientists are keen to develop theories on their formation.

The system also has implications for habitability. The outcomes show that in peas-in-a-pod systems, the planets are often too close to main sequence stars to be habitable. Conversely, these same types of systems around M-dwarfs likely have planets in their stars’ habitable zones. “This may suggest that the majority of habitable planets reside around lower-mass stars in peas-in-a-pod systems,” the authors explain. That brings up the familiar problem of flaring and red dwarf habitability.

Another problem this classification scheme highlights concerns super-Earth habitability. “Most planets in peas-in-a-pod systems are super-Earths, rather than Earth-sized, and may be too large for the canonical definition of a habitable planet,” the authors write.

In their conclusion, the researchers explain that exoplanet systems seem to have clear organizing principles that we can use to classify distinct types of solar systems.

“Though far from complete, we believe this classification provides a better understanding of the population as a whole, and it should be fertile ground for future studies of exoplanet demographics and formation,” the researchers conclude.

The post It’s Time to Start Classifying Exoplanetary Systems appeared first on Universe Today.

How Well Could Earth Life Survive on Exoplanets

Astronomers have found some pretty wild exoplanets. Some are balls of lava the temperature of hell, one is partially made of diamond, and another may rain molten iron. However, not all exoplanets are this extreme. Some are rocky, roughly Earth-sized worlds in the habitable zones of their stars.

Could simple Earth life survive on some of these less extreme worlds?

We currently describe a solar system’s habitable zone by liquid water. If a planet is at the right distance range from its star to host stable surface water, we consider it to be in the habitable zone. However, new research is taking a different approach by emphasizing the role a planet’s atmosphere plays in habitability.

The scientists behind this research tested their idea by seeing if microbes could survive on simulated worlds.

The new research is “The Role of Atmospheric Composition in Defining the Habitable Zone Limits and Supporting E. coli Growth.” It’s available on the pre-print site arxiv.org. The lead author is Asena Kuzucan, a post-doctoral researcher in the Department of Astronomy at the University of Geneva in Switzerland.

We’ve discovered close to 6,000 exoplanets in about 4,300 planetary systems. Our burgeoning catalogue of exoplanets makes us wonder about life. Is there life elsewhere, and are any of these thousands of exoplanets habitable?

Some have teased the possibility. TRAPPIST1-e and Proxima Centauri b are both rocky planets in the habitable zones of their stars. TOI-700 d orbits a small, cool star and may be in its habitable zone. There are many others.

The simple definition of the habitable zone is restricted to a planet’s distance from its star and if liquid water can persist on its surface at that distance. However, scientists know that a planet’s atmosphere plays a large role in habitability. A thick atmosphere on a planet outside the habitable zone could help it maintain liquid water.

“Each atmosphere uniquely influences the likelihood of surface liquid water, defining the habitable zone (HZ), the region around a star where liquid water can exist,” the authors write. Liquid water doesn’t guarantee that a world is habitable, however. In order to understand exoplanet habitability better, the researchers followed a two-pronged approach.

They started by estimating exoplanet surface conditions near the inner edge of a star’s HZ with different atmospheric compositions.

Next, they considered if Earth microbes could survive in these environments. They did lab experiments on E. coli to see how or if they could grow and survive. They focused on the different compositions of gas in these atmospheres. The atmospheric compositions were standard (Earth) air, pure CO2, N2-rich, CH4-rich, and pure molecular hydrogen.

Their experiments used 15 separate bottles, 3 for each of the 5 atmospheric compositions. Each bottle was inoculated with E. coli K-12, a laboratory strain of E. coli that is a cornerstone of molecular biology studies.

This simple graphic shows the atmospheric composition of the test bottles. Each bottle is a combination of different atmospheric composition and pressure. LB stands for Lysogeny broth, a nutrient source for E. coli K12. image Credit: Kuzucan et al. 2025.

“This innovative combination of climate modelling and biological experiments bridges theoretical climate predictions with biological outcomes,” they write in their research.

Along with their laboratory experiments, the team performed a series of simulations with different atmospheric compositions and planetary characteristics. “For each atmospheric composition we simulate, water is a variable component that can condense or evaporate as a function of the pressure/temperature conditions,” they write. For each atmospheric composition, they simulated planets at different orbital distances in order to define the inner edge of the HZ. They also varied the atmospheric pressure.

“Using 3D GCM (General Circulation Model) simulations, this study provides a first look at how these atmospheric compositions influence the inner edge of the habitable zone, offering valuable insights into the theoretical limits of habitability under these extreme conditions,” the authors explain.

This table from the research shows the planetary and stellar characteristics used in the GCM simulations. Image Credit: Kuzucan et al. 2025.

“Our findings indicate that atmospheric composition significantly affects bacterial growth patterns, highlighting the importance of considering diverse atmospheres in evaluating exoplanet habitability and advancing the search for life beyond Earth,” they write.

This figure shows the cell count for E. coli K12 in each simulated atmosphere. Image Credit: Kuzucan et al. 2025.

E. coli did surprisingly well in varied atmospheric compositions. Though there was a lag following inoculation as the E. coli adapted, cell density increased in some of the tests. The hydrogen-rich atmosphere did surprisingly well.

“By the first day after inoculation, cell densities had increased in standard air, CH4-rich, N2-rich, and pure H2 atmospheres,” the authors write. “While cell densities increased similarly in standard air, CH4-rich, and N2-rich atmospheres, a slightly stronger increase was observed in the pure H2 atmosphere. The rapid adaptation of E. coli to pure H2 suggests that hydrogen-rich atmospheres can support anaerobic microbial life once acclimatization occurs.”

Conversely to the H2 results, the CO2 results lagged. “Pure CO2, however, consistently presented the most challenging environment, with significantly slower growth,” the paper states.

Their results suggest that planets with anaerobic atmospheres that are dominated by H2, CH4, or
N2 could still support microbial life, even if the initial growth is slower than it is in Earth’s air. “The ability to adapt to less favourable conditions implies that life could persist on such planets, given sufficient time for acclimatization,” the authors write.

The CO2-rich atmosphere is the outlier in this work. “The consistently poor growth in pure CO2 highlights the limitations of this gas in supporting life, particularly for heterotrophic organisms like E. coli,” Kuzucan and her co-researchers write. However, the authors point out that some life forms can make use of CO2 as a carbon source in some environments. They explain that planets with these types of atmospheres could still host organisms adapted to them, like chemotrophs or extremophiles.

This work combines atmospheric and biological factors to understand exoplanet HZs. “One of our key objectives was to define the limits of the HZ for planets dominated by H2 and CO2 using 3D climate modelling, specifically the Generic PCM model,” the authors explain.

They found that H2 atmospheres have a warming effect, “pushing the inner edge of the HZ to further orbital distances than CO2-dominated atmospheres.” It could extend out to 1.4 AU at 5 bar, while the CO2 atmospheres at the same pressure were limited to 1.2 AU. “This demonstrates the profound impact of atmospheric composition on planetary climate and highlights how H2 atmospheres can extend the
habitable zone further from their host stars,” the researchers write.

Some of the atmospheres they tested are not likely to persist in nature, but the results are still scientifically valuable.

“Although some of the atmospheric scenarios presented here (1-bar H2 and CO2) are simplified, and
may not persist over geological timescales due to processes like hydrogen escape and carbonate-silicate cycling, they nonetheless provide valuable insights into the radiative effects of these gases on habitability,” write the authors.

We know atmospheres are extremely complex, and this research supports that. It also shows how resilient Earth life can be. “Overall, these results highlight both the resilience of E. coli in adapting to diverse atmospheric conditions and the critical role atmospheric composition plays in determining
microbial survival,” the authors explain in their conclusion. Though the authors acknowledge that their findings are rooted in an Earth-centric framework, the results have broader implications. Life could likely thrive in wildly different atmospheric compositions and conditions, according to these results.

“Thus, our study highlights the importance of atmospheric composition and pressure for habitability while acknowledging the limitations of our Earth-centric perspective,” they write.

“By exploring both atmospheric conditions and microbial survival, we gain a deeper understanding of the complex factors that influence habitability, paving the way for future research on the potential for life beyond our solar system.”

The post How Well Could Earth Life Survive on Exoplanets appeared first on Universe Today.

Planet Formation Favors the Metal-Rich Inner Milky Way

Exoplanets have captured the imagination of public and scientists alike and, as the search continues for more, researchers have turned their attention to the evolution of metallicity in the Milky Way. With this answer comes more of an idea about where planets are likely to form in our Galaxy. They have found that stars with high-mass planets have higher metallicity than those with lower amounts of metals. They also found that stars with planets tend to be younger than stars without planets. This suggests planetary formation follows the evolution of a galaxy with a ring of planet formation moving outward over time. 

The search for exoplanets has largely been one of surveying nearby stars.  That generally means we are exploring stars in our region of the Galaxy. As technology develops, our ability to detect them improves and to date, nearly 6,000 planets have been discovered around other stars. A number of different techniques have been used to find them such as the transit method – which detects the dimming of a star’s light due to the presence of the passage of a planet, or the radial velocity method which measures the wobble of a star due to the gravitational tug of a planet. 

This artist’s impression depicts the exomoon candidate Kepler-1625b-i, the planet it is orbiting and the star in the centre of the star system. Kepler-1625b-i is the first exomoon candidate and, if confirmed, the first moon to be found outside the Solar System. Like many exoplanets, Kepler-1625b-i was discovered using the transit method. Exomoons are difficult to find because they are smaller than their companion planets, so their transit signal is weak, and their position in the system changes with each transit because of their orbit. This requires extensive modelling and data analysis.

One key aspect of planetary development in the Galaxy is the presence of metals (elements heavier than hydrogen and helium.) known as metallicity. These elements are formed during the life cycle of a star, especially during supernova explosions. They are scattered through space and form part of the interstellar medium. Understanding the abundance and distribution of metals provides an insight into the age, history and formation rates of stars and planets. 

The Milky Way. This image is constructed from data from the ESA’s Gaia mission that’s mapping over one billion of the galaxy’s stars. Image Credit: ESA/Gaia/DPAC

A team of researchers led by Joana Teixeira from the University of Porto in Portugal have been exploring something known as the Galactic Birth Radii (rBirth) This term relates to the distance from galactic centre that stars and therefore planets are forming. Using photometric, spectroscopic and astrometric data, the team were able to estimate the ages of two groups of stars, those with planets and those without. This enabled them to rBirth for exoplanets based upon the original star positions (having calculated them from their age and levels of metals present within.)

The results of the analysis showed that stars hosting planets had a higher [Fe/H], are younger and were born closer to the centre of the galaxy than those without (Fe/H refers to the amount of iron relative to the amount of hydrogen in a star or galaxy, where the Sun is [Fe/H]=0.3.) The team went further to state that from one data set (from the Stellar Parameters of Stars with Exoplanets Catalog,) the results suggest that stars hosting high mass planets have a different iron to hydrogen radio and age distribution than stars with at least one low mass planet and those with only low mass planets. 

The ESA/NASA Solar Orbiter has given us our highest resolution images of the Sun ever. They show us sunspots, plasma, and magnetic fields, and more. Image Credit: ESA

The research reveals that high mass planets or in other words terrestrial planets tend to form around stars with higher [Fe/H] and younger stars compared to low mass. Similarly, those with a mixture of high and low mass planets also formed around higher [Fe/H], young stars. 

It’s an interesting study worthy of further investigations. Understanding that Earth-like planets tend to form around star systems that formed around the inner regions of the Galaxy. Here the supply of metals is more abundant and, even though the stellar systems can migrate to outer regions of the Milky Way it gives a better focus on the hunt for planetary systems beyond our own. 

Source : Where in the Milky Way Do Exoplanets Preferentially Form?

The post Planet Formation Favors the Metal-Rich Inner Milky Way appeared first on Universe Today.

Dynamically Stable Large Space Structures via Architected Metamaterials

Exoplanet exploration has taken off in recent years, with over 5500 being discovered so far. Some have even been in the habitable zones of their stars. Imaging one such potentially habitable exoplanet is the dream of many exoplanet hunters, however, technology has limited their ability to do that. In particular, one specific piece of technology needs to be improved before we can directly image an exoplanet in the habitable zone of another star – a starshade. Christine Gregg, a researcher at NASA Ames Research Center, hopes to contribute to the effort of developing one and has received a NASA Institute for Advanced Concepts (NIAC) grant as part of the 2025 cohort to work on a star shade that is based on a special type of metamaterial.

To understand the goal of Dr. Gregg and her team, it’s best first to understand what starshades do and what’s holding them back from being deployed. A starshade is designed to float in tandem with a space telescope and block out the light from a specific star, allowing the telescope to capture light directly from the much-less bright planet that is orbiting the star. That light can contain information about its size, orbital period, and even its atmospheric composition that would otherwise be lost in the overwhelming brightness of the planet’s star.

The shape of a starshade, which traditionally looks like a flower petal, might seem counterintuitive at first – if you’re trying to block a star’s light, why not just make the shape circular? But starlight coming from far away can diffract around a simple circle structure. The petals are explicitly designed to stop that from happening and completely block out even diffracted light around the shape’s edges.

Fraser interviews another Starshade expert – Dr. Markus Janson from Stockholm University

But it’s not the shape that makes it hard to deploy—it’s its size. Starshades are typically designed to be hundreds of meters across. Therefore, they are impossible to fit inside a traditional rocket fairing fully assembled. What’s more, they have to move along with the telescope—if the telescope the starshade is meant to accompany is pointed at another star and redirected, the starshade has to move with it.

The wrinkle is that the starshade is likely tens of thousands of kilometers from the telescope it is designed to assist. So, a slight change of a few degrees of inclination for the telescope would mean hundreds of thousands of kilometers of travel for its associated starshade. That kind of movement requires a lot of fuel, which is also costly due to the weight requirements of launching these objects so far away. 

No wonder a starshade has yet to be successfully deployed in space. Combining gigantic sizes that don’t fit inside rocket fairings and massive amounts of fuel to relocate every time the telescope needs to look at a different star are significant strikes against the concept. However, if humanity wants to directly image an exoplanet in the habitable zone of another star, there is still no better way to do so.

NASA animation of the deployment of a starshade

Enter Dr Gregg’s idea—she proposes using metamaterials for her starshade, which is robotically constructed in orbit. Metamaterials have several advantages over existing proposed starshades (one of which, by Nobel Prize winner John Mather, is another NIAC recipient this year). 

First, metamaterials are lighter. As with all things launched into space, being lighter means less cost – or, in this case, the ability to bring more fuel, allowing the starshade to operate longer than alternatives. 

Second, the specific kinds of metamaterials she proposes to use are much less likely to break. As she mentioned to Fraser in an interview, “The more stiffness a material has, the less damping it has. It’s just sort of a natural trade-off”. So, if a starshade is made from traditional materials, it would either be stiff and rigid but prone to vibrational strain when moving between positions or being deployed, or it would be very flexible but would have difficulty holding its shape when it’s supposed to.

This video shows phononic materials in action.
Credit – aiM Program at Duke University YouTube Channel

The metamaterial Dr. Gregg and her colleagues have proposed uses a type of material that both holds its structure well but also suppresses vibration by a unique use of a material called a phononic crystal. These were initially engineered to dissipate sound waves. This means that when used as a material in a starshade, it could dampen any feedback on the structure from things like micrometeoroid impacts, solar radiation, or even the process of deployment and assembly.

Using robots to deploy the starshade is another focal point of Dr. Gregg’s work, as she discusses with Fraser. Still, for this Phase I NIAC project, she is focusing on developing the model for starshade itself and selecting the appropriate material. As with all NIAC projects, she can apply for more funding in a Phase II round upon completion of her Phase I. If she receives it, humanity will be one step closer to seeing a giant floating petal in space – but one with very particular mechanical and structural properties.

Learn More:
NASA / C. Gregg – Dynamically Stable Large Space Structures via Architected Metamaterials
UT – In Order to Reveal Planets Around Another star, a Starshade Needs to Fly 40,000 km Away from a Telescope, Aligned Within Only 1 Meter
UT – Starshade Prepares To Image New Earths
UT – To Take the Best Direct Images of Exoplanets With Space Telescopes, we’re Going to Want Starshades

Lead Image:
Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the Dynamically Stable Large Space Structures via Architected Metamaterials concept. NASA/Christine Gregg

The post Dynamically Stable Large Space Structures via Architected Metamaterials appeared first on Universe Today.

Why The First Stars Couldn’t Grow Forever

Star formation in the early Universe was a vigorous process that created gigantic stars. Called Population 3 stars, these giants were massive, extremely luminous stars, that lived short lives, many of which were ended when they exploded as primordial supernovae.

But even these early stars faced growth limitations.

Stellar feedback plays a role in modern star formation. As young stars grow, they emit powerful radiation that can disperse nearby gas they need to keep growing. This is called protostellar radiative feedback, and it takes place in addition to the restrictive effect their magnetic fields have on their growth.

However, new research shows that the growth of Pop 3 stars was limited by their magnetic fields.

The research is titled “Magnetic fields limit the mass of Population III stars even before the onset of protostellar radiation feedback.” The lead author is Piyush Sharda, an astrophysicist at the Leiden Observatory in the Netherlands. It’s available on the pre-print server arxiv.org.

Scientists observe stars forming in the modern Universe to understand how the process plays out. This is difficult because stars take so much time to form, while we’ve only been watching young stars from a great distance for a few decades. Stars are massive, energetic, complex objects that don’t give up their secrets easily.

There are many unanswered questions about star formation, but a general picture has emerged. It starts with a cloud of cold molecular hydrogen that collapses into dense cores. These cories become protostars, also called young stellar objects (YSOs). Accretion disks form around the young stars, and this is where radiative feedback comes in.

This artist’s concept shows a young stellar object and the whirling accretion disk surrounding it. NASA/JPL-Caltech

As young stars accrete mass, they heat up. They radiate this heat outward into their own accretion disks. As the material in the disk heats, it slows or even stops the accretion process. So radiative feedback limits their growth.

YSOs also rotate more rapidly than more mature stars. The rotation creates powerful magnetic fields, and these fields drive jets from the YSO’s poles. These jets steal away some of the accretion energy, limiting the stars’ growth. The jets can also disperse some of the surrounding gas, further limiting their growth.

However, the picture may look different for Pop 3 stars. To begin with, their existence is hypothetical at this point in time, though theory supports it. If they’re real, astrophysicists want to know how they formed and what their growth limits were. If they’re real, Pop 3 stars played a critical role in the Universe by forging the first metals and spreading them out into space.

According to the authors of the new research, simulations haven’t been thorough enough to explain the masses of Population 3 stars.

“The masses of Population III stars are largely unconstrained since no simulations exist that take all relevant primordial star formation physics into account,” the authors write. “We evolve the simulations until 5000 years post the formation of the first star.”

In the team’s more thorough simulations, which include magnetic fields and other factors, these early stars are limited to about 65 solar masses. “In 5000 yrs, the mass of the most massive star is 65 solar masses in the RMHD <radiation magnetohydrodynamics> simulation, compared to 120 solar masses in simulations without magnetic fields,” they write.

This figure from the research shows a panel from each type of simulation: HD (hydrodynamic), MHD (magneto-hydrodynamic), RHD (radiation-hydrodynamics including ionizing and dissociating radiation feedback), RMHD (radiation-magnetohydrodynamics). They show each simulation at 5,000 years after the first star forms. White dots show the positions of Population 3 stars. Image Credit: Sharda et al. 2025

The results show that both simulation runs that included magnetic fields are fragmented, leading to the formation of Pop 3 star clusters. That means that the evolution of the most massive Pop 3 stars in both runs is influenced by the presence of companion stars.

The difference comes down to gravity and magnetic fields working against each other. As young stars accrete mass, their gravitational power increases. This should draw more material into the star. But magnetic fields counteract the gravity. This all happens before radiative feedback is active.

The results also show that in both simulations that include magnetic fields, the amount of mass that reaches the envelope initially increases, then declines. However, the results were different in the simulations without magnetic fields. In those simulations, mass transfer from the envelope to the accretion disk is fast at first, creating a decline in the mass in the envelope and a build-up of mass in the disk. “This mass is consequently accreted by the star at a high rate,” the authors write.

This figure from the research illustrates some of the simulation results. It shows the mass enclosed within a disk of radius 500 au and height 50 au (from the midplane) around the most massive star. “The mass reservoir that can be accreted onto the central star in the MHD and RMHD runs eventually decreases as magnetic fields suppress gravitational collapse,” the authors explain.

“We learn that magnetic fields limit the amount of gas infalling onto the envelope at later stages by acting against gravity, leading to mass depletion within the accretion disk,” the authors explain. “The maximum stellar mass of Population III stars is thus already limited by magnetic fields, even before accretion rates drop to allow significant protostellar radiative feedback.”

Though Population 3 stars are only hypothetical, our theories of physical cosmology rely on their existence. If they didn’t exist, then there’s something fundamental about the Universe that is beyond our grasp. However, our cosmological theories do a good job of explaining what we see around us in the Universe today. If we’re putting money on it, place your bets on Pop 3 stars being real.

“Radiation feedback has long been proposed as the primary mechanism that halts the growth of Pop III stars and sets the upper mass cutoff of the Pop III IMF (initial mass function),” the authors write in their conclusion. They show that magnetic fields can limit stellar growth before feedback mechanisms come into play.

“This work lays the first step in building a full physics-informed mass function of Population III stars,” the authors conclude.

The post Why The First Stars Couldn’t Grow Forever appeared first on Universe Today.

Ingenuity Measured Windspeeds on Mars During its Flights

One of my gripes with ‘The Martian’ movie was the depiction of the winds on Mars. The lower air density means that the sort of high speed winds we might experience on Earth carry far less of an impact on Mars. During its 72 flights in the Martian air, NASA’s ingenuity helicopter took meticulous records of the conditions. A new paper has been released and reports upon the wind speeds on the red planet at various altitudes. Previous models suggested wind speeds would not exceed 15 m/s but Ingeniuty saw speeds as high as 25 m/s.

Of all the planets in our Solar System, Mars is perhaps the most similar to Earth, similar but with stark differences. The weather on Mars is harsh and extreme, characterised by cold temperatures, a rarefied atmosphere and dust storms. The average temperature is around -60°C but it can reach a toasty 20°C in summer near the equator. It’s atmosphere is composed mostly of carbon dioxide and is about 100 times thinner than Earth’s so it offers little insulation or protection from solar radiation. On occasion, the winds on Mars whip up global dust storms that obscures the planet’s surface from view. 

Mars seen before, left, and during, right, a global dust storm in 2001. Credit: NASA/JPL/MSSS

Our model of the Martian atmosphere was believed to be fairly accurate, that is until Ingenuity arrived and completed more than 70 successful flights. As part of the Mars 2020 mission and the first aerial vehicle to successfully complete powered flight on another world, Ingenuity revealed some surprising conditions. Surprisingly too perhaps, the first attempt at powered flight was supposed to be a technology demonstration but instead, it provided high resolution images to help direct the ground based rover and collected data from the atmosphere and became a key part of Mars 2020. 

The Ingenuity helicopter photographed by the Perseverance rover. Credit: NASA/JPL-Caltech

One of the outcomes from Ingenuity’s flights was a better understanding of Martian winds. In a paper written by Brian Jackson and team in the Planetary Society Journal, the team explained their rather ingenious approach. Knowing that the payload was severely limited on board, the decision was taken to use Ingenuity itself to confirm windspeeds. Previous studies had shown that the tilt of a stably hovering drone can be used to calculate speeds. Drones produce forward thrust by tilting in the direction they need to move, if they are stable and in a hover yet the wind is blowing, the drone will drift. Instead and to counteract the drift, the drone tilts flying into wind to maintain position relative to the ground, tilting more in a stronger headwind. 

Measuring the tilt is relatively straightforward thanks to a collection of engineering sensors, cameras and accelerometers. With all of the information gathered by these onboard pieces of equipment and returned to Earth, the analysis and calculation of the drone at different altitudes has enabled the wind speeds to be accurately calculated.

Part of the Ingenuity rotorcraft

The results were a surprise, showing that the winds on Mars were generally higher than anticipated. Speeds were measured at altitudes from 3 to 24 metres and were found to be blowing at anything up to 25 m/s. This perhaps is a result of Ingenuity’s unique capability of being able to measure speeds at different altitudes over a period of time. Previous measurements have been achieved from probes as they have descent through the atmosphere or from probes on the ground. Taking the success of Ingenuity forward, mission specialists working upon the Dragonfly rotorcraft that will be visiting Titan hope to be able to replicate the results and gain a better understanding of its wind profile too. 

Source : Profiling Near-surface Winds on Mars Using Attitude Data from Mars 2020 Ingenuity

The post Ingenuity Measured Windspeeds on Mars During its Flights appeared first on Universe Today.