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There might be a type of exoplanet without dry land. They’re called “Hycean” worlds, a portmanteau of ‘hydrogen’ and ‘ocean.’ They’re mostly or entirely covered in oceans and have thick hydrogen atmospheres.

They’re intriguing because their atmospheres keep them warm enough to have liquid water outside of the traditional habitable zones. If they do exist, scientists think they’re good candidates to support microbial life.

Hycean worlds are hypothetical, but there is some evidence that they exist. The Kepler mission detected many candidates and provided foundational evidence for their existence. However, it didn’t detect any with certainty.

More recently, JWST observations also supported the idea. The space telescope detected carbon dioxide and methane in the atmosphere of a candidate Hycean world called K2-18b. Both of those molecules can be biosignatures of microbial life under similar conditions as Earth’s oceans.

This infographic shows the chemicals the JWST detected in the atmosphere of K2-18b. In addition to the carbon-bearing molecules methane and carbon dioxide, it detected the potential biosignature dimethyl sulphide. Image Credit: JWST/STScI

New research published in the Monthly Notices of the Royal Astronomical Society examines the potential Hycean worlds hold for the evolution of life and how life might depend on these worlds’ thermodynamic conditions. It’s titled “Prospects for Biological Evolution on Hycean Worlds.” The authors are Emily G Mitchell and Nikku Madhusudhan, both from the University of Cambridge.

“The search for extraterrestrial life is one of the most fundamental quests in human history,” the authors write. “An important recent development in this direction is the possibility of Hycean worlds, which increase both the numbers of potentially habitable planets and the ability to detect biosignatures in their atmospheres.”

Research shows that Hycean Worlds can provide both the chemical and the thermodynamic conditions necessary for microbial life to persist in their oceans. In this research, the authors used the metabolic theory of ecology (MTE) to explore how simple life might evolve in Hycean Worlds under different temperature conditions. In simple terms, MTE says that an organism’s metabolic rate is fundamental to its ability to persist and thrive. It applies to individual processes and community and population processes. A key idea behind MTE is that temperature strongly influences metabolic rates.

Previous studies show that when temperatures in a habitable environment increase, biological activity increases up to a point. In this research, Mitchell and Madhusudhan investigate how ocean surface temperatures affect Earth-like single-celled life and how long it takes them to originate on Hycean Worlds. They also explore how different temperatures affect the detectability of biosignatures.

“This work, in turn, has observable consequences for prominent biosignatures on such planets, considering that unicellular phytoplankton are a major source of key biomarkers in the Earth’s atmosphere, such as dimethyl sulphide, which may be observable in Hycean atmospheres,” the researchers write in their paper.

Dimethyl sulphide is strongly linked to phytoplankton and has a unique spectral signature that the JWST can detect in exoplanet atmospheres.

The researchers focused on several key phytoplankton groups that are abundant on Earth and produce biosignature gases in its atmosphere. Among them are Cyanobacteria (blue-green algae), Methanococccea (a methanogen), and diatoms, which generate as much as 50% of Earth’s oxygen each year. They paid special attention to Aquificota.

Aquificota is a phylum of bacteria named after an early genus in the group Aquifix. Its members are found in fresh water and oceans and can produce water by oxidizing hydrogen.

“In order to illustrate how evolutionary rates change with temperature over planetary timescales, we have calculated the evolutionary rates for an example organism (Aquifix) over the last 4.3 billion years,” the paper states. They used Aquifix because it’s a strong analogue for some of Earth’s first life.

The researchers showed that even marginal changes in Earth’s ocean surface temperature compared to the surface temperature over evolutionary timescales significantly change the origination time and evolutionary rates of important species of simple life. “For example, a 10 K increase relative to Earth
leads to evolutionary rates which are over twice as fast, while a decrease of 10 K halves them,” the authors explain.

They found that warmer oceans can accelerate the rate of evolution, allowing key unicellular groups like archaea and bacteria to appear as early as 1.3 billion years after the origin of life. This indicates that higher temperatures drive a faster progression to complex life. “This increased rate has a significant impact on the origination times of unicellular groups such that for an increase of 10K of surface temperature, all of the major groups will have originated by 1.19 Gyr post-Origin of Life (OlL) and all the key phytoplankton groups by 1.28 Gyr,” the authors write.

This figure from the research shows the effect of temperature on the origination times of major clades. The origination time on Earth of each group is marked with a forward arrow. Red indicates increased
temperature by +10 K, and blue indicates decreased temperature by -10 K. “We find that an increase in the surface temperature of 10K results in all the phytoplankton groups originating with 1.3 Gyr of the OoL,” the authors explain. Cyanobacteria appear particularly early, only 0.25 billion years after the Origin of Life. Image Credit: Mitchell and Madhusudhan 2025.

The reverse is also true. The researchers found that cooler temperatures delay the appearance of key lifeforms by up to several billion years. That could mean that complex life takes longer to appear. “In contrast, a decrease of 10K of median surface temperature severely limits the origination rates, such that by 4 Gyr post-OoL, only Bacteria and Archaea will have evolved but not oxygenic photosynthesis or Eukaryotes,” the authors write.

In that case, it would also affect the appearance of observable biosignatures, and their intensity and ease of detection.

One of their central findings is that only a marginal range of environmental conditions allows for a large range of evolutionary rates and origination times. “First, given the wide range of possible atmospheric conditions in Hycean worlds, an equally wide diversity in microbial life could be expected,” they write. “In particular, the origination of new clades in warm Hycean worlds can happen significantly faster than on Earth.”

If Hycean worlds exist, this research suggests that they could be “rippling with life,” as Carl Sagan put it, on shorter timescales than Earth.

An artist’s illustration of a Hycean World. Image Credit: By Pablo Carlos Budassi – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=135998139

The candidate Hycean worlds we know of are thought to have warmer oceans than Earth. So, by extension, the candidate Hycean World K2-18 b, which is only 2.4 billion years old, could have the conditions necessary for originating and sustaining key unicellular groups. That means that it, and others like it, are good targets in the search for biosignatures.

The authors offer a couple of caveats to their results. They considered only a fairly narrow range of temperature and physical conditions based on Earth. In reality, habitable extraterrestrial planets could exhibit a much wider range. “Future work in this direction could explore a range of other conditions, including the effect of gravity, pressure, larger temperature variations and other environmental factors,” the researchers write in their conclusion.

We don’t know if Hycean Worlds are real. Some scientists think that their hydrogen-rich atmospheres might be unstable. There are also concerns about radiation exposure inhibiting life and atmospheric chemistry working against biochemical processes. The formation pathways for these worlds are also unclear, as are the mechanisms for generating and sustaining their atmospheres.

However, if they do exist, this study makes one thing clear: For different surface temperatures, a warm planet could have a more complex biosphere at a relatively young age, and a cooler one could have a simpler biosphere at a later age.

In the end, we aren’t travelling to any of these worlds, so detecting biosignatures is the name of the game.

“Such biospheres with varied levels of complexity can impact the detectability of life on them, such that warmer planets have the potential to show strong atmospheric biosignatures,” the researchers conclude.

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Kepler was one of the most successful exoplanet-hunting missions so far. It discovered 2,600 confirmed exoplanets – almost half of the total – in its almost ten years of operation. However, most data analysis focused only on one of the 150,000 targets it “intended” to look at. While it was making those observations, there were a myriad of background stars that also had their light captured incidentally. John Bienias and Robert Szabó of Hungary’s Konkoly Observatory have spent a lot of time looking at those background stars and recently published a paper suggesting there might be seven more exoplanet candidates hiding in the data.

As with many space telescope missions, Kepler’s dataset is open to the public. NASA maintains a database with the raw data collected during the space telescope’s observations, and researchers are free to download it and analyze it as they see fit.

Plenty of interesting things are hiding in that data that were overlooked by the more than 3136 peer-reviewed scientific papers that have utilized Kepler’s data. In the past, the authors have published other documents using the same datasets that described eclipsing binary stars and RR Lyrae stars, a type of pulsating variable star already existing in the data.

Fraser discusses the end of Kepler’s mission.

But while looking for more data on another paper about longer-period versions of those phenomena, they came across several stars whose light curve variability indicated something different – a planet passing in front of them. These “transits”, as they are called, are one of the most common ways to identify exoplanet candidates, and have been used for decades, but this might be the first time they’ve been used on some of the 500,000 background stars in Kepler’s data.

That might be because the data is patchier, as the telescope was not focused on the stars in the background, making this resolution more difficult. However, difficult does not mean impossible, and plenty of software solutions have been developed in the six years since the end of Kepler’s primary mission to help facilitate crunching large sets of data to look for planets around other stars.

One such system that has been around for a while is the Lomb-Scargle algorithm, developed in the 1970s and 80s and designed to detect periodic signals within time-series data. This algorithm is a valuable step in finding both the eclipsing binaries the authors were initially looking for and the exoplanet candidates they recently described.

Fraser discusses Kepler’s newest successor – MAUVE.

Other, more modern tools, proved more finicky, such as PSFmachine. This software package is designed to “deblend” light curves in Kepler’s data. Light curves are critical to exoplanet hunting as they show how the brightness of an object changes over time. However, in Kepler’s background, multiple stars might be overlapping, causing a blending of their light curves. PSFmachine is designed to deal with that problem. However, the authors described several issues in using the software, including its inability to create any stand-alone curves in one case. This seemed to be due to the placement of the stars compared to Kepler’s aperture (i.e., they were in the background) and the relatively small variations seen in the data.

Another tool developed near the end of Kepler’s mission was Pytransit, a Python-based software package that estimates the transmit models of light curves, including period, sizes, and orbital eccentricity. Candidate stars were also cross-referenced with the dataset from Gaia, which is designed to capture data about stars. 

Utilizing all the tools, the authors identified seven exoplanet candidates. All were hot Jupiters, with sizes between .89 and 1.52 Jupiter’s radius and orbits between .04 and .07 AU. They also checked to see if any of those dips in light curves might have been caused by second planets orbiting the same star but came up empty-handed.

While seven additional candidate exoplanets might not seem like a lot compared to the 2,600 confirmed ones Kepler already found, combing over already released data shows how much more helpful context is sometimes publicly available if a researcher knows where and how to look. As more powerful software packages and analytical tools are developed, there will undoubtedly be more discoveries coming out of older data sets like Kepler’s for some time to come.

Learn More:
J Bienias & R Szabó – Background exoplanet candidates in the original Kepler field
UT – Old Data from Kepler Turns Up A System with Seven Planets
UT – This is Kepler’s Final Image
UT – It’s Over For Kepler. The Most Successful Planet Hunter Ever Built is Finally out of Fuel and Has Just Been Shut Down.

Lead Image:
Artist’s impression of Kepler
Credit – NASA Amex / JPL-Caltech/T Pyle

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Rovers on alien worlds need to be built of strong stuff. The dry rugged terrain can be punishing on the wheels as they explore the surface. In order to prevent the damage to the wheels, NASA is testing a shape memory alloy material that can return to its original shape after being bent, stretched, heated or cooled.  NASA has already used this material for years but never in tires, in what may be its perfect application.

Rovers are a common sight now as they explore the surface of other planets. Their versatility and ability to respond to the environment and commands from mission controllers make them a valuable exploration tool. Cameras, sensors, collection instruments and analysis tools are common onboard systems that provide information about the local environment. There have been a number of well known examples such as the Mars rovers; Spirit, Opportunity, Curiosity and Perseverance. They have helped us to learn about the geology, atmosphere, presence of water and habitability of the planet. Taken Mars as a case in point, we have only explored 1% so there is most certainly still a need for robotic rover exploration. 

Mars Perseverence rover sent back this image of its parking spot during Mars Solar Conjunction. Courtesy NASA/JPL-Caltech

Perhaps the most robust aspect of a rover is its wheels and tires. They must be capable of coping with rugged, uneven and rocky surfaces yet light enough not to cost a fortune to launch to the alien worlds. NASA has recently undertaken and completed a rigorous round of testing of a new tire using revolutionary shape memory alloys material. The tire technology was developed at the Glenn Research Center in partnership with Goodyear Tire and Rubber. 

The shape memory alloys have been used for numerous applications due to their unique feature of being able to return to their original shape after being deformed. They are typically made from combinations of metals like nickel and titanium which exhibit the property known as super-elasticity. The fascinating property allows the material to ‘remember’ its original shape and have been used in medical devices like stents, wires and various aerospace components. This is the first time NASA have explore their use in tyres. 

Image of the Opportunity rover’s front wheel, taken on June 9th, 2004. Credit: NASA/JPL/Cornell

The idea about their use in rover wheels came about rather by chance. Dr. Santo Padula II, materials research engineer at NASA Glenn Research Center came across Colin Creager a NASA mechanical engineer while leaving a meeting. Creager explained about the work he was doing in the Glenn Simulated Lunar Operations Laboratory (a simulated lunar surface) to improve rover performance. Having enjoyed a tour of the facilities, Padula noticed the rover tyres were made of steel. Padula immediately realised that the steel wheels would get irreversibly damaged through use ultimately leading to their failure to provide traction. On discussing the matter, Creager explained it was the only problem they couldn’t solve. 

As a materials researcher Padula told him about his  work on a new alloy that would solve the problems with wheel irreversible deformations. The SMA tires concept was born. The two joined forces to develop the first nickel-titanium tires that would deform but return to their original shape and, after rigorous testing, the SMA tires became the solution to Creager’s problem. 

The team is now looking for other ways that SMAs can be used in other space exploration such as habitat protection. The extreme environment of space with meteoroid impacts being a regular occurrence make memory alloys the ideal solution. As robotic exploration continues apace and human exploration of our Solar System moves forward, SMAs look set to be a real game changer in ensuring safety and continued operation of a multitude of space hardware. 

Source : NASA Sets Sights on Mars Terrain with Revolutionary Tire Tech

Link : https://www.nasa.gov/technology/nasa-sets-sights-on-mars-terrain-with-revolutionary-tire-tech/

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The study of exoplanets is challenging enough with the immense distances and glare from the host start but astronomers have taken planetary system explorations to the next level. A team of astronomers have recently announced that they have observed belts of icy pebbles in systems with exoplanets. Using a radio telescope they have been able to detect wavelengths of radiation emitted by millimeter-sized pebbles created by exocomet collisions! Based upon this survey, they have found that about 20% of planetary systems contain these exocometary belts.

Our own Solar System is peppered with them so it’s perfectly reasonable to expect to find them in planetary systems around other stars. The so called exocomets are generally only detected when they pass through or near to our own system. It would also be reasonable to assume they are made of the same icy and rocky material as our own comets but they can still provide valuable insights into the formation and evolution of exoplanetary systems. The first such comet was discovered around the star Beta Pictoris in the 19080s.

Comet 12P Pons-Brooks. Credit: Michael Jaeger.

A team of astronomers that have been working upon the REASONS (REsolved ALMA and SMA Observations of Nearby Stars) study and have imaged exocomet belts around nearby stars! ALMA (the Atacama Large Millimeter/submillimeter Array) and SMA (Submillimeter Array) are powerful radio observatories that explore the skies in millimetre and submillimeter wavelengths. ALMA is based in northern Chile and composed of an array of 66 dishes and SMA is in Hawaii consisting of 8 dishes. 

The Atacama Large Millimeter/submillimeter Array (ALMA). Credit: C. Padilla, NRAO/AUI/NSF

The team led by astrophysicists from Trinity College Dublin have been revealed images that reveals pebbles and hence the locations of exocomets. In most cases, they are located tens to hundreds of astronomical units from their host star (one astronomical unit is the average distance from Earth to the Sun.) At theses immense distances from the star the temperatures will be in the between -250 and -150 degrees where any water will be frozen. The observations have detected the radiation emitted from the exocometary collisions. It’s the first time such an in depth analysis has been completed and to date, they have released images from belts in 74 exoplanetary systems. 

The rings are quite varied with some multiple disks and risks, others exhibiting high eccentricity. The eccentricity suggests that there are planets in these systems causing gravitational effects to modify the distribution of the pebbles in the belts.

Co-author of the study Dr Sebastian Marino,  Royal Society University Research Fellow from the University of Exeter explained “The images reveal a remarkable diversity in the structure of belts. Some are narrow rings, as in the canonical picture of a ‘belt’ like our Solar System’s Edgeworth-Kuiper belt. But a larger number of them are wide, and probably better described as ‘disks’ rather than rings.”

The study was able to develop a model showing that the number of pebbles seems to decrease for older planetary systems. This makes sense since an aged system will have run out of exocomets to generate the debris. They also found that the decrease in pebbles is faster when the belt is closer to the star.

Over the last few decades the focus seems to have been on exoplanets but this recent study has shown that the field of exocometary research is well and truly off the starting blocks and revealing fascinating insights into the exoplanetary systems. 

Source : Astrophysicists reveal structure of 74 exocomet belts orbiting nearby stars in landmark survey

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Red dwarfs always make me think of the classic British TV science comedy show in the 90’s that was named after them. The stars themselves better little resemblance to the show though. They are small, not surprisingly red stars that can generate flares and coronal mass ejections that rival many of the much larger stars. A team of astronomers have recently used the Chandra X-Ray Observatory to study Wolf 359 and found it unleashes brutal X-ray flares that would be extremely damaging to life on nearby planets. 

Red dwarf stars are small, cool, and very long-lived stars that shine with only a fraction of the brightness of our Sun. They have a mass less than half of the Sun’s and their surface temperatures range from 2,500 to 4,000 degrees Celsius. Because they burn their fuel so slowly, red dwarfs can last for trillions of years, far outliving more massive stars. They are common across the cosmos making up about 70-80% of all stars in the Galaxy but despite this they are hard to spot with the naked eye. 

An artistic impression of Trappist-1 B shortly before it passes behind the cool, red dwarf star, Trappist-1. Such stars are known for their activity with large starspots and eruptions. Trappist-1 B may experience intense volcanism. Credit Thomas Muller (HDA.MPIA)

Wolf 359 is a one such red dwarf star located about 7.8 light-years away from Earth, making it one of the closest stars to our solar system. It’s still too dim to be seen without a telescope though shining at just one-thousandth the brightness of the Sun. It’s part of the constellation Leo and has a mass only about 12% of our Sun’s, with a surface temperature around 4,000 degrees Celsius. Wolf 359 is a relatively young star, but due to its low mass, it will burn its hydrogen fuel slowly and could remain stable for tens of billions of years.

With the intense radiation emissions from Wolf 359 its very likely that any planets in orbit around it will be unable to maintain a stable life supporting atmosphere. A team of astronomers however have been studying it with NASA’s Chandra X-Ray Observatory and ESA’s XMM Newton. They have found that only a planet that has green house gasses, just like Earth, in its atmosphere could sustain life. Given that red dwarfs are the most prevalent stars in the Universe, astronomers have explored them to find evidence of exoplanets but to date, with little success. The team found evidence for two planets in orbit about Wolf 359 but not all scientists are convinced. 

Artist’s illustration of Chandra

Every star has a habitable zone and its location is determined by the temperature and energy output from the star itself. The outer limits for this zone around Wolf 359 is about 15% of the distance between Earth and Sun. The two yet to be confirmed exoplanets orbit the star outside the habitable zone; one is too close, the other to far. 

As they studied the system over 3.5 days, they observed 18 X-Ray flares from Wolf 359. That was just over 3.5 days though and the team propose that more powerful and more damaging flares will occur from time to time. These intense X-ray flares are the chief reason that any planets in orbit must be within the habitable zone and will need an atmosphere rich in carbon dioxide to sustain habitable conditions. It’s unlikely however, that any planet within the habitable zone will be able to keep its atmosphere due to the strength of the wind blowing upon it. 

Source : Exoplanets Need to Be Prepared for Extreme Space Weather, Chandra Find

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If you want to know what the newly forming Solar System looked like, study planetary disks around other stars. Like them, our star was a single star forming its retinue of worlds and other stars did the same. This all happened 4.5 billion years ago, so we have to look at similar systems around nearby stars.

Recently astronomers used radio and optical telescopes to study a collection of so-called “double planetary disks”. These are collections of material around binary stars, sometimes also called “protoplanetary disks.” They zeroed in on a system called DF Tau because it showed some peculiar characteristics. You’d think the planetary disks in those pairs would be roughly the same since they formed from the same raw materials as their parent stars. However, they show some surprising differences from each other.

DF Tau and Its Double Planetary Disks

DF Tau lies just over 400 light-years away from us in the constellation Taurus. It’s in a giant molecular cloud that contains hundreds of newborn stars. DF Tau is two fairly young stars of equal mass. They’re in a 48-year-long orbital dance with each other, and very likely formed together in the same cloud of gas and dust. However, their disks show distinct differences. The brighter, primary star has an active inner disk. The secondary star’s inner region appears to have almost completely disappeared. What does this say about the formation and evolution of these regions and their planets (if they have any)?

According to Dr Taylor Kutra of Lowell Observatory and one of the researchers looking at this system, it’s complex. “The dispersal of circumstellar disks is a complicated process with many unknowns,” said Kutra. “By looking at systems that form together, we can control one major variable: time. DF Tau and other systems in our survey tell us that disk evolution isn’t strictly a function of time, other processes are at play.”

Disk Mechanics

Think of planetary disks like giant wheels spinning in the hearts of molecular clouds. As it moves, material from the disk clumps together. That forms planetesimals, and ultimately planets. The process of planet formation eventually uses up the material in the disk. It doesn’t take long for the material to dissipate like this. There’s nothing left of our own Solar System’s circumstellar birthplace, so we have to look for other examples to understand our own.

Artist’s depiction of a protoplanetary disk in which planets are forming. Credit: ESO/L. Calçada

Finding such disks around other stars is a snapshot of a planetary crèche early in the formation and evolution process. Finding a pair of them as a binary is an extraordinary chance to understand the complications of planetary formation in such a pair. The fact that one of them has experienced dissipation of its inner region raises a lot of questions. What’s happening to cause that dissipation? Could it be due to planetary formation taking place more rapidly in one disk? Is there formation taking place in the brighter one? What other processes could cause such an imbalance in the two structures?

Kutra and a team of astronomers used the NRAO’s Atacama Large Millimeter Array in Chile, as well as optical and infrared observations from other facilities such as the Keck Observatory to study the pair. Their data should help shed light on the process of planetary formation in the paired disks, and explain the differences. One possibility to explain the differences in dissipation is to look at the viscosities of the individual disks. Another is to look for the presence of a substellar companion carving out gaps in the one surrounding the secondary star. It’s also possible that the newborn stars could affect their disks in different ways. In some systems, those stars work to evaporate their disks quite quickly.

Future Work Needed

DF Tau wasn’t the only system they studied. There are many other sources in the ALMA survey. They allow astronomers to study how circumstellar disks evolve, particularly in binary systems. The DF Tau system merits more study since astronomers are just beginning to understand its characteristics.

Once astronomers get a handle on these processes, it should help us understand planet formation in circumstellar disks. That’s because their evolution directly affects the timing of planetary formation. Astronomers will continue to probe the density of the disks, and the timing of changes in the inner and outer regions—and if all goes well—search for newly forming worlds there and in other systems they find in the future. Since not all stars form as singletons (like the Sun did), checking out more binaries should give us a better understanding of binary star and planet evolution.

For More Information

Double the Disks, Double the Discovery: New Insights into Planet Formation in DF Tau
Sites of Planet Formation in Binary Systems. II. Double the Disks in DF Tau
Star Formation in the Taurus-Auriga Dark Clouds

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A spacecraft takes between about seven and nine months to reach Mars. The time depends on the spacecraft and the distance between the two planets, which changes as they follow their orbits around the Sun. NASA’s Perseverance is the most recent spacecraft to make the journey, and it took about seven months.

If it didn’t take so long, then Mars would be within reach of a human mission sooner rather than later. NASA is exploring the idea of using nuclear electric propulsion to shorten the travel time.

Sending a crewed mission to Mars is much more complicated than sending a robotic explorer like Perseverance. Perseverance will be left there after its mission ends. But humans need to return to Earth. One of the main restrictions is launch windows. These occur every 26 months when the planets are closest to one another, making the trip shorter and more manageable. So, a crewed return mission to Mars could take about four years, depending on factors like the crew’s time on the planet.

A more efficient propulsion system under development could transport a crew to Mars on a round-trip in only about two years, according to its proponents. Engineers at NASA’s Langley Research Center are working on a nuclear electric propulsion system that could bring Mars within reach in these timeframes. These systems use a nuclear reactor to generate electricity, which is used to ionize or positively charge gaseous propellants and create thrust.

But there’s a catch: it has to be assembled in space.

The system is called the Modular Assembled Radiators for Nuclear Electric Propulsion Vehicles, or MARVL. MARVL is connected to NASA’s goal of developing a Mars Transit Vehicle, aka Deep Space Transport, in the next decade or by the late 2030s.

One of the system’s components is its heat dissipation system. The system is an array about the size of a football field once deployed. The idea is to break the system up into separate components that can be robotically assembled in space.

“By doing that, we eliminate trying to fit the whole system into one rocket fairing,” said Amanda Stark, a heat transfer engineer at NASA Langley and the principal investigator for MARVL. “In turn, that allows us to loosen up the design a little bit and really optimize it.”

This simple illustration shows MARVL’s main components, including its football field-sized heat dissipation system. Image Credit: NASA/Tim Marvel

Folding the entire system up into a small enough payload to fit inside a rocket fairing isn’t really an option. Engineers have successfully folded other spacecraft into nosecones and then deployed them after release. The JWST’s mirror is probably the best example of that. But the JWST’s primary mirror is only 6.5 meters (21 ft and 4 inches) across. That’s far smaller than MARVL’s heat dissipation system, and it was still an elaborate challenge.

Making the heat dissipation system modular and assembling it in space with robots opens up new possibilities. The components could be launched into space in any order and in any combination that makes sense.

Space robotics is advancing and will play a larger and larger role as the future unfolds. The entire idea is an engineering challenge, but one that’s not that far out of reach. NASA’s Langley Research Centre has been working on these types of problems for decades.

Langley is a huge complex covering more than 700 acres that employs thousands of engineers, technicians, and scientists. It has made pioneering contributions to flight and spaceflight. The Centre played an important role in the development of the Apollo Lunar Module and contributed to other endeavours like the Hubble Space Telescope and the Viking Mars Lander. Space technology and research is one of their primary focuses.

This is an opportunity to produce a vehicle from the ground up that is designed to be launched in pieces and assembled in space.

“Existing vehicles have not previously considered in-space assembly during the design process, so we have the opportunity here to say, ‘We’re going to build this vehicle in space. How do we do it? And what does the vehicle look like if we do that?’ I think it’s going to expand what we think of when it comes to nuclear propulsion,” said Julia Cline, a mentor for the project in NASA Langley’s Research Directorate. Cline led the center’s participation in the Nuclear Electric Propulsion tech maturation plan development as a precursor to MARVL.

The Nuclear Electric Propulsion (NEP) system wasn’t the only one under consideration. NASA also considered the Nuclear Thermal Propulsion (NTP) system. They also considered a “quad-wing” design for the NEP system because it could be folded into the Space Launch System’s payload fairing. However, that system required a larger surface area, and the deployment systems in that design were heavy and complicated. It also required more propellant.

This illustration shows the basic design of the proposed quad-wing NEP system. Image Credit: From “ECI Modular Assembled Radiators for NEP VehicLes (MARVL), an Overview” by Stark et al. 2024.

The Bi-Wing design has several advantages over the Quad-Wing design. It can be launched piece by piece in commercial launch vehicles without the need for the SLS. The rocket payload fairing doesn’t restrict the radiator size, and it avoids solar flux, which would inhibit cooling.

This illustration shows the MARVL NEP Bi-Wing design. It can be launched on commercial launch vehicles, needs less propellant, and has lightweight joints, among other things. Image Credit: NASA/Tim Marvel

NASA gave the MARVL project team two years to develop the idea. By then, the team hopes to have a small-scale ground demonstration ready.

“One of our mentors remarked, ‘This is why I wanted to work at NASA, for projects like this,'” said Stark, “which is awesome because I am so happy to be involved with it, and I feel the same way.”

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Fast radio bursts (FRBs) are intense flashes of radio light that last for only a fraction of a second. They are likely caused by the intense magnetic fields of a magnetar, which is a highly magnetic neutron star. Beyond that, FRBs remain a bit of a mystery. We know that most of them originate from outside our galaxy, though the few that have occurred within our galaxy have allowed us to pin the source on neutron stars. We also know that some of them repeat, meaning that FRBs can’t be caused by a cataclysmic event such as a supernova. Thanks to one repeating FRB, we now know something new about them.

In a new study published in The Astrophysical Journal Letters, astronomers looked at FRB 20240209A, which was first observed by the CHIME radio telescope in February 2024. The FRB happened to be a repeater and was observed 21 times between February and June. Because it kept repeating, the team was able to observe six of the FRB events from a smaller, companion observatory 60 kilometers away. This allowed the team to pinpoint the source even though it was two billion light-years away.

They found a couple of unusual things. The first is that the FRB originated from the edge region of a galaxy. Most FRBs occur in the more central region of a galaxy because that’s where stars form and therefore where you’re more likely to find neutron stars. The second was that this particular galaxy is more than 11 billion years old, and is well past its star-forming period. What’s surprising about that is that neutron stars are the remnants of massive stars that die as supernovae. Large stars have cosmically short lifetimes, so the fact that this FRB occurred in an old, long-dead galaxy means that the neutron star that generated it must also be old.

The general reasoning was that FRBs are caused by young magnetars. The thought is that they could be caused by magnetic flares, similar to solar flares of the Sun. But since neutron stars can’t generate new heat, they cool and become inactive over time. So we shouldn’t see old neutron stars generating FRBs. This study proves that old stars can create FRBs.

One explanation for this is that the FRB might have occurred not within the galactic edge itself, but rather in a dense globular cluster orbiting at the edge of the galaxy. The galaxy is too far away for us to distinguish between these two options, but globular clusters are known to have numerous stellar mergers. One possibility is that this repeating FRB was caused by merging magnetars. As their magnetic fields merged and realigned, bursts of radio energy were released to create the FRB.

It will take more observations to be sure, but it is now clear that the astrophysical processes that create FRBs are more diverse than we thought.

Reference: Eftekhari, T., et al. “The Massive and Quiescent Elliptical Host Galaxy of the Repeating Fast Radio Burst FRB 20240209A.” The Astrophysical Journal Letters 979.2 (2025): L22.

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At the end of large engineering projects, the design team is typically asked to develop a document, in some cases called a Theory of Operations. This document is meant to describe the design decisions, why they were made, and how they were implemented. The document intends to inform future engineers about why a system operates the way it does so they can assess if any modifications or improvements can be made. It also allows the design engineers to reflect on their work as a whole, sometimes in a new light. Recently, some original members of the design team of the James Webb Space Telescope decided to take their shot at a brief version of such a document, releasing a paper that describes the design history of what is now considered to be one of the crowning jewels of humanity’s space telescope fleet.

Pierre Bely, the (now retired) Chief Engineer for the Space Telescope and Science Institute (STScI), led the paper’s writing. He originally started conceptualizing the idea of a Hubble success back in the 1980s. He was prompted to do so by Riccardo Giacconi, the then-head of the STScI, who, given his experience on other satellites like Chandra and Einstein, knew how long it would take to develop a successor to Hubble. 

Hubble itself, the doyenne of Space Telescopes that served as the workhorse of astronomers for decades, wasn’t eventually launched when Bely was tasked with coming up with plans for a successor. It had taken almost 30 years of lobbying, building, and testing to launch Hubble in 1990, with an additional three years of extensive rework to repair it once it was in orbit. Hubble itself only had a 14-year mission lifetime, so even if its successor had started work before Hubble launched, it wouldn’t be ready to launch before its original mission ended.

Fraser has been watching JWST for a long time.

Budget constraints at STScI proved an initial challenge. The Institute had the staff to operate Hubble but not to design a completely new instrument from scratch. But, Bely did find some time in his role as Chief Engineer to develop some concepts. Preliminary design requirements were hazy, but the consensus between the originators of the idea that became JWST was that it should be able to see into the infrared, which was beyond Hubble’s capabilities. It was also planned with a 10-m mirror, which was intended to match several ground-based telescopes in the design phase.

Fortunately, NASA’s Advanced Concepts Office had already done preliminary work on several designs for a next-generation space telescope. The Very Large Space Telescope (VLST) kept the traditional name of NASA’s telescopes but was designed to be assembled in space by astronauts using the space shuttle. It was essentially just a version of Hubble with a bigger mirror.

The Golay-9 concept was a bit more out-of-the-box. It consisted of nine 1.7m telescopes that would work in concert with one another. However, it was again designed to be assembled by astronauts and placed in LEO.

Artist’s image of the Large Deployable Reflector, including astronaut in the midst of assembly.
Credit – NASA / JPL

Another concept was the Large Deployable Reflector, which was 20m in diameter with segmented mirrors. It would need a significant amount of cryogenics to stay cool as it orbited in LEO close to the space station – mainly ease assembly by astronauts and resupply of cryogenics.

Bely and Francois Roddier, an optics specialist, considered those ideas when designing an original 10m Hubble successor that looks almost nothing like the final form of the satellite. Initially proposed in 1986, it had an all-encompassing shield that was supposed to protect it from the light and heat of the nearby Earth while still being able to fit in the fairing of a modified Energia rocket designed by the then-Soviet Union.

During this time, the project took on a new name—the Next Generation Space Telescope, which it would be known by until it was renamed JWST in 2002. But before that, it had several more preliminary design iterations, including a “Detour via the Moon.” 

Bely and Roddier’s concept telescope.
Credit – P.Y. Bely / F Roddier / STScI

A space telescope doesn’t necessarily have to be free-floating in space – it can also be located on another heavenly body. That was the basis for an idea initially to coincide with President George H. W. Bush’s Space Exploration Initiative to return to the Moon in the 1990s. To match this design, a version of the NGST that housed a 16m mirror on the surface of the Moon that looked more like a traditional Earth-bound telescope than a free-floating space one. However, that idea died with the SEI as it became clear a few years into Bush’s tenure that NASA would not return to the Moon anytime soon – and still hasn’t.

During the late 1980s and early 1990s, many workshops were held to discuss different trade-offs in the design of the NGST. These changed to a more formal structure in 1995, almost 5 years after Hubble had launched, at a workshop to define the design goals of the new Hubble successor that was called by Edward Weiler, NASA’s Chief Scientist for Hubble. That workshop kicked off two years of a study designed to result in a fully formed idea for a space telescope – and is what the modern version of JWST is based on today.

At the end of the study, the general outline of the space telescope was clear, with a sun shield facing the Sun and allowing radiative cooling on the other side while keeping a reasonable temperature for some operational electronics. It would also be located at the Earth-Sun L2 Lagrange point rather than on the Moon or in orbit around Earth. This had the advantage of being far enough away from Earth and the Moon that it no longer had to be completely enclosed as earlier concepts had been, giving it a much wider field of view.

“Yardstick” version of the JWST / NGST
Credit – NASA / GFSC

This version of JWST, known as the “Yardstick,” focused heavily on the design of the optical system, with an 8 m mirror originally proposed. It utilized beryllium due to its advantages for cryogenics on space telescopes, including its high thermal conductivity. It was designed to fit in an Atlast II fairing and be fully expanded after launch.

Even at this early stage in the project, cost was already a consideration, and JWST ran notoriously over budget during its development and testing cycle. However, at the time, the expected budget seemed in line with comparable missions like Hubble. NASA designed to move forward with a concept phase study and asked three aerospace companies to present their NGST ideas at an STScI meeting. That meeting resulted in a report in the summer of 1997 that specified three very different ideas from TRW, Ball Aerospace, and Lockheed Martin.

NASA decided to move forward with the TRW and Ball concepts, though Lockheed continued developing its own project in an effort to win back the business. After a while, TRW and Ball decided to combine their forces into a single mission study. Eventually, in 2001, Northrup Grumman bought TRW, and the division that managed the NGST project changed its name to Northrup Grumman Space Technology (NGST). NASA granted them the right to take the lead contractor role on the JWST.

Some of the discoveries JWST has made are astonishing.

Budget constraints further limited the scope of the mirror down to 6 meters from the planned 8, but at this point, the overall design seemed pretty much in line with what is currently floating in space today. Twenty years later, after much design refinement, manufacturing, and testing, it was successfully launched, and despite being blasted by micrometeorites (which admittedly was always part of the planned design), it has been providing us with fascinating pictures from every corner of space. With this paper, some of the original team members can reflect on their contributions to this marvel of space technology and be proud. In the end, all their efforts seem to have been worth it.

Learn More:
Bely et al – Genesis of the James Webb Space Telescope architecture: The designers’ story
UT – How Webb Stays in Focus
UT – Hubble and Webb are the Dream Team. Don’t Break Them Up
UT – The JWST is Re-Writing Astronomy Textbooks

Lead Image:
Artist’s view of a 16-meter telescope on the Moon, proposed by Bely. Telescope pointing made use of a hexapod with linear actuators. During the lunar day, a shield was to be rolled over the telescope to protect it from heat coming from the Sun
Credit – P. Y. Bely / D. Berry / STSCI

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The discovery of a few thousand type 1a supernovae over the last few decades has helped measure the expansion of the Universe. The new Vera Rubin Observatory will soon to start scour the skies looking for more. Astronomers hope that the discovery and observations of millions more exploding stars will allow the universal expansion to be mapped in unprecedented detail. If all goes to plan, the survey will begin in a few months with the entire southern sky being scanned every few nights. 

A Type Ia supernova is a powerful explosion that occurs when a white dwarf star in a binary system accretes matter from its companion star. Eventually it will reach a critical mass triggering a catastrophic thermonuclear reaction that we see as a Type 1a supernova. They are characterised by a the absence of hydrogen in their spectra, which sets them apart from other types of supernovae. The event releases a phenomenal amount of energy, briefly outshining an entire galaxy. The shockwave from the event can often trigger the formation of new stars. 

2005ke, a Type 1a supernova. Credit: NASA/Swift/S. Immler

These violent explosions have played a key role in understanding the expansion of the universe. Much like cepheid variable stars, these supernovae have a consistent peak brightness due to the predictable nature of the thermonuclear explosion that triggers them. They can therefore be used as “standard candles” to measure astronomical distances. By comparing the apparent brightness of a Type Ia supernova with its known intrinsic luminosity, it’s possible to calculate how far away it is. When combined with redshift measurements (which indicate how much the wavelength of light has stretched as the universe expands), these distance measurements allow scientists to map the rate at which the universe is expanding. 

To date only a relative handful have been observed. This is where the Vera Rubin Observatory comes in. It’s located in the Atacama Desert of Chile and is designed to explore dark matter, dark energy, and the large-scale structure of the universe. Equipped with the world’s largest digital camera, the Legacy Survey of Space and Time (LSST) will capture huge areas of the sky that will enable the mapping of millions of galaxies and track transient cosmic events like just like Type 1a supernovae and asteroids.

Thousands of stars glitter in the black skies above the bone-dry desert of the Atacama in northern Chile. Photo credit: Gerhard Hüdepohl/atacamaphoto.com.

Every night, the observatory – which is funded by the U.S. National Science Foundation and the U.S. Department of Energy’s Office of Science – will capture about 20 terabytes of data, generating an expected 10 million alerts. This in itself is an – ahem – astronomical challenge so alerts will be made available to science teams through seven community software systems. The alerts will be collated with other datasets and machine learning technology will categorise them as kilonovae, variable star or Type 1a supernovae. Astronomers can then utilise filter to hone in on the data most useful for their research.  

If the Vera Rubin Observatory is as successful as it is hoped and if it does indeed discover millions of new Type 1a supernovae, then it will be of great benefit to astronomers. Not only will we be able to build a far more accurate distance map of the cosmos but we will also be able to get a better understanding of its expansion and how it has evolved over time.

Source : NSF–DOE Vera C. Rubin Observatory Will Detect Millions of Exploding Stars

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A short time ago, astronomers observed a distant supermassive black hole (SMBH) located in a galaxy 270 million light-years away in the constellation Draco. For years, this galaxy (1ES 1927+654) has been the focus of attention because of the Active Galactic Nucleus (AGN) at its core. It all began in 2018 when the SMBH’s X-ray corona mysteriously disappeared, followed by a major outburst in the optical, ultraviolet, and X-ray wavelengths. Astronomers began watching it closely, but what they saw next was completely unexpected!

As we covered in a previous article, much of the excitement was generated by the SMBH’s behavior, which suggested it was consuming a stellar remnant (a white dwarf). In addition, astronomers noted a huge increase in radio emissions and the formation of plasma jets extending from the black hole, which all happened over the course of a year. In a new paper, a team led by the University of Maryland Baltimore County (UMBC) describes how they watched a plasma jet forming in real time, something astronomers have never done before.

The team’s paper, which recently appeared in the Astrophysical Journal Letters, was led by UMBC associate professor Eileen Meyer. She was joined by multiple colleagues from UMBC’s Department of Physics and Astronomy, the Joint Space-Science Institute (JSI), and the Center for Space Science and Technology (CSST). Other members included researchers from the Space Telescope Science Institute (STScI), the Technion Israel Institute of Technology, the Joint Institute for Laboratory Astrophysics (JILA), the Institute for Space Astrophysics and Planetology, and the NASA Goddard Space Flight Center.

Active galaxy 1ES 1927+654 (circled in green) harbors a central black hole weighing about 1.4 million solar masses and is located 270 million light-years away. (NASA/GSFC)

Astronomers have observed jets emanating from the poles of several SMBHs in the Universe. Some of these have been shown to accelerate gas and dust particles to close to the speed of light, leading to the term “relativistic jets.” In some cases, astronomers have observed jets extending for thousands or even hundreds of thousands of light-years from their host galaxy. These jets blast material across these distances, and some even trigger the formation of new stars along their paths.

In this case, the jet appeared after a period of variable activity in 1ES 1927+654, where the AGN began consuming more material and becoming 100 times brighter over the course of a few months – a change that normally TAKES thousands or millions of years. After nearly a year of extremely high X-ray emissions, the black hole quieted down again in 2020, only to increase its output again in 2023. At the same time, it began emitting radio waves at 60 times the previous intensity over just a few months, something that has never before been monitored in real time for an SMBH.

Based on radio observations using the Very Large Array (VLA) and Very Large Baseline Array (VLBA), the team obtained high-resolution radio imaging of the SMBH at the center of 1ES 1927+654. These observations clearly showed a pair of plasma jets forming around both poles of the black hole and expanding outward between 2023 and 2024. In recent years, scientists have identified “changing-look AGNs,” supermassive black holes that become far more active at radio frequencies from when they were first observed.

In those instances, astronomers naturally assumed that something must have happened in between since their observations were years or decades apart. This is the first instance where astronomers saw this change happening in real time, thereby offering clues as to how these changes happen. As Meyer said:

“We have very detailed observations of a radio jet ‘turning on’ in real-time, and even more exciting are the VLBI observations, which clearly show these plasma blobs moving out from the black hole. That shows us that this really is an outflow jet of plasma that’s causing the radio flare. It’s not some other process causing increased radio emission. This is a jet moving at likely 20 to 30 percent of the speed of light originating very near a black hole. That’s the exciting thing.”

Radio images of 1ES 1927+654 reveal emerging structures that appear to be jets of plasma erupting from both sides of the galaxy’s central black hole following a strong radio flare. Credit: NSF/AUI/NSF NRAO/Meyer at al. 2025

While these newly-forming jets are relatively small compared to the massive jets observed from some of the most powerful AGNs in the galaxy, they are likely to be more common across the Universe. While the largest jets extend far beyond their host galaxies and last for millions of years, scientists have become aware of smaller, shorter-lived jets – what they call “compact symmetric objects” (CSOs). In this sense, the jets observed in 1ES 1927+654 could represent a unique opportunity to learn more about how these structures form and grow with time.

Similarly, astronomers will keep an eye on this galaxy and its SMBH because of the tidal disruptions that could indicate the presence of a white dwarf that is slowly being consumed. Meyer and his team have also suggested that the appearance of these jets may be associated with “a single ingestion of a star or a gas cloud” and that a single tidal disruption event may be what powers short-term CSOs (for maybe 1,000 years, they venture). Said Meyer:

“We still don’t really understand after all these decades of studying these sources why only a fraction of accreting black holes produce jets and then exactly how they launch them. Until recently we could not literally look into that innermost region to see what’s happening—how the accretion disk surrounding the black hole is interacting with and producing the jet. And so there are still a lot of open questions there.”

While many unanswered questions still exist, several promising models exist for how jets might form. These observations could lead to collaborative efforts with theorists on how to interpret the data so these models can be refined. “There’s a lot of theoretical work to be done to understand what we’ve seen, but the good thing is that we have a massive amount of data,” Meyer says. “We’re going to keep following this source, and it’s going to continue to be exciting.” 

Further Reading: UMBC, The Astrophysical Journal Letters

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Orion the Hunter, resplendent in the northern hemisphere’s night sky in winter, is more than an easily identified constellation. It’s home to the Orion Nebula, the nearest star-forming region to Earth. It’s a mere 1,500 light-years away and can be seen with the naked eye below the three stars that form Orion’s belt.

New Hubble images show how young, newly-formed stars in the Orion Nebula are altering their environments.

The Orion Nebula is one of the most heavily studied features in the sky. By observing Orion, astronomers have made great strides in understanding how stars and planets form. It’s home to hundreds of young protostars, two of which are featured in the Hubble image: HOPS 150 and HOPS 153, though HOPS 150 is actually a binary star. They get their names from the Herschel Orion Protostar Survey, which is a sample of more than 400 young stellar objects (YSOs) in Orion’s molecular clouds.

HOPS 150 is in the image’s upper-right corner. Two young protesters orbit each other, each surrounded by its own disk. These very young stars are still growing by accreting material from these disks. The dark vertical line cutting through them is dust that’s being drawn into the pair of stars. The dust line is enormous, more than 2,000 AU across. Astronomers think that the binary protostar is about halfway to becoming a mature star.

HOPS 153 is actually out of this image’s frame, but its jet is clearly visible. Astronomers think that the YSO is much younger than HOPS 150. It radiates more infrared radiation, indicating that it’s surrounded by more dust than HOPS 150. It’s still firmly ensconced in its dusty birth nebula, and dust absorbs light from the star and re-emits it in the infrared.

Not all of the material that falls into a young protostar will become part of the star. YSOs often emit powerful jets of material from their poles. Research shows that these jets can extract up to 30% of a young star’s accretion power. The jets are visible where they crash into the interstellar medium, lighting it up and creating bow shocks and other features.

Artist’s conception of a star being born within a protective shroud of gas and dust. YSOs rotate rapidly, creating powerful magnetic fields. These fields can drive jets of material from the YSO’s poles, shaping their environment and how other stars form. Image Credit: NASA

YSOs like HOPS 153 spin more rapidly than mature stars and have more powerful magnetic fields as a result. This affects how the material is accreted onto the star and also drives the jets by collimating infalling material. The jets of material interact with the surrounding gas, heating it and causing bubbles to form. That affects how other stars can form from the gas and how planets form around the star. This is how YSOs can shape their environments.

Young stars are complex objects and can be difficult to observe. They’re often obscured by dust, and, like HOPS 153, their jets can be their most visible manifestation. These jets can extend for several light-years into space.

Stars seldom form in isolation, and as YSOs accrete material, they shape their surroundings and the stars that follow them. How exactly this all plays out is an area of intense study for astronomers and astrophysicists. Images like this from the Hubble are an important part of the effort.

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The space debris problem won’t solve itself. We’ve been kicking the can down the road for years as we continue launching more rockets and payloads into space. In the last couple of years, organizations—especially the European Space Association—have begun to address the problem more seriously.

Now they’re asking this question: What will it take to reach zero space debris?

At first glance, it may seem unreal, maybe naive. There are billions of pieces of space junk orbiting Earth, and more than 25,000 of those pieces are larger than 10 cm. Though small, these pieces are travelling fast and can cause significant damage when impacting satellites or space stations. What will it take to get rid of all this debris?

The ESA has released the Zero Debris Technical Booklet to elucidate the challenges to a zero-debris future and propose solutions to get there. The Booklet’s development follows the signing of the Zero Debris Charter by members of the Zero-Debris community.

“Despite several initiatives for space debris mitigation in recent years and modest improvements in public awareness, there is a general consensus that more ambitious actions are urgently needed from all space stakeholders to prevent, mitigate, and remediate debris,” the report states. The report points out that the Guidelines for the Long-term Sustainability of Outer Space Activities of the United Nations Committee on the Peaceful Uses of Outer Space outlines how access to space is hindered by debris.

The booklet defines zero debris targets and presents “technical needs, solutions and key enablers” that can help organizations achieve them.

The obvious first step is to cease creating more debris.

It begins with avoiding the unintentional release of debris. Exposure to the space environment can degrade materials during missions and beyond their end date, and unintentional impacts can also release debris. The Booklet promotes the “Development of multi-layer insulation and coating technologies preventing long-term degradation of materials” and similar developments for materials that can resist impacts. Improved monitoring, simulations, and testing can help us get there.

The Booklet also points out the need for different propulsion technologies. Some propulsion technologies release enormous quantities of small particles. The Booklet promotes the development of alternate propulsion systems based on things like electromagnetic tethers, momentum-transfer tethers, and drag or solar radiation pressure augmentation devices.

This image shows the Tethered Satellite System (TSS). The tether generated electricity as it moved through Earth’s magnetic field and the electricity could be used to adjust the satellite’s orbit without the need for other propulsion. Image Credit: By NASA Johnson Space Center (NASA-JSC), Public Domain

The Booklet also points out how improved Space Traffic surveillance and Coordination (STC) can help solve the problem. “Improved STC will help prevent collisions and reduce the occurrence of unnecessary collision avoidance manoeuvres,” the Booklet states.

That will require a technological solution, but different space agencies will also have to share information, which some will be more reluctant to do than others. The Technical Booklet explains that standardized guidelines will need to be developed and adopted for this to happen.

For existing debris, removal is the only solution. “For space objects which fail to de-orbit themselves for whatever reason, external means can be used to remove these objects from orbit,” the Booklet states.

That begins with assessing defunct satellites to determine the best way to de-orbit them. Are they at risk of breaking up due to de-orbiting methods? Once assessed, we need to develop reliable and configurable methods to remove them. That means a technological approach will be needed, as will communication between different space-faring nations.

The Booklet states that this will require the “Development of interoperable interfaces and requirements that facilitate removal for different types and sizes of objects (e.g. large/Small Spacecraft, launcher stages and elements, constellation spacecraft), adapted for different orbital regions (e.g. LEO, MEO, GEO), for different Disposal strategies (e.g. controlled, uncontrolled re-entry, orbital transfer to graveyard orbit), and with easy adoption in mind,” the Booklet explains.

De-orbiting systems could be as simple as deployable solar sails like the experimental Canadian Advanced Nanospace eXperiment-7 (CanX-7.) It was launched in 2016 and achieved a decay rate of 20/km per year.

The CanX-7 with its sails deployed in a clean room. Image Credit: Space Flight Laboratory

While the CanX-7 and other similar systems are passive, there are also designs for Active Debris Removal (ADR).

One ADR system is Clearspace-1. It will demonstrate technologies for rendezvousing, capturing, and de-orbiting an end-of-life satellite called PROBA-1. After capture, both Clearspace-1 and PROBA-1 will plummet into Earth’s atmosphere and be destroyed.

Predicting and avoiding the risk of collisions between satellites and other objects in space is also part of the Booklet. “The increasing number of debris and the risk associated with collisions in orbit lead to an
ever-increasing need for operators to carry out collision avoidance manoeuvres,” the Booklet states. This can be partially addressed during the design phase but inevitably requires coordination.

Again, the Booklet calls for more cooperation between agencies. The effort needs a standardized set of guidelines for collision assessments and “methods to integrate collision risk assessments from multiple providers.”

When it comes to technology, collision avoidance and prediction will also benefit from the development of machine-learning algorithms, the development and uptake of optical and radio tracking aids, and a longer list of additional developments.

The Technical Booklet summarizes our problem: Space Debris requires standardized methods to assess hazards, avoid hazards, and remove hazards. While the technology needed to address the space debris problem hasn’t been thoroughly developed yet, there’s little doubt that it will be. However, the needed technologies may not be the biggest obstacle to solving the space debris problem. The critical part is cooperation.

Without cooperation, the problem will never be fully solved. However, cooperation can be in short supply. Our species is at least partly defined by our internecine squabbling and the tragedy of the commons. Different nations have different ideologies, politics, and leadership. Can we imagine Russia under Putin taking part in a cooperative effort to reduce space debris? How about China? North Korea? Iran?

What’s worse, some nations are actively creating more debris. In 2007, China conducted an anti-satellite missile test that destroyed a defunct satellite and created a massive amount of debris. In 2017, Russia did the same. India conducted a similar test in 2019, though they claim that it was at such a low altitude that the debris would quickly burn up in Earth’s atmosphere. However, the US Strategic Command said the debris remained in space longer than India claimed.

It doesn’t seem likely that the planet’s nations and space agencies will be cooperating any time soon, and even the once-reliable United States may eschew increased cooperation under its new leadership. Who knows?

But just as with climate change and a host of other problems, we can only solve the space debris problem through cooperation.

The ESA deserves credit for outlining the technical challenges and solutions to the problem. Though daunting, that may turn out to be the easy part.

It’s our politics that hamper the effort.

The post What Will It Take To Reach Zero Space Debris? appeared first on Universe Today.

The exoplanet WASP-127b is an unusual world. It is about 30% larger than Jupiter but has just a fifth of Jupiter’s mass. It is an example of a super-puff planet because of its extremely low density. These puffy worlds are so unusual that we don’t know if they would resemble the gas giants of our solar system, or something more exotic, such as a large super-Earth. But a recent study of WASP-127b shows that super-puff worlds can have tremendous winds.

The team used the CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES+) on ESO’s Very Large Telescope to watch the world as it passed in front of its star. Since some of the starlight passes through the planet’s atmosphere with each transit, the team could capture the absorption spectra of the atmosphere. From this, they identified some molecules in the atmosphere that we would expect, such as carbon monoxide and water vapor, which are present in the atmospheres of our gas planets.

But the team also found a surprise. As the planet began a transit, the spectra of the atmosphere were red shifted, and as it ended the transit, the spectra were blue shifted. By itself, this isn’t unusual, as it simply indicates that the atmosphere is moving through some kind of wind. But when the team calculated the speed of the wind, they found it was nearly 9 km/s, or about 33,000 km/hr (more than 20,000 mph for those in the states). That’s ten times faster than the peak winds of Neptune, which are the fastest winds in the solar system.

This rapid motion isn’t due to a fast rotation of the planet itself. WASP-127b orbits its star very closely, so it is almost certainly tidally locked. This means it rotates on its axis once for every orbital period, which is a bit more than four hours. The winds are six times faster than that. They are, in fact, the fastest wind speeds ever observed in the Universe.

The planet’s locked rotation and low density may explain the world’s intense winds. Since one side of the planet is forever in light and the other is always in darkness, there would likely be a large temperature difference between the two sides. Just as cold and warm regions of Earth’s atmosphere can generate strong winds, so would winds arise on WASP-127b. But with a constant temperature differential and a diffuse atmosphere, the winds on this puffy planet are like nothing we’ve ever experienced.

Reference: Nortmann, L., et al. “CRIRES+ transmission spectroscopy of WASP-127b. Detection of the resolved signatures of a supersonic equatorial jet and cool poles in a hot planet.” arXiv preprint arXiv:2404.12363 (2024).

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China’s Chang’e 7 lunar lander mission will feature a flag fluttering in the vacuum of space.

A CNSA flag flying on the Moon. Credit: CGTN News screenshot.

It’s one of the most often asked questions I get, while showing off the Moon to the public. “Can you see the flag the astronauts left there?” This then leads to a discussion on how far the Moon is, versus the difficulty of seeing a 1.5 by 0.9 meter flag at such a distance. My ‘scope is good, but not that good.

During the U.S. Apollo program, six crewed missions landed on the Moon starting with Apollo 11 in 1969, leaving a like number of flags. Now, China recently announced that one more flag will join the collection in late 2026, when Chang’e 7 heads to the Moon.

Flying a Flag on the Moon

The curious report comes out of the Deep Space Exploration Laboratory (DSEL) via the China Media Group. The free standing flag will actually be designed to ‘flap’ on the airless surface of the Moon. The idea was proposed by elementary school students out of Changsha in China’s Hunan Province. The flag will have closed-loop wires embedded in the fabric, and ‘flap’ using magnetic currents and electromagnetic interactions to create a waving motion.

Coming soon: A ‘flapping flag’ on the Moon…

“This initiative is intended to enhance young students’ understanding of China’s space program and inspire their interest in pursuing space exploration in the future,” says Zhang Tianzhu (DSEL/Institute of Technology) in a recent press release.

A Race to the (Lunar) Pole

Chang’e 7 is designed to carry out some serious science as well. The mission is destined to land near the edge of Shackleton Crater in the Moon’s south polar region. The permanently shadowed floor of the crater is of special interest, as it is suspected to contain water ice. The mission will also carry six instruments from six nations, including a small rover and an observatory built and operated by the International Lunar Observatory Association (ILOA) based out of Hawai’i.

Shackleton crater was one of the candidate landing sites for NASA’s now canceled VIPER rover.

Potential landing sites of interest clustered around the lunar south pole region. Credit: NASA/LRO

While the merits of having a flag flap in space may be limited, it should be an interesting bit of public outreach for the CNSA. Curiously, some of the screen captures show a CNSA logo (not a Chinese national flag) free-standing on a tall pole, meaning a bit of effort and planning will have to be taken to plant it in the lunar soil.

Astronaut Buzz Aldrin and the U.S. Flag on the Moon during Apollo 11. Credit: NASA China in Space 2025

This year and next are busy ones for China’s space agency. The agency plans on launching its first ever asteroid and comet sample return mission Tianwen-2 this May, headed to asteroid Kamo’ oalewa (itself thought to be a fragment of the Moon) then onward to Comet 311P/PanSTARRS. Then, China has plans to launch its own space telescope Xuntian in early 2026. This telescope will station-keep with the crewed Tiangong space station for access for upgrade and maintenance.

The U.S. Flag mounted on the New Horizons mission. Credit: NASA/JPL

Putting flags in space and on the Moon isn’t a new thing. Generally, engineers mount the flags on the spacecraft itself. The U.S. flag placed on NASA’s New Horizons spacecraft is headed out of the solar system. This symbol may well outlive the U.S. and humanity itself. U.S. flags planted by Apollo astronauts on the Moon have most likely been bleached white by intense ultraviolet solar radiation, though images by NASA’s Lunar Reconnaissance Orbiter in low lunar orbit confirm that at least as few are still standing.

Still standing: the Apollo 17 landing site, including the flag. Credit: NASA/LRO

But the award for the very first flag (or at least symbol) on the lunar surface goes to Luna 2, the first mission to hit the Moon in 1959 which carried a pennant of the now defunct Soviet Union:

A replica of the sphere onboard Luna 2, which impacted the Moon. Credit: Patrick Pelletier/Wikimedia Commons Attribution-Share Alike 3.0 Unported license.

It will be a curious moment (and most likely, an internet meme) to see a flag ‘flap’ next year on the surface of the Moon.

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Predicting space weather is more complex than predicting traditional weather here on Earth. One of the most unpredictable kinds of space weather is solar flares, which explode out from the surface of the Sun and can potentially damage sensitive equipment like electrical grids and the ISS. The Carrington Event, one of the most violent solar storms in history, literally caused telegraph lines to catch fire when it occurred in 1859 – a similar storm would be much more devastating today. Due to their potentially destructive potential, scientists have long looked for ways to predict when a storm will happen, and now a team led by Emily Mason of Predictive Sciences, Inc. in San Diego thinks they might have found a way to do just that.

Solar flares typically occur in highly magnetic areas of the Sun. However, they aren’t the only events that occur in those regions—another, less potentially hazardous event is a coronal loop. These look like giant arches of particles that start from and connect back to the Sun’s outer layer, also called its corona. 

Scientists have long thought there might be some sort of tie between coronal loops and the solar flares that emerge from the same region. However, the lifespan for coronal loops ranges from seconds to weeks, and scientists have yet to find a valid link between that metric, or any other, and the occurrence of a solar flare in the same region.

Fraser discusses the danger of solar storms.

Dr. Mason and her colleagues thought they might take a different approach. They got some observational time on the Solar Dynamics Observatory (SDO), a telescope in geosynchronous orbit explicitly designed to observe the coronal layer. They used SDO’s extreme ultraviolet wavelength observational capabilities to observe coronal loops in regions that eventually formed a flare versus those that didn’t.

They observed areas that produced around 50 flares and found that the amount of variability in extreme ultraviolet light the coronal loops in those areas put off was much higher than in the areas that didn’t produce a flare. Essentially, the coronal loops acted like “flashing warning lights” in a certain kind of light spectrum, according to a press release from NASA’s Goddard Institute, some of whose scientists contributed to the paper. 

The discovery was critical because the flashing appeared to take place consistently a few hours before a flare was formed. In technical terms, they accurately predicted the onset of a flare about 2-6 hours beforehand, about 60-80% of the time. That might not seem like great odds and even lesser warning, but some warning is better than none. When given the decision between frying half of the Earth’s electrical grid in a few hours and taking preventive measures, I think policymakers would at least appreciate the opportunity to have a choice.

Fraser talks about how bad the Carrington Event was, even almost 200 years ago.

There are some other nuances in the data, such as stronger flares appear to be predicted by earlier peaking flickering, however more work still needs to be done. Ultimately, this research aims to develop a system of automatically warning the appropriate authorities if there is a potentially hazardous solar event coming our way, but without so many false positives that they feel the system is crying wolf.

That automated system is still a little way off, but this research is a step in the right direction. SDO was initially launched in 2010 and has long outlived its original 5-year mission plan. However, there are plenty of instruments constantly watching the Sun, and undoubtedly, there will be more soon. Maybe they will someday contribute to finalizing a system that will one day save civilization from an avoidable catastrophe.

Learn More:
NASA – NASA Solar Observatory Sees Coronal Loops Flicker Before Big Flares
Kniezewski et al – 131 and 304 Å Emission Variability Increases Hours Prior to Solar Flare Onset
UT – New Research Indicates the Sun may be More Prone to Flares Than we Thought
UT – High-Resolution Images of the Sun Show How Flares Impact the Solar Atmosphere

Lead Image:
NASA’s Solar Dynamics Observatory captured this image of coronal loops above an active region on the Sun in mid-January 2012. The image was taken in the 171 angstrom wavelength of extreme ultraviolet light.
Credit – NASA/Solar Dynamics Observatory

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Exoplanets come in a variety of forms and one particular type, the Hot Jupiters have recently captured the attention of astronomers. They are usually found orbiting extremely close to their host star, completing an orbit in a few days or even hours. It has been thought that they migrated further out from the star, bullying other planets out of their way. Sometimes hurling them into the star or throwing them out of the system entirely. A new study however, suggests their evolution is not quite so violent since a Hot Jupiter has been found in a system with a Super-Earth and an icy giant. 

Hot Jupiters are a class of exoplanet that not surprisingly resemble our own planetary neighbour Jupiter. They are gas giants but that’s where the similarity ends; they have a high temperature and orbit their star at close distance. It can take just a few days to complete an orbit that’s compared to Jupiter’s orbit of 12 years! The intense levels of radiation and heating from their host star can cause temperatures in upper layers to reach over 1,000°C and the planet to swell to greater than expected size. 

This full-disc image of Jupiter was taken on 21 April 2014 with Hubble’s Wide Field Camera 3 (WFC3).

Current theories of planetary formation describe inner planets as composed of more dense material since lighter elements are driven to outer reaches of the system. The outer planets by contrast are made from these lighter elements. The presence of gas planets like Hot Jupiters so close to a star are in direct conflict with this model. Instead it has been thought that they form further out from the star and then migrate inwards as the system evolves. Recent studies have revealed that, until now, Hot Jupiters seem to be the only planet in orbit around their host star. This observation suggests the migration process is likely to lead to an ejection or accretion of any planet closer to the star. 

This artist’s impression shows a Jupiter-like exoplanet that is on its way to becoming a hot Jupiter — a large, Jupiter-like exoplanet that orbits very close to its star. Courtesy: NOIRLab/NSF/AURA/J. da Silva

That was until now! A team of astronomers led by the Astronomy Department of the UNIGE Faculty of Science in partnership with UNIBE and UZH and other organisations have suggested another model. They announced the discovery of a multiple planetary system that includes a Hot Jupiter, a Super-Earth on an inner orbit and another gas giant on an outer orbit, much like conventional gas giants. The discovery suggests there must be an alternative migration model that enables the preservation of the system. 

Using photometric measurements of WASP-132 over 400 light years away, the data reveals that WASP-132b was 0.41 Jupiter masses and an orbital period of just 7.1 days. Measurements from the HARPS spectrograph at the La Silla observatory in 2022 revealed the Super-Earth has a mass 6 times that of the Earth. The analysis of the system is still ongoing as the measurements are fine tuned. The Gaia satellite is now measuring the tiny variations in the position of the star to hone in on the planetary masses and orbits. 

Artist’s impression of the Gaia spacecraft detecting artificial signals from a distant star system. In this synchronization scheme, the star system’s inhabitants send the signal shortly after witnessing a supernova, which is also seen by telescopes on Earth. (Credit: Danielle Futselaar / Breakthrough Listen)

What this all tells us is that the current migrations models that enable the gas giants to be orbiting where they are may not be complete. Instead it suggests a more “cool” migration path and less violent journey through the protoplanetary disc for the Hot Jupiter. Quite what the refinement to the model is, still needs to be understood but further measurements of the system will help and the search for similar systems is underway. 

Source : Not all Hot Jupiters orbit solo

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Back in the 60’s and 70’s it was all about the Moon. The Apollo program took human beings to the Moon for the first time and now over 50 years later things are really hotting up again. The latest mission to head toward our celestial neighbour is a SpaceX Falcon 9 rocket launching Blue Ghost Mission 1 and the HAKUTO-R lander. The Blue Ghost is part of NASA’s Commercial Lunar Payload Services (CLPS) and it carries a total of 10 NASA payloads, the other is a private Japanese enterprise to explore the Moon. The launch went well and both landers will arrive shortly. 

The exploration of the Moon has been a key part of space research offering key insight into the origins of the Moon and the Solar System itself. With the possibility of future human bases on the Moon the interest in lunar exploration has started to gain momentum. Of particular note is NASA’s Artemis program and other international missions like those from China and India are making great progress. They not only intend to learn more about the Moon and its physical properties but also hope to serve as stepping stones for future exploration. 

Global map of the Moon, as seen from the Clementine mission, showing the lunar near- and farside. If we’re going back to the Moon, we’ll need a Lunar GPS. Credit: NASA.

Yet another chapter has opened in the book of lunar exploration with a launch atop a Falcon 9 rocket. This reusable two-stage launch vehicle was designed and developed by SpaceX to reduce the cost of a launch. It’s first flight was back in 2010 and since then has enjoyed success with around 200 successful launches to its name. One of its two charges this time was the Commercial Lunar Payload.

Carrying the a payload from Firefly Aerospace, the Commercial Lunar Payload set off on its journey from launch complex 39A ahead of its landing on 2 March 2025. As wonderfully articulated by NASA’s Deputy Administrator Pam Melroy ‘The mission embodies the bold spirit of NASA’s Artemis campaign – a campaign driven by scientific exploration and discovery.’

A SpaceX Falcon 9 rocket launches with NASA’s Imaging X-ray Polarimetry Explorer (IXPE) spacecraft onboard from Launch Complex 39A, Thursday, Dec. 9, 2021, at NASA’s Kennedy Space Center in Florida. The IXPE spacecraft is the first satellite dedicated to measuring the polarization of X-rays from a variety of cosmic sources, such as black holes and neutron stars. Launch occurred at 1 a.m. EST. Credits: NASA/Joel Kowsky

It’s destination is near a volcanic feature called Mons Latreille within Mare Crisium. On arrival at lunar the surface, it will test and demonstrate drilling capability, collection technology of the lunar regolith, the use of GPS, radiation tolerant computing and lunar dust protection methods. The mission will help to set the stage for a later human visit to the Moon, possibly even to develop a permanent lunar base. 

NASA has selected three commercial Moon landing service providers that will deliver science and technology payloads under Commercial Lunar Payload Services (CLPS) as part of the Artemis program. Each commercial lander will carry NASA-provided payloads that will conduct science investigations and demonstrate advanced technologies on the lunar surface, paving the way for NASA astronauts to land on the lunar surface by 2024…The selections are:..• Astrobotic of Pittsburgh has been awarded $79.5 million and has proposed to fly as many as 14 payloads to Lacus Mortis, a large crater on the near side of the Moon, by July 2021…• Intuitive Machines of Houston has been awarded $77 million. The company has proposed to fly as many as five payloads to Oceanus Procellarum, a scientifically intriguing dark spot on the Moon, by July 2021…• Orbit Beyond of Edison, New Jersey, has been awarded $97 million and has proposed to fly as many as four payloads to Mare Imbrium, a lava plain in one of the Moon’s craters, by September 2020. ..All three of the lander models were on display for the announcement of the companies selected to provide the first lunar landers for the Artemis program, on Friday, May 31, 2019, at NASA’s Goddard Space Flight Center in Greenbelt, Md. ..Read more: https://go.nasa.gov/2Ki2mJo..Credit: NASA/Goddard/Rebecca Roth

There will be a total of ten payloads on as part of the CLPS; Lunar Instrumentation for Subsurface Thermal Exploration with Rapidity, Lunar PlanetVac, Next Generation Lunar Retroflector, Regolith Adherence Characterisation, Radiation Tolerant Computer, Electrodynamic Dust Shield, Lunar Environment heliospheric X-ray Imager, Lunar Magnetotelluric Sounder, Lunar GNSS Receiver Experiment and Stereo Camera for Lunar Plume Surface Studies. 

Being launched alongside Blue Ghost but following its own trajectory to the Moon is the Japanese built HAKUTO-R M2 Resilience lander. Unlike Blue Ghost, HAKUTO-R will take a low energy trajectory to the Moon arriving in about four months time in Mare Frigoris. On arrival, it will deploy a lunar rover called Tenacious which will collect small samples of lunar regolith. Under a contract which was awarded by NASA back in 2020, the regolith will be sold back to NASA for $5,000 USD. 

Source : Liftoff! NASA Sends Science, Tech to Moon on Firefly, SpaceX Flight

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NASA’s Curiosity Rover has been exploring Mars since 2012 and, more recently has found evidence of ice-free ancient ponds and lakes on the surface. The rover found small undulations like those seen in sandy lake-beds on Earth. They would have been created by wind-driven water moving back and forth across the surface. The inescapable conclusion is that the water would have been open to the elements instead of being covered by ice. The discovery suggests the ripples formed 3.7 billion years ago. 

Mars it the fourth planet in our Solar System and the second smallest of all the major planets. It’s known for its strong red colour which is caused by iron oxide in the surface material. Classed as a terrestrial planet, Mars is similar in many ways to Earth with valleys, volcanoes and even evidence of dried up river beds. The similarities end there though with polar caps made mostly of carbon dioxide ice, an unbreathable atmosphere and a surface that is cold and dry. It’s always held a special fascination for us due largely to vague hints through the centuries of alien intelligent but more recently that it may have once been habitable. 

A full-disk view of Mars, courtesy of VMC. Credit: ESA

Once such rover that has been exploring the Martian landscape is the Curiosity Rover that was sent by NASA in 2011. It arrived at Mars in August 2012 and has been exploring the region around Gale Crater ever since. The main objective of Curiosity is to investigate the climate and geology and to assess if it could support primative life in the past. To achieve that end, it’s equipped with an array of instruments from drills to collect soil samples, cameras and instruments to analyse atmospheric samples. 

New simulations are helping inform the Curiosity rover’s ongoing sampling campaign. Credit:NASA/JPL-Caltech/MSSS

A paper recently published in the journal Science Advances by Caltech’s John Grotzinger, Harold Brown Professor of Geology and Michael Lamb, Professor of Geology shared their findings. They found two sets of what seem to be ancient wave ripples on the surface of Mars now thought to be dried up bodes of water with the ripples preserved in rock. The ripples are tiny undulations and are often seen in beaches and lake-beds on Earth as wind-driven water flows across the shallows. The team are particularly excited that this means the water was not frozen and was once open to the elements as liquid. 

The ripples discovered by Curiosity in Gale Crater are the strongest evidence to date that there have been bodies of liquid water in the history of the red planet. Analysis of the rocks and ripples suggest they formed 3.7 billion years ago. It’s thought that the atmosphere and climate of Mars must have been far warmer than it is today and more dense. Dense enough to support liquid water in open air.

NASA’s Curiosity rover continues to search for signs that Mars’ Gale Crater conditions could support microbial life. Photo credit: NASA/JPL-Caltech/MSSS.

The team were able to create computer models from the ripples they found to attempt to discover the size of lake. The size of the ripples and separation helps to determine how much water was present. The ripple height of 6mm and 4 to 5 cm separation tells us that the lake was shallow, possibly even less than 2 metres deep. One of the sets of ripples known as the Prow outcrop was found in an area that was once wind blown dunes. The other set was found nearby in the sulcate-rich Amapari Marker Band of rocks. The two regions come from slightly different times telling us that the warm dense atmosphere occurred at multiple times or at least for a long period of time. 

The discovery has been a massive help to Mars paleoclimate studies that have tried to map the changing conditions on Mars. NASA’s Opportunity rover was the first mission to discover ripples on the surface but the nature of the bodies of water was uncertain. This latest discovery has given a fascinating insight into the early conditions on Mars, with perhaps, bodies of liquid dotted across the landscape. Further investigation is needed to see how commonplace the ripples are. 

Source : Signatures of Ice-Free Ancient Ponds and Lakes Found on Mars

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Gas is the stuff of star formation, and most galaxies have enough gas in their budget to form some stars. However, the picture is a little different for dwarf galaxies. They lack the mass required to hold onto their gas when more massive neighbouring galaxies are siphoning it off.

New research shows that even isolated dwarf galaxies with no overbearing galactic neighbours struggle to form stars. What’s going on?

The research is centred on ultra-faint dwarf (UFD) galaxies. These tiny galaxies are the faintest galaxies in the Universe and contain only a few hundred stars, up to about one thousand. UFDs also contain ample amounts of dark matter. They’re different from globular clusters because globulars contain tens of thousands up to millions of stars and have very little dark matter, maybe none at all.

Because they’re so faint, astronomers struggle to locate them. The ones that have been found are close to the Milky Way. However, that makes them difficult to study because their massive neighbour dominates them. The Milky Way’s gravity and hot corona can siphon the UFDs’ gas away, making it challenging to understand their natural evolution.

Astronomers working with the DECam and the Gemini South Telescope have successfully located three UFDs well beyond the Milky Way’s gravitational influence. Although they weren’t easy to find, astronomers have made significant discoveries about UFDs from them.

The results are in new research published in The Astrophysical Journal Letters. It’s titled “Three Quenched, Faint Dwarf Galaxies in the Direction of NGC 300: New Probes of Reionization and Internal Feedback.” The lead author is David Sand, an astronomer from the Steward Observatory at the University of Arizona.

Sand found the three UFDs during a painstaking manual search. The UFDs are so faint that algorithmic searches couldn’t detect them.

“It was during the pandemic,” recalled Sand. “I was watching TV and scrolling through the DESI Legacy Survey viewer, focusing on areas of sky that I knew hadn’t been searched before. It took a few hours of casual searching, and then boom! They just popped out.”

The three UFDs are in the direction of the spiral galaxy NGC 300 and the Sculptor constellation. They’re called Sculptor A, Sculptor B, and Sculptor C.

Sculptor A is about 1.35 Mpc away and is likely at the edge of the Local Group, similar to Tucana B. It’s not a direct satellite of NGC 300.

Sculptor B is about 2.48 Mpc away and is likely behind NGC 300.

Sculptor C is about 2.04 Mpc away and is a satellite of NGC 300.

All three UFDs share some characteristics. They contain mostly old, metal-poor stars, are quenched and do not form any new stars, contain no neutral atomic hydrogen (H i), and emit no UV. “None of the three dwarfs are detected in H i line emission in the H i Parkes All Sky Survey, suggesting that they are not gas rich,” Sand and his co-researchers explain in their paper.

The lack of H I and UV both indicate that the galaxies are quenched and star formation has ceased. “Any younger blue stellar population either has few stars associated with it or is below our detection limit,” the authors write.

The discovery of the Sculptor galaxies, as they’re called, supports theories that say UFDs are dead galaxies that ceased star formation a long time ago in the early Universe. So, finding these faint quenched galaxies is entirely expected.

The jarring thing about their discovery is that they’re isolated. They’re not in proximity to any other larger galaxies that could’ve stripped away their gas and quenched their star formation. “The three dwarf galaxies in this work are among the faintest quenched dwarfs discovered outside the Local Group,” the authors write.

“Many of the recently discovered faint dwarf galaxies beyond the Local Group show distinct signs of recent star formation, although a growing subset also appears to be quenched, with little to no recent star formation,” the authors explain. “The mix of stellar populations of faint dwarf galaxies in the “field” is a critical ingredient for understanding the role of reionization, stellar feedback, and ram pressure from the cosmic web in driving the evolution of the smallest galaxies.”

Finding these three UFDs is significant because of their isolation. Only one of them, Sculptor C, is clearly associated with the nearby NGC 300. Sculptors A and B are isolated. Studying them is an opportunity to learn more about how star formation is affected by internal feedback mechanisms in low-mass galaxies. It’s also an opportunity to learn more about ram-pressure stripping, which is when gas is removed from a galaxy through interactions with the surrounding medium and even cosmic reionization.

During cosmic reionization, also known as the Epoch of Reionization, light from the first stars and galaxies reionized the neutral hydrogen in the intergalactic medium. The high-energy UV photons from the stars and galaxies could’ve effectively boiled away the gas in dwarf galaxies, ending their star formation.

An alternative explanation for UFDs losing their gas is supernova explosions. If some of the first stars in UFDs exploded, they could have expelled the gas and ended star formation. Ram-pressure stripping could also have been responsible.

Astronomers still need to learn more about reionization and if it’s responsible, and the Sculptor galaxies can help them.

“We don’t know how strong or uniform this reionization effect is,” explained Sand. “It could be that reionization is patchy, not occurring everywhere all at once. We’ve found three of these galaxies, but that isn’t enough. It would be nice if we had hundreds of them. If we knew what fraction was affected by reionization, that would tell us something about the early Universe that is very difficult to probe otherwise.”

“The Epoch of Reionization potentially connects the current day structure of all galaxies with the earliest formation of structure on a cosmological scale,” said Martin Still, NSF program director for the International Gemini Observatory. “The DESI Legacy Surveys and detailed follow-up observations by Gemini allow scientists to perform forensic archeology to understand the nature of the Universe and how it evolved to its current state.”

Ultimately, astronomers need to find more of these isolated UFDs to constrain their findings.

“Many more faint and ultrafaint dwarf galaxies are predicted at the edges of the Local Group and in nearby, low-density environments, but initial efforts to find them have not always been successful,” the authors write in their conclusion. That only emphasizes the importance of this discovery.

“Several upcoming programs such as Euclid, the Roman Space Telescope, and the Rubin Observatory Legacy Survey of Space and Time are sure to find many more examples in the years ahead, which will provide demographic properties across environments,” the authors conclude.

Sand presented these results at the recent 245th Meeting of the American Astronomical Society. Find them at the 32:00 mark of this video.

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