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By NASA
NASA/Rachel Tilling Sea ice is frozen seawater that floats in the ocean. This photo, taken from NASA’s Gulfstream V Research Aircraft on July 21, 2022, shows Arctic sea ice in the Lincoln Sea north of Greenland.
This image is the NASA Science Image of the Month for September 2025. Each month, NASA’s Science Mission Directorate chooses an image to feature, offering desktop wallpaper downloads, as well as links to related topics, activities, and games.
Text and image credit: NASA/Rachel Tilling
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Scientists believe giant impacts — like the one depicted in this artist’s concept — occurred on Mars 4.5 billion years ago, injecting debris from the impact deep into the planet’s mantle. NASA’s InSight lander detected this debris before the mission’s end in 2022.NASA/JPL-Caltech Rocky material that impacted Mars lies scattered in giant lumps throughout the planet’s mantle, offering clues about Mars’ interior and its ancient past.
What appear to be fragments from the aftermath of massive impacts on Mars that occurred 4.5 billion years ago have been detected deep below the planet’s surface. The discovery was made thanks to NASA’s now-retired InSight lander, which recorded the findings before the mission’s end in 2022. The ancient impacts released enough energy to melt continent-size swaths of the early crust and mantle into vast magma oceans, simultaneously injecting the impactor fragments and Martian debris deep into the planet’s interior.
There’s no way to tell exactly what struck Mars: The early solar system was filled with a range of different rocky objects that could have done so, including some so large they were effectively protoplanets. The remains of these impacts still exist in the form of lumps that are as large as 2.5 miles (4 kilometers) across and scattered throughout the Martian mantle. They offer a record preserved only on worlds like Mars, whose lack of tectonic plates has kept its interior from being churned up the way Earth’s is through a process known as convection.
A cutaway view of Mars in this artist’s concept (not to scale) reveals debris from ancient impacts scattered through the planet’s mantle. On the surface at left, a meteoroid impact sends seismic signals through the interior; at right is NASA’s InSight lander.NASA/JPL-Caltech The finding was reported Thursday, Aug. 28, in a study published by the journal Science.
“We’ve never seen the inside of a planet in such fine detail and clarity before,” said the paper’s lead author, Constantinos Charalambous of Imperial College London. “What we’re seeing is a mantle studded with ancient fragments. Their survival to this day tells us Mars’ mantle has evolved sluggishly over billions of years. On Earth, features like these may well have been largely erased.”
InSight, which was managed by NASA’s Jet Propulsion Laboratory in Southern California, placed the first seismometer on Mars’ surface in 2018. The extremely sensitive instrument recorded 1,319 marsquakes before the lander’s end of mission in 2022.
NASA’s InSight took this selfie in 2019 using a camera on its robotic arm. The lander also used its arm to deploy the mission’s seismometer, whose data was used in a 2025 study showing impacts left chunks of debris deep in the planet’s interior.NASA/JPL-Caltech Quakes produce seismic waves that change as they pass through different kinds of material, providing scientists a way to study the interior of a planetary body. To date, the InSight team has measured the size, depth, and composition of Mars’ crust, mantle, and core. This latest discovery regarding the mantle’s composition suggests how much is still waiting to be discovered within InSight’s data.
“We knew Mars was a time capsule bearing records of its early formation, but we didn’t anticipate just how clearly we’d be able to see with InSight,” said Tom Pike of Imperial College London, coauthor of the paper.
Quake hunting
Mars lacks the tectonic plates that produce the temblors many people in seismically active areas are familiar with. But there are two other types of quakes on Earth that also occur on Mars: those caused by rocks cracking under heat and pressure, and those caused by meteoroid impacts.
Of the two types, meteoroid impacts on Mars produce high-frequency seismic waves that travel from the crust deep into the planet’s mantle, according to a paper published earlier this year in Geophysical Research Letters. Located beneath the planet’s crust, the Martian mantle can be as much as 960 miles (1,550 kilometers) thick and is made of solid rock that can reach temperatures as high as 2,732 degrees Fahrenheit (1,500 degrees Celsius).
Scrambled signals
The new Science paper identifies eight marsquakes whose seismic waves contained strong, high-frequency energy that reached deep into the mantle, where their seismic waves were distinctly altered.
“When we first saw this in our quake data, we thought the slowdowns were happening in the Martian crust,” Pike said. “But then we noticed that the farther seismic waves travel through the mantle, the more these high-frequency signals were being delayed.”
Using planetwide computer simulations, the team saw that the slowing down and scrambling happened only when the signals passed through small, localized regions within the mantle. They also determined that these regions appear to be lumps of material with a different composition than the surrounding mantle.
With one riddle solved, the team focused on another: how those lumps got there.
Turning back the clock, they concluded that the lumps likely arrived as giant asteroids or other rocky material that struck Mars during the early solar system, generating those oceans of magma as they drove deep into the mantle, bringing with them fragments of crust and mantle.
Charalambous likens the pattern to shattered glass — a few large shards with many smaller fragments. The pattern is consistent with a large release of energy that scattered many fragments of material throughout the mantle. It also fits well with current thinking that in the early solar system, asteroids and other planetary bodies regularly bombarded the young planets.
On Earth, the crust and uppermost mantle is continuously recycled by plate tectonics pushing a plate’s edge into the hot interior, where, through convection, hotter, less-dense material rises and cooler, denser material sinks. Mars, by contrast, lacks tectonic plates, and its interior circulates far more sluggishly. The fact that such fine structures are still visible today, Charalambous said, “tells us Mars hasn’t undergone the vigorous churning that would have smoothed out these lumps.”
And in that way, Mars could point to what may be lurking beneath the surface of other rocky planets that lack plate tectonics, including Venus and Mercury.
More about InSight
JPL managed InSight for NASA’s Science Mission Directorate. InSight was part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supported spacecraft operations for the mission.
A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), supported the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors.
News Media Contacts
Andrew Good
Jet Propulsion Laboratory, Pasadena, Calif.
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Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
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Last Updated Aug 28, 2025 Related Terms
InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) Jet Propulsion Laboratory Mars Explore More
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By NASA
This graphic features data from NASA’s Chandra X-ray Observatory of the Cassiopeia A (Cas A) supernova remnant that reveals that the star’s interior violently rearranged itself mere hours before it exploded. The main panel of this graphic is Chandra data that shows the location of different elements in the remains of the explosion: silicon (represented in red), sulfur (yellow), calcium (green) and iron (purple). The blue color reveals the highest-energy X-ray emission detected by Chandra in Cas A and an expanding blast wave. The inset reveals regions with wide ranges of relative abundances of silicon and neon. This data, plus computer modeling, reveal new insight into how massive stars like Cas A end their lives.X-ray: NASA/CXC/Meiji Univ./T. Sato et al.; Image Processing: NASA/CXC/SAO/N. Wolk The inside of a star turned on itself before it spectacularly exploded, according to a new study from NASA’s Chandra X-ray Observatory. Today, this shattered star, known as the Cassiopeia A supernova remnant, is one of the best-known, well-studied objects in the sky.
Over three hundred years ago, however, it was a giant star on the brink of self-destruction. The new Chandra study reveals that just hours before it exploded, the star’s interior violently rearranged itself. This last-minute shuffling of its stellar belly has profound implications for understanding how massive stars explode and how their remains behave afterwards.
Cassiopeia A (Cas A for short) was one of the first objects the telescope looked at after its launch in 1999, and astronomers have repeatedly returned to observe it.
“It seems like each time we closely look at Chandra data of Cas A, we learn something new and exciting,” said Toshiki Sato of Meiji University in Japan who led the study. “Now we’ve taken that invaluable X-ray data, combined it with powerful computer models, and found something extraordinary.”
As massive stars age, increasingly heavy elements form in their interiors by nuclear reactions, creating onion-like layers of different elements. Their outer layer is mostly made of hydrogen, followed by layers of helium, carbon and progressively heavier elements – extending all the way down to the center of the star.
Once iron starts forming in the core of the star, the game changes. As soon as the iron core grows beyond a certain mass (about 1.4 times the mass of the Sun), it can no longer support its own weight and collapses. The outer part of the star falls onto the collapsing core, and rebounds as a core-collapse supernova.
The new research with Chandra data reveals a change that happened deep within the star at the very last moments of its life. After more than a million years, Cas A underwent major changes in its final hours before exploding.
“Our research shows that just before the star in Cas A collapsed, part of an inner layer with large amounts of silicon traveled outwards and broke into a neighboring layer with lots of neon,” said co-author Kai Matsunaga of Kyoto University in Japan. “This is a violent event where the barrier between these two layers disappears.”
This upheaval not only caused material rich in silicon to travel outwards; it also forced material rich in neon to travel inwards. The team found clear traces of these outward silicon flows and inward neon flows in the remains of Cas A’s supernova remnant. Small regions rich in silicon but poor in neon are located near regions rich in neon and poor in silicon.
The survival of these regions not only provides critical evidence for the star’s upheaval, but also shows that complete mixing of the silicon and neon with other elements did not occur immediately before or after the explosion. This lack of mixing is predicted by detailed computer models of massive stars near the ends of their lives.
There are several significant implications for this inner turmoil inside of the doomed star. First, it may directly explain the lopsided rather than symmetrical shape of the Cas A remnant in three dimensions. Second, a lopsided explosion and debris field may have given a powerful kick to the remaining core of the star, now a neutron star, explaining the high observed speed of this object.
Finally, the strong turbulent flows created by the star’s internal changes may have promoted the development of the supernova blast wave, facilitating the star’s explosion.
“Perhaps the most important effect of this change in the star’s structure is that it may have helped trigger the explosion itself,” said co-author Hiroyuki Uchida, also of Kyoto University. “Such final internal activity of a star may change its fate—whether it will shine as a supernova or not.”
These results have been published in the latest issue of The Astrophysical Journal and are available online.
To learn more about Chandra, visit:
https://science.nasa.gov/chandra
Read more from NASA’s Chandra X-ray Observatory Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release features a composite image of Cassiopeia A, a donut-shaped supernova remnant located about 11,000 light-years from Earth. Included in the image is an inset closeup, which highlights a region with relative abundances of silicon and neon.
Over three hundred years ago, Cassiopeia A, or Cas A, was a star on the brink of self-destruction. In composition it resembled an onion with layers rich in different elements such as hydrogen, helium, carbon, silicon, sulfur, calcium, and neon, wrapped around an iron core. When that iron core grew beyond a certain mass, the star could no longer support its own weight. The outer layers fell into the collapsing core, then rebounded as a supernova. This explosion created the donut-like shape shown in the composite image. The shape is somewhat irregular, with the thinner quadrant of the donut to the upper left of the off-center hole.
In the body of the donut, the remains of the star’s elements create a mottled cloud of colors, marbled with red and blue veins. Here, sulfur is represented by yellow, calcium by green, and iron by purple. The red veins are silicon, and the blue veins, which also line the outer edge of the donut-shape, are the highest energy X-rays detected by Chandra and show the explosion’s blast wave.
The inset uses a different color code and highlights a colorful, mottled region at the thinner, upper left quadrant of Cas A. Here, rich pockets of silicon and neon are identified in the red and blue veins, respectively. New evidence from Chandra indicates that in the hours before the star’s collapse, part of a silicon-rich layer traveled outwards, and broke into a neighboring neon-rich layer. This violent breakdown of layers created strong turbulent flows and may have promoted the development of the supernova’s blast wave, facilitating the star’s explosion. Additionally, upheaval in the interior of the star may have produced a lopsided explosion, resulting in the irregular shape, with an off-center hole (and a thinner bite of donut!) at our upper left.
News Media Contact
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Corinne Beckinger
Marshall Space Flight Center, Huntsville, Alabama
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corinne.m.beckinger@nasa.gov
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Last Updated Aug 28, 2025 EditorLee MohonContactCorinne M. Beckingercorinne.m.beckinger@nasa.govLocationMarshall Space Flight Center Related Terms
Chandra X-Ray Observatory General Marshall Astrophysics Marshall Space Flight Center Supernova Remnants Supernovae The Universe Explore More
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By NASA
The 33rd SpaceX commercial resupply services mission for NASA, scheduled to liftoff from the agency’s Kennedy Space Center in Florida in late August, is heading to the International Space Station with an important investigation for the future of bone health.
The experiment will test how microgravity affects bone-forming and bone-degrading cells and explore potential ways to prevent bone loss. This research could help protect astronauts on future long-duration missions to the Moon and Mars, while also advancing treatments for millions of people on Earth who suffer from osteoporosis.
Mesenchymal stem cells (MSCs) are derived from human bone marrow and stained with rapid red dye NASA Space’s Hidden Health Mystery
During long-duration missions, astronauts may experience a gradual reduction in bone density—typically around 1% to 2% per month—even with consistent exercise routines. While scientists understand how bones work on Earth, they aren’t sure exactly why bones weaken so quickly in microgravity.
Previous research aboard the space station revealed that microgravity changes how stem cells behave and what substances they release. Scientists now want to dig deeper into these cellular changes to better understand what causes bone loss in space and explore potential ways to prevent it.
Blocking a Potential Bone Thief
The Microgravity Associated Bone Loss-B (MABL-B) investigation focuses on special stem cells called mesenchymal stem cells, or MSCs. As these cells mature, they build new bone tissue in the body.
Scientists suspect that a protein called IL-6 might be the culprit behind bone problems in space. Data from the earlier MABL-A mission suggests that microgravity promotes the type of IL-6 signaling that enhances bone degradation. The MABL-B experiment will investigate this by testing ways to block this IL-6 signaling pathway.
The experiment will grow mesenchymal stem cells alongside other bone cells in special containers designed for space research. Cells will be cultured for 19 days aboard the space station, with crew members periodically collecting samples for analysis back on Earth.
How this benefits space exploration
The research could lead to targeted treatments that protect astronauts from bone loss during long-duration missions to the Moon, Mars, and beyond. As crews venture farther from Earth, bone health becomes increasingly critical since medical evacuation or emergency return to Earth won’t be possible during Mars missions.
How this benefits humanity
The findings could provide new insights into age-related bone loss that affects millions of people on Earth. Understanding how the IL-6 protein affects bone health may lead to new treatments for osteoporosis and other bone conditions that come with aging.
Related Resources
Microgravity Associated Bone Loss-B (MABL-B) Microgravity Associated Bone Loss-A (MABL-A) Microgravity Expanded Stem Cells About BPS
NASA’s Biological and Physical Sciences Division pioneers scientific discovery and enables exploration by using space environments to conduct investigations not possible on Earth. Studying biological and physical phenomenon under extreme conditions allows researchers to advance the fundamental scientific knowledge required to go farther and stay longer in space, while also benefitting life on Earth.
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By European Space Agency
Using data from several Earth-observing satellites, including ESA’s CryoSat and the Copernicus Sentinel-1 and Sentinel-2 missions, scientists have discovered that a huge flood beneath the Greenland Ice Sheet surged upwards with such force that it fractured the ice sheet, resulting in a vast quantity of meltwater bursting through the ice surface.
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