Study Findings: Deimos’s Shape and Geology Explained by a Subcatastrophic Impact

Posted on by onespaceman2000
Image (Credit): Image of Mars (left), Phobos (center), and Deimos (right). (NASA)

Nature Astronomy abstract of study findings:

Small planetary bodies record the processes that shaped the Solar System, but their surfaces and interiors often evolve in unexpected ways. Deimos, the potato-shaped, 12-km-diameter outer satellite of Mars, has a strikingly smooth surface covered by fine regolith, in contrast to its heavily cratered and grooved sibling, 22-km-diameter Phobos. Moreover, Deimos’s topography is dominated by a single large south-polar depression, whose formation we simulate to constrain the moon’s interior and surface geomechanical properties and to explain the origin and distribution of its regolith. Here we find that an oblique impact by a 320-m-diameter projectile can quantitatively account for this depression, the global regolith layer and surface features such as bright streaks and crater infill. Our results show that Deimos’s upper layers are extremely weak and that its interior is highly porous and dissipative, resembling the recently visited rubble-pile asteroids rather than lunar regolith. This suggests that small dark moons and asteroids, despite their specific histories, may converge on similar physical states.

Citation: Raducan, S.D., Agrusa, H.F., Asphaug, E. et al. Deimos’s shape and geology explained by a subcatastrophic impact. Nat Astron (2026).

DOI: https://doi.org/10.1038/s41550-026-02956-w

Study-related stories:

Science Daily – “One Asteroid Strike May Explain Two Mysteries of Mars’ Moon Deimos”

Phys.org – “A Single Asteroid Impact May Explain the Appearance of Mars’ Moon Deimos”

Universe Today– “Mars’s Funky Moon Deimos was Shaped by an Impact”

Space Stories: Dragon Delays, Odd Black Holes, and Surprising Martian Warmth

Posted on by onespaceman2000
Image (Credit): SpaceX Dragon capsule. (SpaceX)

Here are some recent space-related stories of interest.

—Space.com: “SpaceX, NASA Delay Next Astronaut Launch to ISS Due To Leak on Dragon Spacecraft”

SpaceX’s next astronaut mission to the International Space Station won’t launch on Sept. 12 after all. That flight, known as Crew-13, has been delayed due to an oxidizer leak in the propulsion system of SpaceX’s Dragon spacecraft, NASA announced on Saturday (Aug. 29). Joint NASA and SpaceX teams are performing additional tests and data review and will complete any necessary rework prior to launch,” NASA officials wrote in an update on Saturday. “A new target date will be announced once available.”

—Earth.com: “Giant Black Holes Appeared Too soon After the Big Bang, and Astronomers May Know Why“

Nearly every large galaxy keeps a giant black hole at its center. Some of those giants already weighed a billion Suns when the universe was less than 700 million years old. Astronomers have struggled for decades to explain how anything grew that heavy that fast. A new study built on James Webb Space Telescope observations suggests one possible answer. The researchers describe a young black hole wrapped in gas so dense that the whole object shines like a single enormous star. Astronomers call objects like it black hole stars. The light from this one has been traveling for 13 billion years, since a moment just 660 million years after the Big Bang, and no earlier example has been found.

—Caltech: “Thermal Anomaly Discovered Below Mars’s South Pole“

Based on gravitational measurements that give clues to the Red Planet’s interior structure, Mars’s interior southern hemisphere is around 200 to 400 degrees Celsius warmer than the northern half of the planet and partially molten. The surprising finding adds additional context to Martian history and the periods of time in which it may have hosted conditions favorable for life. The research was led by Caltech alumnus Alexander Berne (PhD ’26), who is now a postdoctoral associate at the University of Arizona. The findings are reported in a paper appearing in the journal Nature on August 27.

Note: Here is the podcast version of this post.

WiCOR Discovers a Mega-Earth

Posted on by onespaceman2000
Credit: WiCOR.

The Wisconsin Center for Origins Research (WiCOR) at the University of Wisconsin has two questions as part of its mission:

  • How do habitable planets form?
  • How does life emerge on habitable planets?

And now, the center has discovered its first exoplanet that brings up an unexpected question – Why is the newly discovered exoplanet GJ 523b a Mega-Earth rather than a gas giant like Saturn or Jupiter?

This new exoplanet, located about 87 light-years away, is 2.5 times the size of our Earth and 23 times its mass. To date, it was understood that something this large would become the core of a gas giant and not just a rocky planet like Earth. So what is the story here?

The results will appear shortly in a new paper, which will include some theories as to how this happened. You can read more about the discovery and at least one theory at the WiCOR site now.

Study Findings: Potential Survivable Niches for Microbial Life on the Lunar South Pole

Posted on by onespaceman2000
Credit: Image by Mohamed Hassan from Pixabay.

Science Advances abstract of study findings:

Most lunar surface conditions are incredibly harsh for microbial survival. High ultraviolet radiation, temperatures, and energetic particle radiation limit survival over most unprotected lunar surfaces, particularly in equatorial regions where all previous crewed exploration occurred. However, whether these harsh conditions are widespread at lunar poles has not been examined considering topographical effects. Here, we show that recent microorganism survivability data and lunar surface remote sensing reveal likely survivable niches in lunar polar regions. Analysis of topography and latitude-driven surface conditions using remote sensing data and high-resolution illumination models indicates the lunar south pole has substantial regions with persistent low temperatures and ultraviolet flux. Comparing these conditions to survivability data of specific microorganisms, we find that significant lunar polar areas likely have surface conditions amenable to microbial survival. Our findings suggest that lunar polar regions may be less hostile to microbial survival than previously assumed. This does not encompass growth likelihood, but survival in a cryptobiotic state where growth would be possible if habitable conditions were present. Potential microbial survivability at lunar poles is particularly significant given many examined microbes will likely be transported to the Moon during crewed lunar south pole exploration planned in numerous near-term missions. Thoughtfully planning exploration and tracking its impact is key to limiting and understanding potential unintended life transfer to the Moon.

Citation: Saxena, P., Bertone, S., Heather V. Graham, H. et al. Potential survivable niches for microbial life on the lunar south pole. Science Advances, Vol 12, Issue 34 (2026).

DOI: 10.1126/sciadv.aec0811

Study-related stories:

Tech Explorist – “Microbes From Earth May Be Able to Survive the Moon’s South Pole”

Scientific American – “Some Microbes Could Survive on the Moon—That’s a Big Problem for NASA”

The Jerusalem Post– “NASA Finds Some Microbes Could Survive on Moon, Raising Concerns Over Unintended Life Transfer”

Space Stories: Martian Spiders, Space Constipation, and an Exploding Chinese Rocket

Posted on by onespaceman2000
Image (Credit): Spider-like shapes on the surface of Mars. (ESA/TGO/CaSSIS)

Here are some recent space-related stories of interest.

—ZME Science: “NASA Finally Figured Out What’s Up With Those “Mars Spiders”“

For years, satellites around Mars kept finding mysterious, spider-like geological structures. Mars spiders, scientifically known as araneiform terrain, are unique geological formations predominantly found in the southern hemisphere of Mars. They appear as branching, spider-like channels etched into the Martian surface, sometimes spanning over a kilometer in length. In 2024, NASA-led lab experiments pinned down the likeliest way these “spiders” form: seasonal CO₂ ice. Now, a 2026 follow-up showed that the soil beneath the ice can make or break the process, and that these structures could hold clues to Mars’ wet past.

—Earth.com News: “Why Do Astronauts Get Constipated in Space? Scientists Have a New Clue“

Astronauts have complained about constipation for as long as people have flown to space. Nobody could say exactly why. Researchers have long suspected that living without gravity changes how quickly food moves through the gut. Blood drawn from crew members on long stays aboard the International Space Station now points to an answer. Giorgia La Barbera, a joint first author of the study and an associate professor at the University of Copenhagen’s Department of Nutrition, Exercise and Sports, led the work with NASA. “We see changes in astronauts’ blood samples that indicate that the gut bacteria begin to ferment protein to a greater extent than usual within weeks after the astronauts arrive in space, and this change continues until they are back on Earth,” La Barbera said.

—CNN: “Chinese Rocket Carrying Satellite Explodes Seconds After Launch“

A Chinese rocket set to launch a satellite into orbit blew-up seconds after liftoff Monday, marking the relatively rare failure for a rocket considered a workhorse of Beijing’s space program. The Long March 7A rocket erupted into a massive fireball just 85 seconds after blasting off from the Wenchang Space Launch Site on the island of Hainan on Monday night, video showed. Unlike other successful launches, the incident appears to have been downplayed on China’s state media with scant mention of the explosion.

Note: Here is the podcast version of this post.