Jump to content

Making Mars’ Moons: Supercomputers Offer ‘Disruptive’ New Explanation


Recommended Posts

  • Publishers
Posted
5 Min Read

Making Mars’ Moons: Supercomputers Offer ‘Disruptive’ New Explanation

mars-moons-simulations.png?w=875

A NASA study using a series of supercomputer simulations reveals a potential new solution to a longstanding Martian mystery: How did Mars get its moons? The first step, the findings say, may have involved the destruction of an asteroid. 

The research team, led by Jacob Kegerreis, a postdoctoral research scientist at NASA’s Ames Research Center in California’s Silicon Valley, found that an asteroid passing near Mars could have been disrupted – a nice way of saying “ripped apart” – by the Red Planet’s strong gravitational pull.

The team’s simulations show the resulting rocky fragments being strewn into a variety of orbits around Mars. More than half the fragments would have escaped the Mars system, but others would’ve stayed in orbit. Tugged by the gravity of both Mars and the Sun, in the simulations some of the remaining asteroid pieces are set on paths to collide with one another, every encounter further grinding them down and spreading more debris. 

Many collisions later, smaller chunks and debris from the former asteroid could have settled into a disk encircling the planet. Over time, some of this material is likely to have clumped together, possibly forming Mars’ two small moons, Phobos and Deimos.

To assess whether this was a realistic chain of events, the research team explored hundreds of different close encounter simulations, varying the asteroid’s size, spin, speed, and distance at its closest approach to the planet. The team used their high-performance, open-source computing code, called SWIFT, and the advanced computing systems at Durham University in the United Kingdom to study in detail both the initial disruption and, using another code, the subsequent orbits of the debris.

In a paper published Nov. 20 in the journal Icarus, the researchers report that, in many of the scenarios, enough asteroid fragments survive and collide in orbit to serve as raw material to form the moons. 

“It’s exciting to explore a new option for the making of Phobos and Deimos – the only moons in our solar system that orbit a rocky planet besides Earth’s,” said Kegerreis. “Furthermore, this new model makes different predictions about the moons’ properties that can be tested against the standard ideas for this key event in Mars’ history.”

Two hypotheses for the formation of the Martian moons have led the pack. One proposes that passing asteroids were captured whole by Mars’ gravity, which could explain the moons’ somewhat asteroid-like appearance. The other says that a giant impact on the planet blasted out enough material – a mix of Mars and impactor debris – to form a disk and, ultimately, the moons. Scientists believe a similar process formed Earth’s Moon.

The latter explanation better accounts for the paths the moons travel today – in near-circular orbits that closely align with Mars’ equator. However, a giant impact ejects material into a disk that, mostly, stays close to the planet. And Mars’ moons, especially Deimos, sit quite far away from the planet and probably formed out there, too. 

“Our idea allows for a more efficient distribution of moon-making material to the outer regions of the disk,” said Jack Lissauer, a research scientist at Ames and co-author on the paper. “That means a much smaller ‘parent’ asteroid could still deliver enough material to send the moons’ building blocks to the right place.”

It’s exciting to explore a new option for the making of Phobos and Deimos – the only moons in our solar system that orbit a rocky planet besides Earth’s.

Jacob Kegerreis

Jacob Kegerreis

Postdoctoral research scientist at NASA’s Ames Research Center

Testing different ideas for the formation of Mars’ moons is the primary goal of the upcoming Martian Moons eXploration (MMX) sample return mission led by JAXA (Japan Aerospace Exploration Agency). The spacecraft will survey both moons to determine their origin and collect samples of Phobos to bring to Earth for study. A NASA instrument on board, called MEGANE – short for Mars-moon Exploration with GAmma rays and Neutrons – will identify the chemical elements Phobos is made of and help select sites for the sample collection. Some of the samples will be collected by a pneumatic sampler also provided by NASA as a technology demonstration contribution to the mission. Understanding what the moons are made of is one clue that could help distinguish between the moons having an asteroid origin or a planet-plus-impactor source.

Before scientists can get their hands on a piece of Phobos to analyze, Kegerreis and his team will pick up where they left off demonstrating the formation of a disk that has enough material to make Phobos and Deimos. 

“Next, we hope to build on this proof-of-concept project to simulate and study in greater detail the full timeline of formation,” said Vincent Eke, associate professor at the Institute for Computational Cosmology at Durham University and a co-author on the paper. “This will allow us to examine the structure of the disk itself and make more detailed predictions for what the MMX mission could find.”  

For Kegerreis, this work is exciting because it also expands our understanding of how moons might be born – even if it turns out that Mars’ own formed by a different route. The simulations offer a fascinating exploration, he says, of the possible outcomes of encounters between objects like asteroids and planets. These events were common in the early solar system, and simulations could help researchers reconstruct the story of how our cosmic backyard evolved. 

This research is a collaborative effort between Ames and Durham University, supported by the Institute for Computational Cosmology’s Planetary Giant Impact Research group. The simulations used were run using the open-source SWIFT code, carried out on the DiRAC (Distributed Research Utilizing Advanced Computing) Memory Intensive service (“COSMA”), hosted by Durham University on behalf of the DiRAC High-Performance Computing facility.

For news media:

Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.

Keep Exploring

Discover More Topics From NASA

View the full article

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By NASA
      Explore This Section Perseverance Home Mission Overview Rover Components Mars Rock Samples Where is Perseverance? Ingenuity Mars Helicopter Mission Updates Science Overview Objectives Instruments Highlights Exploration Goals News and Features Multimedia Perseverance Raw Images Images Videos Audio More Resources Mars Missions Mars Sample Return Mars Perseverance Rover Mars Curiosity Rover MAVEN Mars Reconnaissance Orbiter Mars Odyssey More Mars Missions Mars Home 3 min read
      An Update From the 2025 Mars 2020 Science Team Meeting
      A behind-the-scenes look at the annual Mars 2020 Science Team Meeting
      Members of the Mars 2020 Science Team examine post-impact sediments within the Gardnos impact structure, northwest of Oslo, Norway, as part of the June 2025 Science Team Meeting. NASA/Katie Stack Morgan Written by Katie Stack Morgan, Mars 2020 Acting Project Scientist 
      The Mars 2020 Science Team gathered for a week in June to discuss recent science results, synthesize earlier mission observations, and discuss future plans for continued exploration of Jezero’s crater rim. It was also an opportunity to celebrate what makes this mission so special: one of the most capable and sophisticated science missions ever sent to Mars, an experienced and expert Science Team, and the rover’s many science accomplishments this past year.  
      We kicked off the meeting, which was hosted by our colleagues on the RIMFAX team at the University of Oslo, with a focus on our most recent discoveries on the Jezero crater rim. A highlight was the team’s in-depth discussion of spherules observed at Witch Hazel Hill, features which likely provide us the best chance of determining the origin of the crater rim rock sequence.   
      On the second day, we heard status updates from each of the science instrument teams. We then transitioned to a session devoted to “traverse-scale” syntheses. After 4.5 years of Perseverance on Mars and more than 37 kilometers of driving (more than 23 miles), we’re now able to analyze and integrate science datasets across the entire surface mission, looking for trends through space and time within the Jezero rock record. Our team also held a poster session, which was a great opportunity for in-person and informal scientific discussion.  
      The team’s modern atmospheric and environmental investigations were front and center on Day 3. We then rewound the clock, hearing new and updated analyses of data acquired during Perseverance’s earlier campaigns in Jezero’s Margin unit, crater floor, and western fan. The last day of the meeting was focused entirely on future plans for the Perseverance rover, including a discussion of our exploration and sampling strategy during the Crater Rim Campaign. We also looked further afield, considering where the rover might explore over the next few years.  
      Following the meeting, the Science Team took a one-day field trip to visit Gardnos crater, a heavily eroded impact crater with excellent examples of impact melt breccia and post-impact sediment fill. The team’s visit to Gardnos offered a unique opportunity to see and study impact-generated rock units like those expected on the Jezero crater rim and to discuss the challenges we have recognizing similar units with the rover on Mars. Recapping our Perseverance team meetings has been one of my favorite yearly traditions (see summaries from our 2022, 2023, and 2024 meetings) and I look forward to reporting back a year from now. As the Perseverance team tackles challenges in the year to come, we can seek inspiration from one of Norway’s greatest polar explorers, Fridtjof Nansen, who said while delivering his Nobel lecture, “The difficult is that which can be done at once; the impossible is that which takes a little longer.”
      Share








      Details
      Last Updated Jul 01, 2025 Related Terms
      Blogs Explore More
      2 min read Curiosity Blog, Sols 4584–4585: Just a Small Bump


      Article


      1 hour ago
      4 min read Curiosity Blog, Sols 4582-4583: A Rock and a Sand Patch


      Article


      3 days ago
      2 min read Curiosity Blog, Sols 4580-4581: Something in the Air…


      Article


      5 days ago
      Keep Exploring Discover More Topics From NASA
      Mars


      Mars is the fourth planet from the Sun, and the seventh largest. It’s the only planet we know of inhabited…


      All Mars Resources


      Explore this collection of Mars images, videos, resources, PDFs, and toolkits. Discover valuable content designed to inform, educate, and inspire,…


      Rover Basics


      Each robotic explorer sent to the Red Planet has its own unique capabilities driven by science. Many attributes of a…


      Mars Exploration: Science Goals


      The key to understanding the past, present or future potential for life on Mars can be found in NASA’s four…

      View the full article
    • By NASA
      7 min read
      A New Alloy is Enabling Ultra-Stable Structures Needed for Exoplanet Discovery
      A unique new material that shrinks when it is heated and expands when it is cooled could help enable the ultra-stable space telescopes that future NASA missions require to search for habitable worlds.
      Advancements in material technologies are needed to meet the science needs of the next great observatories. These observatories will strive to find, identify, and study exoplanets and their ability to support life. Credit: NASA JPL One of the goals of NASA’s Astrophysics Division is to determine whether we are alone in the universe. NASA’s astrophysics missions seek to answer this question by identifying planets beyond our solar system (exoplanets) that could support life. Over the last two decades, scientists have developed ways to detect atmospheres on exoplanets by closely observing stars through advanced telescopes. As light passes through a planet’s atmosphere or is reflected or emitted from a planet’s surface, telescopes can measure the intensity and spectra (i.e., “color”) of the light, and can detect various shifts in the light caused by gases in the planetary atmosphere. By analyzing these patterns, scientists can determine the types of gasses in the exoplanet’s atmosphere.
      Decoding these shifts is no easy task because the exoplanets appear very near their host stars when we observe them, and the starlight is one billion times brighter than the light from an Earth-size exoplanet. To successfully detect habitable exoplanets, NASA’s future Habitable Worlds Observatory will need a contrast ratio of one to one billion (1:1,000,000,000).
      Achieving this extreme contrast ratio will require a telescope that is 1,000 times more stable than state-of-the-art space-based observatories like NASA’s James Webb Space Telescope and its forthcoming Nancy Grace Roman Space Telescope. New sensors, system architectures, and materials must be integrated and work in concert for future mission success. A team from the company ALLVAR is collaborating with NASA’s Marshall Space Flight Center and NASA’s Jet Propulsion Laboratory to demonstrate how integration of a new material with unique negative thermal expansion characteristics can help enable ultra-stable telescope structures.
      Material stability has always been a limiting factor for observing celestial phenomena. For decades, scientists and engineers have been working to overcome challenges such as micro-creep, thermal expansion, and moisture expansion that detrimentally affect telescope stability. The materials currently used for telescope mirrors and struts have drastically improved the dimensional stability of the great observatories like Webb and Roman, but as indicated in the Decadal Survey on Astronomy and Astrophysics 2020 developed by the National Academies of Sciences, Engineering, and Medicine, they still fall short of the 10 picometer level stability over several hours that will be required for the Habitable Worlds Observatory. For perspective, 10 picometers is roughly 1/10th the diameter of an atom.

      NASA’s Nancy Grace Roman Space Telescope sits atop the support structure and instrument payloads. The long black struts holding the telescope’s secondary mirror will contribute roughly 30% of the wave front error while the larger support structure underneath the primary mirror will contribute another 30%.
      Credit: NASA/Chris Gunn
      Funding from NASA and other sources has enabled this material to transition from the laboratory to the commercial scale. ALLVAR received NASA Small Business Innovative Research (SBIR) funding to scale and integrate a new alloy material into telescope structure demonstrations for potential use on future NASA missions like the Habitable Worlds Observatory. This alloy shrinks when heated and expands when cooled—a property known as negative thermal expansion (NTE). For example, ALLVAR Alloy 30 exhibits a -30 ppm/°C coefficient of thermal expansion (CTE) at room temperature. This means that a 1-meter long piece of this NTE alloy will shrink 0.003 mm for every 1 °C increase in temperature. For comparison, aluminum expands at +23 ppm/°C.

      While other materials expand while heated and contract when cooled, ALLVAR Alloy 30 exhibits a negative thermal expansion, which can compensate for the thermal expansion mismatch of other materials. The thermal strain versus temperature is shown for 6061 Aluminum, A286 Stainless Steel, Titanium 6Al-4V, Invar 36, and ALLVAR Alloy 30.
      Because it shrinks when other materials expand, ALLVAR Alloy 30 can be used to strategically compensate for the expansion and contraction of other materials. The alloy’s unique NTE property and lack of moisture expansion could enable optic designers to address the stability needs of future telescope structures. Calculations have indicated that integrating ALLVAR Alloy 30 into certain telescope designs could improve thermal stability up to 200 times compared to only using traditional materials like aluminum, titanium, Carbon Fiber Reinforced Polymers (CFRPs), and the nickel–iron alloy, Invar.
      The hexapod assembly with six ALLVAR Alloy struts was measured for long-term stability. The stability of the individual struts and the hexapod assembly were measured using interferometry at the University of Florida’s Institute for High Energy Physics and Astrophysics. The struts were found to have a length noise well below the proposed target for the success criteria for the project. Credit: (left) ALLVAR and (right) Simon F. Barke, Ph.D. To demonstrate that negative thermal expansion alloys can enable ultra-stable structures, the ALLVAR team developed a hexapod structure to separate two mirrors made of a commercially available glass ceramic material with ultra-low thermal expansion properties. Invar was bonded to the mirrors and flexures made of Ti6Al4V—a titanium alloy commonly used in aerospace applications—were attached to the Invar. To compensate for the positive CTEs of the Invar and Ti6Al4V components, an NTE ALLVAR Alloy 30 tube was used between the Ti6Al4V flexures to create the struts separating the two mirrors. The natural positive thermal expansion of the Invar and Ti6Al4V components is offset by the negative thermal expansion of the NTE alloy struts, resulting in a structure with an effective zero thermal expansion.
      The stability of the structure was evaluated at the University of Florida Institute for High Energy Physics and Astrophysics. The hexapod structure exhibited stability well below the 100 pm/√Hz target and achieved 11 pm/√Hz. This first iteration is close to the 10 pm stability required for the future Habitable Worlds Observatory. A paper and presentation made at the August 2021 Society of Photo-Optical Instrumentation Engineers conference provides details about this analysis.
      Furthermore, a series of tests run by NASA Marshall showed that the ultra-stable struts were able to achieve a near-zero thermal expansion that matched the mirrors in the above analysis. This result translates into less than a 5 nm root mean square (rms) change in the mirror’s shape across a 28K temperature change.
      The ALLVAR enabled Ultra-Stable Hexapod Assembly undergoing Interferometric Testing between 293K and 265K (right). On the left, the Root Mean Square (RMS) changes in the mirror’s surface shape are visually represented. The three roughly circular red areas are caused by the thermal expansion mismatch of the invar bonding pads with the ZERODUR mirror, while the blue and green sections show little to no changes caused by thermal expansion. The surface diagram shows a less than 5 nanometer RMS change in mirror figure. Credit: NASA’s X-Ray and Cryogenic Facility [XRCF] Beyond ultra-stable structures, the NTE alloy technology has enabled enhanced passive thermal switch performance and has been used to remove the detrimental effects of temperature changes on bolted joints and infrared optics. These applications could impact technologies used in other NASA missions. For example, these new alloys have been integrated into the cryogenic sub-assembly of Roman’s coronagraph technology demonstration. The addition of NTE washers enabled the use of pyrolytic graphite thermal straps for more efficient heat transfer. ALLVAR Alloy 30 is also being used in a high-performance passive thermal switch incorporated into the UC Berkeley Space Science Laboratory’s Lunar Surface Electromagnetics Experiment-Night (LuSEE Night) project aboard Firefly Aerospace’s Blue Ghost Mission 2, which will be delivered to the Moon through NASA’s CLPS (Commercial Lunar Payload Services) initiative. The NTE alloys enabled smaller thermal switch size and greater on-off heat conduction ratios for LuSEE Night.
      Through another recent NASA SBIR effort, the ALLVAR team worked with NASA’s Jet Propulsion Laboratory to develop detailed datasets of ALLVAR Alloy 30 material properties. These large datasets include statistically significant material properties such as strength, elastic modulus, fatigue, and thermal conductivity. The team also collected information about less common properties like micro-creep and micro-yield. With these properties characterized, ALLVAR Alloy 30 has cleared a major hurdle towards space-material qualification.
      As a spinoff of this NASA-funded work, the team is developing a new alloy with tunable thermal expansion properties that can match other materials or even achieve zero CTE. Thermal expansion mismatch causes dimensional stability and force-load issues that can impact fields such as nuclear engineering, quantum computing, aerospace and defense, optics, fundamental physics, and medical imaging. The potential uses for this new material will likely extend far beyond astronomy. For example, ALLVAR developed washers and spacers, are now commercially available to maintain consistent preloads across extreme temperature ranges in both space and terrestrial environments. These washers and spacers excel at counteracting the thermal expansion and contraction of other materials, ensuring stability for demanding applications.
      For additional details, see the entry for this project on NASA TechPort.
      Project Lead: Dr. James A. Monroe, ALLVAR
      The following NASA organizations sponsored this effort: NASA Astrophysics Division, NASA SBIR Program funded by the Space Technology Mission Directorate (STMD).
      Share








      Details
      Last Updated Jul 01, 2025 Related Terms
      Technology Highlights Astrophysics Astrophysics Division Science-enabling Technology Explore More
      7 min read NASA Webb ‘Pierces’ Bullet Cluster, Refines Its Mass


      Article


      1 day ago
      2 min read Hubble Captures an Active Galactic Center


      Article


      4 days ago
      2 min read NASA Citizen Scientists Find New Eclipsing Binary Stars


      Article


      5 days ago
      View the full article
    • By European Space Agency
      Video: 00:04:13 Daniel Neuenschwander, ESA head of Space and Robotic Exploration, explains that Ignis mission will include an ambitious technological and scientific programme with several experiments led by ESA and proposed by the Polish space industry.
      On 26 June 2025, ESA project astronaut Sławosz Uznański-Wiśniewski from Poland and his crewmates arrived to the International Space Station on the Axiom-4 mission (Ax-4).
      The Polish project astronaut is the second of a new generation of European astronauts to fly on a commercial human spaceflight opportunity with Axiom Space.
      View the full article
    • By European Space Agency
      At the Living Planet Symposium, attendees have been hearing how ESA’s Next Generation Gravity Mission could provide the first opportunity to directly track a vital ocean circulation system that warms our planet – but is now weakening, risking a possible collapse with far-reaching consequences.
      View the full article
    • By European Space Agency
      The European Space Agency’s Mars Express has captured a swirl of colour on the Red Planet, with yellows and rust-oranges meeting deep reds and browns. Lurking within this martian palette are not one but four dust devils, each snaking their way across the surface.
      View the full article
  • Check out these Videos

×
×
  • Create New...