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By NASA
5 Min Read Making Mars’ Moons: Supercomputers Offer ‘Disruptive’ New Explanation
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
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.
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Last Updated Nov 20, 2024 Related Terms
Mars Ames Research Center Ames Research Center's Science Directorate General High-Tech Computing Mars Moons Martian Moon Exploration (MMX) Missions NASA Centers & Facilities Planets Technology The Solar System Explore More
5 min read NASA’s Swift Reaches 20th Anniversary in Improved Pointing Mode
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By European Space Agency
ESA’s solar eclipse-making Proba-3 mission is about to leave Europe, to head to its launch site in India. The mission’s two spacecraft – which will manoeuvre precisely in Earth orbit so that one casts a shadow onto the other – have departed the facilities of Redwire Space in Kruibeke, Belgium. The pair will be flown to the Satish Dhawan Space Centre, near Chennai, for the launch campaign to begin.
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By NASA
2 min read
ESA/NASA’s SOHO Spies Bright Comet Making Debut in Evening Sky
The tail of comet C/2023 A3 Tsuchinshan-ATLAS spanned the view of the Solar and Heliospheric Observatory (SOHO) on Oct. 10, 2024. ESA/NASA The ESA (European Space Agency) and NASA Solar and Heliospheric Observatory (SOHO) has captured images of the second-brightest comet to ever pass through its field of view during the spacecraft’s nearly 29-year career.
The bright comet is C/2023 A3 Tsuchinshan-ATLAS, which has been garnering a lot of attention from skywatchers recently, displaying a long, dusty tail in pre-dawn skies throughout late September and early October. (Comet McNaught, viewed in 2007, holds the record as the brightest comet SOHO has seen.)
Between Oct. 7 and 11, the comet blazed through the view of SOHO’s LASCO (Large Angle and Spectrometric Coronagraph Experiment) instrument, which uses a disk to block out the bright light of the Sun so it’s easier to see details and objects near the Sun. This image, taken by SOHO on Oct. 10, 2024, shows the comet and its bright tail streaming from the upper left to the right. Mercury appears as a bright dot on the left.
After crossing through SOHO’s field of view, the comet will begin putting on an evening show for skywatchers around the world just after sunset starting Saturday, Oct. 12. Each day throughout October, the comet will gradually rise higher and higher in the western sky as it moves farther away from the Sun. But as it does, it will become fainter and fainter. Eagle-eyed skywatchers may be able to spot it with the naked eye for a few days, but after that, observers will likely need binoculars or a telescope to see it as it grows fainter.
Even if you are unable to spot this comet yourself, you can help SOHO search for others. Scientists and members of the general public have discovered more than 5,000 comets in SOHO imagery, and you can help find even more by visiting the Sungrazer Project.
By Vanessa Thomas
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Oct 11, 2024 Related Terms
Comets Goddard Space Flight Center Heliophysics Heliophysics Division Skywatching SOHO (Solar and Heliospheric Observatory) The Sun The Sun & Solar Physics Explore More
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By NASA
14 Min Read The Making of Our Alien Earth: The Undersea Volcanoes of Santorini, Greece
The expedition team and crew prepare to deploy Nereid Under Ice (NUI) into the sea. The following expedition marks the third installment of NASA Astrobiology’s fieldwork series, the newly rebranded Our Alien Earth, streaming on NASA+. Check out all three episodes following teams of astrobiologists from the lava fields of Holuhraun, Iceland, to the Isua Greenstone Belt of Greenland, and finally, the undersea volcanoes of Santorini, Greece. And stay tuned for the lava tubes of Mauna Loa, Hawaii in 2025.
THE VOYAGE BEGINS
My career at NASA has always felt like a mad scientist’s concoction of equal parts hard work, perseverance, absurd luck, and happenstance. It was due to this mad blend that I suddenly found myself on the deck of a massive tanker ship in the middle of the Mediterranean sea, watching a team of windburnt scientists, engineers, and sailors through my camera lens as they wrestled with a 5,000lb submersible hanging in the air.
The expedition team and crew prepare to deploy Nereid Under Ice (NUI) into the sea. “Let it out, Molly, slack off a little bit…” shouts deck boss Mario Fernandez, as he coordinates the dozen people maneuvering the vehicle. It’s a delicate dance as the hybrid remotely operated vehicle (ROV), Nereid Under Ice (NUI), is hoisted off the ship and deployed into the sea. “Tagline slips, line breaks… you’ve got a 5,000lb wrecking ball,” recounts Mario in an interview later that day.
How did I get here?
A few years ago I found myself roaming the poster halls of the Astrobiology Science Conference in Bellevue, Washington, struggling to decipher the jargon of a dozen disciplines doing their best to share their discoveries; phrases like lipid biomarkers, anaerobic biospheres, and macromolecular emergence floated past me as I walked. I felt like a Peanuts character listening to an adult speak.
Until I stumbled upon a poster by Dr. Richard Camilli entitled, Risk-Aware Adaptive Sampling for the Search for Life in Ocean Worlds. I was quickly enthralled in a whirlwind of icy moons, fleets of deep sea submersible vehicles, and life at sea.
Dr. Richard Camilli, principal investigator of a research expedition to explore undersea volcanoes off the coast of Santorini. “Are you free in November?”
“Absolutely,” I replied without checking a single calendar.
Five months and three flights later, I arrived at the port of Lavrio, Greece, as Dr. Camilli and his team were unloading their suite of vehicles from gigantic shipping crates onto the even more massive research vessel. I stocked up on motion sickness tablets, said a silent farewell to land, and boarded the ship destined for the undersea Kolumbo volcano.
Greece is a great place to study geology, because it’s a kind of supermarket of natural disasters.
Dr. Paraskevi NomikoU
University of Athens
The expedition sets out to sea as the sun sets in the distance. LIFE AT SEA
Documenting astrobiology fieldwork has taken me to some pretty remote and rough places. Sleeping in wooden shacks in Iceland without running water and electricity, or bundled up in a zero-degree sleeping bag in a tent while being buffeted by gale force winds in the wilderness of Greenland. But life at sea? Life at sea is GOOD.
Filmmaker Mike Toillion takes a selfie, holding up a peace sign with members of the science team. From left to right: NASA Astrobiology/Mike Toillion Mike Toillion, creator of Our Alien Earth, taking a selfie with members of the glider team. From left to right: Matt Walter and Gideon Billings of the autonomous sampling team inside the ship’s control room.
I was fortunate to have a personal cabin all to myself: a set of bunk beds, a small bathroom with a shower, and a small desk with plenty of outlets for charging my gear. I would also be remiss if I didn’t mention the mess hall. Aside from a freshly rotated menu of three hot meals a day, it was open 24/7 with a constant lineup of snacks to keep bellies full and morale high. This was luxury fieldwork. The ability to live, work, and socialize all in the same place would make this trip special in its own right, and allowed me to really get to know the team and capture every angle of this incredibly complex and multi-faceted expedition.
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The ship in the port of Lavrio, Greece. The team will spend two full days docked here while preparing for the voyage ahead. NASA Astrobiology/Mike Toillion SEARCHING FOR LIFE ON OCEAN WORLDS
“The goal of this program is cooperative exploration with under-actuated vehicles in hazardous environments,” explains Dr. Camilli as we stand on the bow of the ship, the sun beginning to set in the distance. “These vehicles work cooperatively in order to explore areas that are potentially too dangerous or too far away for humans to go.”
This is the problem at hand with exploring icy ocean worlds like Jupiter’s moon, Europa. The tremendous distance between Earth and Europa means we will barely be able to communicate and control vehicles that we send to the surface, and will face even more difficulty once those vehicles dive below the ice. This makes Earth’s ocean a perfect testbed for developing autonomous, intelligent robotic explorers.
“I’ve always been struck at how parallel ocean exploration and space exploration is,” says Brian Williams, professor from the Computer Science and Artificial Intelligence Laboratory at MIT. “Once you go through the surface, you can’t communicate. So, somehow you have to embody the key insights of a scientist, to be able to look and see: is that evidence of life?”
One of the gliders, an autonomous scouting vehicle equipped with multple sensors to map the seafloor and report back to the ship. NASA Astrobiology/Mike Toillion MEET THE FLEET
Exploring anywhere in space begins with a few simple steps: first, you need to get a general map of the area, which is typically done by deploying orbiters around a celestial body. The next step is to get a closer look, by launching lander and rover missions to the surface. Finally, in order to understand the location best, you need to bring samples back to Earth to study in greater detail.
“So you can think of what we’re doing here as being very parallel, that the ship is like the orbiter and is giving us a broad view of the Kolumbo volcano, right? Once we do that map, then we need to be able to explore interesting places to collect samples. So, the gliders are navigating around places that look promising from what the ship told us. And then, it looks to identify places where we might want to send NUI. NUI is very capable in terms of doing the samples, but it can’t move around nearly as much. And so, we finally put NUI at the places where the gliders thought that they were interesting.”
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The expedition team works into the night preparing NUI for its upcoming mission to the Kolumbo volcano. NASA Astrobiology/Mike Toillion THE SCIENTIST’S ROBOTIC APPRENTICE
As the espresso machine in the mess hall whirred away pouring out a much needed shot of caffeine, I sat with Eric Timmons, one of the expedition’s computer science engineers. Eric wears a few hats on the ship, but today we are discussing automated mission planning, the first step to true autonomy in robotic exploration.
“In any sort of scientific mission, you’re going to have a list of goals, each with their own set of steps, and a limited amount of time to achieve them. And so, Kirk works on automating that.” Kirk is the nickname of one of the many algorithms involved in the team’s automated mission planning. It’s joined by other algorithms, all named after Star Trek characters, collectively known as Enterprise, each responsible for different aspects of planning a mission and actively adapting to new mission parameters.
Dr. Richard Camilli explains further: “Basically, we have scientists onboard the ship that are feeding policies to these automated planners. [The planners] then take those policies plus historical information, the oceanographic context, and new information being transmitted by the vehicles here and now; they take all that information, and combine it to construct a mission that gets to the scientific deliverables, while also being safe.”
These are areas that humans aren’t designed to go to. I guess the best analogy would be like hang gliding in Midtown Manhattan at night.
Dr. richard camilli
Woods Hole Oceanographic Institution
OK, let’s recap the story so far: the ship’s sonar and other instruments create a general map of the Kolumbo volcano. That information, along with data from previous missions, is fed to Enterprise’s team of algorithms, which generates a mission for the gliders. The gliders are deployed, and using their sensors, provide higher-fidelity data about the area and transmit that knowledge back to the ship. The automated mission planners take in this new data, and revise their mission plan, ranking potential sites of scientific interest, which are then passed onto NUI, which will conduct its own mission to explore these sites, and potentially sample anything of interest.
DIVE, DIVE, DIVE
After a few days on the ship, the routine of donning my steel-toed boots and hard hat when walking around the deck has started to become second nature. My drone skills have greatly improved, as the magnetic field produced by the ship and its instruments forced me to take-off and land manually, carefully guiding the drone in and around the many hazards of the vessel. This morning, however, I’ve been invited to step off the ship for the first time to get a first-hand look at deploying the gliders. Angelos Mallios from the glider team leads me down into the bowels of the ship to the lower decks, as we arrive at a door that opens to the outside of the ship, waves lapping about six feet below. A zodiac pulls up to the door and we descend down a ladder into the small boat.
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Riding in the zodiac with the glider team, led by Angelos Mallios. NASA Astrobiology/Mike Toillion Meanwhile, the rest of the glider team is on the main deck of the ship, lifting the gliders with a large, motorized crane, and lowering them onto the surface of the water. The zodiac team approached to detach the glider and safely set it out into the sea, while I dipped a monopod-mounted action camera in and out of the water to capture the process. Unbeknownst to me at the time, this would become some of my favorite footage of the trip, sunlight dancing off the surface of the waves, while the gliders floated and dove beneath.
Angelos’ radio began to chatter. Eric Timmons was onboard the ship ready to command the gliders to begin their mission plan assigned by Enterprise. A moment passed and the yellow fin of the glider dipped below the water’s surface and disappeared.
Angelos Mallios from the Woods Hole Oceanographic Institution, leans out of a zodiac to deploy a glider, an autonomous vehicle and the forward scout for the expedition. NUI VERSUS THE VOLCANO
The following day, it was time to see the star of the show in action; the expedition team was ready to deploy the aforementioned 5,000lb wrecking ball, NUI. The gliders had been exploring the surrounding area day and night, using their suite of sensors to detect areas of scientific interest. Since this mission is about searching for life, the gliders know that warmer areas could indicate hydrothermal vent activity; a literal hotspot for life in the deep ocean. Kirk, along with the science planner algorithm, Spock, determined a list of possible candidates that fit that exact description.
“There’s always a bit of tension in the operations, where, do you go strike out in an area that is unstudied and potentially come back with nothing? Or do you go to a site that you know and try to understand it a little bit more, that kind of incremental advance?” Dr. Camilli pauses to take a quick swig of sparkling water after a long day of diving operations, as he recounts a moment in the control room earlier that day. All the scientists onboard this expedition are extremely skilled and knowledgable, and this mission is asking them to put aside their instincts, and follow the suggestions of computer algorithms; a hard pill to swallow for some.
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Underwater footage from Nereid Under Ice, showing a thriving community on the sea floor, including a never before seen species. NASA Astrobiology/Mike Toillion and WHOI “We stuck with the Spock program, and it paid great dividends. And all of the scientists were amazed at what they saw. The first site that we went to was spectacular. The second site we went to was spectacular. Each of the five sites that it identified as interesting were interesting, and they were each interesting in a different way; totally different environments.”
Interesting, in this case, was quite the understatement. As the expedition team and I crowded into the ship’s control room to look at the camera feeds transmitted by NUI, now fully deployed to the seafloor, audible gasps erupted from multiple people. Bubbles filled the monitor as live fumaroles, active vents from the volcano, were pouring out heat and chemical-rich fluid into the water. Thick, microbial mats covered the surrounding rock, and multicellular lifeforms dotted the landscape. The expedition team had found a live hydrothermal vent, and life thriving around it.
SOUVENIRS FROM THE OCEAN FLOOR
“I’ve never seen anything like that before,” recalls Casey Machado, expedition lead and the main pilot for Nereid Under Ice (NUI). Casey is sitting in an office chair surrounded by glowing monitors, a joystick in their left hand, and a gaming controller in their right. Since NUI is a hybrid ROV, it can be controlled manually from the ship by remote, or receive autonomous instructions from the Enterprise mission planners. Today, the team plans on manually controlling NUI to retrieve samples from the first site of interest.
NUI is a strange looking vehicle. Only a small section of its body is watertight, where many of its critical components are housed. The remainder is fairly open, and upon arriving at the first site recommended by Spock, the front of the ROV opens up its front double doors to reveal a multi-jointed manipulator arm, stereo camera set, and other instruments. I’m instantly reminded of the space shuttle mission to repair the Hubble Space Telescope, which had a similar mechanism.
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Casey Machado, pilot of the hybrid ROV Nereid Under Ice (NUI), pilots the manipulator arm to take a rock sample. NASA Astrobiology/Mike Toillion Casey deftly maneuvers each joint of the arm to approach a rock covered in microbial mats. The end of NUI’s arm is equipped with two sampling instruments: a claw-like grabbing mechanism and a vacuum-like hose called the “slurp gun”. The end of the arm twists and turns as Machado aligns it with the rock, eventually opening and closing it around the target. With a gentle pull, the rock comes loose, and with a few more careful manipulations places it delicately into NUI’s sample cache. I offer a high-five, which Casey nonchalantly returns like the whole task was nothing.
TEACHING A ROBOT TO FISH
At this point, the expedition team has collected dozens of samples and achieved multiple engineering milestones, enough to fill years’ worth of scientific papers, but they are far from finished. A true mission to an ocean world will have to be pilotless, as Dr. Gideon Billings from MIT explains: “They need to operate without any human intervention. They need to be able to understand the scene through perception and then make a decision about how they want to manipulate to take a sample or achieve a task.”
Gideon sits in the control room to the left of the piloting station, working alongside Casey as they prepare to demonstrate NUI’s automated sampling capabilities. His laptop screen shows a live 3D-model of the craft, its doors open, arm extended. Projected around the craft is a 3D reconstruction, or point cloud, of the seafloor created from the stereo camera pair mounted inside the vehicle. Similarly to how our brains take the two visual feeds from both of our eyes to see three-dimensionally, a stereo camera pair uses two cameras to achieve the same effect. By clicking on the model and moving its position in the software, NUI performs the same action thousands of meters under the ocean.
Shared autonomy between the automated sampling team and the ROV Nereid Under Ice. “That is shared autonomy, where you could imagine a pilot indicating a desired pose
for the arm to move to, but then a planner taking over and coming up with the path that the arm should move to reach that goal. And then, the pilot just essentially hitting a button and the arm following that path.”
Over the course of multiple dives, Gideon tested various sampling techniques, directing the manipulator arm to use its claw-like device to grab different tools and perform a variety of tasks. “We were able to project the point cloud into that scene, and then command the arm to grab a push core and move it into a location within that 3D reconstruction. We verified that that location matched up. That showed the viability of an autonomous system.” This seemingly small victory is a huge step towards exploring planets beyond Earth. Since this expedition, the engineering team has not only improved this shared autonomy system, but has also implemented a natural language interface, allowing a user to use their normal speaking voice to give commands to the ROV, further blurring the lines between reality and science fiction.
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The sun rises over the Mediterranean Sea on the final day of the research cruise. NASA Astrobiology/Mike Toillion SOMEWHERE BEYOND THE SEA
I cannot help but envy the life of those who chose to make the ocean their place of work. The time I’ve spent with oceanographers has me questioning all my life choices; clearly they knew something I didn’t.
Watching the sunrise every morning, peering through the murky depths of the deep sea, unlocking the secrets of Earth’s final frontier. All in a day’s work for Dr. Richard Camilli and his team of intrepid explorers.
Watch Our Alien Earth and The Undersea Volcanoes of Santorini, Greece on NASA+ and follow the full story of this incredible expedition.
Watch Our Alien Earth on NASA+
Panorama of a sunrise at sea. View the full article
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