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By NASA
8 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Return to 2024 SARP Closeout Faculty Advisors:
Dr. Tom Bell, Woods Hole Oceanographic Institution
Dr. Kelsey Bisson, NASA Headquarters Science Mission Directorate
Graduate Mentor:
Kelby Kramer, Massachusetts Institute of Technology
Kelby Kramer, Graduate Mentor
Kelby Kramer, graduate mentor for the 2024 SARP Ocean Remote Sensing group, provides an introduction for each of the group members and shares behind-the scenes moments from the internship.
Lucas DiSilvestro
Shallow Water Benthic Cover Type Classification using Hyperspectral Imagery in Kaneohe Bay, Oahu, Hawaii
Lucas DiSilvestro
Quantifying the changing structure and extent of benthic coral communities is essential for informing restoration efforts and identifying stressed regions of coral. Accurate classification of shallow-water benthic coral communities requires high spectral and spatial resolution, currently not available on spaceborne sensors, to observe the seafloor through an optically complex seawater column. Here we create a shallow water benthic cover type map of Kaneohe Bay, Oahu, Hawaii using the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) without requiring in-situ data as inputs. We first run the AVIRIS data through a semi-analytical inversion model to derive color dissolved organic matter, chlorophyll concentration, bottom albedo, suspended sediment, and depth parameters for each pixel, which are then matched to a Hydrolight simulated water column. Pure reflectance for coral, algae, and sand are then projected through each water column to create spectral endmembers for each pixel. Multiple Endmember Spectral Mixture Analysis (MESMA) provides fractional cover of each benthic class on a per-pixel basis. We demonstrate the efficacy of using simulated water columns to create surface reflectance spectral endmembers as Hydrolight-derived in-situ endmember spectra strongly match AVIRIS surface reflectance for corresponding locations (average R = 0.96). This study highlights the capabilities of using medium-fine resolution hyperspectral imagery to identify fractional cover type of localized coral communities and lays the groundwork for future spaceborne hyperspectral monitoring of global coral communities.
Atticus Cummings
Quantifying Uncertainty In Kelp Canopy Remote Sensing Using the Harmonized Landsat Sentinel-2 Dataset
Atticus Cummings
California’s giant kelp forests serve as a major foundation for the region’s rich marine biodiversity and provide recreational and economic value to the State of California. With the rising frequency of marine heatwaves and extreme weather onset by climate change, it has become increasingly important to study these vital ecosystems. Kelp forests are highly dynamic, changing across several timescales; seasonally due to nutrient concentrations, waves, and predator populations, weekly with typical growth and decay, and hourly with the tides and currents. Previous remote sensing of kelp canopies has relied on Landsat imagery taken with a eight-day interval, limiting the ability to quantify more rapid changes. This project aims to address uncertainty in kelp canopy detection using the Harmonized Landsat and Sentinel-2 (HLS) dataset’s zero to five-day revisit period. A random forest classifier was used to identify pixels that contain kelp, on which Multiple Endmember Spectral Mixture Analysis (MESMA) was then run to quantify intrapixel kelp density. Processed multispectral satellite images taken within 3 days of one another were paired for comparison. The relationship between fluctuations in kelp canopy density with tides and currents was assessed using in situ data from an acoustic doppler current profiler (ADCP) at the Santa Barbara Long Term Ecological Research site (LTER) and a NOAA tidal buoy. Preliminary results show that current and tidal trends cannot be accurately correlated with canopy detection due to other sources of error. We found that under cloud-free conditions, canopy detection between paired images varied on average by 42%. Standardized image processing suggests that this uncertainty is not created within the image processing step, but likely arises due to exterior factors such as sensor signal noise, atmospheric conditions, and sea state. Ultimately, these errors could lead to misinterpretation of remotely sensed kelp ecosystems, highlighting the need for further research to identify and account for uncertainties in remote sensing of kelp canopies.
Jasmine Sirvent
Kelp Us!: A Methods Analysis for Predicting Kelp Pigment Concentrations from Hyperspectral Reflectance
Jasmine Sirvent
Ocean color remote sensing enables researchers to assess the quantity and physiology of life in the ocean, which is imperative to understanding ecosystem health and formulating accurate predictions. However, without proper methods to analyze hyperspectral data, correlations between spectral reflectance and physiological traits cannot be accurately derived. In this study, I explored different methods—single variable regression, partial least squares regressions (PLSR), and derivatives—in analyzing in situ Macrocystis pyrifera (giant kelp) off the coast of Santa Barbara, California in order to predict pigment concentrations from AVIRIS hyperspectral reflectance. With derivatives as a spectral diagnostic tool, there is evidence suggesting high versus low pigment concentrations could be diagnosed; however, the fluctuations were within 10 nm of resolution, thus AVIRIS would be unable to reliably detect them. Exploring a different method, I plotted in situ pigment measurements — chlorophyll a, fucoxanthin, and the ratio of fucoxanthin to chlorophyll a—against hyperspectral reflectance that was resampled to AVIRIS bands. PLSR proved to be a more successful model because of its hyperdimensional analysis capabilities in accounting for multiple wavelength bands, reaching R2 values of 0.67. Using this information, I constructed a model that predicts kelp pigments from simulated AVIRIS reflectance using a spatial time series of laboratory spectral measurements and photosynthetic pigment concentrations. These results have implications, not only for kelp, but many other photosynthetic organisms detectable by hyperspectral airborne or satellite sensors. With these findings, airborne optical data could possibly predict a plethora of other biogeochemical traits. Potentially, this research would permit scientists to acquire data analogous to in situ measurements about floating matters that cannot financially and pragmatically be accessed by anything other than a remote sensor.
Isabelle Cobb
Correlations Between SSHa and Chl-a Concentrations in the Northern South China Sea
Isabelle Cobb
Sea surface height anomalies (SSHa)–variations in sea surface height from climatological averages–occur on seasonal timescales due to coastal upwelling and El Niño-Southern Oscillation (ENSO) cycles. These anomalies are heightened when upwelling plumes bring cold, nutrient-rich water to the surface, and are particularly strong along continental shelves in the Northern South China Sea (NSCS). This linkage between SSHa and nutrient availability has interesting implications for changing chlorophyll-a (chl-a) concentrations, a prominent indicator of phytoplankton biomass that is essential to the health of marine ecosystems. Here, we evaluate the long-term (15 years) relationship between SSHa and chl-a, in both satellite remote sensing data and in situ measurements. Level 3 SSHa data from Jason 1/2/3 satellites and chl-a data from MODIS Aqua were acquired and binned to monthly resolution. We found a significant inverse correlation between SSHa and chl-a during upwelling months in both the remote sensing (Spearman’s R=-0.57) and in situ data, with higher resolution in situ data from ORAS4 (an assimilation of buoy observations from 2003-2017) showing stronger correlations (Spearman’s R=-0.75). In addition, the data reveal that the magnitude of SSH increases with time during instances of high correlation, possibly indicating a trend of increased SSH associated with reduced seasonal chl-a concentrations. Thus, this relationship may inform future work predicting nutrient availability and threats to marine ecosystems as climate change continues to affect coastal sea surface heights.
Alyssa Tou
Exploring Coastal Sea Surface Temperature Anomalies and their effect on Coastal Fog through analyzing Plant Phenology
Alyssa Tou
Marine heat waves (MHW) have been increasing in frequency, duration and intensity, giving them substantial potential to influence ecosystems. Do these MHWs sufficiently enhance coastal precipitation such that plant growth is impacted? Recently, the Northeast Pacific experienced a long, intense MHW in 2014/2015, and another short, less intense MHW in 2019/2020. Here we investigate how the intensity and duration of MHWs influence the intensity and seasonal cycle of three different land cover types (‘grass’, ‘trees’, and a combination of both ‘combined’’) to analyze plant phenology trends in Big Sur, California. We hypothesize that longer intense MHWs decrease the ocean’s evaporative capacity, decreasing fog, thus lowering plant productivity, as measured by Normalized Difference Vegetation Index (NDVI). Sea surface temperature (SST) and NDVI data were collected from the NOAA Coral Reef Watch, and NASA MODIS/Terra Vegetation Indices 16-Day L3 Global 250m products respectively. Preliminary results show no correlation (R2=0.02) between SSTa and combined NDVI values and no correlation (R2=0.01) between SST and NDVI. This suggests that years with anomalously high SST do not significantly impact plant phenology. During the intense and long 2014/2015 MHW, peak NDVI values for ‘grass’ and ‘combined’ pixels were 2.0 and 1.7 standard deviations above the climatological average, while the shorter 2019/2020 MHW saw higher peaks of 3.2 and 2.4 standard deviations. However, the ‘grass’, ‘tree’ and ‘combined’ NDVI anomalies were statistically insignificant during both MHWs, showing that although NDVI appeared to increase during the shorter and less intense MHW, these values may be attributed to other factors. The data qualitatively suggest that MHW’s don’t impact the peak NDVI date, but more data at higher temporal resolution are necessary. Further research will involve analyzing fog indices and exploring confounding variables impacting NDVI, such as plant physiology, anthropogenic disturbance, and wildfires. In addition, it’s important to understand to what extent changes in NDVI are attributed to the driving factors of MHWs or the MHWs themselves. Ultimately, mechanistically understanding the impacts MHW intensity and duration have on terrestrial ecosystems will better inform coastal community resilience.
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Last Updated Nov 22, 2024 Related Terms
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By NASA
NASA has awarded Bastion Technologies Inc., of Houston, the Center Occupational Safety, Health, Medical, System Safety and Mission Assurance Contract (COSMC) at the agency’s Ames Research Center in California’s Silicon Valley.
The COSMC contract is a hybrid cost-plus-fixed-fee and firm-fixed-price contract, with an indefinite-delivery/indefinite-quantity component and maximum potential value of $53 million. The contract phase-in begins Thursday, Jan. 2, 2025, followed by a one-year base period that begins Feb. 14, 2025, and options to extend performance through Aug. 13, 2030.
Under this contract, the company will provide support for occupational safety, industrial hygiene, health physics, safety and health training, emergency response, safety culture, medical, wellness, fitness, and employee assistance. The contractor also will provide subject matter expertise in several areas including system safety, software safety and assurance, quality assurance, pressure system safety, procurement quality assurance, and range safety. Work will primarily be performed at NASA Ames and NASA’s Armstrong Flight Research Center in Edwards, California, as needed.
For information about NASA and agency programs, visit:
https://www.nasa.gov
-end-
Tiernan Doyle
NASA Headquarters, Washington
202-358-1600
tiernan.p.doyle@nasa.gov
Rachel Hoover
Ames Research Center, Silicon Valley, Calif.
650-604-4789
rachel.hoover@nasa.gov
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By NASA
5 min read
5 Surprising NASA Heliophysics Discoveries Not Related to the Sun
With NASA’s fleet of heliophysics spacecraft, scientists monitor our Sun and investigate its influences throughout the solar system. However, the fleet’s constant watch and often-unique perspectives sometimes create opportunities to make discoveries that no one expected, helping us to solve mysteries about of the solar system and beyond.
Here are five examples of breakthroughs made by NASA heliophysics missions in other fields of science.
This graphic shows missions in NASA’s Heliophysics Division fleet as of July 2024. NASA Thousands and Thousands of Comets
The SOHO mission — short for Solar and Heliospheric Observatory, which is a joint mission between ESA (European Space Agency) and NASA — has a coronagraph that blocks out the Sun in order to see the Sun’s faint outer atmosphere, or corona.
It turns out SOHO’s coronagraph also makes it easy to spot sungrazing comets, those that pass so close to the Sun that other observatories can’t see them against the brightness of our star.
Before SOHO was launched in December 1995, fewer than 20 sungrazing comets were known. Since then, SOHO has discovered more than 5,000.
The vast number of comets discovered using SOHO has allowed scientists to learn more about sungrazing comets and identify comet families, descended from ancestor comets that broke up long ago.
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Two sungrazing comets fly close to the Sun in these images captured by ESA/NASA’s SOHO (Solar and Heliospheric Observatory). They were the 3,999th and 4,000th comets discovered in SOHO images. ESA/NASA/SOHO/Karl Battams Dimming of a Supergiant
In late 2019, the supergiant star Betelgeuse began dimming unexpectedly. Telescopes all over the world — and around it — tracked these changes until a few months later when Betelgeuse appeared too close to the Sun to observe. That’s when NASA’s STEREO (Sun-watching Solar Terrestrial Relations Observatory (STEREO) came to the rescue.
For several weeks in the middle of 2020, STEREO was the only observatory able to see Betelgeuse. At the time, the STEREO-A spacecraft was trailing behind Earth, at a vantage point where Betelgeuse was still far enough away from the Sun to be seen. This allowed astronomers to keep tabs on the star while it was out of view from Earth.
STEREO’s observations revealed another unexpected dimming between June and August of 2020, when ground-based telescopes couldn’t view the star.
Astronomers later concluded that these dimming episodes were caused by an ejection of mass from Betelgeuse — like a coronal mass ejection from our Sun but with about 400 times more mass — which obscured part of the star’s bright surface.
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The background image shows the star Betelgeuse as seen by the Heliospheric Imager aboard NASA’s STEREO (Solar Terrestrial Relations Observatory) spacecraft. The inset figure shows measurements of Betelgeuse’s brightness taken by different observatories from late 2018 to late 2020. STEREO’s observations, marked in red, revealed an unexpected dimming in mid-2020 when Betelgeuse appeared too close to the Sun for other observatories to view it. NASA/STEREO/HI (background); Dupree et al. (inset) The Glowing Surface of Venus
NASA’s Parker Solar Probe studies the Sun’s corona up close — by flying through it. To dive into the Sun’s outer atmosphere, the spacecraft has flown past Venus several times, using the planet’s gravity to fling itself closer and closer to the Sun.
On July 11, 2020, during Parker’s third Venus flyby, scientists used Parker’s wide-field imager, called WISPR, to try to measure the speed of the clouds that obscure Venus’ surface. Surprisingly, WISPR not only observed the clouds, it also saw through them to the surface below.
The images from that flyby and the next (in 2021) revealed a faint glow from Venus’ hot surface in near-infrared light and long wavelengths of red (visible) light that maps distinctive features like mountainous regions, plains, and plateaus.
Scientists aimed WISPR at Venus again on Nov. 6, 2024, during Parker’s seventh flyby, observing a different part of the planet than previous flybys. With these images, they’re hoping to learn more about Venus’ surface geology, mineralogy, and evolution.
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As Parker Solar Probe flew by Venus on its fourth flyby, it captured these images, strung into a video, showing bright and dark features on the nightside surface of the planet. NASA/APL/NRL The Brightest Gamma-Ray Burst
You’ve heard of the GOAT. But have you heard of the BOAT?
It stands for the “brightest of all time”, a gamma-ray burst discovered on Oct. 9, 2022.
A gamma-ray burst is a brief but intense eruption of gamma rays in space, lasting from seconds to hours.
This one, named GRB 221009A, glowed brilliantly for about 10 minutes in the constellation Sagitta before slowly fading.
The burst was detected by dozens of spacecraft, including NASA’s Wind, which studies the perpetual flow of particles from the Sun, called the solar wind, just before it reaches Earth.
Wind and NASA’s Fermi Gamma-Ray Space Telescope measured the brightness of GRB 221009A, showing that it was 70 times brighter than any other gamma-ray burst ever recorded by humans — solidifying its status as the BOAT.
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Astronomers think GRB 221009A represents the birth of a new black hole formed within the heart of a collapsing star. In this artist’s concept, the black hole drives powerful jets of particles traveling near the speed of light. The jets emit X-rays and gamma rays as they stream into space. NASA/Swift/Cruz deWilde A Volcano Blasts Its Way to Space
NASA’s ICON (Ionospheric Connection Explorer) launched in 2019 to study how Earth’s weather interacts with weather from space. When the underwater Hunga Tonga-Hunga Ha‘apai volcano erupted on Jan. 15, 2022, ICON helped show that the volcano produced more than ash and tsunami waves — its effects reached the edge of space.
In the hours after the eruption, ICON detected hurricane-speed winds in the ionosphere — Earth’s electrified upper atmospheric layer at the edge of space. ICON clocked the wind speeds at up to 450 miles per hour, making them the strongest winds the mission had ever measured below 120 miles altitude.
The ESA Swarm mission revealed that these extreme winds altered an electric current in the ionosphere called the equatorial electrojet. After the eruption, the equatorial electrojet surged to five times its normal peak power and dramatically flipped direction.
Scientists were surprised that a volcano could affect the electrojet so severely — something they’d only seen during a strong geomagnetic storm caused by an eruption from the Sun.
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The Hunga Tonga-Hunga Ha’apai eruption on Jan. 15, 2022, caused many effects, some illustrated here, that were felt around the world and even into space. Some of those effects, like extreme winds and unusual electric currents were picked up by NASA’s ICON (Ionospheric Connection Explorer) mission and ESA’s (the European Space Agency) Swarm. Illustration is not to scale. NASA’s Goddard Space Flight Center/Mary Pat Hrybyk-Keith By Vanessa Thomas
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Nov 20, 2024 Related Terms
Comets Fermi Gamma-Ray Space Telescope Gamma-Ray Bursts Goddard Space Flight Center Heliophysics Heliophysics Division ICON (Ionospheric Connection Explorer) Parker Solar Probe (PSP) SOHO (Solar and Heliospheric Observatory) Stars STEREO (Solar TErrestrial RElations Observatory) The Sun The Sun & Solar Physics Uncategorized Venus Volcanoes Wind Mission Explore More
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
A prototype of a robot designed to explore subsurface oceans of icy moons is reflected in the water’s surface during a pool test at Caltech in September. Conducted by NASA’s Jet Propulsion Laboratory, the testing showed the feasibility of a mission concept for a swarm of mini swimming robots.NASA/JPL-Caltech In a competition swimming pool, engineers tested prototypes for a futuristic mission concept: a swarm of underwater robots that could look for signs of life on ocean worlds.
When NASA’s Europa Clipper reaches its destination in 2030, the spacecraft will prepare to aim an array of powerful science instruments toward Jupiter’s moon Europa during 49 flybys, looking for signs that the ocean beneath the moon’s icy crust could sustain life. While the spacecraft, which launched Oct. 14, carries the most advanced science hardware NASA has ever sent to the outer solar system, teams are already developing the next generation of robotic concepts that could potentially plunge into the watery depths of Europa and other ocean worlds, taking the science even further.
This is where an ocean-exploration mission concept called SWIM comes in. Short for Sensing With Independent Micro-swimmers, the project envisions a swarm of dozens of self-propelled, cellphone-size swimming robots that, once delivered to a subsurface ocean by an ice-melting cryobot, would zoom off, looking for chemical and temperature signals that could indicate life.
Dive into underwater robotics testing with NASA’s futuristic SWIM (Sensing With Independent Micro-swimmers) concept for a swarm of miniature robots to explore subsurface oceans on icy worlds, and see a JPL team testing a prototype at a pool at Caltech in Pasadena, California, in September 2024. NASA/JPL-Caltech “People might ask, why is NASA developing an underwater robot for space exploration? It’s because there are places we want to go in the solar system to look for life, and we think life needs water. So we need robots that can explore those environments — autonomously, hundreds of millions of miles from home,” said Ethan Schaler, principal investigator for SWIM at NASA’s Jet Propulsion Laboratory in Southern California.
Under development at JPL, a series of prototypes for the SWIM concept recently braved the waters of a 25-yard (23-meter) competition swimming pool at Caltech in Pasadena for testing. The results were encouraging.
SWIM Practice
The SWIM team’s latest iteration is a 3D-printed plastic prototype that relies on low-cost, commercially made motors and electronics. Pushed along by two propellers, with four flaps for steering, the prototype demonstrated controlled maneuvering, the ability to stay on and correct its course, and a back-and-forth “lawnmower” exploration pattern. It managed all of this autonomously, without the team’s direct intervention. The robot even spelled out “J-P-L.”
Just in case the robot needed rescuing, it was attached to a fishing line, and an engineer toting a fishing rod trotted alongside the pool during each test. Nearby, a colleague reviewed the robot’s actions and sensor data on a laptop. The team completed more than 20 rounds of testing various prototypes at the pool and in a pair of tanks at JPL.
“It’s awesome to build a robot from scratch and see it successfully operate in a relevant environment,” Schaler said. “Underwater robots in general are very hard, and this is just the first in a series of designs we’d have to work through to prepare for a trip to an ocean world. But it’s proof that we can build these robots with the necessary capabilities and begin to understand what challenges they would face on a subsurface mission.”
Swarm Science
A model of the final envisioned SWIM robot, right, sits beside a capsule holding an ocean-composition sensor. The sensor was tested on an Alaskan glacier in July 2023 through a JPL-led project called ORCAA (Ocean Worlds Reconnaissance and Characterization of Astrobiological Analogs). The wedge-shaped prototype used in most of the pool tests was about 16.5 inches (42 centimeters) long, weighing 5 pounds (2.3 kilograms). As conceived for spaceflight, the robots would have dimensions about three times smaller — tiny compared to existing remotely operated and autonomous underwater scientific vehicles. The palm-size swimmers would feature miniaturized, purpose-built parts and employ a novel wireless underwater acoustic communication system for transmitting data and triangulating their positions.
Digital versions of these little robots got their own test, not in a pool but in a computer simulation. In an environment with the same pressure and gravity they would likely encounter on Europa, a virtual swarm of 5-inch-long (12-centimeter-long) robots repeatedly went looking for potential signs of life. The computer simulations helped determine the limits of the robots’ abilities to collect science data in an unknown environment, and they led to the development of algorithms that would enable the swarm to explore more efficiently.
The simulations also helped the team better understand how to maximize science return while accounting for tradeoffs between battery life (up to two hours), the volume of water the swimmers could explore (about 3 million cubic feet, or 86,000 cubic meters), and the number of robots in a single swarm (a dozen, sent in four to five waves).
In addition, a team of collaborators at Georgia Tech in Atlanta fabricated and tested an ocean composition sensor that would enable each robot to simultaneously measure temperature, pressure, acidity or alkalinity, conductivity, and chemical makeup. Just a few millimeters square, the chip is the first to combine all those sensors in one tiny package.
Of course, such an advanced concept would require several more years of work, among other things, to be ready for a possible future flight mission to an icy moon. In the meantime, Schaler imagines SWIM robots potentially being further developed to do science work right here at home: supporting oceanographic research or taking critical measurements underneath polar ice.
More About SWIM
Caltech manages JPL for NASA. JPL’s SWIM project was supported by Phase I and II funding from NASA’s Innovative Advanced Concepts (NIAC) program under the agency’s Space Technology Mission Directorate. The program nurtures visionary ideas for space exploration and aerospace by funding early-stage studies to evaluate technologies that could transform future NASA missions. Researchers across U.S. government, industry, and academia can submit proposals.
How the SWIM concept was developed Learn about underwater robots for Antarctic climate science See NASA’s network of ready-to-roll mini-Moon rovers News Media Contact
Melissa Pamer
Jet Propulsion Laboratory, Pasadena, Calif.
626-314-4928
melissa.pamer@jpl.nasa.gov
2024-162
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Last Updated Nov 20, 2024 Related Terms
Europa Jet Propulsion Laboratory NASA Innovative Advanced Concepts (NIAC) Program Ocean Worlds Robotics Space Technology Mission Directorate Technology Explore More
5 min read Making Mars’ Moons: Supercomputers Offer ‘Disruptive’ New Explanation
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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.
For news media:
Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.
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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
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