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By NASA
NASA’s Dawn spacecraft captured this image of Vesta as it left the giant asteroid’s orbit in 2012. The framing camera was looking down at the north pole, which is in the middle of the image.NASA/JPL-Caltech/UCLA/MPS/DLR/IDA Known as flow formations, these channels could be etched on bodies that would seem inhospitable to liquid because they are exposed to the extreme vacuum conditions of space.
Pocked with craters, the surfaces of many celestial bodies in our solar system provide clear evidence of a 4.6-billion-year battering by meteoroids and other space debris. But on some worlds, including the giant asteroid Vesta that NASA’s Dawn mission explored, the surfaces also contain deep channels, or gullies, whose origins are not fully understood.
A prime hypothesis holds that they formed from dry debris flows driven by geophysical processes, such as meteoroid impacts, and changes in temperature due to Sun exposure. A recent NASA-funded study, however, provides some evidence that impacts on Vesta may have triggered a less-obvious geologic process: sudden and brief flows of water that carved gullies and deposited fans of sediment. By using lab equipment to mimic conditions on Vesta, the study, which appeared in Planetary Science Journal, detailed for the first time what the liquid could be made of and how long it would flow before freezing.
Although the existence of frozen brine deposits on Vesta is unconfirmed, scientists have previously hypothesized that meteoroid impacts could have exposed and melted ice that lay under the surface of worlds like Vesta. In that scenario, flows resulting from this process could have etched gullies and other surface features that resemble those on Earth.
To explore potential explanations for deep channels, or gullies, seen on Vesta, scientists used JPL’s Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE, to simulate conditions on the giant asteroid that would occur after meteoroids strike the surface.NASA/JPL-Caltech But how could airless worlds — celestial bodies without atmospheres and exposed to the intense vacuum of space — host liquids on the surface long enough for them to flow? Such a process would run contrary to the understanding that liquids quickly destabilize in a vacuum, changing to a gas when the pressure drops.
“Not only do impacts trigger a flow of liquid on the surface, the liquids are active long enough to create specific surface features,” said project leader and planetary scientist Jennifer Scully of NASA’s Jet Propulsion Laboratory in Southern California, where the experiments were conducted. “But for how long? Most liquids become unstable quickly on these airless bodies, where the vacuum of space is unyielding.”
The critical component turns out to be sodium chloride — table salt. The experiments found that in conditions like those on Vesta, pure water froze almost instantly, while briny liquids stayed fluid for at least an hour. “That’s long enough to form the flow-associated features identified on Vesta, which were estimated to require up to a half-hour,” said lead author Michael J. Poston of the Southwest Research Institute in San Antonio.
Launched in 2007, the Dawn spacecraft traveled to the main asteroid belt between Mars and Jupiter to orbit Vesta for 14 months and Ceres for almost four years. Before ending in 2018, the mission uncovered evidence that Ceres had been home to a subsurface reservoir of brine and may still be transferring brines from its interior to the surface. The recent research offers insights into processes on Ceres but focuses on Vesta, where ice and salts may produce briny liquid when heated by an impact, scientists said.
Re-creating Vesta
To re-create Vesta-like conditions that would occur after a meteoroid impact, the scientists relied on a test chamber at JPL called the Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE. By rapidly reducing the air pressure surrounding samples of liquid, they mimicked the environment around fluid that comes to the surface. Exposed to vacuum conditions, pure water froze instantly. But salty fluids hung around longer, continuing to flow before freezing.
The brines they experimented with were a little over an inch (a few centimeters) deep; scientists concluded the flows on Vesta that are yards to tens of yards deep would take even longer to refreeze.
The researchers were also able to re-create the “lids” of frozen material thought to form on brines. Essentially a frozen top layer, the lids stabilize the liquid beneath them, protecting it from being exposed to the vacuum of space — or, in this case the vacuum of the DUSTIE chamber — and helping the liquid flow longer before freezing again.
This phenomenon is similar to how on Earth lava flows farther in lava tubes than when exposed to cool surface temperatures. It also matches up with modeling research conducted around potential mud volcanoes on Mars and volcanoes that may have spewed icy material from volcanoes on Jupiter’s moon Europa.
“Our results contribute to a growing body of work that uses lab experiments to understand how long liquids last on a variety of worlds,” Scully said.
Find more information about NASA’s Dawn mission here:
https://science.nasa.gov/mission/dawn/
News Media Contacts
Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
818-287-4115
gretchen.p.mccartney@jpl.nasa.gov
Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
2024-178
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Last Updated Dec 20, 2024 Related Terms
Dawn Asteroids Ceres Jet Propulsion Laboratory Vesta Explore More
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Seen at the center of this image, NASA’s retired InSight Mars lander was captured by the agency’s Mars Reconnaissance Orbiter using its High-Resolution Imagine Science Experiment (HiRISE) camera on Oct. 23, 2024.NASA/JPL-Caltech/University of Arizona New images taken from space show how dust on and around InSight is changing over time — information that can help scientists learn more about the Red Planet.
NASA’s Mars Reconnaissance Orbiter (MRO) caught a glimpse of the agency’s retired InSight lander recently, documenting the accumulation of dust on the spacecraft’s solar panels. In the new image taken Oct. 23 by MRO’s High-Resolution Imaging Science Experiment (HiRISE) camera, InSight’s solar panels have acquired the same reddish-brown hue as the rest of the planet.
After touching down in November 2018, the lander was the first to detect the Red Planet’s marsquakes, revealing details of the crust, mantle, and core in the process. Over the four years that the spacecraft collected science, engineers at NASA’s Jet Propulsion Laboratory in Southern California, which led the mission, used images from InSight’s cameras and MRO’s HiRISE to estimate how much dust was settling on the stationary lander’s solar panels, since dust affected its ability to generate power.
NASA retired InSight in December 2022, after the lander ran out of power and stopped communicating with Earth during its extended mission. But engineers continued listening for radio signals from the lander in case wind cleared enough dust from the spacecraft’s solar panels for its batteries to recharge. Having detected no changes over the past two years, NASA will stop listening for InSight at the end of this year.
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NASA’s InSight Mars lander acquires the same reddish-brown hue as the rest of the planet in a set of images from 2018 to 2024 that were captured by the agency’s Mars Reconnaissance Orbiter using its High-Resolution Imagine Science Experiment (HiRISE) camera.NASA/JPL-Caltech/University of Arizona Scientists requested the recent HiRISE image as a farewell to InSight, as well as to monitor how its landing site has changed over time.
“Even though we’re no longer hearing from InSight, it’s still teaching us about Mars,” said science team member Ingrid Daubar of Brown University in Providence, Rhode Island. “By monitoring how much dust collects on the surface — and how much gets vacuumed away by wind and dust devils — we learn more about the wind, dust cycle, and other processes that shape the planet.”
Dust Devils and Craters
Dust is a driving force across Mars, shaping both the atmosphere and landscape. Studying it helps scientists understand the planet and engineers prepare for future missions (solar-powered and otherwise), since dust can get into sensitive mechanical parts.
When InSight was still active, scientists matched MRO images of dust devil tracks winding across the landscape with data from the lander’s wind sensors, finding these whirling weather phenomena subside in the winter and pick up again in the summer.
The imagery also helped with the study of meteoroid impacts on the Martian surface. The more craters a region has, the older the surface there is. (This isn’t the case with Earth’s surface, which is constantly recycled as tectonic plates slide over one another.) The marks around these craters fade with time. Understanding how fast dust covers them helps to ascertain a crater’s age.
Another way to estimate how quickly craters fade has been studying the ring of blast marks left by InSight’s retrorocket thrusters during landing. Much more prominent in 2018, those dark marks are now returning to the red-brown color of the surrounding terrain.
HiRISE has captured many other spacecraft images, including those of NASA’s Perseverance and Curiosity rovers, which are still exploring Mars, as well as inactive missions, like the Spirit and Opportunity rovers and the Phoenix lander.
“It feels a little bittersweet to look at InSight now. It was a successful mission that produced lots of great science. Of course, it would have been nice if it kept going forever, but we knew that wouldn’t happen,” Daubar said.
More About MRO and InSight
The University of Arizona, in Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. A division of Caltech in Pasadena, California, JPL manages the MRO project and managed InSight for NASA’s Science Mission Directorate, Washington.
The InSight mission was part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supported spacecraft operations for the mission.
A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), supported the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors.
For more about the missions:
https://science.nasa.gov/mission/insight
science.nasa.gov/mission/mars-reconnaissance-orbiter
News Media Contacts
Andrew Good
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-2433
andrew.c.good@jpl.nasa.gov
Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
2024-175
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Last Updated Dec 16, 2024 Related Terms
InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) Jet Propulsion Laboratory Mars Mars Reconnaissance Orbiter (MRO) Radioisotope Power Systems (RPS) Explore More
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By NASA
5 Min Read Scientists Share Early Results from NASA’s Solar Eclipse Experiments
On April 8, 2024, a total solar eclipse swept across a narrow portion of the North American continent from Mexico’s Pacific coast to the Atlantic coast of Newfoundland, Canada. This photo was taken from Dallas, Texas. Credits:
NASA/Keegan Barber On April 8, 2024, a total solar eclipse swept across North America, from the western shores of Mexico, through the United States, and into northeastern Canada. For the eclipse, NASA helped fund numerous research projects and called upon citizen scientists in support of NASA’s goal to understand how our home planet is affected by the Sun – including, for example, how our star interacts with Earth’s atmosphere and affects radio communications.
At a press briefing on Tuesday, Dec. 10, scientists attending the annual meeting of the American Geophysical Union in Washington, D.C., reported some early results from a few of these eclipse experiments.
“Scientists and tens of thousands of volunteer observers were stationed throughout the Moon’s shadow,” said Kelly Korreck, eclipse program manager at NASA Headquarters in Washington. “Their efforts were a crucial part of the Heliophysics Big Year – helping us to learn more about the Sun and how it affects Earth’s atmosphere when our star’s light temporarily disappears from view.”
Changes in the Corona
On April 8, the Citizen CATE 2024 (Continental-America Telescopic Eclipse) project stationed 35 observing teams from local communities from Texas to Maine to capture images of the Sun’s outer atmosphere, or corona, during totality. Their goal is to see how the corona changed as totality swept across the continent.
On Dec. 10, Sarah Kovac, the CATE project manager at the Southwest Research Institute in Boulder, Colorado, reported that, while a few teams were stymied by clouds, most observed totality successfully — collecting over 47,000 images in all.
These images were taken in polarized light, or light oriented in different directions, to help scientists better understand the processes that shape the corona.
This preliminary movie from the Citizen CATE 2024 project stitches together polarized images of the solar corona taken from different sites during the total solar eclipse on April 8, 2024. SwRI/Citizen CATE 2024/Dan Seaton/Derek Lamb Kovac shared the first cut of a movie created from these images. The project is still stitching together all the images into the final, hour-long movie, for release at a later time.
“The beauty of CATE 2024 is that we blend cutting-edge professional science with community participants from all walks of life,” Kovac said. “The dedication of every participant made this project possible.”
Meanwhile, 50,000 feet above the ground, two NASA WB-57 aircraft chased the eclipse shadow as it raced across the continent, observing above the clouds and extending their time in totality to approximately 6 minutes and 20 seconds.
On board were cameras and spectrometers (instruments that analyze different wavelengths of light) built by multiple research teams to study the corona.
This image of the total solar eclipse is a combination of 30 50-millisecond exposures taken with a camera mounted on one of NASA’s WB-57 aircraft on April 8, 2024. It was captured in a wavelength of light emitted by ionized iron atoms called Fe XIV. This emission highlights electrified gas, called plasma, at a specific temperature (around 3.2 million degrees Fahrenheit) that often reveals arch-like structures in the corona. B. Justen, O. Mayer, M. Justen, S. Habbal, and M. Druckmuller On Dec. 10, Shadia Habbal of the University of Hawaii, who led one of the teams, reported that their instruments collected valuable data, despite one challenge. Cameras they had mounted on the aircraft’s wings experienced unexpected vibrations, which caused some of the images to be slightly blurred.
However, all the cameras captured detailed images of the corona, and the spectrometers, which were located in the nose of the aircraft, were not affected. The results were so successful, scientists are already planning to fly similar experiments on the aircraft again.
“The WB-57 is a remarkable platform for eclipse observations that we will try to capitalize on for future eclipses,” Habbal said.
Affecting the Atmosphere
On April 8, amateur or “ham” radio operators sent and received signals to one another before, during, and after the eclipse as part of the Ham Radio Science Citizen Investigation (HamSCI) Festivals of Eclipse Ionospheric Science. More than 6,350 amateur radio operators generated over 52 million data points to observe how the sudden loss of sunlight during totality affects their radio signals and the ionosphere, an electrified region of Earth’s upper atmosphere.
Students from Case Western Reserve University operate radios during the 2024 total solar eclipse. HamSCI/Case Western Reserve University Radio communications inside and outside the path of totality improved at some frequencies (from 1-7 MHz), showing there was a reduction in ionospheric absorption. At higher frequencies (10 MHz and above), communications worsened.
Results using another technique, which bounced high-frequency radio waves (3-30 MHz) off the ionosphere, suggests that the ionosphere ascended in altitude during the eclipse and then descended to its normal height afterward.
“The project brings ham radio operators into the science community,” said Nathaniel Frissell, a professor at the University of Scranton in Pennsylvania and lead of HamSCI. “Their dedication to their craft made this research possible.”
Also looking at the atmosphere, the Nationwide Eclipse Ballooning Project organized student groups across the U.S. to launch balloons into the shadow of the Moon as it crossed the country in April 2024 and during a solar eclipse in October 2023. Teams flew weather sensors and other instruments to study the atmospheric response to the cold, dark shadow.
The eclipse’s shadow was captured from a camera aboard Virginia Tech’s balloon as part of the Nationwide Eclipse Ballooning Project on April 8, 2024. Nationwide Eclipse Ballooning Project/Virginia Tech This research, conducted by over 800 students, confirmed that eclipses can generate ripples in Earth’s atmosphere called atmospheric gravity waves. Just as waves form in a lake when water is disturbed, these waves also form in the atmosphere when air is disturbed. This project, led by Angela Des Jardins of Montana State University in Bozeman, also confirmed the presence of these waves during previous solar eclipses. Scientists think the trigger for these waves is a “hiccup” in the tropopause, a layer in Earth’s atmosphere, similar to an atmospheric effect that is observed during sunset.
“Half of the teams had little to no experience ballooning before the project,” said Jie Gong, a team science expert and atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But their hard work and research was vital in this finding.”
By Abbey Interrante and Vanessa Thomas
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Dec 10, 2024 Related Terms
2024 Solar Eclipse Citizen Science Goddard Space Flight Center Heliophysics Solar Eclipses The Sun Uncategorized Explore More
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