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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
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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
Caption: Expedition 70 Flight Engineer Nikolai Chub from Roscosmos is pictured during a spacewalk to inspect a backup radiator, deploy a nanosatellite, and install communications hardware on the International Space Station’s Nauka science module.Credit: NASA NASA will provide live coverage as two Roscosmos cosmonauts conduct a spacewalk outside of the International Space Station on Thursday, Dec. 19.
NASA’s live coverage begins at 9:45 a.m. EST, Thursday on NASA+. Learn how to watch NASA content through a variety of platforms, including social media. The spacewalk is scheduled to begin at approximately 10:10 a.m. and last about six and a half hours.
Expedition 72 crewmates Alexey Ovchinin and Ivan Vagner will venture outside the station’s Poisk module to install an experiment package designed to monitor celestial x-ray sources and new electrical connector patch panels and remove several experiments for disposal. The two cosmonauts also will relocate a control panel for the European robotic arm, which is attached to the Nauka multipurpose laboratory module. Roscosmos cosmonaut Alexsandr Gorbunov will operate the arm during the spacewalk from inside the station.
Roscosmos spacewalk 63 will be the second for Ovchinin and the first for Vagner. Ovchinin will wear an Orlan spacesuit with red stripes, and Vagner will wear a spacesuit with blue stripes. It will be the 272nd spacewalk in support of space station assembly, maintenance, and upgrades.
Get breaking news, images, and features from the space station on the station blog, Instagram, Facebook, and X.
Learn more about the International Space Station at:
https://www.nasa.gov/station
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Claire O’Shea / Josh Finch
Headquarters, Washington
202-358-1100
claire.a.o’shea@nasa.gov / joshua.a.finch@nasa.gov
Sandra Jones
Johnson Space Center, Houston
281-483-5111
sandra.p.jones@nasa.gov
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Last Updated Dec 17, 2024 LocationJohnson Space Center Related Terms
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By NASA
NASA On Nov. 30, 2002, NASA astronauts John Herrington (pictured) and Michael Lopez-Alegria performed the third and final spacewalk of the STS-113 mission. The goal of the mission was to install and activate the Port 1 Integrated Truss Assembly (P1). The first major component installed on the left side of the Station, the P1 truss provides an additional three External Thermal Control System radiators.
Herrington, an enrolled member of the Chickasaw Nation, was the first Native American in space. On STS-113, he logged over 330 hours in space, including 3 spacewalks totaling 19 hours and 55 minutes.
Image credit: NASA
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