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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
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By NASA
NASA/Jamie Peer In this image from Oct. 3, 2024, NASA’s mobile launcher 1 makes its way back to the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida, after undergoing upgrades and tests in preparation for the agency’s Artemis II mission.
Artemis II is the first crewed mission on NASA’s path to establishing a long-term presence at the Moon for science and exploration through Artemis. Artemis II will send four astronauts around the Moon, testing NASA’s foundational human deep space exploration capabilities, the SLS rocket, and Orion spacecraft.
Image credit: NASA/Jamie Peer
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Sols 4327-4328: On the Road Again
This image was taken by NASA’s Mars rover Curiosity using its Left Navigation Camera on sol 4326 — Martian day 4,326 of the Mars Science Laboratory mission — on Oct. 7, 2024, at 01:16:16 UTC. NASA/JPL-Caltech Earth planning date: Monday, Oct. 7, 2024
After successfully completing investigations within Gediz Vallis, Curiosity is back on the road through the Mg-sulfate (magnesium sulfate) bearing unit. The terrain under our wheels is a familiar collection of broken up blocks, and we’re keeping our rover eyes on the more distant stratigraphy and the deposits within the Gediz Vallis channel (as seen in the above Navcam image). Our traverse along this side of the channel is a great chance to understand the erosional and depositional history of Gediz Vallis from a different perspective, and to characterize variations in the sulfate unit.
I was on shift as Long-Term Planner today, and it was a pretty straightforward two-sol plan, with contact science on the first sol and driving on the second sol. The team planned a great collection of measurements to characterize the rocks in our workspace and more distant features.
The plan starts with remote sensing, including ChemCam LIBS on a gray, smooth slab at “Paloma Meadows,” followed by two long-distance RMI mosaics to assess the thickness and distribution of white clasts in Gediz Vallis. Then Mastcam will document Paloma Meadows and a distant dark clast at “Sky Parlor Meadow” to understand the variety of rock types and where they might have come from. The remote sensing block also includes a Navcam observation to search for dust devils. Later in the afternoon Mastcam will acquire a mosaic looking back towards “Whitebark Pass” including the white clasts (some of which were previously tied to observations of high sulfur) and the distribution of deposits within “Pinnacle Ridge.” Then Curiosity will use the instruments on the arm to assess one of the blocks in our workspace at “Pincushion Peak.” We’ll use the DRT, MAHLI, and APXS to assess the grain size, textures, and composition of a nodular block of bedrock. On the second sol Curiosity will acquire ChemCam LIBS and Mastcam of Pincushion Peak, which will make for a nice set of coordinated observations. The second sol also includes a long-distance RMI mosaic of an interesting dark block to assess sedimentary structures, and two Navcam observations to characterize atmospheric opacity and the movement of fines on the rover deck. Then Curiosity will continue driving, and take post-drive imaging to prepare for a similar plan on Wednesday. Looking forward to continuing to explore what’s under our wheels and on the horizon!
Written by Lauren Edgar, Planetary Geologist at USGS Astrogeology Science Center
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Last Updated Oct 09, 2024 Related Terms
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Sols 4289-4290: From Discovery Pinnacle to Kings Canyon and Back Again
This image shows the workspace in front of NASA’s Mars rover Curiosity, taken by the Left Navigation Camera aboard the rover on sol 4287 — Martian day 4,287 of the Mars Science Laboratory mission — on Aug. 28, 2024, at 02:23:27 UTC. NASA/JPL-Caltech Earth planning date: Wednesday, Aug. 28 2024
We are back … almost, anyways. Today’s parking location is very close to where we parked on sol 4253, and in an area near one of the previous contact science targets “Discovery Pinnacle.” You can read in this blog post that most of the team, this blogger included, was in Pasadena for our team meeting when we were last in this area. That was July and Curiosity was about to turn 12 on Mars. Coming back is a very rare occasion and is always planned carefully. Once or twice during the last 12 years it happened because we saw something “in the rear mirror.” One of the examples is the target “Old Soaker,” where we spotted mud cracks in the images from a previous parking position, and promptly went back because this was such an important discovery. At other times it was carefully planned, such as the “walkabout” at “Pink Cliffs,” which you can watch in this video from as long back as Earth year 2015. In the past few planning cycles, it’s more of the latter as we made our way from Discovery Pinnacle, where we were on sol 4253, “Just passing through” “Russell Pass” and arriving at “Kings Canyon,” our drill location, which we reached on sol 4257. You can follow all the action of the drilling at Kings Canyon on the blogs. It took a while — it always does — because it’s an activity with many steps and investigations to complete. We actually celebrated Curiosity’s 12th birthday at Kings Canyon! We departed on sol 4283, came back via “Cathedral Peak,” and are now near the Discovery Pinnacle location again. After that little walkabout through the history of (some) of Curiosity’s walkabouts, especially the very last one, let’s look at today’s plan.
It is a pretty normal two-sol plan, with a one-hour science block before we drive away from this location. We were greeted by a nicely flat surface, and the engineers informed us that we have all six wheels firmly on flat and stable ground. That’s always a relief, because only then can we use the arm. That nice piece of flat rock Curiosity is so firmly parked on became our science target …well, mostly. Some of the little pebbles on the surface attracted our attention, too. The very eagle-eyed can spot a small white spot in the image above. It’s right between the arm and the rover itself, about where the C is written. That’s a rock that we likely broke up with our wheel and that has a very white part to it. We called it “Thousand Island Lake,” and will image it with MAHLI. APXS is investigating a target called “Eichorn Pinnacle,” squarely on the big flat area. LIBS is also making the most of the large target underneath and in front of us, investigating the target “Nine Lakes Basin.”
In recent blogs you will have read about the dust-storm watch making the atmospheric investigations even more important, so we don’t miss any changes. We are looking for dust devils, atmospheric opacity, and are of course monitoring the weather throughout the plan.
Our drive will hopefully — if Mars agrees — be a long one, and we will also plan an activity that we call MARDI sidewalk. That’s when we take very frequent pictures with the MARDI instrument while driving. This results in a long strip of images nicely showing the nature of the terrain the rover has driven over. This is in addition to the MARDI single frame we are taking every time the rover stops. I often get the question, why are we taking an image just downwards whenever the rover stops? Well, humans are easy to bias toward the outliers, toward the things that look special, and of course the Curiosity team is no exception. For some things this is great, because it allows for the discoveries of new things. But it doesn’t provide an unbiased overview. That’s what MARDI does: It always points down and reliably records the terrain under the rover. We don’t have to do anything but put the commands for that one image into our plan after the drive — something that’s pretty routine after 12 years now!
Written by Susanne Schwenzer, Planetary Geologist at The Open University
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