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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Tests on Earth appear to confirm how the Red Planet’s spider-shaped geologic formations are carved by carbon dioxide.
Spider-shaped features called araneiform terrain are found in the southern hemisphere of Mars, carved into the landscape by carbon dioxide gas. This 2009 image taken by NASA’s Mars Reconnaissance Orbiter shows several of these distinctive formations within an area three-quarters of a mile (1.2 kilometers) wide. NASA/JPL-Caltech/University of Arizona Dark splotches seen in this example of araneiform terrain captured by NASA’s Mars Reconnaissance Orbiter in 2018 are believed to be soil ejected from the surface by carbon dioxide gas plumes. A set of experiments at JPL has sought to re-create these spider-like formations in a lab. NASA/JPL-Caltech/University of Arizona Since discovering them in 2003 via images from orbiters, scientists have marveled at spider-like shapes sprawled across the southern hemisphere of Mars. No one is entirely sure how these geologic features are created. Each branched formation can stretch more than a half-mile (1 kilometer) from end to end and include hundreds of spindly “legs.” Called araneiform terrain, these features are often found in clusters, giving the surface a wrinkled appearance.
The leading theory is that the spiders are created by processes involving carbon dioxide ice, which doesn’t occur naturally on Earth. Thanks to experiments detailed in a new paper published in The Planetary Science Journal, scientists have, for the first time, re-created those formation processes in simulated Martian temperatures and air pressure.
Here’s a look inside of JPL’s DUSTIE, a wine barrel-size chamber used to simulate the temperatures and air pressure of other planets – in this case, the carbon dioxide ice found on Mars’ south pole. Experiments conducted in the chamber confirmed how Martian formations known as “spiders” are created.NASA/JPL-Caltech “The spiders are strange, beautiful geologic features in their own right,” said Lauren Mc Keown of NASA’s Jet Propulsion Laboratory in Southern California. “These experiments will help tune our models for how they form.”
The study confirms several formation processes described by what’s called the Kieffer model: Sunlight heats the soil when it shines through transparent slabs of carbon dioxide ice that built up on the Martian surface each winter. Being darker than the ice above it, the soil absorbs the heat and causes the ice closest to it to turn directly into carbon dioxide gas — without turning to liquid first — in a process called sublimation (the same process that sends clouds of “smoke” billowing up from dry ice). As the gas builds in pressure, the Martian ice cracks, allowing the gas to escape. As it seeps upward, the gas takes with it a stream of dark dust and sand from the soil that lands on the surface of the ice.
When winter turns to spring and the remaining ice sublimates, according to the theory, the spiderlike scars from those small eruptions are what’s left behind.
These formations similar to the Red Planet’s “spiders” appeared within Martian soil simulant during experiments in JPL’s DUSTIE chamber. Carbon dioxide ice frozen within the simulant was warmed by a heater below, turning it back into gas that eventually cracked through the frozen top layer and formed a plume.NASA/JPL-Caltech Re-Creating Mars in the Lab
For Mc Keown and her co-authors, the hardest part of conducting these experiments was re-creating conditions found on the Martian polar surface: extremely low air pressure and temperatures as low as minus 301 degrees Fahrenheit (minus 185 degrees Celsius). To do that, Mc Keown used a liquid-nitrogen-cooled test chamber at JPL, the Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE.
“I love DUSTIE. It’s historic,” Mc Keown said, noting that the wine barrel-size chamber was used to test a prototype of a rasping tool designed for NASA’s Mars Phoenix lander. The tool was used to break water ice, which the spacecraft scooped up and analyzed near the planet’s north pole.
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This video shows Martian soil simulant erupting in a plume during a JPL lab experiment that was designed to replicate the process believed to form Martian features called “spiders.” When a researcher who had tried for years to re-create these conditions spotted this plume, she was ecstatic. NASA/JPL-Caltech For this experiment, the researchers chilled Martian soil simulant in a container submerged within a liquid nitrogen bath. They placed it in the DUSTIE chamber, where the air pressure was reduced to be similar to that of Mars’ southern hemisphere. Carbon dioxide gas then flowed into the chamber and condensed from gas to ice over the course of three to five hours. It took many tries before Mc Keown found just the right conditions for the ice to become thick and translucent enough for the experiments to work.
Once they got ice with the right properties, they placed a heater inside the chamber below the simulant to warm it up and crack the ice. Mc Keown was ecstatic when she finally saw a plume of carbon dioxide gas erupting from within the powdery simulant.
“It was late on a Friday evening and the lab manager burst in after hearing me shrieking,” said Mc Keown, who had been working to make a plume like this for five years. “She thought there had been an accident.”
The dark plumes opened holes in the simulant as they streamed out, spewing simulant for as long as 10 minutes before all the pressurized gas was expelled.
The experiments included a surprise that wasn’t reflected in the Kieffer model: Ice formed between the grains of the simulant, then cracked it open. This alternative process might explain why spiders have a more “cracked” appearance. Whether this happens or not seems dependent on the size of soil grains and how embedded water ice is underground.
“It’s one of those details that show that nature is a little messier than the textbook image,” said Serina Diniega of JPL, a co-author of the paper.
What’s Next for Plume Testing
Now that the conditions have been found for plumes to form, the next step is to try the same experiments with simulated sunlight from above, rather than using a heater below. That could help scientists narrow down the range of conditions under which the plumes and ejection of soil might occur.
There are still many questions about the spiders that can’t be answered in a lab. Why have they formed in some places on Mars but not others? Since they appear to result from seasonal changes that are still occurring, why don’t they seem to be growing in number or size over time? It’s possible that they’re left over from long ago, when the climate was different on Mars— and could therefore provide a unique window into the planet’s past.
For the time being, lab experiments will be as close to the spiders as scientists can get. Both the Curiosity and Perseverance rovers are exploring the Red Planet far from the southern hemisphere, which is where these formations appear (and where no spacecraft has ever landed). The Phoenix mission, which landed in the northern hemisphere, lasted only a few months before succumbing to the intense polar cold and limited sunlight.
News Media Contacts
Andrew Good
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-2433
andrew.c.good@jpl.nasa.gov
Karen Fox / Molly Wasser
Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
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Last Updated Sep 11, 2024 Related Terms
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By NASA
The Roscosmos Soyuz MS-26 spacecraft will launch from the Baikonur Cosmodrome in Kazakhstan to the International Space Station with (pictured left to right) NASA astronaut Don Pettit and Roscosmos cosmonauts Alexey Ovchinin and Ivan Vagner.Credit: Gagarin Cosmonaut Training Center NASA astronaut Don Pettit will launch aboard the Roscosmos Soyuz MS-26 spacecraft, accompanied by cosmonauts Alexey Ovchinin and Ivan Vagner, to the International Space Station where they will join the Expedition 71 crew in advancing scientific research.
Pettit, Ovchinin, and Vagner will lift off at 12:23 p.m. EDT Wednesday, Sept. 11 (9:23 p.m. Baikonur time) from the Baikonur Cosmodrome in Kazakhstan.
Coverage will stream on NASA+, the NASA app, and the agency’s website. Learn how to stream NASA content through a variety of platforms including social media.
After a two-orbit, three-hour trajectory to the station, the spacecraft will automatically dock at 3:33 p.m. at the orbiting laboratory’s Rassvet module. Shortly after, hatches will open between the spacecraft and the station.
Once aboard, the trio will join NASA astronauts Tracy C. Dyson, Mike Barratt, Matthew Dominick, Jeanette Epps, Butch Wilmore, and Suni Williams, as well as Roscosmos cosmonauts Nikolai Chub, Alexander Grebenkin, and Oleg Kononenko.
NASA’s coverage is as follows (all times Eastern and subject to change based on real-time operations):
11:15 a.m. – Launch coverage begins on NASA+, the NASA app, YouTube, and the agency’s website.
12:23 p.m. – Launch
2:30 p.m. – Rendezvous and docking coverage begins on NASA+, the NASA app, YouTube, and the agency’s website.
3:33 p.m. – Docking
5:30 p.m. – Hatch opening and welcome remarks coverage begins on NASA+, the NASA app, YouTube, and the agency’s website.
5:50 p.m. – Hatch opening
The trio will spend approximately six months aboard the orbital laboratory as Expedition 71 and 72 crew members before returning to Earth in the spring of 2025. This will be the fourth spaceflight for Pettit and Ovchinin, and the second for Vagner.
For more than two decades, people have lived and worked continuously aboard the International Space Station, advancing scientific knowledge, and making research breakthroughs that are not possible on Earth. The station is a critical testbed for NASA to understand and overcome the challenges of long-duration spaceflight and to expand commercial opportunities in low Earth orbit. As commercial companies focus on providing human space transportation services and destinations as part of a robust low Earth orbit economy, NASA is focusing more resources on deep space missions to the Moon as part of Artemis in preparation for future human missions to Mars.
Learn more about International Space Station research and operations at:
https://www.nasa.gov/station
-end-
Joshua Finch / Claire O’Shea
Headquarters, Washington
202-358-1100
joshua.a.finch@nasa.gov / claire.a.o’shea@nasa.gov
Sandra Jones
Johnson Space Center, Houston
281-483-5111
sandra.p.jones@nasa.gov
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Last Updated Sep 06, 2024 LocationNASA Headquarters Related Terms
International Space Station (ISS) Astronauts Donald R. Pettit Humans in Space ISS Research Johnson Space Center View the full article
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By European Space Agency
Video: 00:14:09 The Copernicus Sentinel-2C satellite lifted off on 5 September at 03:50 CEST (4 September 22:50 local time) aboard the last Vega rocket, flight VV24, from Europe’s Spaceport in French Guiana.
Sentinel-2C will continue the legacy of delivering high-resolution data that are essential to Copernicus – the Earth observation component of the EU Space Programme. Developed, built and operated by ESA, the Copernicus Sentinel-2 mission provides high-resolution optical imagery for a wide range of applications including land, water and atmospheric monitoring.
Sentinel-2C was the last liftoff for the Vega rocket – after 12 years of service this was the final flight, the original Vega is being retired to make way for an upgraded Vega-C.
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