WEST LAFAYETTE – Frozen water is hiding beneath the dust-covered surface of Mars, and scientist Ali Bramson wants to find it. She sees a chance to both sustain future human explorers and answer questions about the red planet’s climate.
Bramson, a Purdue University assistant professor of planetary science, was part of recent research to determine the location and depth of the subsurface ice. The results of the NASA Subsurface Water Ice Mapping (SWIM) project were published in Nature Astronomy.
Her work in SWIM focused on radar subsurface discovery and mapping of ice deposits in Mars’ northern hemisphere. Another SWIM project Bramson participated in, completed in December, examined the southern hemisphere.
Bramson said work toward finding the ice deposits – possibly created by snowfall – and determining how accessible it is from the surface has been building in recent years. Findings will offer early ideas about where Mars habitats could be located.
“Having shallow ice and knowing where to excavate it will be very important for humans going to Mars,” she said. “If we’re going to send humans to Mars one day, we’re going to have to find the lowest latitude where it’s warmer with more sunlight, but still has ice available.”
She said winter at Mars’ north and south poles lasts several months without sunlight, eliminating potential solar-powered habitats there.
Through the Department of Earth, Atmospheric, and Planetary Sciences, Bramson studies the processes that affect the surfaces of planets in our solar system. The research is done through spacecraft remote sensing observations in combination with theoretical modeling and supplemented by field work at terrestrial analog sites and experimental studies.
“Mars is like a natural laboratory for understanding planets,” she said.
The SWIM research combined and examined 20 years of orbital data from several NASA spacecraft. Bramson focused on radar analysis of potential thick ice deposits, looking for the base of deposits that extend deeper than 30-65 feet. Other techniques examined the surface temperature and hydrogen content to look for areas of shallow ice.
Comparing the information from the varying data techniques found areas with indications of widespread ice beneath the surface in Mars’ Arcadia plains region. The results suggest this ice is most pure close to the surface. Ice also was found in the glaciers of the Deuteronilus Mensae region. Both are in the middle latitudes of Mars’ northern hemisphere.
Bramson said the research answered several questions about Mars subsurface ice. But other questions remain.
“Are these areas unique or is this ice everywhere,” she said. “Especially if you’re going to do something like sending human habitats there, you want to make sure you’re sending them to the best location with the best chances of resources like water to melt and drink and convert to rocket fuel when people want to return.”
She said there are also blind spots at 5-10-meter depths where the analysis was unable to sense the consistency of the ice deposits. The upper several meters where habitats will want to drill could be pure ice or several layers of dust embedded in the ice in layers.
Determining the variability within the ice will be important in how to extract the ice and what kind of technologies are needed. Bramson is advocating for a higher frequency radar at Mars for additional research to take the next step in understanding subsurface ice before humans go there.
Preparing for human exploration of Mars isn’t the only opportunity offered by studying the ice deposits. Bramson said the simple presence of the deposits raises a number of questions for her about Mars’ climate history in general, given that the red planet undergoes a lot of climate changes on natural time scales due to changes in the planet’s tilt and orbit.
“It’s really interesting from a science point of view to understand what are the climate conditions that led to the ice being there,” Bramson said. “Presumably these thick deposits of pure ice were formed from snowfall on Mars. But today some of these latitudes of Mars are too warm to form these ice deposits there. This ice, therefore, represents a record of the conditions on Mars in the past.”
The SWIM research was led by the Planetary Science Institute and funded by NASA’s Jet Propulsion Laboratory with a number of other participating universities and organizations.