American researchers have identified nine caves that could be suitable shelters for future astronauts on Mars. These subterranean environments could give crews some respite, protecting them from the harsh conditions on the surface.
A shelter for astronauts
NASA is preparing to go to the Moon to better target Mars. According to current plans, the American agency would consider a first manned mission to late 2030s involving a team of four people, two of whom could go to the surface. The round trip would take about five hundred days. The astronauts would remain on site for thirty days, evolving in a pressurized rover. They could then perform several spacewalks to explore the surface.
To establish themselves permanently, future explorers will need more sophisticated and larger habitats that will be able to protect astronauts from the unforgiving environment of the red planet. Some already have put forward ideas and the preferred option remains the lava tubes. These underground caves, which can also be found on Earth and on the Moon, are indeed presented as real natural pads against radiation, temperature variations and other impacts of meteorites.
As part of a recent studya team led by Nicole Bardabelias, a geoscientist at the University of Arizona, identified several candidate caves for possible future exploration. For this work, the researchers first consulted the Mars Global Cave Candidate Catalog, which is a kind of image bank collected by instruments aboard the Mars Odyssey spacecraft and the Mars Reconnaissance Orbiter. Since this database lists more than a thousand potential caves, the team had to “filter” their searches, much like we might when searching for an apartment or a house.
A handful of potential caves
The researchers thus restricted the catalog by imposing two criteria. The first is that any potential cave must be within less than one hundred kilometers from a suitable landing site. Such a site must also be located below an altitude of about one thousand meters. These relatively low spots are indeed more favorable, as they give the lander more time to slow through the thin Martian atmosphere.
” Mars has just enough atmosphere that you can’t ignore it, but not enough to give you a significant amount of aerobraking“, details Nicole Bardabelias. ” If you don’t have enough space between when you hit the top of the atmosphere and where you’re supposed to land, it’s going to be very, very difficult for you to do the entry, descent sequence correctly and landing. »
For the second criterion, the researchers required that high resolution images are available for each candidate cave. These photos are captured by HiRISE, one of the Mars Reconnaissance Orbiter cameras. This instrument is capable of discerning dimensions on Mars as small as about one meter in diameter.
That being said, of the more than a thousand candidate caves, only 139 seemed to meet the team’s criteria. A closer inspection finally reduces this sample to nine caves. The others were mostly just bridge-like rock formations, when others didn’t extend far enough below the surface.
These potential caves, the largest of which has an opening that could swallow up a football pitch, will be worth a closer look. Unfortunately, none of the rovers currently operating on Mars are close enough to explore them. For the time being, this task therefore falls to the orbiters. Follow-up images taken from different angles and under different lighting conditions by the HiRISE instrument will likely reveal new details in the coming years.