The blue area on this map of Mars is the area where NASA has detected surface water ice (from the equator to 60 degrees north latitude). Scientists can use this map – part of a groundwater ice mapping project – to decide where the first astronauts to set foot on the Red Planet should land. The map can help NASA decide where the first astronauts will land on the Red Planet. The more water available, the less water the mission will need to carry.
For the first people to set foot on Mars, ice buried underground will be a vital resource that can be used as a key ingredient in drinking water and rocket fuel. But it will also be an important scientific goal: astronauts or robots could one day drill ice cores like scientists on Earth, uncover the climate history of Mars, and explore potential habitats (past or present) for microbial life.
These global maps of Mars, which show the possible distribution of water ice buried within 3 feet (1 meter) of the Martian surface, represent the latest data from the SWIM project. Buried ice will be an important resource for Martian astronauts, serving as a key ingredient in drinking water and rocket fuel. Photo credit: NASA/JPL-Caltech/PSI
Unstable water conditions on Mars
The reason why you need to look for ice beneath the surface is because liquid water is not stable on the surface of Mars: the Martian atmosphere is very thin and water evaporates immediately. There is a lot of ice at the poles of Mars – mostly made of water, although carbon dioxide or dry ice can also be found – but these areas are too cold for astronauts (or robots) to survive for long.
This is where the groundwater ice mapping project, funded by NASA, comes in. The SWIM project recently released its fourth set of maps, which is the most detailed set of maps since the project was launched in 2017.
Led by the Institute for Planetary Science in Tucson, Arizona, and managed by NASA's Southern California Jet Propulsion Laboratory (JPL), the SWIM project brings together data from NASA's multiple missions, including the Mars Reconnaissance Orbiter (MRO), the 2001 Mars Odyssey, and the now-defunct Mars Global Surveyor. Using these datasets, scientists have identified the most likely places to find Martian ice, which future missions can access from the surface.
The ice crater in the center of this image is an example of what scientists are looking for when mapping the sites of future astronauts landing on Mars. This is one of several such impact craters included in the latest version of a series of surface water ice maps of the Red Planet funded by NASA. Source: NASA/JPL-Caltech/University of Arizona
Instruments on board these spacecraft have detected what looks like a large amount of frozen water beneath the surface in the mid-latitudes of Mars. The northern mid-latitudes are particularly attractive because the atmosphere here is thicker than most other areas on Mars, making it easier to slow down the descent. The ideal astronaut landing site should be one of the best locations in the southernmost part of the region – far north enough for ice to exist, but close enough to the equator to ensure that astronauts can enjoy the warmest temperatures in areas of snow and ice.
Sydney Do, SWIM project manager at JPL, said: "If you send humans to Mars, you're definitely going to want to get them as close to the equagator as possible. The less energy is needed to keep astronauts and their auxiliary equipment warm, the more energy there is to meet their other needs. "
In this artist's concept image, NASA astronauts are drilling underground on Mars. A new map produced by the agency shows where future astronauts will have the easiest access to ice. Source: NASA
Enhance the drawing process
Previous iterations of the map relied on low-resolution imagers, radar, thermal imagers, and spectrometers, all of which hinted at buried ice, but did not fully confirm its presence or quantity. For the latest SWIM map, the scientists relied on two higher-resolution cameras on the MRO. Data from background cameras were used to further refine the map of the Northern Hemisphere, while data from the High Resolution Imaging Science Experiment (HiRISE) were incorporated for the first time to provide the most detailed view of the ice boundary line as close to the equator as possible.
Scientists often use HiRISE to study new impact craters caused by meteoroids, which may have excavated large chunks of ice. Most of these craters are no more than 33 feet (10 meters) in diameter, but in 2022, HiRISE photographed a 492-foot-wide (150-meter-wide) crater, revealing ice mines hidden beneath the surface.
Boulder-sized blocks of water ice can be seen from the rim of the Martian impact crater captured by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The crater was formed on December 24, 2021, by the impact of a meteoroid in the Amazonis Planitia region. Image credit: NASA/JPL-Caltech/University of Arizona
Gareth Morgan, co-head of SWIM at the Institute for Planetary Science, said: "These impacts that reveal ice provide a valuable ground reality because they show us where the surface ice is clearly present. We can use these locations to verify that our mapping methods are correct. "
New discoveries and future prospects
In addition to the impact of ice exposure, the new map includes the so-called "polygonal terrain" discovered by HiRISE, where the seasonal expansion and contraction of the ice beneath the surface causes polygonal fissures to form in the ground. Seeing these polygons stretch around new, ice-filled impact craters again suggests that there is more ice hidden beneath the surface in these places.
Scientists can also use the map to study a number of other mysteries.
Nathaniel Putzig, another co-leader of the SWIM program at the Institute for Planetary Science, said: "The amount of water ice found in the mid-latitudes of Mars is not consistent; Some areas seem to have more water ice than others, but no one really knows why. The latest SWIM map may offer new hypotheses about why these changes occurred. He added that it could also help scientists adjust models of the evolution of Mars' paleoclimate over time, so that some areas have more ice deposits and others have smaller ones. "
SWIM scientists hope the project will lay the groundwork for the proposed Mars Ice Imager mission – an orbiter that will be equipped with a specially designed high-power radar to search for near-surface ice beyond the ice that HiRISE has already confirmed to exist.