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  • Writer's pictureSven Piper

Water resources on Mars

Artist's impression of the Mars Express probe in front of the ice finds in Korolev Crater
Artist's impression of the Mars Express probe in front of the ice finds in Korolev Crater (Copyright ESA)

The fact that Mars must have once had an ocean was clear to many scientists due to the dried-up river courses, but for a long time, it was not known exactly where all the water had gone.

Some researchers assumed that it had escaped into space due to the low gravity on Mars, while others suspected that it was still on Mars. However, only in recent years has evidence of Martian water ice been found.

Ice Found by the Mars Odyssey Probe

The Americans made the first discovery. Thanks to its gamma-ray spectrometer, NASA's Mars Odyssey probe provided evidence in 2002 that there is still water on Mars. It lies about 30 cm below the surface of Mars at the planet's south pole.

Mars has surprised us again. The initial results from the gamma-ray spectrometer team are better than we expected,” said Dr. R. Stephen Saunders of NASA's Jet Propulsion Laboratory.

Even though this water ice is not pure because it contains large amounts of “dirty” elements, it is important for future missions. Moreover, where there is water, there could also be life.

Ice Found by the Mars Express Probe

The European Mars Express probe has also made its contribution to the exploration of Martian water deposits. First, the OMEGA instrument (Visible and Infrared Mineralogical Mapping Spectrometer) confirmed the presence of permanent ice deposits at the planet's south pole [1] - and thus the data from the Mars Odyssey probe - and later the MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) also showed the presence of deep-lying subsurface water ice layers at the north pole [2].

Water ice in Korolev Crater
Water ice in Korolev Crater (Copyright ESA/DLR/FU Berlin)

In particular, the High Resolution Stereo Camera (HRSC) image from 2005 showed that there are also water ice deposits on the surface of the planet. The image comes from the Vastitas Borealis region and shows a previously unnamed crater (70.5° North and 103° East) with a diameter of 35 kilometers at a resolution of 15 m per pixel.

Discovery of Pure Water Ice by the Mars Reconnaissance Orbiter

In 2009, researchers discovered five fresh craters with water ice in images taken by the American Mars Reconnaissance Orbiter probe. These craters, located halfway between the north pole of Mars and the equator, are between half a meter and 2.5 meters deep and did not appear in earlier images of the region.

However, the researchers had to hurry with the confirmation because within a few weeks the bright spots darkened as the exposed water ice quickly evaporated in the thin Martian atmosphere.

Annoying but true, the Viking Lander 2 also landed in exactly this region in 1976 and could have discovered the underground water ice if it had been able to dig 10 cm deeper. It could also have tested for traces of life.

NASA Confirms Evidence of Liquid Water on Mars Today

In 2015, NASA revealed that new findings from the Mars Reconnaissance Orbiter (MRO) spacecraft provide the strongest evidence to date that liquid water flows intermittently on present-day Mars. [3]

Using the MRO probe's spectrometer, researchers discovered signatures of hydrated minerals on slopes where mysterious streaks can be seen on the Red Planet. These dark spots seem to disappear over time. They darken and appear to flow down steep slopes during the warm seasons, then disappear during the cooler seasons. They appear in several places on Mars when temperatures are around minus 23 degrees Celsius and disappear at colder times.

Discovery of Liquid Salt Water Under the South Pole of Mars

In 2018, scientists discovered a 20-kilometer-wide reservoir of salty liquid water beneath the planet's south pole. This discovery was confirmed in 2020, and scientists also found three more underground saltwater lakes surrounding the main lake. These lakes are thought to be remnants of an ancient ocean that once covered Mars and are potential habitats. [4]

Life on Mars?

The theory that there could once have been life on Mars is not new, as scientists have been arguing about possible evidence at least since the Martian meteorite ALH84001. But astrobiologists say that liquid water is an important criterion for the emergence of primitive life forms, and there was plenty of it on Mars [5], because the water deposits found at the south pole of Mars would be enough to submerge the entire planet 11 meters deep if they melted. [6]

However, data from the Mars Exploration Rover has put a slight damper on hopes for life on Mars, as the data presented in 2008 on the high salt concentration in the early history of Mars seems unsuitable for the emergence of life.

Not all water is suitable for drinking,” said biologist Andrew Knoll from Harvard University.

Previous Experiments

It is also interesting to note in this context that NASA was twice on the verge of discovering the water ice earlier. The Mars Polar Lander was supposed to land in exactly the right place in 1999 and had suitable instruments on board to detect the ice. The Mars Climate Orbiter probe also had suitable instruments on board to detect the ice, but unfortunately, both missions failed. The problem with the Mars Climate Orbiter was that a NASA supplier calculated in inches instead of meters, which is why the probe came much closer to the planet than planned and probably broke apart in the planet's atmosphere.

Note: You can find out more about this topic in my book “Exoplanets - The Search for a Second Earth”.

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