Lakes on Mars

Lakes on Mars Article written by Jim Secosky. Jim is a retired science teacher who has used the Hubble Space Telescope, the Mars Global Surveyor, and HiRISE.

It is believed that there were hundreds of lakes on Mars—over 200 inside of craters.^[1] ^[2] Water for the lakes came from various sources such as rainfall, runoff from surrounding land, melting of glaciers, and from groundwater sapping.^[3] ^[4]

Crater with glaciers drawn in white. Glaciers were on walls. When they melted, channels took the water to the center of crater, and created a lake. The channels are now inverted. That is they formed ridges.
Inverted channels on a crater floor. They run from where the glaciers were toward the center.

Crater showing valleys that formed from sapping--that is the water flowed out of the ground. Eventually, the water formed a lake.
Red arrows show deltas that formed from water that issued from the ground in sapping valleys. This is evidence that water came out of the ground and made a lake.

One evidence for lakes is the presence of deltas in craters. Deltas form when water flows into a quiet body of water.

Images of possible deltas

Possible delta in Margaritifer Sinus quadrangle as seen by THEMIS.
Probable delta in Eberswalde Crater that lies to the NE of Holden Crater, as seen by Mars Global Surveyor. Image in Margaritifer Sinus quadrangle.
Delta in Lunae Palus quadrangle, as seen by THEMIS.
Delta that fills a crater in Lunae Palus quadrangle, as seen by HiRISE.
Jezero Crater delta - chemical alteration by water (hi-res)

Some places that are believed to have once held lakes are Holden Crater, Jezero Crater, Gale Crater, Ritchey Crater, Columbus Crater, Valles Marineris, Argyre basin, Hellas Basin, and large areas in Eridania.

Holden Crater, as seen by THEMIS
Columbus Crater

Gale Crater with Aeolis Mons rising from the center. The noted Curiosity landing area is near Peace Vallis in Aeolis Palus. Curiosity landed in the northern part of the crater.

                View from the "Kimberley" formation on Mars taken by NASA's Curiosity rover.  Layered rock formed under lake.

Map showing estimated water depth in different parts of Eridania Sea This map is about 530 miles across.
Features around Eridania Sea labeled

Another major form of evidence is the finding of minerals such as clays, carbonates, and sulfates. These minerals require water to be produced. These minerals were both detected from orbit and from rovers on the surface of Mars. The Curiosity Rover has been exploring Gale crater for years with very sophisticated instruments. Many of the minerals identified were hydrated which required water. Some of these hydrated minerals are actinolite, montmorillonite, saponite, jarosite, halloysite, szomolnokite and magnesite. In some places 40 vol% of the minerals were hydrous minerals. ^[5]

Underground Lakes Near the South Pole

Deep penetrating radar detected several possible lakes of liquid water (or brine) under the polar cap near the South Pole. It was thought that these were kept liquid by geothermal heat. However, modelling suggested that they should freeze. Currently the theory is that they are not lakes at all, but bands of clay material. Under the right amount of pressure, they would give a radar return like water.^[6]

References

↑ Fassett C. I. and Head J. W. 2008. Icarus. 195 61
↑ Goudge T. A., Aureli K. L., Head J. W., Fassett C. I. and Mustard J. F. 2015 Icarus. 260 346
↑ Benjamin D. Boatwright and James W. Head. 2021. Planet. Sci. J.Volume 2. Number 2. p. 52
↑ Salese F., Pondrelli M., Neeseman A., Schmidt G. and Ori G. G. 2019. JGRE. Vol. 124. P. 374
↑ Lin H.; et al. (2016). "Abundance retrieval of hydrous minerals around the Mars Science Laboratory landing site in Gale crater, Mars". Planetary and Space Science. 121: 76–82.
↑ https://www.scientificamerican.com/article/buried-lakes-on-mars-may-just-be-frozen-clay/