Scientists report the presence of a subglacial lake on Mars, 1.5 km (0.93 mi) below the southern polar ice cap and extending sideways about 20 km (12 mi), the first known body of water on the planet.
Lake Vostok in Antarctica may have implications for liquid water still existing on Mars, because if water existed before the polar ice caps on Mars, so it is thought possible that there is still liquid water below the ice caps. Then in July 2018, scientists from the Italian Space Agency reported the detection of a subglacial lake on Mars, 1.5 kilometres (1 mi) below the southern polar ice cap, and spanning 20 kilometres (10 mi) horizontally, the first evidence for a stable body of liquid water on the planet. The evidence for the Mars lake was deduced from a bright spot in the radar echo sounding data, collected between May 2012 and December 2015, using the MARSIS radar on board the European Mars Express orbiter. The detected lake is centered at 193Â°E, 81Â°S, a flat area that does not exhibit any peculiar topographic characteristics but is surrounded by higher ground, except on its eastern side, where there is a depression. The SHARAD radar on board NASA's Mars Reconnaissance Orbiter has seen no sign of the lake, but the team will take another look to try to confirm the finding when its orbital parameters are favorable. It is unlikely that SHARAD will detect the lake, as it has much lower ground-penetrating abilities than MARSIS does.
Because the temperature at the base of the polar cap is estimated at 205 K (âˆ’68 Â°C; âˆ’91 Â°F), scientists assume that the water may remain liquid by the antifreeze effect of magnesium and calcium perchlorates. The 1.5-kilometre (0.93 mi) ice layer covering the lake is composed of water ice with 10 to 20% admixed dust, and seasonally covered by a 1-metre (3 ft 3 in)-thick layer of CO2 ice. Since the raw-data coverage of the south polar ice cap is limited, the discoverers stated that "there is no reason to conclude that the presence of subsurface water on Mars is limited to a single location."
The lake may consist of clear water, or may be mixed with soil to form a sludge. The lake's high levels of salt would present difficulties for most lifeforms, but on Earth, organisms called halophiles thrive in salty conditions, though not in dark, cold, concentrated perchlorate solutions.