Mars Water: Evidence, Source, Drinkability, Composition
Evidence found on the surface shows that abundant water once flowed across Mars, and a wealth of accumulated data now paints a picture of the planet’s water story. Study concludes that the most likely source of liquid water today is the atmosphere, yet water, albeit briny, still flows on the surface in features known as recurring slope lineae.
Space rocks delivered the original inventory as asteroids and comets from beyond 2.5 AU provided Mars with its early water, while 30-99 percent of that ancient endowment is now trapped within crustal minerals. Any ice mined for human use will be laced with perchlorates, making it undrinkable unless treated. Future crews may collect the present-day brine and, after processing, turn it into safe drinking water.
Does Mars have water?
Mars has water. Evidence for solid, liquid, and gaseous forms of water has been found on Mars. Seismic data from NASA’s Insight lander indicate deep, porous rock filled with liquid water, while new results suggest huge amounts of water locked far beneath the planet’s surface. These mid-crust cracks hold enough water to cover Mars with an ocean 0.62-1.24 miles deep, a volume that exceeds the once proposed for ancient Martian oceans.
Phoenix confirmed the presence of water ice on Mars, and the Gamma Ray Spectrometer on Mars Odyssey discovered vast areas rich in water. Mars has enough ice just beneath the surface to fill Lake Michigan twice, and polar ice plus large quantities of subsurface ice are present across the planet. Mars rovers Spirit and Opportunity found plenty of evidence of past water on the planet. Ancient river valley networks, deltas, and lakebeds testify to a watery past. Recurring slope lineae, downhill flows seen today, provide tentative evidence of liquid water on Mars, and different forms of liquid water like subsurface melt water, liquid brines, and groundwater likely exist.
Where is Mars’ water located?
Mars’ largest known reserve of liquid water lies deep inside the rocky outer crust. Seismic recordings show a continuous layer between 3.4 and 5 miles (5.4-8 km) down, while a broader reservoir stretches from 7 to 13 miles (11.5-20 km) below the surface. This water fills tiny cracks and pores in mid-crustal rock, kept liquid by pressure and salinity.
Closer to the surface, ice is widespread yet shallow. From 55° latitude to each pole, the ground is rich in ice only centimetres beneath the dust. At lower mid-latitudes (35°N-45°S) ice is present, sometimes within a few centimetres of the surface. The seasonal and residual polar caps themselves contain thick stacks of water ice, and buried glaciers add further stores at intermediate depths. Sorption water is held chemically within the top regolith, and transient clouds or cirrus deliver trace snowfalls.
Together these zones-deep-crust liquid, high-latitude shallow ice, polar caps, buried glaciers and adsorbed films account for the planet’s total water budget, confirming that the polar caps alone cannot explain the missing volume.
Where did Mars’ water come from?
Mars’ water is postulated to have come from asteroids and comets. Studies of hydrogen isotopic ratios indicate that asteroids and comets from beyond 2.5 astronomical units provided water to Mars. These impacts of small asteroids and comets constituted a late veneer that added water to Mars. The total volume delivered equals 6-27 % of Earth’s present ocean, a depth equivalent to 600-2700 m on the Martian surface.
Where has Mars’ water gone?
Some water disappeared from Mars via atmospheric escape. In 2020, scientists reported that Mars’s current loss of atomic hydrogen from water is largely driven by seasonal processes and dust storms that transport water directly to the upper atmosphere. Previously scientists suggested that water escaped into space, victim of Mars’s low gravity and the solar wind that is free to strip away the planet’s atmosphere and any water vapour.
New findings conclude that atmospheric escape does not account for most of its water loss. A 2021 study estimated that between 30 and 99 percent of the water on Mars is trapped in the crust. A fraction of this water is retained on modern Mars, locked into the structure of abundant water-rich materials including clay minerals (phyllosilicates) and sulfates.
Does Mars’ atmosphere contain water?
Mars’ atmosphere contains trace levels of water vapor. Water vapor is a trace gas in the Martian atmosphere and has huge spatial, diurnal, and seasonal variability. Viking orbiter measurements suggested that the entire global total mass of water vapor is equivalent to about 1 to 2 km³ of ice. Evidence for gaseous water has been found on Mars, and water vapor has been detected in small amounts in the atmosphere.
The currently thin Martian atmosphere prohibits the existence of liquid water on the surface of Mars. The atmosphere is too thin for water to last long on the surface in a liquid state. Studies suggest that the Martian atmosphere was much thicker in the past. NASA’s MAVEN mission scientists reported that Mars once had a thick atmosphere that retained surface liquid water for extended periods of time.
Does water flow on Mars?
Water flows on Mars. NASA’s Mars Reconnaissance Orbiter (MRO) provides the strongest evidence yet that liquid water flows intermittently on present-day Mars. The signals come from recurring slope lineae, downhill flows that lengthen in warm seasons and fade in cold ones, hinting that briny liquid water is seeping today across equator-facing slopes. Ojha et al. (2015) confirmed these dark streaks contain hydrated salts, the first mineral evidence confirming the presence of liquid water. Valley networks branching across the southern highlands add the shape of channels carved by short-lived runoff, while extended dark features on steep terrain remain related to existing sources of liquid water located on these slopes. Water is flowing today on the surface of Mars, though only in thin, salty films and only for brief, sporadic intervals.
Is Mars’ water safe to drink?
Mars’ water is not safe to drink as it is impure. The water is contaminated by toxic perchlorates. Perchlorates are hazardous to human wellness even at low concentrations. They are potent oxidizers that cause equipment corrosion. They make water undrinkable. TSubsurface ice is contaminated by toxic perchlorates. Martian water must be detoxified to remove contaminating solutes.
Detoxified Martian water can be used for human consumption. Synthetic biology method makes water suitable for drinking by humans. NASA will develop a method of using synthetic biology to remove toxic perchlorates. Removing toxic perchlorates makes water suitable for drinking.
Water on Mars can be used as a resource. Human missions will harvest Martian water for drinking water. Drinkable liquid water on Mars will reduce water carried by crewed missions.
How does Mars’ water compare to Earth?
Mars’ water is about 700 ppm denser than Earth’s water under equivalent conditions. The concentration of heavy water on Mars is higher than on Earth. Deuterium on Mars is eight times as much as on Earth. On Mars, there is one deuterium for every 1,284 hydrogens. This finding was derived from the ratio of water and deuterium in the modern Martian atmosphere compared to the ratio found on Earth. Scientists compared the ratio of HDO to H₂O in water on Mars today with the ratio in water trapped in a Mars meteorite dating from about 4.5 billion years ago.
A primitive ocean on Mars held more water than Earth’s Arctic Ocean, yet the loss of its atmosphere and water to space is a major reason Mars is cold and dry compared to warm and wet Earth. The same process happens on Earth, but unlike Mars, Earth’s plate tectonics cycles this water back up to the surface. Water on Earth is confined close to the surface because of something called the hygropause, whereas new results suggest there are huge amounts of water locked far beneath the Martian surface.
