Water on Mars

Water on Mars

The area around the southern pole of Mars, below which a water body has been recently confirmed. Credits: NASA/JPL/Malin Space Science Systems

The area around the southern pole of Mars, below which a water body has been recently confirmed. Credits: NASA/JPL/Malin Space Science Systems

Prior to the age of space exploration, the red planet was deemed to almost be like another earth, with telescope observations showing surface features that looked akin to water canals and seasonally changing water bodies. The red planet was believed, for a long time, to hold vast oceans and swathes of vegetation, making it one of the more anticipated locations to visit in the solar system.

Such high expectations of life elsewhere were unfortunately met with one of the biggest let-downs in history for hopeful astrobiologists. The Mariner and Viking missions removed all illusions that Mars was a lush, fertile planet, showing instead a barren landscape with no surface water in sight. However, the data which brought about the radical anti-climax also carried a wealth of unparalleled knowledge on the red planet that opened other areas of interest. Formations on the Martian surface pointed to the presence of surface water some time in Mars’s history; however, for some reason, that water ‘disappeared’ over the course of millions, or even billions, of years.

The mystery surrounding the loss of Mars’s ancient oceans has been resolved since then. It is now believed that Mars lost its magnetic field billions of years ago as a result of its rapidly cooling core solidifying. When this happened, the Martian atmosphere was exposed to incoming high energy solar radiation, and Mars slowly lost its atmosphere as a result. As Mars lost its atmospheric constituents, the planet cooled, and eventually carbon dioxide started solidifying out of the atmosphere at the poles. This in turn resulted in further cooling of the planet, as it lost more of its atmosphere. At some point, atmospheric pressure was too low to sustain liquid water at the surface, and the Martian oceans slowly started to evaporate away or solidify to ice.

Although the search for liquid water on the surface of the red planet proved futile, hope for the presence of water bodies trapped below the Martian surface remained. Indeed, just a few weeks ago, the presence of an underground water lake near the Martian southern pole has been confirmed from observations with a radar, MARSIS, on board the Mars Express spacecraft. Although hints of such a subsurface lake had been observed in the past, this is the first time that a confirmation has been successfully made.

What does this mean for the possibility of life on Mars? We’re still not sure, and it will unfortunately be years before we will be able to sample such a subsurface lake to look for organic materials, or perhaps, even simple lifeforms. However, it does present us with a new outlook on the presence of such water bodies hidden beneath the surface on Mars and other planets or moons, extending the potential habitable areas for life in the solar system, and other solar systems, beyond our home planet.

Josef Borg is currently a PhD student within the Institute of Space Sciences and Astronomy, University of Malta, and also the President of the Astronomical Society of Malta.

Did you know?

Mars has two small moons, Phobos and Deimos. The two Martian moons are much smaller than earth’s moon, and are in fact irregularly shaped rather than spherical. Measuring just 22km and 12.6km in diameter, the two moons have been thought to be captured main belt asteroids, flung gravitationally towards Mars by Jupiter in the past. They are much closer to Mars’s surface than our moon to earth’s surface, with Phobos orbiting just 6,000km and Deimos around 23,000km above the red planet’s surface.

The largest mountain in the solar system can be found on Mars. Mars plays host to some spectacular geological features. Perhaps the most well-known is Olympus Mons, a mountain towering nearly 25km above the Martian surface. By comparison, Mount Everest is just under nine kilometres tall.

Mars sometimes experiences planet-wide dust storms. Even currently, Mars is experiencing one of the more severe dust storms to swathe the planet in recent years. Dust storms on Mars tend to cover significant parts of the planet at a time, sometimes even covering Mars globally. The timing of the current dust storm unfortunately coincides with one of the closest approaches of the red planet to earth in living memory, and surface features which would normally be easily visible on the Martian surface with earth-based telescopes during such a close approach are unfortunately shrouded from view.

Sound bites

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