Environmental Mysteries of Mars

Robotic explorers from Earth have visited Mars over the last five decades. Their quest? To find evidence of life, search for water; and understand how the planet has changed over time.

Hundreds of thousands of images sent back to Earth from Mars missions show a world that at one time may have been like Earth: a warm climate, abundant water, and perhaps microbial life. However, Mars today is a cold world of windswept deserts, bone-dry riverbeds, and extinct volcanoes.

Something happened on the planet that created its current environmental conditions. Understanding the Martian water cycle could unlock some of the mysteries around the planet's history and its weather.

Mars is half the size of the Earth, although it has the same land mass. Its thin atmosphere is made almost entirely of carbon dioxide. The air pressure is only 1% of Earth's, and it's extremely cold: between -87ºC at night to -25ºC during the day. Liquid water cannot exist on the surface, and ice is vaporized in these conditions.

Water on Mars: The excitement builds

Evidence from Mars rovers and orbiters show that the Red Planet had lots of liquid water in the distant past, and that there is still water trapped as ice in the soil, frozen in the ice caps, and blown around in the atmosphere.

Exciting recent images from Mars Global Surveyor show what looks like liquid water at the surface that forms gullies down the sides of craters..

To find water, you just need to know where to look.

The Phoenix science team believes that soil in the arctic where the lander takes samples may hold up to 80 % water as ice within a metre of the surface. Phoenix will verify the existence of this potential source of water, following the discovery of near-surface water ice in the region by the Mars Odyssey orbiter.

Phoenix has a robotic arm capable of digging 100 cm deep trenches into the frozen soil. With its wrist camera, scientists can get their first look underground. They hope to find evidence of periodic melting and test for chemical signatures that indicate life.


An example of a gully that formed down the side of a crater (Photo courtesy of NASA)


Polar region of Mars, and the landing site for the Phoenix mission (Image: NASA)


Phoenix lander (Photo: NASA)

carte Topographique

The locations of past and present missions are shown on this topographic map of Mars (Image: NASA)

Eau sur mars

As this artist's concept shows, Mars once had enough water for a global ocean several hundred metres deep, but where has it gone? (Illustration: NASA/Greg Shirah)