During the last years the interest for Mars has greatly whitened among solar system exploration programmes.

This extreme and mysterious planet keeps jealously the traces of its own past and, when scientists believe to be near to reach a good level of knowledge of its habitat, a new discovery cancels or modifies the acquired certainties.

Over the past three decades the results of Mars missions have contributed to represent a world in some ways familiar, but rocky, desert and cold, wrapped up in a reddish and dark sky.

Mars is very similar to Earth; as Earth it has two polar caps, an atmosphere with clouds, an hydrosphere, a cryosphere and a lithosphere, in other words it has systems of water, ice and geology which, interacting, form the Martian environment. It has volcanoes, canyons, hills and other characteristics similar to Earth, on its dusty and arid landscapes seasons change, nevertheless its environment is completely different from Earth.

In the table below are compared Mars and Earth morphological characteristics:




Average Distance from Sun

142 million miles

93 million miles

Average Speed in Orbiting Sun

14.5 miles per second

18.5 miles per second


4,220 miles

7,926 miles

Tilt of Axis

25 degrees

23.5 degrees

Length of Year

687 Earth Days

365.25 Days

Length of Day

24 hours 37 minutes

23 hours 56 minutes


.375 that of Earth

2.66 times that of Mars


Average -81 degrees F

Average 57 degrees F


mostly carbon dioxide some water vapor

nitrogen, oxygen, argon, others

# of Moons



Scientists believe that it has not always been so, but that, on the contrary, in a distant and undefined time, water was present plentiful on Mars, making it very similar to Earth.
Deep streaks in its terrain, drained river beds, rocks and minerals, which form only in the presence of water, and polar caps with layers covered by ice, witness a global change in Mars climate and environment.

As water means life, its presence in the past on Mars surface and/or at present under its surface, lets suppose a past and/or present existence of some kind of life, at least as micro-organisms.
For this reason scientists give a great importance to the search for water , also for a future opportunity of human colonization of the Red Planet.

The priority is to study in depth Mars present environment to arrive to the knowledge of its past and to understand why from a condition of water existence (some scientists maintain that once existed a great ocean in Mars northern hemisphere) its environment is now characterized by a total dryness.

To give an answer to these questions, Mars great missions analyze the aspects of this change, from a geological and climatic point of view, by advanced sensors designed and realized with the aim of probing, studying and photographing in depth every part of the planet.

As far as the search for water is concerned, two radars have been designed and realized: respectively,  MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding)  for the  European Space Agency  Mars Express  mission, and  SHARAD (SHAllow RADar)  for NASA  Mars Reconnaissance Orbiter  mission.
CO.RI.S.T.A. participates in both projects in Thales Alenia Space Italy team.

Mars, Twin Peaks - Credits: NASA-JPL

Mars and Earth orbits around the Sun
NASA reconstruction