Mars Express, so called because of the rapid and streamlined development time, represents ESA's first visit to another planet in the Solar System. Already this spacecraft has advanced our knowledge of the red planet, through numerous high resolution pictures. The Mars Express has several instruments on-board (High Resolution Stereo Camera, OMEGA Visible and Infrared Mineralogical Mapping Spectrometer, MARSIS Sub-Surface Sounding Radar Altimeter, among others). Now after a series of delays, the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) is finally ready to be deployed, which will look for the presence of water upto a few kilometers under the surface of Mars.

MARSIS searching water (Courtesy: JPL)MARSIS instrument consists of three long fibreglass tubes strung with wires that will bounce radio waves off the planet. Some waves will penetrate the surface – potentially revealing oases of water, in liquid or ice form. In the first few months of the experiment, Mars Express will pass over an equatorial region that some scientists suggest harbours a frozen sea just beneath the surface.
A successful find has huge consequences. It will dramatically increase the chances of success of any future human mission to Mars. Also, presence of water will significally boost the possibility of life on Mars :):).