Mars Express hopes to answer that question with two spacecraft that will work in tandem.
Only Europe, which operates the Mars Express orbiter, has had beginner's luck on Mars.
Europe entered the Mars race in 2003 with the Mars Express Orbiter and the Beagle 2 lander.
Despite repeated attempts at contact, including with Mars Express, no trace of the British-built lander can be found.
The ESA's Mars Express leads the pack of several probes expected to land on Mars in the next decade.
Mars Express is still operating, but the lander never communicated from the surface.
Mars Express will map the Red Planet in unprecedented detail - its best images will see objects down to two metres.
The instruments on board Venus Express had been developed as back-ups for either Esa's Mars Express spacecraft or Esa's comet-chaser mission, Rosetta, due for launch in January.
That clever piece of engineering was a tiny lander that was carried to the Red Planet in 2003 on board the European Space Agency's Mars Express orbiter.
The Mars Express -- the first of three missions to Mars in June -- will try to find out if there is, or ever was, life on Mars.
So far the excellent performance of Mars Express has been somewhat overshadowed by the loss of its lander Beagle 2, which should have touched down on the planet on Christmas Day.
But the main means of communication with Beagle 2 was always intended to be its mother ship, the European Space Agency's Mars Express, from which it was released on December 19th.
ECONOMIST: The current crop of Mars missions has got off to a bad start
Mars Express continues to listen out for Beagle's call but if no contact is made by early February, the lander segment of this first solo European mission to another planet will be declared lost.
Mars Express went into an initial orbit around Mars at about the time that Beagle 2 was landing, and it is now being manoeuvred into an operational orbit that will take it over both poles.
ECONOMIST: The current crop of Mars missions has got off to a bad start
"The role of liquid water on Mars is of great importance for its habitability and this study using Mars Express describes a very large zone where groundwater was present for a long time, " said Olivier Witasse, a project scientist with ESA's Mars Express.
MSN: New proof that water existed underground on ancient Mars
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