Now a new mission, the first to look specifically for signs of life on the red planet, is looking to feed our fascination.
A spacecraft is set to land there on Wednesday (October 19), part of a joint project between European Space Agency (ESA) and Roscosmos, Russia’s space agency.
Here is what you need to know.
What’s the purpose of the mission?
The principal goal is to establish whether life has existed on Mars.
The spacecraft that will orbit the red planet, the Trace Gas Orbiter (TGO), will carry an atmospheric probe to search for the presence of methane – a gas strongly linked to life on Earth – and other atmospheric gases.
Scientists believe that methane could have been left by micro-organisms that either became extinct millions of years ago, and left the gas frozen below the planet’s surface, or that they still exist in some form.
What’s the history of Mars research?
Since the 1960s there have been more than 40 space missions dedicated to finding out more about Earth’s neighbour.
This mission is the second time ESA has put a spacecraft into orbit around Mars.
But the new mission’s TGO is better able to detect methane than its predecessor and marks a ‘new era of Mars exploration’, says ESA.
How will the mission unfold?
The ExoMars mission launched in March this year and, after a seven-month journey, it passed a key test on Sunday (October 16) with the successful separation of the space orbiter, TGO, and its lander, called Schiaparelli, which began a three-day descent to the planet’s surface.
The next step is for the disc-shaped Schiaparelli to land on Mars, a notoriously difficult task that has previously proved too much for the Russians, and, to a lesser extent, NASA. It is Europe’s second attempt to land on Mars, after Britain’s failed Beagle 2 mission in 2003.
Schiaparelli is only intended to survive on the surface for a few days. Its primary purpose is to provide data to help with future missions, in particular phase two of the ExoMars mission, planned for 2020, which will see a rover and a ‘fixed science platform’ explore and take samples from the surface.
Is NASA involved?
No. NASA and ESA had agreed in 2009 to undertake robotic exploration of Mars together, but the Americans pulled out of the 1.3 billion euro ExoMars programme in 2012, due to budgetary constraints.
NASA has a similar mission, called MAVEN, which is concentrating on monitoring ‘atmosphere escape’ from Mars.
ESA says both missions are very different but that they will compare results.
TGO is expected to begin its monitoring of Mars in 2018, before the launch of the rover onto the planet’s surface two years later.
Longer term, Elon Musk’s SpaceX is developing a massive rocket and capsule to transport large numbers of people and cargo to Mars with the ultimate goal of colonising the planet. Musk hopes to launch the first crew as early as 2024.
Main picture: Mars as seen by the webcam on ESA’s Mars Express orbiter on 16 October 2016, courtesy of the ESA