At first glance, you might think that this grainy image is the first picture of man setting foot on Mars. Sadly, it's just a couple of guys in space suits pottering around a sandpit in Moscow. Mike Wall explains all.

Alexander Nemenov / AFP - Getty Images
A photo taken from a monitor at the Korolev Space Mission Control Center outside Moscow shows volunteers of the Mars500 experiment, Diego Urbina of Italy and Alexander Smoleyevsky of Russia, taking a mock walk on Mars on Feb. 14. Two members of a group of volunteers isolated from the outside world for eight months stepped out on a mock-up of Mars, half-way through their experiment to study the effects of a Red Planet mission. The men's first steps were relayed to the Russian control center that monitors real space missions, as part of an experiment organized by the European Space Agency and Moscow's institute of biomedical problems.