Six men have “returned to earth” after spending 18 months on a simulated mission to Mars. Meanwhile the latest spacecraft to make the journey for real has arrived at Cape Canaveral.

As we noted at the half-way stage, the Mars500 project featured six men spending 520 days in a mock-up spacecraft in Russia, matching the time a real return journey and mission would take. Three of the crew donned spacesuits and spent 10 days making journeys outside the craft into a darkened room full of sand designed to simulate the Mars surface.

The aim of the experiment was to learn more about the physical and psychological effects of the isolation from the real world, along with having to share a space with the same five people for well over a year. It also tested tactics for choosing equipment to make the journey bearable. As well as having specially designed gym equipment, the crew had a Nintendo Wii and Guitar Hero, along with a mini-greenhouse for growing fresh vegetables.

The men were taken into quarantine after “landing” but initials tests suggest all are in good health.

The BBC notes there are discussions to carry out similar tests on the International Space Station, such as introducing communication delays of 20 or more minutes to simulate the effects of being closer to Mars than Earth, or restricting crew members to particular areas of the station to simulate the even closer confinement of a Mars shuttle.

There’s no immediate prospect of a manned mission to Mars as, even if the duration of the journey was manageable, there’s currently no way to be certain of protecting a crew from cosmic radiation. However, the unimaginatively named “NASA’s Mars Science Laboratory” rover vehicle is only a few weeks away from beginning a trip to the planet where it will spend one Martian year (687 days on Earth). Its mission is to explore a crater with a 3-mile-high mountain.