After 520 days in isolation, the six-member crew that was simulating a voyage to Mars, has "landed."

Mars500, a $15 million project sponsored by the European Space Agency (ESA), China, and Russia, set out to answer a crucial question in the quest to send a crew to the Red Planet: can people maintain their health and sanity in the 17 months it takes to get to Mars and back?

The crew emerged from their mock spacecraft on Thursday and was briefly allowed to greet family and friends before they were whisked into the last phase of the experiment, a three-day quarantine period that rounds out the Mars mission experiment.

"On this mission we've achieved the longest isolation ever so that humankind can go to a distant but reachable planet," crew member Diego Urbina said.

However, psychologists worry that the return to normal life could be a shock to the crew. In a press release, the ESA said the men will undergo "extensive" medical and psychological evaluations in their first few days of freedom. They will greet the media on November 8, and the mission will technically end in December as the astronauts are debriefed, tested, and evaluated, to collect the final results of the mission.

"Time seems to have flown by since we closed the hatch last year," Igor Ushakov, head of the Russian Institute for Biomedial Problems, the organization that runs the faux ship, told Reuters.

Throughout the simulation, the crew lived exactly as they would if they were traveling to Mars. They subsisted on food provided to actual astronauts, showered infrequently, took daily urine and blood samples, and were subject to surveillance everywhere but the toilets. They also performed more than 100 different experiments onboard.

When the ship , the crew spent 10 days on the Red Planet and simulated three "Marswalks."

Though the Mars500 crew has "returned" to Earth, according to Reuters, space experts say it will be "decades" before a crew can safely make the 35 million mile trek to Mars.