A NASA-backed research crew who have been cooped up in a Mars-like habitat on a remote Hawaii volcano since January have emerged from isolation.
The six-member group was part of a study designed to better understand the psychological impacts a long-term space mission would have on astronauts.
Data from the simulated voyage to Mars "will contribute to the future exploration of Mars and the future exploration of space in general", science officer Samuel Paylor said on Sunday.
NASA hopes to send humans to the red planet by the 2030s.
The US space agency will use the data to select individuals and groups with the right mix of traits to best cope with the stress, isolation and danger of a two-to-three year trip to the planet.
"We've learned, for one thing, that conflict, even in the best of teams, is going to arise," said Kim Binsted, the project's lead investigator.
"So what's really important is to have a crew that, both as individuals and a group, is really resilient, is able to look at that conflict and come back from it."
The group of four men and two women were quarantined for eight months on a vast plain below the summit of the Big Island's Mauna Loa, the world's largest active volcano.
They were tasked with conducting geological surveys, mapping studies and maintaining their self-sufficient habitat as if they were living on Mars.
While isolated, they wore space suits and travelled in teams whenever they left their small dome living structure.
All of their communications with the outside world were subjected to a 20-minute delay - the time it takes for signals to get from Mars to Earth.
The crew wore specially-designed sensors that could gauge their moods and played games designed to measure their compatibility and stress levels.
The study also tested ways to help the crew cope with stress.
When they became overwhelmed, they could use virtual reality devices to take them away to a tropical beach or other familiar landscapes.
They ate mostly freeze-dried or canned food and some vegetables they grew during the eight months in isolation.
Joshua Ehrlich, the mission's biology specialist, said they grew carrots, potatoes, peppers, pak choy and parsley.
"I mean it was phenomenal, just that delicious fresh taste from home really was good," he said.
The project is the fifth in a series of six NASA-funded studies at the University of Hawaii facility called the Hawaii Space Exploration Analog and Simulation, or HI-SEAS.
NASA has dedicated about $2.5m for research at the facility.
Source: AP news agency