Six "astronauts" backed by NASA who have been shacked up in a dome as part of an experiment have now emerged from their isolation, seeing the sun for the first time in eight months.

The crew aimed to simulate what it would be like to live in space for a long period, setting up a closed habitat on the slopes of the Mauna Loa volcano in Hawaii. It marked the fifth mock Mars mission of the NASA-backed Hawaii Space Exploration Analog and Simulation, which is operated by the University of Hawaii. NASA has given the project about $2.5 million for research.

The project looked at how groups of people would work together on long-term missions while in small, cramped environments. While there, the four men and two women mostly ate shelf-stable food, as Space reports. But they also consumed lab-grown vegetables.

Fifth Hawaii Space Exploration Analog And Simulation Experiment

Everything was simulated, down to the communication delay. If a person were to send a message from Mars all the way to Earth, it would take 20 minutes. This was also true of the six-person crew inside the dome, where communicating with the outside world involved a simulated 20-minute delay. In addition, they had to wear spacesuits if they needed to venture outside.

"It's really gratifying to know that the knowledge gained here from our mission and the other missions that HI-SEAS has done will contribute to the future exploration of Mars and the future exploration of Space in general," said science officer Samuel Paylor, as The Washington Post reports.

Preparations For Manned Missions To Mars

The mission will aid NASA in selecting the right group of people who have the traits best suited to cope with the stress, isolation, and dangers of a Mars trip, which can take as much as three years. NASA hopes to begin Mars-bound space travels by the 2030s.

Laura Lark, the crew's information technology specialist, thinks a manned Mars mission is a reasonable goal. The HI-SEAS experiments are a way of knowing and gauging the human component of a manned mission to Mars, and according to Lark, it's absolutely possible to overcome challenges — changing moods, conflict, stress, and others — that arise within a group in isolation.

The crew lived inside a shelter the size of a small two-bedroom home with small sleeping quarters for each member. It also features a kitchen, bathroom, and laboratory. There was only one shower and two composting toilets.

The sixth mission is scheduled to begin in 2018 and will similarly last eight months.