Astronauts isolated for eight months in a tent return to normal life

The group were kept in isolation on a remote Hawaiian volcano to test how humans would react to living in confined conditions for an extended period of time.

Samuel Payler, a doctoral candidate at the UK Centre for Astrobiology at the University of Edinburgh, and five other researchers entered the HI-SEAS (Hawaii Space Exploration Analog and Simulation) habitat on Mauna Loa in January.

The experiment intended to help Nasa determine the requirements for sendingastronauts on long missions, including trips to Mars.

They emerged to cheers and applause before devouring fresh fruit and vegetables, having eaten mainly freeze-dried food since the start of the year.

Mr Payler said: "We need to send humans out because it's important for the future of the species.

"I think it's actually really important to get off Earth. If you look back at the geological record, it is just full of mass extinctions."

The 1,200 sq ft site included small sleeping quarters for the crew members, a kitchen, laboratory, bathroom and simulated airlock area.

The crew's daily routine involved preparing food from shelf-stable ingredients, exercise, scientific research and tracking use of resources such as food, power and water.

Communication with support crew on the outside world was allowed but a 20-minute delay was imposed on messages to imitate what the reception would be like between Earth and the red planet.

Four men and two women made the dome their home for most of this year.

Mr Payler's co-residents were Ansley Barnard, an engineer from Reno, Nevada; Laura Lark, a computer scientist who spent five years as a software engineer at Google; systems engineer Joshua Ehrlich; freelance researcher James Bevington; and Brian Ramos, a Portuguese-American who has a master's degree in international space studies.

The project was run by the University of Hawaii, with Dr Kim Binsted as its principal investigator.

She said: "The university is going to be giving NASA essential information about how you pick individual astronauts and how you put them together in a crew, but also how you support them over these long duration missions."