Six people returned from a year-long experiment in a simulated environment made to resemble life on Mars on Sunday. They were put up in a dome next to a Hawaiian volcano, Mauna Loa, in almost total isolation without access to fresh air, proper food or any kind of privacy.

The experiment was conducted in a bid to understand the impact of isolation for an extended period of time on Earth before launching a mission to Mars – which NASA is aiming for at some point after 2030.

They were required to step out wearing spacesuits and mimic conditions that would be experienced by astronauts if they chose to participate in a manned mission to the Red Planet.

The Hawaii Space Exploration Analog and Simulation, or HI-SEAS, had six scientists who could communicate with the outside world with the help of the internet as well audio and video. The catch was that every message would face a 20-minute delay, to replicate actual conditions.

The next simulation experiments are already being planned for 2017 and 2018 by the same group of researchers. Potential members of the crew will get a chance to experience the same conditions for a period of eight months.