A team of six people have completed a Mars simulation in Hawaii, where they lived in near isolation for a year.
Since 29 August 2015, the group lived in close quarters in a dome, without fresh air, fresh food or privacy.
Experts estimate a human mission to the Red Planet could take between one and three years.
The Nasa-funded study run by the University of Hawaii was the longest of its kind, after a Russian mission that lasted 520 days.
"The researchers are looking forward to getting in the ocean and eating fresh produce and other foods that weren't available in the dome", said Kim Binsted, principal investigator for the Hawaii Space Exploration Analog and Simulation.
The team consisted of a French astro-biologist, a German physicist and four Americans - a pilot, an architect, a journalist and a soil scientist.
The experiment dealt with the human element of exploration.
While conducting research, the six had to live with limited resources, wear a space-suit when outside the dome, and work to avoid personal conflicts.
They each had a small sleeping cot and a desk inside their rooms. Provisions included powdered cheese and canned tuna.
Missions to the International Space Station normally only last six months.