US space agency NASA has wrapped up an experiment with a volunteer crew of four people spending one year in a facility that simulates living on Mars.

The aim of the mission was to learn about the possible impact for astronauts staying on the planet in the future. The four volunteers entered the simulated Mars habitat at Johnson Space Center in the US state of Texas in June last year.

The facility features 3D printed private crew quarters and workstations. It also has an area with red sand resembling the surface of Mars.

The crew conducted various experiments, including growing vegetables to help with food self-sufficiency.

On Saturday, the four members left the facility for the first time in about a year. They were welcomed by applause as the door opened.

One of the participants, biologist Kelly Haston, said she is proud and honored to be part of "the work being done here on earth that will one day enable humans to explore and live on Mars."

The United States is leading the international lunar exploration program Artemis, which also aims to eventually facilitate human missions on Mars.

NASA plans to analyze the data obtained and use it for future space explorations.