NASA is looking for applicants to spend a year pretending they are isolated on Mars.
The space agency wants people to apply so that it can prepare for eventually sending astronauts to the red planet.
Applications opened on Friday for four people to live for a year in Mars Dune Alpha.
The 1,700-square-foot Martian habitat, created by a 3D printer, is based inside a building at Johnson Space Centre in Houston, Texas.
There will be no windows, and the applicants will consume ready-to-eat space food.
The paid volunteers work a simulated Martian exploration mission which includes spacewalks, limited communications back home, restricted food and resources and equipment failures.
Three of these experiments are being planned by NASA, with the first one starting in the autumn of 2022.