Six people are about to shut them inside a dome in Hawaii for a year, in the longest US isolation experiment yet aimed at helping NASA prepare for a pioneering journey to Mars.
The crew includes a French astrobiologist, a German physicist and four Americans - a pilot, an architect, a doctor/journalist and a soil scientist.
They are based on a barren, northern slope of Mauna Loa, living inside a dome that is 11 metres across and six metres tall.
They will close themselves in at 3pm Hawaii time on Friday (local time), marking the official start to the 12 month mission.
The men and women have their own small rooms, with space for a sleeping cot and desk, and will spend their days eating foods like powdered cheese and canned tuna, only going outside if dressed in a spacesuit, and having limited access to the internet.
So what kind of person wants to spend a year of their life this way?
Crew member Sheyna Gifford described the team as "six people who want to change the world by making it possible for people to leave it at will," she wrote on her blog, LivefromMars.life.
NASA's current technology can send a robotic mission to the Red Planet in eight months, and the space agency estimates that a human mission would take between one and three years.
With all that time spent in a cramped space without access to fresh air, food, or privacy, conflicts are certain to occur.
The US space agency is studying how these scenarios play out on Earth - in a program called Hawaii Space Exploration Analog and Simulation (HI-SEAS) - before pressing on toward Mars, which NASA hopes to reach sometime in the 2030s.
The first HI-SEAS experiment involved studies about cooking on Mars, and was followed by a four-month and an eight-month co-habitation mission.
NASA is spending US$1.2 million (NZ$1.85 million) on these simulations, and has just received funding of another million for three more in the coming years according to principal investigator Kim Binsted.
"That is very cheap for space research," she told AFP.
"It is really inexpensive compared to the cost of a space mission going wrong."
Binsted said that during the eight-month co-habitation mission, which ended earlier this year, conflicts did arise but the crew was able to work through their problems.
"I think one of the lessons is that you really can't prevent interpersonal conflicts. It is going to happen over these long-duration missions, even with the very best people," she told AFP.
"But what you can do is help people be resilient so they respond well to the problems and can resolve them and continue to perform well as a team."
Jocelyn Dunn, a crew member from the previous eight-month mission, said she came to love the inside jokes among the crew, doing daily workouts, and learning to cook things like bagels and pizza dough with the ingredients on hand.
Then, just days after the mission ended in mid-June, she described the joy of being "on Earth" again, eating fresh vegetables, using a knife to cut meat, swimming, and drinking soda and champagne.
"I couldn't believe how much I had missed the flavours and textures of a juicy steak," she wrote.