Holed up in an abandoned volcano quarry with few resources and only limited communication with friends and family, six volunteers are simulating a yearlong mission to Mars.

If NASA wants to land humans on the red planet by the 2030s, it will need to prepare them to handle the isolation of distant outer space, where cargo deliveries will take months to arrive and contact with Earth will be on a time delay of at least several minutes.

Now more than halfway through their experiment, the HI-SEAS 4 (Hawaii Space Exploration Analog and Simulation) crew members describe to Quartz in the video above, some of the all-too-real challenges they’re dealing with, living and working in their simulated Mars environment.