airlock

Two students are currently living, working and communicating with the outside world as if they were on a mission to Mars.

Whenever they go outside their small, round habitat where eight people are spending a two-week "mission," they don spacesuits and pass through an airlock.

When they send e-mail, it takes 20 minutes before the recipient can see it -- the time it takes for radio waves to travel to and from the red planet.