Sim Mars

The European Space Agency is calling for volunteers to be sealed inside a "spaceship" for 17 months to simulate a trip to Mars. According to the BBC,

With the exception of weightlessness and radiation, the crew will experience most other aspects of long-haul space travel, such as cramped conditions, a high workload, lack of privacy, and limited supplies.

I'm confused. Are they simulating space travel or working as a code writer at Microsoft?