Four men have agreed to be locked away in a steel container for 18 months in order to simulate a mission to Mars which will test the physical and mental stress of long spaceflight. A Belgian, two Frenchmen and a Colombian-Italian have agreed to join an existing Russian crew for the Mars500 project which is due to start in May. The container will hold all the vitals required to sustain them over the year-and-a-half period such as food and water. After 250 locked away, the crew will be divided in tow, and three “cosmonauts” will be moved to a separate “spacecraft” in order to walk on the surface of Mars wearing specially adapted Russian Orlan spacesuits. "I think you've got to be a little bit crazy to undertake this venture, but it's a healthy craziness," said Diego Urbina, a 26-year-old electronic engineer from Italy. "I will definitely miss my family and friends, and Nature itself - all the things we take for granted here on Earth, such as the internet. And girls - that's something I'll definitely miss," he told BBC News. The Mars500 facility, which is located on the IBMP site in Moscow, comprises four sealed interconnected modules with a total interior volume of about 550 cubic metres and no windows.