The six researchers on a 520-day mock flight to Mars are all feeling strong and ready to 'land' on the Red Planet, the mission director said on Jan 22.
The crew are 31-year-old Frenchman Romain Charles and 27-year-old Italian-Colombian Diego Urbina who are engineers by training. China's 26-year-old Wang Yue is an employee at China's space training centre.
The 38-year old Russian captain, Alexey Sitev, has worked at the Russian cosmonaut training centre and the two other Russians, Sukhrob Kamolov and Alexander Smoleyevsky are doctors.
They communicate with the outside world via e-mails and video messages - occasionally delayed to give them the feel of being more than a few yards away from mission control.
Their 3.6 metre wide and 20 metre long craft, parked in a Moscow car park next to a block of flats, contains six tiny sleeping pods with cot-like beds, a living room, a eat-in kitchen, a working zone, a toilet, a laboratory and greenhouse.
And although they have been given permission to abandon the mission anytime, none of them have done so.
"They are still motivated, but there is a certain fatigue, which is natural," the Daily Mail quoted Boris Morukov as saying.
The six men are due to 'land' on Mars on February 12 and spend two days researching the planet. They then begin the long 'return flight' to Earth, expected to be the most challenging part of the mission.
"It will be very tough on the boys because of the monotony. The fatigue and the thought that the mission is over can be fraught with negative consequences," he said.
The Mars-500 experiment is being conducted by the Moscow-based Institute for Medical and Biological Problems, the European Space Agency and China's space training centre.