Soviet policy makers have wanted to go to Mars since the late 1960s. That's when it became clear that the race to the moon was lost and their main focus switched to long-term human spaceflight.

"In order to achieve this goal, four main questions had to be answered," said Dr. Anatoly Grigoriev, a Director of the Institute of Biomedical Problems, the leading Russian research institute in the field of space medicine and biology. "The first one was how to provide medical support during a mission to Mars. The next was how to assure the psychological compatibility among the members of the small, isolated group. The third was how to create a durable and effective life-support system; and the fourth was to provide an effective protection from space radiation."

Cosmonaut Dr. Valery Polyakov made a 437-day space flight - long enough to make a round trip to Mars.

"The key element of medical support in a mission to Mars will be the incorporation of a physician into the interplanetary crew," said cosmonaut Valery Polyakov, IBMP Deputy Director. "This physician will have to solve all medical problems during the flight by using the on-board equipment and his or her own experience ranging from surgery to therapy -- and tele-medicine."

Russian specialists are working on a self-sufficient regenerative type of life-support system, which will include an on-board greenhouse. Dr. Potapov says, "the size of the greenhouse will be determined by a number of crewmembers 2 square meters (21.5 square feet) per person. This greenhouse will totally satisfy the crews demand for C and A vitamins and partially for PP, B1, and B2 vitamins."

According to Dr. Potapov, the IBMP specialists have determined that six crew members will need about 37.5 tons of water during a two-year mission to Mars. However, an on-board water-recovery system, together with a threefold emergency water reserve will decrease the amount to 7.5 tons. The food supply should be approximately the same amount.

Psychological problems can stem from isolation, unpredictable situations, small-group interaction, a heavy work load and the pressure of making the mission successful. Dr. Potapov has conducted a number of long-term experiments in confinement. The most recent experiment lasted 240 days and proved that life in isolation is hard. There were incidents of violence and sexual harassment -- one person even walked out.

The EU-100 prototype of a spacecraft for Mars voyagers.

"The key condition for the success of the mission will be to compose the crew long before the flight so that crew members will have enough time to know how to live and work with each other and to become a real team," said Dr. Grigoriev. "We believe that six people is the optimal number," he continued. "It should include a mission commander who will also be a pilot, a co-pilot, a flight engineer, a physician and two scientists."

Longer periods away from Earth's protective atmosphere also increase interplanetary travelers' exposure time to potentially lethal doses of space radiation. Dr. Potapov said protecting [a] crew from space radiation is a matter of timing and distance. "A mission to Mars should take place during the less-intensive phase ofsolar activity. The flight itself should be made as short as possible. Special protection means includingon-board shelter, medicines and specially engineered spacecraft skin. Overall, we believe that 10 grams (0.35 ounce) of aluminum per 1 square centimeter (0.15 square inch) will be enough to provide an adequate crew protection from radiation during Mars journey."

Valery Polyakov, who made his record-breaking spaceflight when he was in his early 50s, believes that the age of the future Mars voyagers should be between 50 and 60, and even older when there are no medical problems. "This is the age when a person reaches a peak in his or her physiological, psychological and social stability. Besides, interplanetary travel might involve an unknown risk for [the] reproductive systems of cosmonauts."

Dr. Anatoly Grigoriev, Director of Institute of Biomedical Problems (IBMP).

The jury is still out on whether a future mission to Mars crew should involve both sexes. Dr. Potapov believes that incorporating women into the crew will introduce an unnecessary emotional and hormonal disturbance into an all-male team. However, IBMP specialists say a woman who participated in an experiment with men had greater concentration, orientation and intuition than the men.

Any problems on a mission to Mars could be solved, says cosmonaut Polyakov. "Look, after 437 days of exposure to weightlessness, I walked out of the landing capsule myself. This was one of the goals of my flight -- to prove that a cosmonaut will be able to work on Mars after a long space journey."