After nearly four months aboard the Russian space station Mir, U.S. astronaut Norman Thagard and his two cosmonaut crewmates have become willing guinea pigs for researchers eager to learn more about the body’s response to long-term weightlessness.
If humans ever are to return to the moon to build permanent colonies or take three-year trips to Mars and back, scientists say they must have a much better understanding of the changes - including weakening of bones and loss of blood volume - that occur when we lose the constant embrace of gravity.
Biomedical studies of astronauts have been under way since the dawn of the space age in the 1960s. But there are drawbacks in both the U.S. and Russian research programs that the current shuttle-Mir docking mission hopes to redress.
Toward that end much of the work Saturday aboard the joined spacecraft involved biomedical studies of physician-astronaut Thagard and the two Russians, who have been aboard Mir for more than 100 days. National Aeronautics and Space Administration officials said the two spacecraft were operating well as the crews prepared to undock them Tuesday morning.
The Russians have put cosmonauts in space for many months at a time, including endurance champ Valery Polyakov, who returned to Earth from Mir March 22 after 439 days in space. But the health data from their flights - particularly during the Soviet era - were often difficult for the United States to obtain, U.S. officials say. Also, the Russian Soyuz transport vehicle does not have the room or the refrigeration equipment to return large numbers of stored biological samples - blood, urine, saliva - from orbit.
Except for several missions aboard the old Skylab space station in the 1970s lasting up to 84 days, the United States has depended on shuttle flights lasting only about 10 days, about the same length as the Apollo flights to the moon.
The new cooperation in space with Russia has provided NASA with its first long-duration space traveler - Thagard - since the Skylab period. And the Russians will be getting regular visits from a space shuttle able to transport back hundreds of pounds of scientific samples and gear from Mir and with advanced instruments onboard to allow continuous monitoring of the astronauts and cosmonauts as they return to Earth.
To counter the muscle-atrophying effects of weightlessness, the Mir crews wear jumpsuits with elastic cords laced into them. In space the cords tend to pull the cosmonauts into the fetal position unless they continually extend their limbs against the pressure. Space crews also use exercise bikes and other equipment to help maintain muscle tone.