America's space shuttle system is about to cross the threshold of a new operational era. Up to now, ground controllers have watched helplessly when Earth satellites failed or ran out of fuel. Astronauts on the coming Challenger mission will practice techniques of satellite repair and refueling that could begin to overcome such frustration.
At this writing, the eight-day mission, designated 41-B, was scheduled for a Feb. 3 launch at 8 a.m. Eastern standard time.
Like its predecessors, the five-man astronaut crew has some commercial work, as well as experiments, on its schedule. It will launch two communications satellites - Western Union's Westar 6 and Indonesia's Palapa B-2.
But then the astronauts will begin a schedule of activities that, for space veterans, will be reminiscent of the old Gemini rendezvous exercises of the mid- 1960s. Mission commander Vance D. Brand, pilot Robert L. Gibson, and mission specialist Bruce McCandless II will take the shuttle Challenger through a series of rendezvous maneuvers with a 6.5-foot diameter striped balloon.
The maneuvers will take a day and a half. During that time, Challenger will drift 140 miles from the balloon, catch up with it again, and approach to within 300 feet. Ground trackers will help guide the astronauts. But when they are within eight miles of their target, they will try to use their rendezvous radar. They will also test a powerful searchlight, which should illuminate the balloon from distances up to 1,000 feet.
All of this is preparation for next April's mission when astronauts are to recover and repair the Solar Maximum Mission satellite. The approach to within 300 feet was chosen because astronaut George D. Nelson will cross such a gap when he helps recover the Solar Max vehicle in April.
He will be using a maneuvering unit backpack - sort of a personal rocket ship. Mission specialists McCandless and Robert L. Stewart expect to give two such units a thorough workout during two five- to six-hour EVAs next week. EVA (extravehicular activity) is NASA jargon for working outside the shuttle.
The two astronauts will fly the units within the shuttle bay. Then they will make excursions from the ship to distances of 150 and 300 feet. These will be the first untethered orbital flights by individuals. Up to now, all United States astronauts and Soviet cosmonauts have used tethers while taking space walks. However, National Aeronautics and Space Administration (NASA) planners thought a tether might be more of a hindrance than a safeguard if it entangled an astronaut.
The maneuvering units are considered highly reliable. Neither astronaut would be stranded were his unit to fail. His buddy could rescue him using the second backpack. Also, Brand could bring the shuttle close enough for rescue.
Besides testing their skill as independent 700-pound satellites, McCandless and Stewart have a series of important satellite repair tasks. Working with mockups, they will practice removing and installing equipment and try refueling operations. McCandless will work with a mockup of the Landsat-4 fuel system to see if it is practical to try to refuel that ailing satellite.
Landsat-4 is a US Earth resource survey satellite on which some communications equipment has failed. NASA is considering trying to recover and repair that satellite in October 1985.
Since Landsat-4 is in a polar orbit, the shuttle would have to be launched from the pad now being built at Vanderberg Air Force Base in California.
Besides rescuing Landsat, the success of such a mission would point the way toward long-lived military reconnaissance satellites that could be serviced in orbit.
McCandless and Stewart also expect to test-ride the shuttle's Canadian-supplied manipulator arm like telephone repair personnel on a ''cherry picker.''
While one or the other of them is on the arm's platform, secured with foot restraints, mission specialist Ronald E. McNair, the fifth crew member, will move the arm from within Challenger's cabin.
On Feb. 11, as a finale to this very busy mission, the flight team has planned hopefully for a landing at Cape Canaveral shortly after 7 a.m. EST.
If weather permits, this will be the first of the long-anticipated demonstrations of the shuttle's ability to return directly to its home base.