Flying the Seatless Chair
Despite a satellite loss, Challenger opens a new era in orbit
When the space shuttle Challenger lifted off from Florida last week, the roaring flames signaled the start of NASA's busiest year in space. Ten missions are scheduled for 1984, including one with a secret Pentagon payload. But Challenger had barely settled into orbit 190 miles above the earth on the tenth shuttle mission when space gremlins struck. A multimillion-dollar communications satellite, one of two carried on board, mysteriously vanished into the void. Still, in spite of the embarrassing loss, NASA hoped to redeem itself with another of its spectaculars. This week, for the first time, astronauts plan to take a true step into space, leaving the safety of the mother ship without so much as a frail wire to prevent them from drifting off toward infinity.
These orbital theatrics have a high purpose. In pushing off from Challenger's open cargo bay, Astronauts Bruce McCandless II, 46, and Robert Stewart, 41, both of whom are making their initial shuttle trips, will be rehearsing the first repair of a satellite in orbit. That is slated to take place in April, when astronauts attempt to retrieve and revive a $150 million robot scientific observatory nicknamed Solar Max, which has been spinning helplessly since it broke down three years ago. If this tinkering succeeds, it could pave the way for even more ambitious efforts, including the assembly of President Reagan's proposed space station.
For the moment, however, NASA'S attention was more pressingly diverted. Just eight hours into the flight, Mission Specialist Ronald McNair, 33, a physicist making his first flight, successfully sent Western Union's $75 million Westar VI spinning out of Challenger's big cargo bay. But soon all contact with Westar, built by Hughes Aircraft, was lost. Its transmitters were silent. Ground-based trackers could not tell whether its booster, which was to have propelled it into a geostationary "parking place" 22,300 miles above the equator, had misfired or some onboard electronics had failed. Desperately trying to bring the satellite back to life, if indeed there were still any electronic stirrings in the complex machine, the controllers blindly sent radio signals into space. Later the trackers detected a number of unidentified objects orbiting behind the shuttle. Officials gloomily speculated that they might be fragments from an explosion that destroyed the satellite.
The failure immediately confronted NASA with the question of whether it should go ahead with the launch of Westar's twin, Indonesia's Palapa B2, scheduled for the next day. Palapa is to be used as a telecommunications link between the 13,677 islands of the sprawling Indonesian archipelago. At week's end, NASA decided to postpone the launch at least for a day while ground controllers probed the Westar accident. If Indonesia requested a deferral until a later mission, the shuttle would have to bring the satellite back to earth. The added weight would speed the shuttle's descent on landing, possibly forcing NASA to scrub a Florida touchdown.
Although the lost satellite cast a shadow over the mission, Challenger's commander, Vance Brand, 52, a former Marine pilot on his third spaceflight, and his four crewmen, including Copilot Robert ("Hoot") Gibson, 37, a space novice, faced other weighty matters. In many ways Flight 41-B, as the mission is called under a new numbering system fathomable only to NASA bureaucrats, is the most ambitious sortie into space to date. It features a full agenda of experiments, including one intriguing test devised by a high school student to see if zero-g can relieve the agony of arthritic rats in a mid-deck cage. The astronauts will operate the shuttle's sinewy remote-controlled arm, using it to lift out into space a German-built platform known as SPAS (for Shuttle Pallet Satellite), which is loaded with scientific instruments. More significant, they are slated for a two-day game of tag with a 6½-ft.-diameter Mylar balloon. As the sphere drifts as far as 120 miles away, the crew will use radar and optical tracking to find their way back to it. The maneuvers are a rehearsal for April's retrieval of Solar Max.
Yet the mission's unquestioned highlights are the untethered space walks on Tuesday and Thursday. Spacemen have been venturing outside their spacecraft ever since Cosmonaut Alexis Leonov undertook the first EVA (for extravehicular activity, in NASA jargon) in 1965. But they have always been securely hooked to a lifeline. This time they will rely entirely on a Buck Rogers-type contraption called, with a touch of sexism, a manned maneuvering unit (MMU).
The $15 million device resembles nothing so much as a clumsy overstuffed armchair without a seat. On earth it weighs 340 lbs., but in zero-g an MMU can fly like a bird. A squirt or two of nitrogen gas from any of its 24 small jet thrusters can propel it in any direction. Strapped into this flying chair, an astronaut need only work the handle-like controls built into the armrests.
The flight plan calls for the astronauts to move up to 300 ft. away from the shuttle. Only one man will fly at a time; the other will remain tethered in the cargo bay. If the MMU'S thrusters fail, a stranded astronaut could be rescued by his partner or even the shuttle. No tethers are used during the lengthy, complex sorties because an astronaut might become tangled in a line. During the space walks, the astronauts will practice snaring Solar Max by hooking themselves onto the SPAS. But this is not as easy as it sounds. In zero-g, obtaining leverage is exasperatingly difficult. For example, in using a screwdriver, an astronaut is as likely to twist as the screw. While they are working on SPAS, the astronauts will hook their feet in a restraint attached to the end of the remote-controlled arm.
NASA also has its eyes on another first. If winds and weather are fair in Florida at the end of Challenger's seventh day in orbit — and the problem of Palapa has been resolved — the winged spacecraft will land on the Kennedy Space Center's three-mile-long shuttle runway rather than on the hard-packed sands of California's Edwards Air Force Base. Such a feat would not only go a long way toward proving the shuttle's versatility but also save NASA at least $1 million a mission, the cost of piggybacking the orbiter back from California after each flight.
By Frederic Golden, Reported by Jerry Hannifin/Kennedy Space Center and Geoffrey Leavenworth/Houston
February 18, 1984