Putting an Arm on Space

By Frederic Golden

Columbia is back with upside-down experiments

Nothing quite like it has ever been attempted in space. As the gleaming white-and-black orbiter hurtles across the skies, a long, mechanical arm, rather like the boom of a cherry picker, will emerge slowly from the spacecraft's cargo bay. Bending and flexing its metallic muscles, the multijointed limb will reach out into space almost as if it were guided by an independent intelligence of its own.

The high-level arm-twisting should be the highlight of the space shuttle Columbia 's second flight, slated to begin with another thunderous Florida lift-off at 7:30 a.m., E.S.T., this Wednesday.

When the shuttle made its first flight last April, NASA sought to prove to itself and the world that the craft could really roar up into space like a rocket, then glide safely back to earth like a plane. This week the U.S. space agency is engaging in quite another sort of test. Flying "upside down" high above the earth, Columbia will try out a $100 million, Canadian-built "arm in space." Unless the Remote Manipulator System, as the huge skyhook is called in NASA jargon, really works, the shuttle will be unable to perform one of its key roles in space: to place satellites into orbit and retrieve them when they fail.

NASA's unsurprising name for the second test of its Space Transportation System is S.T.S.-2. Columbia will be piloted by a new crew, Air Force Colonel Joe H. Engle, 49, the lean, affable mission commander who likes to hunt bear with bow and arrow, and Navy Captain Richard H. Truly, 43. Both are veteran pilots who began training as astronauts in the 1960s but who only now will be making orbital flights. The shuttle will be packed with more fuel and equipment than it was last April, including seven experiments, and it is slated to stay aloft at least five days instead of only two. After 83 complete orbits of the earth, if all goes according to plan, Engle will pilot the orbiter to another dead-stick landing on the dusty, dried-out old lake bed of California's Edwards Air Force Base. Estimated touchdown time: shortly after noon, Eastern time, next Monday, Nov. 9.

For a while it looked like the second flight might never get off the pad. Miscalculations and errors caused repeated delays. In the first flight an unexpectedly powerful shock wave from the initial blast of the shuttle's solid-fuel rockets caused the control flaps on the trailing edge of Columbia's delta wings to flutter so wildly that they approached the breaking point. The shock also bent and buckled several of the metal trusses linking Columbia to its big external fuel tank. To prevent a recurrence of this near disaster, engineers had to undertake a complete overhaul of the shock-suppression system, deluging the flame pits on the launch pad beneath Columbia's solid-fuel rockets with even more water.

Still another costly delay followed a mishap on the pad that occurred during a supposedly routine fueling operation when a jammed valve caused a back-up of nitrogen tetroxide. The corrosive liquid, which was part of the mix that powers 14 small maneuvering rockets on Columbia 's nose, spilled down the orbiter's sides, loosening some 50 of the craft's 31,000 heat-shielding tiles and damaging others. In all, 379 tiles had to be detached, cleaned and reglued. One consequence of these nagging mishaps: NASA officials no longer talk of refurbishing, refueling and sending the shuttle back into orbit every two weeks, and have cut the number of flights over the next four years from 44 to only 32.

After reaching an altitude of 158 miles, the astronauts will open the shuttle's big cargo-bay doors, power up their experiments and conduct the usual checkout of the shuttle's systems. Using its maneuvering rockets, Columbia will be rolled over, so that the instruments in the cargo bay look directly down upon earth. Floating freely in "zero gravity," the astronauts will be unaffected by their topsy-turvy view of the world.

Besides the large mechanical arm, the shuttle's cargo bay will be carrying an open pallet, or platform, to which five experiments will be attached. The pallet is part of Spacelab, Europe's contribution to the shuttle program. On future flights, the lab will be carried aloft and let scientists perform experiments in orbit.

During this trip, however, the experiments will be operating largely on their own, like Carl Sagan's semi-intelligent robots. Their purpose: to show that while the shuttle can perform important military duties in the new high ground of space, it is also a powerful scientific research tool.

Using a radar beacon, one experiment will search the earth's surface for geological features that could indicate oil or other commercially exploitable minerals. A second will test a multifrequency infrared scanner that assesses the mineral content in the earth's rock formations. A third battery of sensors will try to distinguish vegetation, water, snow, clouds and bare ground from space. The remaining two will measure carbon monoxide in the atmosphere and the concentrations of algae and fish in the oceans, both of them important indicators of the earth's environmental wellbeing.

Meanwhile, the astronauts will conduct two experiments in the cabin. One involves filming lightning flashes with a hand-held 16-mm movie camera to see if such techniques could be used for a storm warning system on a weather satellite. Engle and Truly will also act as space garden ers, tending 72 dwarf sunflower plants to find out how much moisture they need for optimal growth in zero g.

Mission Control in Houston, as well as the Canadian builders, will be especially concerned with the tests of the robot arm. Truly, who will work the space crane with hand grips at an observation post in the back of the command cabin, had originally been scheduled to try the arm's gripping apparatus on a fixture in the cargo bay. But the trial was scrubbed because of problems with the arm's hand, known in NASAese as an "end effector." Eventually, the spider-web-like wire snare should be able to capture any satellite equipped with appropriately mated hooks. On this voyage, Truly will only guide the 50-ft.-long arm through various manipulations of its "shoulder," "elbow" and "wrist" joints. If the machinery jams when the arm is extended, one of the spacemen will have to climb into a pressure suit and go outside to reel the limb in. If that fails, the arm will have to be jettisoned in space. For unless the shuttle's big, heat-shielded cargo doors are shut tight, Columbia will not survive the scorching descent through the atmo sphere back to earth.

With reporting by Jerry Hannifin

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