(2 of 3)
There was, nevertheless, plenty of suspense as Skylab slipped ever closer to its doom. The craft was monitored by the worldwide network of NASA and NORAD's space-tracking stations. From NORAD'S underground headquarters in Colorado Springs, Colo., calculations about the craft's flight were transmitted to the Skylab Control Center at the Lyndon B. Johnson Space Center near Houston. There Charles Harlan, the Skylab flight director, estimated the vehicle's probable reentry point, and the possible dangers. He, in turn, was responsible for advising the Skylab Coordination Center at NASA headquarters in Washington whether anything should be done to change Skylab's trajectory. The final decision was up to NASA Administrator Robert A. Frosch, aided by his Skylab task force director, Richard G. Smith, who worked in a guarded, sixth-floor NASA office.
At the Houston center, Skylab's final orbit (No. 34,981) looked ideal to Harlan, since it was over the ocean and sparsely populated areas. But one big problem soon emerged: the experts' best guesses as to where the satellite was first likely to re-enter the atmosphere were slightly wrong. Instead of over the middle Atlantic, as expected, Skylab could begin breaking up over Canada, endangering the Montreal area and parts of Maine. Harlan got permission from Washington to cause Skylab to tumble in space, which would delay its impact with earth by about 30 minutes.
The crucial command could be given only during the three minutes that Skylab was within radio range of NASA's tracking station in Santiago, Chile. The coded words were phoned by Houston Flight Controller Cindy Major, 27, to the Santiago center. "Load mark," she said, "one, zero, six, two." The order caused Skylab's adjusting jets to fire briefly, propelling the craft into the wobbling motion. Said Harlan: "We shot our last wad."
But the space station proved more durable than expected. To the astonishment rf the controllers, the craft still was sending out signals when it came within range )f the NASA station on Ascension Island in the Atlantic. Said Harlan: "I got to thinking that we couldn't kill the thing " Soon, however, the signs of deterioration were clear. At a height of 69 miles over the ocean, some of Skylab's batteries registered a temperature of 100° F far above the normal 60° F. Then the radio signals faded, and finally stopped. Breakup had begun, and the projected "footprint" of Skylab's debris seemed to be safely in the Indian Ocean. Houston's perspiring controllers relaxed. The monitoring team gave Johnson Space Center Director Christopher Kraft a Skylab SPLAT DOWN (instead of splashdown) T shirt For a time, Skylab still refused to die After losing its solar panels, the vehicle skipped as it hit the dense atmosphere like a flat rock bouncing off the surface of a lake. Moving through a gap in the U.S. tracking network, Skylab slid on in radio silence, with no one aware of precisely where it was. NASA'S final maneuver, though based on the best information available to its controllers, had actually pushed the dying craft closer to Australia than intended. Not until Skylab reached the skies about six miles above Kalgoorlie, with its speed slowed to 270 m.p.h., did its flaming parts begin to plunge almost vertically toward the earth.