Nov 1 1981
From The Space Library
November 1-12: NASA reported that its $2 million quick-fix shock-prevention water system was hooked up November 1 during a countdown "notable for its smoothness," the Washington Post said. Designed hastily over the past five months, the shock-absorber system would flush 400,000 gallons of water in 35 seconds into the Shuttle's exhaust. Food for the journey was loaded aboard the spacecraft, and the next task would be loading chemicals for the ship's electric and environmental systems.
Liftoff had been scheduled for 7:30 a.m. EDT on November 4, but officials called off the countdown at 9:35 a.m., when rising oil pressures in the Shuttle's power generators, apparently caused by waxy contaminants, threatened to impair control of the hydraulic system that moved aerodynamic surfaces, such as the elevons, landing gear, and rudder and body flaps, and swiveled the nozzles on the Shuttle's three main rocket engines. L. Michael Weeks, acting associate administrator for STS, said that the engineers would have to analyze the trouble, correct it, and lay out a plan for resuming countdown; the delay would be "approximately one week." NASA was considering two courses of action: changing the oil and the filters in the auxiliary power units or replacing them with backup units. Engineers at KSC or JSC were not sure which course would take longer; neither, however, would mean hauling Columbia with its attached fuel tank and booster rockets back from the launch pad into the processing hangar for reworking.
The launch team had noticed the lubrication problem while the countdown was halted to grapple with other problems. Pressure in the liquid-oxygen chamber of the external tank had dropped below the limit for launch, and a similar glitch occurred in three smaller tanks feeding the electricity-producing fuel cells inside the Shuttle. Flight controllers decided that they could live with the pressure drops and instructed the control computers to ignore the warning signals. Two of the computers accepted the instruction but "logic got hung up in the system" leading to the third computer, which stopped the clock governing countdown at T minus 31 seconds. This was the point at which Columbia's on-board computers were supposed to take over control of all remaining steps in the countdown, but-having detected a problem-they refused to continue.
Controllers at the Cape and at mission control in Houston called up data displays to locate the trouble, and Shuttle operations director George F. Page finally announced that there would be no launch. Astronauts Col. Joe H. Engle and Capt. Richard H. Truly, who emerged from the Shuttle about an hour after the launch was scrubbed, seemed to take the delay "in stride," the New York Times said.
What persuaded controllers to call off the launch was the finding that oil pressure for two of the units had stabilized at 100 pounds per square inch, about 40 over normal. Neil B. Hutchinson, a flight director at JSC, said that contaminants in the oil had previously clogged Shuttle filters, which resembled the oil filter in an automobile. However, replacing a filter along with the lubricant it was supposed to keep clean would take far more time than in an automobile. If the auxiliary power units now in the Shuttle were to be used, technicians would have to drain the present oil, change filters, and flush the system before the flight could proceed. This had never been done on the launch pad; engineers would have to go ahead without knowing how long it would take. NASA spokesman Charles Redmond noted that General Motors found out about such problems "at the proving grounds, behind high screens, while we're doing it in public." Either changing filters and lubricant or completely replacing the two power units would be time-consuming because the units deep inside the ship would be difficult to reach. The power-unit fuel hydrazine, suspected of gumming up the works by interacting with the lubricating oil, was highly toxic, and the location of the power units would have to be purged with nitrogen. The nitrogen, which also could be fatal, would have to be purged in its turn.
The next procedure was the flushing and reservicing of the auxiliary powerunit (APU) gearboxes and installation of new filters. Tests to see what would happen if the APU was operated with a clogged filter (using the oil and filter removed from Columbia) showed that the filter would clear after about 10 minutes of operation, as the temperature increased. Launch was reset for November 12.
A second countdown to launch November 12 was delayed 2 hours and 40 minutes by trouble in the cockpit electronics. Engineers discovered November 11 that a 15-pound device, called multiplexer-demultiplexer (MUX/DEMUX), that collected information from all over the spacecraft about its condition to display both on video terminals for the astronauts and on the ground for analysis by engineers, was not working properly; it was quickly replaced with a substitute that did not work as well as the original. Officials sent for two of the instruments from the Challenger orbiter, still unfinished at Rockwell's Palmdale plant, to be flown to KSC and installed on Columbia. One went into Columbia's cockpit; the other would be carried as a spare. Countdown was at a built-in hold designed for emergencies such as the one that had occurred; it would resume early November 12 with the loading of 3-million gallons of supercold liquid oxygen and hydrogen fuel into the external tank, delaying launch until at least 10 a.m. The latest delays would cost NASA more than $26 million; every day of delay, including the eight in this last series, cost $3 million. The MUX/DEMUX delay cost an extra $2 million from handling, overtime, travel costs, and additional launch and landing tracking report. Launch of the second mission finally occurred at 10:10 a.m. EST November 12. About 2'/z hours into the mission, during the third orbit, fuel cell one showed a voltage drop; by the sixth orbit, it was so erratic that the astronauts were told to turn it off and use one of the other two. The faulty cell failed when one of the lines feeding hydrogen into it caused a water buildup that spilled onto an electrically charged manifold, breaking down the water into a potentially explosive mixture of gaseous hydrogen and oxygen. The failure took flight directors by surprise, as the cells had been used in 25 manned U.S. spacecraft since 1965 and had never before failed in flight. Hutchinson noted that "the good thing about this" was that the Shuttle could sustain a fuel-cell failure and continue operations. At 10 p.m. November 12, one of the standby cells was producing 7.5 kilowatts of electricity, and the other, 8.5, enough to do nearly everything except run all five instruments while the Shuttle arm was in operation. If the two good cells continued satisfactory, the flight would proceed as scheduled and return November 16 to Edwards Air Force Base in California; if either showed signs of weakening, the crew would return November 13 or 14. (W Post, Nov 2/81, A-3; Nov 6/81, A-9; Nov 13/81, A-1; NY Times, Nov 5/81, A-1; NASA MOR M-989-81-02 [postlaunch] Dec 17/81)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
