Worrying Discovery

Overall, her three-month processing run after STS-75 had gone exceptionally well, further demonstrating the efforts during her last modification period at Palmdale to reduce turnaround times and improve her capabilities. The only problems were the need to replace and retest a Tactical Air Navigation (TACAN) device - a landing aid - and correct a software error with one of Columbia's Master Events Controllers, which fire the pyrotechnics to separate the tank and boosters during ascent. Finally, on 18 June, NASA managers opted to open her aft compartment and X-ray the power drive units for the External Tank access doors in her belly.

The latter were suspected of having loose screws in their circuitry boards (a similar problem had been discovered during routine inspections of Space Shuttle Atlantis), but the X-rays proved them to be secure. Right on time, at 2:49 pm on 20 June, at the opening of a two-and-a-half-hour window for that day, Columbia duly rocketed into orbit for what was already expected to be a record-breaking 17-day Shuttle flight. Officially, it was scheduled for just under 16 days, but NASA managers expected that conservation of electrical power reserves should be sufficient to extend STS-78 by 24 hours or more.

Commander Henricks provided television viewers with a unique perspective of his fourth launch into orbit - and his second on board Columbia - thanks to the presence of a small video camera mounted in the forward section of the flight deck. Its footage began just before the thunderous ignition of the main engines and boosters and proceeded through the separation of the External Tank until the spacecraft settled into her preliminary orbit. The launch itself was certainly a bone-jarring affair, although a subsequent analysis of the recovered boosters revealed worrying damage to their field joints caused by searing hot gases.

It was through such 'blow-by' of one of the boosters' seals that Challenger had been lost in January 1986 and, although the STS-78 ascent did not compromise the astronauts' safety, it was the first time that the new-specification Redesigned Solid Rocket Motor (RSRM) joints had experienced such 'combustion-product penetration'. NASA managers quickly pointed out that there was a hot gas 'path' through the motor field joints, but not through the 'capture' joint, and that, therefore, the motors performed within their design requirements. However, the incident did raise questions over an environmentally friendly adhesive that had been added to the boosters.

Even as Columbia circled the Earth, a problem with the adhesive was already

A worrying discovery 269

A worrying discovery 269

STS-78 blasts off on 20 June 1996 to begin the record-setting, 17-day STS-78 mission.

expected to delay the next Shuttle mission, STS-79. Unfortunately, NASA was unable to revert to its old-style adhesive because environmental regulations had banned its methyl-based material. Developing a new adhesive ''could take a while'', admitted Shuttle manager Tommy Holloway. The potential damage to the boosters was more serious, however, prompting Holloway to tell reporters: ''This is a serious situation until we determine it's not serious.'' He stressed at the same time that the damage did not affect the rubbery O-rings within Columbia's boosters. ''This joint is an order of magnitude more robust than the joint on Challenger.'' In total, engineers found six joints where hot gas had apparently penetrated their heat shields. Ultimately, the discovery and the repairs that had to be put in place led to the postponement of the next Shuttle mission, STS-79, from 31 July to the middle of September.

This meant that NASA astronaut Shannon Lucid was obliged to spend longer than expected on the Russian Mir space station. ''Of course,'' she said from her Earth-orbital home, ''that always happens, no matter where you are.'' Lucid had been sent to Mir on STS-76 in March 1996 as the second NASA astronaut to spend a period of several months at the station. When she finally returned to Earth on STS-79, she had spent more than six months aloft, setting a new American record.

Aside from the booster concerns, which did not come to light until the end of June, during their post-retrieval disassembly and inspection, Columbia's climb to orbit was nominal. The only other problem was a failure of one of the five GPCs; this unit held a backup set of flight software in case the other four computers became corrupted. One of the four primary computers was loaded with the backup software and the head of NASA's Mission Management Team, Loren Shriver, told journalists that he expected the mission to run to the planned duration.

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