Despite their heavy workload, and several unsympathetic questions from the media, the rookies nevertheless managed to enjoy their first experience of spaceflight. ''On the tenth or eleventh day, I wanted to do one full [orbit] and sit and watch the Earth,'' recalled Chawla. ''Doing so was mind-boggling. It really instilled this huge sense of how small Earth is. An hour and a half and I could go around it! I could do all of the math and logic for why that was, but in the big picture the thing that stayed with me is this place is very small! I felt every person needs to experience this, because maybe we would take better care of this place. This planet below you is our campsite and you know of no other camp ground. I didn't think this view would be something so philosophical - I thought I would go around and see the continents and the oceans. But it was much more than that.'' It was a memory that would stay with her long after Kregel brought Columbia smoothly to land on Runway 33 at KSC at 12:20 pm on 5 December, wrapping up a bittersweet, two-and-a-half-week mission.
''We had a very interesting and eventful 16 days,'' he told the assembled journalists as the crew posed on the runway. ''We had a lot of successes. We had a little bit of downtrodden times there, but together as a team, I think we ended up with a very super mission.'' Columbia, however, had returned home having endured significant damage to her thermal-protection coating: light spots were easily detectable on many tiles and her overall condition was ''not normal''. Ordinarily, around 40 tiles' worth of damage was expected; on STS-87, more than a hundred tiles were found to be irreparable!
Such damage, as the STS-107 disaster has tragically taught us, is mainly caused by fragments of ice or foam falling from the External Tank during ascent, but the impacts on Kregel's flight did not follow aerodynamic expectations and were far higher in number. No fewer than 308 'hits' were counted during post-flight inspections, over a hundred of which were greater than 2.5 cm across and some penetrated 75% of the total depth of the heat-shielding tiles. The chief suspects were new, environmentally friendly products added to the External Tank, including a new foam insulation, of which large quantities had apparently hit Columbia.
It was ultimately determined, through a combination of theoretical modelling and still photography, that foam fell from the massive fuel tank and was carried by
aerodynamic flows to 'pelt' the Shuttle's nose and fuselage during her climb to orbit. Possible causes included a defective coating of primer or the new foam insulation on the External Tank. The worrying STS-87 incident would take centre stage in the Columbia Accident Investigation Board's findings less than six years later ...
Meanwhile, another investigatory board - chaired by former astronaut Rick Hieb - had already got its teeth into identifying the cause of the Spartan failure. Initially, it blamed 'crew error', but later absolved Chawla, acknowledging that instructions given to the astronauts might have been unclear. ''They [the investigative team] decided on things that were missing from our training,'' she said later. ''For example, we did not simulate lighting conditions. Also, we don't have established rules for how to match [rotation] rates. Later, it became apparent that we couldn't match that rate, so we were just wasting propellant. The biggest thing against the crew was crew resource management, where if more people had been watching what was going on, it could have been prevented. But then again, NASA said there was no margin for error with the Spartan deployment.''
Kregel added that the failure gave them a chance to demonstrate their ability to develop alternate procedures in orbit, which would undoubtedly be needed to work around problems encountered during International Space Station operations. ''A big success was, in a short timeframe, all the folks [got] together [and] came up with a plan to retrieve a very valuable asset. If that doesn't show the ability of humans to adapt to changing situations in space, then I don't know what is.''
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