>> Sunday, May 24, 2009
For those of you who come here for a healthy dose of space and stuff, you might have been disappointed recently. After all, here we were working one of the greatest telescopes of all time, for the last time, an historic mission that almost didn't happen, and I haven't said a word.
Good heavens, one might wonder, why not? After all, I was the EVA Safety lead on the last two Hubble Servicing Missions. I know this stuff. I know the people doing this work. Why not talk it up on my blog? Why not tell people what was happening when it happened?
Well, I should have. I wanted to. I just couldn't. Not until it touched down safely, which it did this morning, thank goodness. I didn't want to jinx it because this was the mission, of all the remaining Shuttle missions, that scared me most. And they made it back safely. That, for me, is the most important thing.
I'm going to tell you how remarkable this mission was, why what they did was so remarkable, so incredibly, so admirable. I want to tell you about our exceptional crewmembers and the work they did for all of us to get several more years of amazing pictures from the Hubble Space Telescope until the James Webb Telescope is launched. And I will.
Today, though, I'm going to tell you why I was so worried.
A lot has been made of the fact that this mission almost didn't happen. They newspapers sneer over the original reluctance to fly it. The scientists who count on Hubble information decried the reluctance as if it were an irrational prejudice against astronomy. They made the point that ISS was still getting missions.
I was one of those that didn't want to fly this flight. Folks, it's not the same. NASA moved heaven and earth to fly this mission and we will all benefit by it. But it wasn't because it was easy.
See, since Columbia, we've been flying with a backup flight, which we need to launch within weeks in case we see catastrophic (unrepairable) damage on the thermal protection system. But you have some time to wait in a habitable environment that has it's own resources. There is no place to shelter at the Hubble Space Telescope, which is why the rescue mission must be launchable within days, not weeks, which is a sizable constraint.
And transferring from one Orbiter to another isn't as simple as having people leave the ISS into a different Orbiter. Everyone must suit and transfer between too close but not docked Orbiters. Dicey. They had a plan, but it's not like anything we've ever done before.
Also, although the ascent risk is probably comparable between Hubble and ISS missions, the orbital debris environment is not the same. HST is at a higher altitude which has been dirtier than the ISS altitude, for some time. However, two ugly debris incidents the last year or two (the Chinese ASAT test) and the Iridium collision have added a great deal of debris to that (and other) environments as both occured just a bit higher than HST is flying.
But, despite all the challenges (and the considerable challenges in a heavy load of EVAs - which I'll describe in a later post), they pulled it off. They dodged any catastrophic ascent or orbital debris. The faced the fears (and had contingency plans we never had to use) and came out successful. They did a hell of a job and were successful. Our gamble paid off.
I was never so happy to be wrong.