On Tue, 11 Mar 2008 03:18:40 -0400, you (Jonathan McDowell <jcm@head.cfa.harvard.edu>) wrote: >David, I don't think it was the photo flashes ... I have seen these >quasi-periodic flares on previous launches. I guess it's the RCS burns, >but they seem awfully bright. I don't suppose it could be the tumbling ET? The ET starts to tumble *very* slowly after separation, and takes a while to pick up a period worth mentioning, certainly quite a few minutes - leaving aside sunlight illumination considerations. My money would be on the RCS plumes during separation and flip-over maneuvering, I think that's the most likely candidate. Maybe worth mentioning here is that a few RCSs failed early in the ascent (a controller card went dead), so it's probably not ruled out that they used a different set or config of thrusters than nominal after separation. If that's even of any significance. Considering the spectacular ET venting that the post-separation video from onboard STS-122 showed, I wonder if the ET venting has ever been observed from the ground. Granted it's been a few years, but I've seen the Shuttle and ET just after separation coming over the hump passing over Europe, though I surely didn't notice any signs of venting then. I'm also wondering if the photo flashes maybe could be observed after all, but I don't know how bright they are to begin with. Again on STS-122, I've seen the Shuttle passing into and way beyond (its) dusk and sunset merely illuminated by what can only have been the payload bay floodlights, which came as no little surprise. After shadow entry, it was so faint that I had to look past it (avoiding the blind spot in the retina) to keep following it with binoculars, but it did work. ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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