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Shuttle circular de-orbiting ?
Right now, for de-orbit, they make one big burn, putting the shuttle
into an elliptical orbit whose perigee brings the shuttle low enough to hit "dense" atmosphere for re-entry interface. What if they lowered the Shuttle's orbit in a more circular fashion (multiple smaller burns) ? The shuttle would still lose the same amount of energy from the de-orbit burns, but it would not hit dense atmosphere right away and be able to bleed more energy from orbiting through light atmosphere, and this would also gradually lower its orbit, giving a much more gradual deceleration, and by the time it his dense atmosphere, wouldn't it have bled much more energy than the current scenario, hence less heat load on the heat shield ? If de-orbiting in a circular fashion would not bring teh shuttle low enough to hit sufficient atmosphere to slow it down, perhaps a hybrid solution could be use with just a slightly eliptical orbit where multiple passes through atmosphere at the perigee would bleed more still slow the shuttle down before it actually get low enough to really start to heat up ? Has this ever been studied before ? |
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Shuttle circular de-orbiting ?
John Doe wrote:
Right now, for de-orbit, they make one big burn, putting the shuttle into an elliptical orbit whose perigee brings the shuttle low enough to hit "dense" atmosphere for re-entry interface. What if they lowered the Shuttle's orbit in a more circular fashion (multiple smaller burns) ? The shuttle would still lose the same amount of energy from the de-orbit burns, but it would not hit dense atmosphere right away and be able to bleed more energy from orbiting through light atmosphere, and this would also gradually lower its orbit, giving a much more gradual deceleration, and by the time it his dense atmosphere, wouldn't it have bled much more energy than the current scenario, hence less heat load on the heat shield ? If de-orbiting in a circular fashion would not bring teh shuttle low enough to hit sufficient atmosphere to slow it down, perhaps a hybrid solution could be use with just a slightly eliptical orbit where multiple passes through atmosphere at the perigee would bleed more still slow the shuttle down before it actually get low enough to really start to heat up ? Has this ever been studied before ? Nice idea, but a 100NM circular orbit would have very little less energy than the current 200NMx35NM (aproximately) the shuttle is in now post deorbit burn -- a few 100's of feet per second vs. a total of about 25,000 ft/sec. This idea of going to a lower circular would work if the shuttle was coming home from a very hight altidude, e.g. geosync. An other big problem with the low circular would be to control landing point. It would be next to impossible to control what point in the orbit the shuttle would "bite" into the air and come home. On a related topic, I have heard that both Mercury and Vostok were put in a low enough orbit that is they did not get off the deorbit burn, the orbit would have decayed before life support ran out. I have read a document to confirm this for Vostok, but not for Mercury. I am a bit skeptical on Mercury, because it was much smaller than Vostok and had a much more limited life support system. Danny Dot www.mobbinggonemad.org |
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