Also remember that during launch the space shuttle is facing directly into the direction of travel thus presenting the lowest drag (and least friction). During re-entry the space shuttle lifts its nose a bit to expose more area of the underside of the craft to produce more drag. This increases friction. As the shuttle descends, air density increases which increases friction. The shuttle slows due to this friction. The decent path is a smaller rate of decent (lower angle) than launch which is nearly vertical at first. This gives more time for slowing due to atmospheric friction. All this produces very high temperatures. Too steep a decent would increase temperatures beyond what the tiles on the skin of the shuttle can withstand and the shuttle would burn up just like a meteor. Hope this helps understanding.
Ed (just an old retired NASA engineer - not quite rocket scientist).
At 05:04 PM 2/14/2008, Jim Jerzycke wrote:
Because on the way up, as its accelerating, the air is getting thinner. On the way down it only has the drag of the atmosphere to slow it, so it caries more of its velocity into the thicker air. Jim KQ6EA
--- Joe nss@mwt.net wrote:
Hi All,,
Since we are somewhat off topic for the moment with the conversation about the bird to come down shortly.. Ok, the question is, and i've asked it to several other places, and yet to even get a answer,
The question is,,,
Space shuttle launches,, starts off at sea level, and in less than ten minutes goes from zero to 17K MPh (or so) And gets to orbital altitude.
Time to come down,, the de-orbit burn happens to slow it down just a bit to cause the orbit to more or less decay.. It's at orbital altitude.. and moving at about 17K MPh.. 45 minutes or so later it's back on the ground and moving at zero MPh..
So in actuality it comes down from space even slower than going up. Yes? 45 min vs 10.
Ok, same goes with any satellite,,
How come, going up,, 0 to 17K MPh through the atmosphere, all is fine.. BUT
coming down,, 17K MPh to 0 unless it has protection it will burn up in the atmosphere from friction with the air.
why is it different?
Joe WB9SBD & NSS _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb