if a shuttle could move slow?

if a shuttle could move slow going into the atmosphere would it still burn up?

Originally posted by masterofpuppets
if a shuttle could move slow going into the atmosphere would it still burn up?

Im pretty sure that the shuttle has to move fast just to make it out of our atmosphere.

it wouldn't burn up because it would just hit the atmosphere and skip back off into space. it has to be going at least a certain velocity to be able to punch its way into the atmosphere.

Correct me if i'm wrong. I don't think it's a certain volocity, but a certain angle. If you come in to shallow of an angle, you'll skip (like skipping rocks on water). come in too steep and you'll smash to pieces.

I've often wondered the same thing MoP. Although i think it would be really hard to do, if not impossible. But if you were able to slowly fall down to Earth, there would be less friction, and thus no burn up.

That's what i figure anyway.

Originally posted by jra
Correct me if i'm wrong. I don't think it's a certain volocity, but a certain angle. If you come in to shallow of an angle, you'll skip (like skipping rocks on water). come in too steep and you'll smash to pieces.

it's velocity, angle, and mass that all play a part into anything's entry into the atmosphere.

isn't that the whole point of slowing down the shuttle as it enters the atmosphere? to keep it from burning up? duh.........

Originally posted by silQ
isn't that the whole point of slowing down the shuttle as it enters the atmosphere? to keep it from burning up? duh.........

as the shuttle enters the atmosphere the friction is was heats up the shuttle and slows it down. it's the friction that causes the heat that causes it to burn up. there's no avoiding the friction.

Contrary to what you might imagine, the Shuttle is not 'floating' up there. It is falling around the earth, fast enough to keep falling just over the horizon, i.e. in orbit.

If they started to slow the shuttle down even a little, it would immediately begin to fall to Earth. They could never slow it down enough for what you're thinking without it falling to Earth WAY earlier.

Nice explanation Htuttle - thanks.

Hi!

Actually, the "slower" a shuttle goes (i.e. the slower the angular speed) the "faster" the shuttle re-enters, and therefore the greater the heat.

The steeper the angle, the greater the heat. So you come in at a relative high angular speed (a speed less than required to maintain an orbit) at a specific angle. If the angle is too shallow, you bounce back or you do a catastrophic nose-up maneuver that will only be performed once :: If the angle is too steep, you over-heat your leading edges and burn up.

Hope that helps!

There is still the option of a slower Powered Descent though. But that would be an insanely massive waste of fuel when we can so easily use the atmosphere to brake the Shuttle. Not to mention that a powered descent is probably just as dangerous as the current method.

Kano,

True. They could descend in multiple orbits and decrease the heating that way. But you are talking about butt-loads of fuel.

Originally posted by Valhall
Kano,

True. They could descend in multiple orbits and decrease the heating that way.

once you enter into the thickness of earth's atmosphere there's no orbiting around more. also, as they come into earth the shuttle would speed up in orbit. it can be related to kepler's second law. the closer in an object is the faster it will orbit.

it would be neat though to see a giant fireball orbiting the earth several times...

Originally posted by cmdrkeenkid
it would be neat though to see a giant fireball orbiting the earth several times...

...ummm... probably wouldn't be neat for the astronauts inside the shuttle...

Originally posted by cmdrkeenkid

Originally posted by Valhall
Kano,

True. They could descend in multiple orbits and decrease the heating that way.

once you enter into the thickness of earth's atmosphere there's no orbiting around more. also, as they come into earth the shuttle would speed up in orbit. it can be related to kepler's second law. the closer in an object is the faster it will orbit.

Thanks...understand Kepler's law. And by the way - the lower the orbit, the lower the orbital speed. That's why things fall out of orbit instead of floating out of orbit.

The issue is the rapid descent frictional heating. And yes, you can orbit until the cow's come home. There is rarefied "atmosphere" where the station orbits. They, in fact, have to do CMG TEA (torque equilibrium attitude) control in order to offset the cyclic attitude errors introduced by 1. the atmospheric bulge due to solar effects on one side of the orbit which creates drag, and 2. torque due to gravity effects in other portions of the orbit.

There's a "great distance" of draggy orbits between where the shuttle comes in and the lower level atmosphere. You could increment your speed down and "step through" these orbits. You would also need a fuel tanker behind you about the size of the shuttle itself probably.

the shuttle better can use a artificial atmosphere so the shield around the shuttle adapts to the earths atmosphere. so no friction is around. so the atmosphere thinks the shuttle isn't there only it self but its really there.

In some of the first re-entry vehicles the heat-oblative surfaces used were a "wasting" type of heat-oblation (i.e. some of the early heat shields were OAK and burned away thereby dispersing the heat by their own consumption).

Sometimes I think we ought to look backward and see if the material advances we have made today, combined with the techniques of the past wouldn't be better than what we are currently doing.

Who knows? I might be a nidget too!



[Edited on 3-24-2004 by Valhall]

I heard somewhere that they re-enter at a 2� angle. It would bounce off at 1�.

Originally posted by masterofpuppets
if a shuttle could move slow going into the atmosphere would it still burn up?

well they dont burn up under normal reentry conditions. columbia did cause it had a hole in the wing. and if it did move slower you have to like chnage the entry angle, and the point where the shuttle did enter the atmosphere.

There is still the option of a slower Powered Descent though. But that would be an insanely massive waste of fuel when we can so easily use the atmosphere to brake the Shuttle. Not to mention that a powered descent is probably just as dangerous as the current method.

Well said...

So, to sum up...

Could they? YES, but it would require more effort than one would be willing to do.

Should they? NO, the current method works more efficiently.