Why do so many pieces of the shuttle make it to the ground? Why didn’t they burn up going thru the atmosphere?
I suspect most of the material burned up.
The same reason a large meteor will sometimes not entirely burn up and land on someones kitchen table, as a small rock.
Say you have a 6 foot piece of the wing, and as it goes through the “re-entry burn up process” it burns off 5 feet of the wing. The air resistance (speed and air friction) will sort of clean off the carbon and debris on the piece before it lands on the ground. So the final result is a sort of clean looking 1 foot piece that you couldn`t tell had gone through the “re-entry burn up process”.
Forgot to say this,
A lot of the material that survived was probably on the trailing end of the prticular piece of mass it was connected to.
Also, of course, some components were specifically designed not to burn up…
Once they’re torn apart from the shuttle, wouldn’t a lot of the material slow down to the point where frictional/compressional heating would be significantly lessened? Most pieces probably wern’t too aerodynamic.
Just so that I understand, is it the speed that is the big problem as opposed to just going thru the atmosphere?
If so, would it be possible to slow down these shuttles more drastically before they hit the atmosphere?
Though the shuttle was going fast, it had slowed down a lot.
Furthermore, a piece flying off would indeed slow down quickly. It’s like the difference between throwing a baseball, and then chopping the baseball into dusty flakes. Toss the flaked baseball and it’ll go a few feet at most. The mass versus surface-area is much smaller for a fragment of the shuttle.
A piece flying off the shuttle would also toss and turn, distributing the heat from friction across the whole surface. Then, the slower speed during the fall would actually cool it down.
It seems to me that the major effect in the destruction was not the heat, but being ripped apart by shearing forces of the air.
The pieces, as FranticMad said, slowed down a lot. One woman on the news described a flat piece of debris that she saw land in her parking lot. She said it came down like a leaf, flipping and swaying side to side.
Yes. The high speed results in heating due to friction and compression of the air.
Theoretically, yes. But you need to use a rocket engine for that, and you need a huge amount of fuel to go from 7 km/sec to zero. In fact, you need almost as much fuel as for launch. It’s far more efficient to carry a heat shield and use the atmosphere to slow down.
I’ve read somewhere that the spherical fuel storage tanks used in space tend to survive. They find them in the middle-of-nowhere Australia occasionally. Between the thick walls, the relatively streamlined shape, and the ability to easily spin and present different faces to the direction vector, this makes sense.
lieu has it. A piece that winds up with a high aerodynamic drag for its mass will slow up quickly, absorbing little heat along the way, possibly enough to avoid rapid oxidation. That would include just about every section of Columbia forward of the left wing leading edge, including the crew compartment, all of which seems to have broken up almost immediately once attitude control was finally lost. There are pictures in the public of internal frames, including the cockpit window frames and the cargo bay access hatch frame, with almost nothing else still attached to them
“possibly enough to avoid rapid oxidation.”
Or in the absence of enough oxygen to support oxidation, simple vaporization. Burning up is a bit of a misnomer here.
Do you remember where you read that? I’m not nagging you, I’m just interested. The only time this happened that I’ve heard is from the Skylab space station.
The UN Office for Outer Space Affairs keeps a list of space debris finds that goes all the way back to 1968. Spheres and cylinders are well represented on that list.
I used to have a piece of a wall of a missile–two sheets of curved metal with some honeycomb-shaped metal inbetween. It was very light yet rigid. I suspect the shuttle is also made of light-but-rigid stuff. If this piece were pitched, even at 18x the speed of sound, it would slow down very quickly.
I’m not aware of any post-skylab (1979) space debris of NASA origin impacting in Australia.
I found this document, which lists 54 items that have fallen over the years. A 0.5 meter diameter sphere like the ones listed is a big chunk of something to fall out of the sky. TheLoadedDog, maybe not NASA, but:
Despite that, I was actually probably mixing together Skylab with Squink’s cite from S. Africa, because I found a lot of references to that incident.
Good example. Indeed, let’s think about it: the intact vehicle had enough momentum to carry it all the way to the Atlantic coast fo Florida under controlled flight, turning, banking and further aerodynamically braking over the next 16 minutes. The disassembled pieces essentially fell ballistically down upon East Texas.
What would be interesting to me would be-
How does the temperature of the object vary based upon speed/altitude?
That is, at 200,000 feet and a speed of 12,000 MPH the temperature on the skin of the shuttle is 3000 degrees (for example)
How does this vary based upon a different speed at a different altitude?
It seems like speed is the overwhelming factor.(once you are in the “atmosphere”) That is, if the speed was 500 MPH, the altitude becomes insignificant and the temperature is relatively insignificant.
Correct?
Friction increases by the square of the speed. So, for example,
Let’s say 500 mph gives 1 unit of friction (imagine a giant tornado with more than enough friction to rip houses apart and suck cows into the sky).
500 mph yields 1 unit of friction
1,000 mph = 4 units of friction (2 squared)
10,000 mph = 400 units of friction (20 squared)
12,000 mph = 576
17,000 mph = 1,156
You can actually feel this effect driving in your car by holding your hand outside the window at 20/40/80 mph. The pressure on your hand increases exponentially. 20 feels like a light breeze. 40 is a breeze. 80, watch out! If you drove 160 it would slam your hand against the car and break your arm.
There is a point at re-entry where air-pressure and speed create peak temperature and pressure on the shuttle. Coming in from orbit, the air is very very thin at first. Air pressure gradually increases, friction increases, but shuttle speed decreases too. It’s a balancing act, and the arc of re-entry is carefully designed.
At one point, around 200,000 feet altitude, the heating by friction has reached its peak, and starts to decrease. This is pretty awsome considering there is so little air up there that you’d die of oxygen starvation all the way down to 25,000 feet. But the shuttle is so fast that it’s plowing through lots of air molecules.
Although the air pressure gets really significant below 200,000 feet, the speed of the shuttle has decreased enough that the friction can no longer increase the shuttle’s skin temperature. Hence, the shuttle broke up at a point where the stresses on it were pretty fierce.