2006-07-12 03:38:31 · 6 answers · asked by Scott W 2 in Science & Mathematics ➔ Astronomy & Space
2 reasons.
1) An airplane is kept up by the force of air flowing over the wings. In space there is no air, so a space craft is kept up by the centrifugal force of its orbital speed, which is 17,500 miles per hour. Any slower and it starts to fall into the atmosphere. So as soon as the space craft slows a little bit, it falls into the atmosphere, still going very fast.
2) It takes almost all the fuel to get up to orbital speed, so there is not enough left over to slow down. Why not carry more fuel you ask? Because the shuttle is too small. The empty shuttle weighs about 230,000 pounds and the fuel it takes to get it up to a speed of 17,500 miles per hour weighs over 4 million pounds. That is right, the fuel weighs about 20 times more than the shuttle does. It is not like a car at all, where a few pounds of fuel drives a few thousand pound car. Rockets are almost all fuel and very little car. It is like a soda can, the can is very light weight compared to the soda it contains. Now to slow down from 17,500 miles per hour to zero, using only rockets and no air friction, would require another 4 million pounds of fuel. So the shuttle would need to have 4 million pounds of fuel after reaching orbit to have enough to slow down before falling into the atmosphere. And carrying that 4 million pounds of fuel to orbit would require 20 times more fuel, or 80 million pounds of fuel to launch the heavier shuttle. The shuttle is already gigantic, making it 20 times bigger would just be totally out of the question!
2006-07-12 04:23:52 · answer #1 · answered by campbelp2002 7 · 0⤊ 0⤋
Space ships has to have a minimum velocity in order to be in the orbit. To reduce this velocity they have to carry breaking and control rockets with fuel. This adds weight and launching rockets has to be redesigned and carry more fuel. So the efficient way is the way they are doing it now. More safer to. Malfunctioning of brake rockets adds to the risk.
2006-07-12 10:57:56 · answer #2 · answered by Dr M 5 · 0⤊ 0⤋
umm.. they do anf that is why and how some peole get upduted from their homes because aleins are entering our atmosphere very slowly to where we can't hear there ships and that is also haw they are undeteced.
2006-07-12 10:49:45 · answer #3 · answered by ? 2 · 0⤊ 0⤋
Because they need to overcome gravity. That is why they go so fast getting out!
2006-07-12 10:41:44 · answer #4 · answered by Elizabeth 4 · 0⤊ 0⤋
Because gravity pulls them in quickly.
2006-07-12 10:42:17 · answer #5 · answered by casey_leftwich 5 · 0⤊ 0⤋
longer exposure to friction = hotter.
2006-07-12 10:41:45 · answer #6 · answered by bequalming 5 · 0⤊ 0⤋