Why are big booster rockets needed to lift the shuttles out of the atmosphere and into space?

Question

If the atmosphere gets thinner and thinner, and gravity diminishes as you increase elevation, why cant shuttles, or jets for that matter, simply go higher and higher, until they just slip out into space? (Why is it so hard to escape the upper atmosphere that is so thin, and gravity so light?)

Answer 1

Question 1:
Because the shuttle's main engines don't have enough thrust by themselves to get the shuttle & the fuel tank off of the launch pad. The two SRBs provide 71.4 percent of the thrust at lift- off and during first-stage ascent.

Question 2:
*The shuttle doesn't take off and land at two points on the earth as an airplane does.
* Jets cannot go higher and higher because they need air under their wings to generate lift. Eventually the lack of air will equal the pull of gravity and they won't be able to climb higher.
* Jets need oxygen to burn their fuel and produce thrust, which in turn moves them through the air fast enough for their wings to generate lift. If they'd carry their own oxygen, then they'd be heavier, so they'd need more lift...which is not supported as well by thin air.

* The pull of Earth's gravity decreases by 1/R^2, with R being the distance from the center of the earth. Earth's radius is roughly 6,378 km at the equator. Some orbits are only 300 km high. This translates into a 12% change between the two locations. That's not that big of a change in gravity.

Answer 2

it is not the upper atmosphere that is hard, it is the whole trip

you have to lift that huge weight from where it starts to beyond the significant pull of gravity

the first half is harder than the last half, it isn't the slipping into space that requires all the energy

for a rocket, the thickness of the atmosphere is mostly irrelevant
the lift would require almost as much energy if there were no atmosphere

for a jet, the thickness of the atmosphere is very important
jet propulsion is based on taking air into the jet engine and by heating it, expelling it out much faster than it came in, producing force

thin air will not provide substance for jet propulsion

Answer 3

First of all, as you go up higher and higher, the air gets thinner and thinner. In order for a rocket, or jet to perform, there must be a source of Oxygen, so that combustion can take place. If you get to outter space, a standard jet's thruster cannot perform due to the lack of oxygen. However, space shuttles have large air reserve tanks, to allow for such combustion to occur, in oxygen-free zones (such as space.) The big booster rockets are there so the space shuttle can be lifted, at the expense of only the rockets. A space shuttle can weigh anywhere from 45tons to 500tons depending on the load

Answer 4

lets start with the Jet Idea first.
Jets do need air to burn the fuel so they can only go so high before they run out of air. Also they use the wings to fly. With out air jet would fall.

Rockets carry the air and fuel. Mixing them in the engine is what creates the big ball of fire you see. They use that big ball of fire to fly and can go fast enough. But it takes ALOT of fuel & air to get that fast and that high.

Lastly the gravity does not decrease that much as you higher. In order to get into orbit you need to go so fast that as you are falling you miss hitting the earth. You just circle around. Weightless ( zero gravity ) is not the lack of gravity. It is you falling. But again you are going fast enough to miss the earth.

If you were not moving at orbital speed, Or Better, you would hit the earth.

Answer 5

it would want to take too a lot power (i.e. gas) for a managed sluggish descent. for this reason the vehicle has to easily drop by skill of the ambience and at an rather extreme %. This causes friction between the vehicle and the ambience which in turn creates extreme warmth. If the vehicle hits the ambience on the incorrect perspective it is going to bounce off into area, somewhat like a shifting motor vehicle hitting a unexpected gust of wind.

Answer 6

Because the shuttle can't carry enough fuel by itself.
The 'escape velocity' is about 7.5 miles/sec and the fuels we use cannot generate a high enough exhaust nozzle speed to handle that.
Also the booster tanks are jettisoned after they burn out, thus decreasing the final mass that gets boosted into orbit.
Phillip R down below doesn't have clue! All of his info is totally wrong, amazingly so.

Answer 7

you need the power... that's why.

listen, thousands of nasa scientists have thought about the best way to send a shuttle into space, and they didn't want to to cost a penny more than necessary since the extra penny was going to go into their salary. So, the rocket boosters were necessary. (well, they could have used liquid propellant, but they would simply have needed a fuel tank 10 times bigger than the one they now have : it would have cost more your way than their way)

Answer 8

cause theyre needed to break away form the gravity of earth.