Question: I have a question about space flight?

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Answer #1:

That's an interesting question, but it has a complex answer.

1. Atmospheric drag will affect all spacecraft in orbit below a couple hundred miles altitude. By the time you get to 1000 miles, you won't have significant drag to bother you for millenia. However, that high up, you get into the Van Allen radiation belts which mean you need special electronics if you're going to stay there. People don't want to be in orbit at that altitude. Below 200 miles, the radiation isn't an issue, but drag becomes one. At 80 miles, drag begins to start to heat things up and slow them down more quickly.

2. To escape from Earth's gravity (climb out of the gravity well is another way to describe it) you need to get about 25,000 miles per hour velocity. You don't want to go that fast below 80 miles, because of atmospheric drag. The shuttle and the ISS travel at about 18,000 miles an hour, at an altitude of about 200 miles. The ISS is so large though that it needs a periodic boost into a higher orbit. This is not a function of altitude, other than the drag issue... it is just a function of having enough speed so that your orbit's apogee is undefined -- 25,000 mph works pretty well to go to the Moon, and not too much more to go on to Mars or Venus or beyond.

Put the shuttle up in orbit several hundred miles and it won't come back down in your lifetime. There is no place around here where Earth's gravity ceases -- but it does become small and that of other bodies gets larger -- gravitational forces become smaller -- proportionally to the inverse square of the distance between the objects (twice as far away means 1/4 the force, three times as far away means 1/9 the force, and so on).

Answer #2:

Basically, it's not gonna happen.

We would have to do the calculations, but please realize that when they are in normal orbit, they are still close to earth. They don't even have enough fire power to escape into lunar orbit. And, a few seconds of power from the engines would be enough only to adjust the orbit, not to change it much. Finally, even if they were , say , 2,000 miles up, their orbit would eventually decay and they'd end up re-entering the atmosphere.

Take a look at this site, and look under Satellites/ Height of the ISS...interesting graph showing how their orbit decays from about 350 km to about 338 over a year.

oops, forgot to include the site....

Click Here

Answer #3:

Unless the shuttle departs Earth at a speed of 25,000mph it will ALWAYS be pulled back to it by gravity. The Moon is held in orbit by Earth's gravity, and that is 250,000 miles away. Unless it reaches 17,500mph it won't even go into orbit around the Earth but will fall right back down again. Height is irrelevanrt. Speed is the key.





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