21
Physics, Astronomy & Cosmology / Re: Why Does Re-Entry Have To Be Fast ?
« on: 05/08/2005 13:21:17 »
No Neil (and Simeonie, I see) , I'm afraid without antigravity that will never happen.
If you're in space everything 'just hangs there' because of no gravity, but near Earth, everything tends to fall towards it, faster and faster. Meaning you burn up if you don't keep your distance. Now the cheapest way of doing that, is by falling towards Earth and just miss it by the narrowest margin.
This is what we call an 'orbit'. Circling around is actually falling towards. Now to land on Earth again, you'll find that coming to a full stop will make you fall towards Earth again, so just lowering your speed will suffice. Finding the best average between falling around and falling inwards will get you where you want and is called 'landing'.
Sounds like a much more passive ride than 'normal' spaceflight, but we could not afford to do it otherwise. It takes a HUGE amount of juice to fly those machines, and they're not luxury convenience vehicles that can drop you off at any given location at whim.
Errare humanum esd. -- Biggus D.
If you're in space everything 'just hangs there' because of no gravity, but near Earth, everything tends to fall towards it, faster and faster. Meaning you burn up if you don't keep your distance. Now the cheapest way of doing that, is by falling towards Earth and just miss it by the narrowest margin.
This is what we call an 'orbit'. Circling around is actually falling towards. Now to land on Earth again, you'll find that coming to a full stop will make you fall towards Earth again, so just lowering your speed will suffice. Finding the best average between falling around and falling inwards will get you where you want and is called 'landing'.
Sounds like a much more passive ride than 'normal' spaceflight, but we could not afford to do it otherwise. It takes a HUGE amount of juice to fly those machines, and they're not luxury convenience vehicles that can drop you off at any given location at whim.
Errare humanum esd. -- Biggus D.