From: gallatinwilson@comcast.net
"Ghazan Haider" wrote in message
news:2f57764a.0401162113.433d90aa@posting.google.com...
> Research baloons have flown at 51km above sea level, and yet the
> sputnik 1 flew at 31km. 20 km below where the highest baloon can fly
> would yield enough resistance not to allow that, so I have this
> question: How high is the lowest possible orbit and how high is the
> highest baloon range? OK thats two questions...
>
> Building and launching baloons are the currently cheapest way to send
> payload high above. A rocket launched horizontally and then detaching
> could further push the payload to the lowest orbit. I would imagine
> for a 1kg payload, the rocket can be pretty small and maybe a single
> stage solid fuel, which is legal for amateur rocketry in many places.
You have missed the point. What happens to you if you are dropped from 51km?
You fall. For a long time. Until you hit the surface.
Orbit is a function of speed as well as distance. You could orbit a
perfectly spherical planet (with no atmosphere, of course) at 1 meter
altitude forever, were you moving at the appropriate speed.
In the presence of an atmosphere, a sustainable orbit requires that you both
stay out of the bulk of atmospheric drag and be moving at exactly the escape
velocity for that particular body at that particular distance. Were the
earth perfectly spherical and airless, that velocity, at the aforementioned
1 meter altitude, would be about 9.8 kilometers/second. At Sputnik's orbital
distance (227 x 945km), 9 km/s would be more like it.
Getting to altitude inside the atmosphere (or even the ionosphere) is
relatively easy. Getting to 9 km/s, now _that's_ hard.
As for the lowest possible orbit - a circular orbit at 300km would decay in
30-60 days.
Jonathan Wilson
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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