Re: Question about using balloons to get into space

From: Jeffrey Cornish (jcornish.nospam_at_nospam.speakeasy.net.retro.com)
Date: 09/02/04 

Date: Thu, 2 Sep 2004 14:23:31 -0700
To: sci-space-tech@moderators.isc.org

Richie,

A very good question that I will counter with another question. What
happens if that USAF Captain Kittenger stepped off the platform?

He'd fall, right? Right.

What direction?

Down, of course. It's a silly sounding question, but consider this. What
altitude would the good Captain have to be at where he _would not_ fall down
towards the Earth (removing the effects of objects such as the Moon, Sun,
and planets)

The answer is at an infinite altitude. Gravity ALWAYS attracts. The Earth
pulls on the Captain, his balloon and the atmosphere.

So lets say our good Captain is at 100,000 feet, and instead of just
dropping, he leaps out to the East at, say, 10 feet a second. If the
atmosphere didn't drag at him (as we often say in these illustrations), he'd
keep moving at 10 feet a second that direction (Good old Newton's laws say
that's whats going to happen, because during free fall, other than the
Earth's Gravity accelerating him downward, nothing is going to interfere
with his slow Eastward motion). The Captain will land some thousands of
feet to the East.

Okay, so now our Captain is back up at 100,000 feet altitude and he has a
rocket pack. The rocket will accelerate him to a final speed of 200 miles
per hour (or 288 feet per second). Turning to the East the Captain releases
himself from the balloon and ignites the rocket. The Captain will land
miles further East than he did just leaping.

If we substitute a rocket pack that can accelerate him to Mach 25 (and
increase his altitude to about 120 miles, about triple his jump off
altitude), the good Captain will be in orbit.

Basically an orbit is falling to the ground and missing, because your
horizontal velocity is high enough that by the time you would have hit the
ground you have passed around the curvature of the planet.

You could be in orbit at an altitude of 1 foot, assuming you could avoid
mountains, hills, stop signs and such.

On Earth there is a _second_ complication, the atmosphere. The atmosphere
drags on objects passing through it.

The fuel used to get to orbit used for two things, accelerating to the
velocity where the craft won't hit the ground/atmosphere (the later will
drag on the craft, slowing it so it will hit the former), and countering
losses from drag (and gravity) on the way up.

Jeffrey Cornish

"richie086" <richie086@gmail.com> wrote in message
news:50gZc.10673$5w4.2149@fe22.usenetserver.com...
> Hey.. I have a question.
>
> would the use of balloons to lift some sort of delivery vehicle or rocket
> into the very upper atmosphere work? has this ever been attempted?
>
>
> What got me thinking about this was a show about a US Air Force captain
> (joke kittenger) back in 1960, riding a balloon up to 100,000 feet and
> then jumping off of the platform he was sitting on. I understand he was
> wearing a space suit and you would very easily die if exposed at such
> elevations. After seeing the movie that was taken from a film camera
> attached to him somehow, it's very obvious that he was at the very edge of
> space. Isn't half the cost of putting the space shuttle up or any rocket
> into orbit due to how much the fuel costs?
>
> I'm sure this has been thought of, it's just a question I've always
> wondered about and the people here seem a lot more willing to answer
> questions rather than on some other groups where everyone is too busy
> flaming everyone else rather than helping others :)
>
> Richie086
>

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