# Re: To space without rockets ?

Berrie (staring@worldonline.nl)
Tue, 28 Oct 1997 13:59:11 +0100

Carl Feynman wrote:

> I think I see the misconception at work here; it is a common one.
>
> The Earth's gravity does not stop just 100 km up. It goes out forever,
> growing weaker with distance. It declines as one divided by the square
of
> the distance from the center of the Earth. We call the gravity 1 g at the
> surface (6400 km from center) so at 100 km altitude (6500 km from
center),
> it is still .97 g (this is (6400/6500)^2). You could probably not even
> notice the difference in gravity if you stood on a 100 km high platform.
>

Ok. I see the problem. So you hardly save anything (fuel) by starting from
100 km. This means thus, that everything will automatically float/fall back
to earth.

> What keeps satellites in orbit is not that they are beyond the reach of
> gravity, but that they are going sideways very fast. Like anything
thrown
> sideways, their path bends downwards as they begin to fall. However,
they
> are going so fast that after they have fallen 1 km, the earth below them
> has receded more than 1 km becuse of its curvature. So they keep falling
> toward the Earth, but missing.
>

Ok. If I'm correct we move approx. 2000 km per hour with the earth.
Is it possible, instead of making a cable on to a astroid, that we bring
up the contra weight ourselves ? I hope I can explain it a bit better.

Just imagine that the soda-straw-tower works.
The first part is held up by big balloons, until X-km, or if
this does not work, by some other pressure. At "some" point
the spinning (rotation of earth) from the weight "takes-over" ?
If I look at your figures, maybe I think to small !

What height would be sufficient ? into orbit ? or can we do
with a smaller tower. I mean by sufficient, a height were we
could have a working-space, to build rockets an other things.
Is it hard to calculate at what perfect height, what perfect contra
weight is needed to keep up the tower, and allow an elevator trough?

If I look it the simple way: when I turn around with a cord, I only need
a very small weight at the end of it to keep the cord as a straight line.

The question above, is of cause without the winds !

Kennita: what I don't understand is, why when it's length is
going up, the same has to be true for the diameter. Do you need
this for the strength?
Also, what do you think of the "open"-structure.
Is that still not wind-proof :-)
I can't imagine the forces on the structure, but isn't there any
material today that could be woven to a "net", that can stand
these winds. Is it also a particular height, were these winds are
at top-speed. ?

What I find very hard to grasp. Is were the Air is so light, you/things
are weightless, is this gradually building up from the surface of the
earth, or are you at some magical point weightless ?
I know this last one can't be the case, but picturing it :-)

It's a bit double, when I think you/things have enough height,
I forget about the gravity, and when I think of escaping gravity, I think
to easily that your in space (so, you are weightless) and therefor
nothing is pulling you back. Which as I start to learn isn't so.
I try to project visual (in my head) all the different influences on the
tower, to
understand how it works up there.

Thanks again for all the help, I guess these contributions are not
really what a lot of you are looking for in this list. But being new
to extropy/transhumanism and with an average understanding of
science, it's hard for newbies to get a grip at this movement.
Maybe you should think of an entry-test :-)

Greetings,

Berrie

PS: we are working very hard in the Netherlands at the moment on
the Excedo (>H-foundation). And yes, we do have some
people aboard with some descent scientific knowledge :-)
In case you start to worry........................
====================================
Berrie Staring Email : staring@worldonline.nl
Member : Excedo Dutch >H
Site: present in november 1997
" if we agree; that what you do to someone....
.....can be done to you....................................
.you know love is an option and violence not"
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