can earth based lasers and electromagnetic tethers

Tony Rusi wrote:
put the ISS in the inclination as the moon?

Yes, (assuming you meant "same inclination") but there would be little
point.

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(Tony Rusi) writes:

can earth based lasers and electromagnetic tethers
put the ISS in the inclination as the moon?

Lasers will be utterly useless. What makes you think they would do anything
to the ISS's orbit ???

A properly designed electrodynamic tether could change the orbital
inclination of the ISS (albeit not very effectively, as the Earth's
magnetic field has a rather weak East/West component compared to its
North/South component, so electrodynamic tethers are much more effective
at speeding up or slowing down a object in a modest-inclination orbit
than at changing its plane). However, there would be very little point
in doing so, since the plane of the ISS's orbit was chosen to make it
accessible to vehicles launched from Kennedy Spaceport and Baikonur
Cosmodrome, and lowering its inclination to match the Moon's would
make it inaccessible to anyone not launching from a facility near the
equator (i.e., no one but the ESA).

Also, there is no good reason for anything to _be_ on such an orbit,
as a vehicle with sufficient delta-vee to be capable of being launched
to or returning from the Moon can do so to/from virtually any LEO orbital
plane. (Plane changes are cheap if the apogee is in high orbit.)


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

Lasers will be utterly useless. What makes you think they would do anything
to the ISS's orbit ???

Well photo-pressure for one thing, but really I was thinking about the
idea below.

I was assuming you could generate extra electrical power aboard the
ISS by hitting the PV-arrays with the proper wavelength. That
electrical power would be used to power the e-tethers with no impact
on the power budget of the ISS. Thus re-boost fuel would never have to
be brought up to the ISS again. I believe the ISS experiences about
three pounds of drag force at its median altitude. Is there any reason
given enough time, that the ISS could not be moved to L5, using lasers
and e-tethers to create a permanent space station?

The re-entry of skylab, the salyuts, and mir seem to be such a waste,
they too could have been placed at L1 and L5.

In article ,
Tony Rusi wrote:
I was assuming you could generate extra electrical power aboard the
ISS by hitting the PV-arrays with the proper wavelength.

At least in principle, yes. Bear in mind that they are pointed at the
Sun, not at the Earth, although they could be Earth-pointed easily enough
during orbital night. A bigger problem is, just how many laser stations
were you thinking of building? Bear in mind that ISS is within sight of
any particular point on the ground for only a few minutes, a few times a
day.

That
electrical power would be used to power the e-tethers with no impact
on the power budget of the ISS.

Almost certainly it is easier to increase available power by just adding
more solar arrays.

Thus re-boost fuel would never have to be brought up to the ISS again.

Approaches like this were seriously considered. One practical problem is
that the tether will occasionally be cut by space debris. Another is that
the detailed physics of orbiting electrodynamic tethers are not very well
understood, so performance prediction is difficult.

...Is there any reason
given enough time, that the ISS could not be moved to L5...

Two big ones. First, ISS's electronics -- never mind its people! -- are
not sufficiently radiation-hard to handle slowly working its way out
through the Van Allen belts. Second, the effectiveness of electrodynamic
tethers deteriorates rapidly as altitude rises, because both the strength
of Earth's magnetic field and the density of the local plasma fall off
quickly with altitude.
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JRS: In article , seen in
news:sci.space.tech, Gordon D. Pusch posted
at Wed, 9 Jul 2003 08:26:53 :-

However, there would be very little point
in doing so, since the plane of the ISS's orbit was chosen to make it
accessible to vehicles launched from Kennedy Spaceport and Baikonur
Cosmodrome, and lowering its inclination to match the Moon's would
make it inaccessible to anyone not launching from a facility near the
equator (i.e., no one but the ESA).

The Moon can be overhead from parts of Florida, I believe; did not the
Columbiad depend on that?

Then the ESA are not the only ones who can launch from near the Equator.

The Russians have, I believe, an agreement to use Kourou, and doubtless
other friendly countries might negotiate similar with the ESA. Then the
Indians - the proper ones, nor the Reds - must be launching from
moderately low latitude already, and should be able to find a site below
ten degrees north.

Sea Launch can manage the equator exactly, if required.

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Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
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(Tony Rusi) wrote in message om...

snip

The re-entry of skylab, the salyuts, and mir seem to be such a waste,
they too could have been placed at L1 and L5.

Some words of caution here. They might be placed at L1 or L5, but I
suspect that they would get in the way at a future date. That was the
real reason they were deorbited in the first place. Note that L1 and
L5 are well outside of Earth's magnetosphere (most of the time except
when passing through the tail) so the shielding on these craft
wouldn't be adequate for human survival.


Karl Hallowell

In article ,
Tony Rusi wrote:
I used to work with a 25 year vet from TRW. He said that even the
backs of PV-arrays generate some power when facing the earth and are
collecting earthshine.

I'm a bit skeptical about that, because the cells are usually mounted on a
backing plate, or at least a backing film, and the usual materials for
that are thoroughly opaque.

(Some early spacecraft used double-sided arrays, which may be what he was
thinking of.)

Approaches like this were seriously considered. One practical problem is
that the tether will occasionally be cut by space debris...

Hoyt and Forward had a multi-strand tether to avoid such problems.

There are several approaches along those lines, yes... but they do
complicate the design, especially for tethers that have to be conductive.

Second, the effectiveness of electrodynamic
tethers deteriorates rapidly as altitude rises, because both the strength
of Earth's magnetic field and the density of the local plasma fall off
quickly with altitude.

This sounds like a show stopper! You would have to switch to M2P2 at
some altitude I guess.

Unfortunately, M2P2 probably isn't going to do much for you until you are
outside Earth's magnetosphere, and certainly won't do much for you below
synchronous altitude (below there, the magnetic field is moving slower
than orbital speed, so passive interaction with it creates *drag* rather
than thrust). And electrodynamic tethers have problems well before then.

There is one possible escape hatch. By thrusting only at perigee, you can
pump the apogee up to high altitudes, while keeping the perigee down low
where the field is strong and the plasma dense. The trouble is that this
takes a *long* time, far longer than continuous-thrust strategies.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

(Karl Hallowell) wrote in message . com...
(Tony Rusi) wrote in message om...

snip

The re-entry of skylab, the salyuts, and mir seem to be such a waste,
they too could have been placed at L1 and L5.

Some words of caution here. They might be placed at L1 or L5, but I
suspect that they would get in the way at a future date. That was the
real reason they were deorbited in the first place. Note that L1 and
L5 are well outside of Earth's magnetosphere (most of the time except
when passing through the tail) so the shielding on these craft
wouldn't be adequate for human survival.

I just spent the last three years at Bigelow Aerospace refining the
design of a flexible packable shield that you can add to the outside
of any spacecraft or spacebase.