Search for snoopy

In article id,
says...

In sci.space.history message -
september.org, Wed, 28 Sep 2011 09:10:01, Jeff Findley
posted:

In article d392c631-e05d-45ca-b238-f4c134eec084
, says...

some things should remain for historic purposes.......

But ISS isn't one of those things, given that your plan would probably
cost more than building it in the first place.

the first multinational long term operational space station, and
likeky the last is not historic?

The cost of preserving ISS would be quite high. The benefit would be
infinitesimal. It's not like you're going to be able to open it up for
tourists who would pay for the continued preservation through an
admission fee or donations.

ISS's US solar panels give a little more than 30kW, and the Russian
panels also give some. Of that, 50+-50% is not needed if experiments
are turned off and crew depart. Assume that a little under the middle
figure, 15kW, becomes spare on average.

If VASIMR works, it should be possible to install a 15kW VASIMR on ISS.
How would the thrust of such an engine compare with the atmospheric drag
on ISS, I have estimated that drag as 0.133 N from the rare of drop of
altitude, but ICBW.

OTOH, http://en.wikipedia.org/wiki/Vasimr more-or-less answers the
question, favourably.

From the Wikipedia article:

The first VASIMR engine model VX-50 proved to be capable of
0.5 newtons (0.1 lbf) thrust.[citation needed] Published data
on the VX-50 engine, capable of processing 50 kW of total
radio frequency power, showed thruster efficiency to be 59%
calculated as: 90% NA coupling efficiency × 65% NB ion speed
boosting efficiency. It was hoped that the overall efficiency
of the engine could be increased by scaling up power levels.
[citation needed]

That is enough thrust to raise the orbit of ISS if you assume the vast
majority of ISS's solar array output is fed to the VASMIR engine.

But this WILL NOT WORK for the purpose of moving ISS to an orbit above
GEO, which is what Bob is advocating. The relatively low power
available from the ISS solar panels means a very low thrust VASMIR
engine is all you could realistically install. This would mean a very
slow traversal of the van-Allen radiation belts, which would fry the
ISS's solar panels. Reducing power means less VASMIR thrust, which
means an even longer traversal which means more radiation damage which
means less power...

In other words, the reduced power from the solar panels means the VASMIR
engine eventually quits working and all of the electronics on ISS fry
since it's now stuck in the van-Allen radiation belt. I don't think
high radiation is going to be a selling point for a commercial tourist
wanting to visit ISS.


The *only* way VASMIR could work for this task would be using a big
honking nuclear reactor to produce orders of magnitude more electricity
than the ISS solar arrays produce. And it means using several big
VASMIR engines in order to traverse the van-Allen belts quick enough
that ISS's solar panels and electronics don't fry.

This is obviously going to be far too expensive to be practical. Yes
you could do it in theory, but it would cost tens of billions of dollars
to develop the reactor and the big VASMIR engines.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker

On Sep 30, 10:19*am, Jeff Findley wrote:
In article id,
says...







In sci.space.history message -
september.org, Wed, 28 Sep 2011 09:10:01, Jeff Findley
posted:

In article d392c631-e05d-45ca-b238-f4c134eec084
, says...

some things should remain for historic purposes.......

But ISS isn't one of those things, given that your plan would probably
cost more than building it in the first place.

the first multinational long term operational space station, and
likeky the last is not historic?

The cost of preserving ISS would be quite high. *The benefit would be
infinitesimal. *It's not like you're going to be able to open it up for
tourists who would pay for the continued preservation through an
admission fee or donations.

ISS's US solar panels give a little more than 30kW, and the Russian
panels also give some. *Of that, 50+-50% is not needed if experiments
are turned off and crew depart. *Assume that a little under the middle
figure, 15kW, becomes spare on average.

If VASIMR works, it should be possible to install a 15kW VASIMR on ISS.
How would the thrust of such an engine compare with the atmospheric drag
on ISS, *I have estimated that drag as 0.133 N from the rare of drop of
altitude, but ICBW.

OTOH, http://en.wikipedia.org/wiki/Vasimr more-or-less answers the
question, favourably.

From the Wikipedia article:

* *The first VASIMR engine model VX-50 proved to be capable of
* *0.5 newtons (0.1 lbf) thrust.[citation needed] Published data
* *on the VX-50 engine, capable of processing 50 kW of total
* *radio frequency power, showed thruster efficiency to be 59%
* *calculated as: 90% NA coupling efficiency × 65% NB ion speed
* *boosting efficiency. It was hoped that the overall efficiency
* *of the engine could be increased by scaling up power levels.
* *[citation needed]

That is enough thrust to raise the orbit of ISS if you assume the vast
majority of ISS's solar array output is fed to the VASMIR engine. *

But this WILL NOT WORK for the purpose of moving ISS to an orbit above
GEO, which is what Bob is advocating. *The relatively low power
available from the ISS solar panels means a very low thrust VASMIR
engine is all you could realistically install. *This would mean a very
slow traversal of the van-Allen radiation belts, which would fry the
ISS's solar panels. *Reducing power means less VASMIR thrust, which
means an even longer traversal which means more radiation damage which
means less power...

In other words, the reduced power from the solar panels means the VASMIR
engine eventually quits working and all of the electronics on ISS fry
since it's now stuck in the van-Allen radiation belt. *I don't think
high radiation is going to be a selling point for a commercial tourist
wanting to visit ISS.

The *only* way VASMIR could work for this task would be using a big
honking nuclear reactor to produce orders of magnitude more electricity
than the ISS solar arrays produce. *And it means using several big
VASMIR engines in order to traverse the van-Allen belts quick enough
that ISS's solar panels and electronics don't fry. *

This is obviously going to be far too expensive to be practical. *Yes
you could do it in theory, but it would cost tens of billions of dollars
to develop the reactor and the big VASMIR engines.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
* up anymore... and when they can, it doesn't stay up long. "
* *- tinker- Hide quoted text -

- Show quoted text -

a out of box thought, add more solar panels to increase output, then
once the station arrives in its higher orbit the panels can be
undocked and reused elsewhere..

it could also be a good reason for a space tug

On Oct 1, 5:36*pm, Fred J. McCall wrote:
bob haller wrote:

a out of box thought, add more solar panels to increase output, then
once the station arrives in its higher orbit the panels can be
undocked and reused elsewhere..

it could also be a good reason for a space tug

That's a though that is well outside the box. *That box is labeled
'Sanity'.

So now in addition to engines, fuel tanks, and a power buss redesign,
we also need to boost up a bunch of solar panels (that currently have
no point of attachment, so that would have to be engineered, too).

Then you're going to send people up through the Van Allen belts to
undo all that work and bring the parts back?

--
"Ordinarily he is insane. But he has lucid moments when he is
*only stupid."
* * * * * * * * * * * * * * -- Heinrich Heine

no dock where progress docks and use a orbital tug to do the moving.
undock once above geo sync, and reuse the tug for other proposes. this
adds a important in space ability and spreads the cost over a wider
range of uses.

no humans needed, a totally robotic operation, and great test bed for
new booster system

On Oct 1, 8:37*pm, Fred J. McCall wrote:
bob haller wrote:
On Oct 1, 5:36*pm, Fred J. McCall wrote:
bob haller wrote:

a out of box thought, add more solar panels to increase output, then
once the station arrives in its higher orbit the panels can be
undocked and reused elsewhere..

it could also be a good reason for a space tug

That's a though that is well outside the box. *That box is labeled
'Sanity'.

So now in addition to engines, fuel tanks, and a power buss redesign,
we also need to boost up a bunch of solar panels (that currently have
no point of attachment, so that would have to be engineered, too).

Then you're going to send people up through the Van Allen belts to
undo all that work and bring the parts back?

no dock where progress docks and use a orbital tug to do the moving.

Oh, you've confused yourself, then. *What was that about putting on
extra solar panels and using VASIMIR engines, then?

Does the thrust from where Progress docks pass through the CG of the
station? *Is the docking port stressed for what you propose? *What's
your TUG use for fuel and engines?



undock once above geo sync, and reuse the tug for other proposes. this
adds a important in space ability and spreads the cost over a wider
range of uses.

You're spreading cost over uses that don't exist. *Non-existent users
tend to pay very small shares of the cost of things.



no humans needed, a totally robotic operation, and great test bed for
new booster system

TOASTERSSSSSS IIIIIINNNNNNNN SPAAAAAAAAAAAACE!!!!!!

--
"Ordinarily he is insane. But he has lucid moments when he is
*only stupid."
* * * * * * * * * * * * * * -- Heinrich Heine- Hide quoted text -

- Show quoted text -

the tug could be solar or nuke powered with a vasimir engine

the tug could be solar or nuke powered with a vasimir engine

Or it could just run on farts or perhaps captive Thrust Daemons....


imagine being able to launch satellites from earth, put into orbit.
then are handy dandy space tug moves them to their desired orbit,
detaches and returns to earth.......

having a space tug available would be a very useful asset

Fred J. McCall wrote:

TOASTERSSSSSS IIIIIINNNNNNNN SPAAAAAAAAAAAACE!!!!!!

Now there's a thing. Where does NASA stand on the
Marmite-versus-Vegemite issue? Has either of these
yeast-based spreads been flight-rated?

My guess is that Sellers, Foale, etc. wouldn't subject
themselves to a long duration in orbit without recourse
to yeasty goodness.

On Oct 3, 12:17*am, Fred J. McCall wrote:
bob haller wrote:
the tug could be solar or nuke powered with a vasimir engine

Or it could just run on farts or perhaps captive Thrust Daemons....

imagine being able to launch satellites from earth, put into orbit.
then are handy dandy space tug moves them to their desired orbit,
detaches and returns to earth.......

having a space tug available would be a very useful asset

Imagination is a wonderful thing, but it doesn't provide much delta-V.
And orbital plane changes take a preposterous amount of delta-V.

If a space tug was so useful and such a win, someone would have put
one up by now. *You see anyone doing that?

--
"Some people get lost in thought because it's such unfamiliar
*territory."
* * * * * * * * * * * * * * * * * * * --G. Behn

there have been proposals over the years....

a space tug and universal docking mechasim on all sats could be very
useful......

In article aaf9d1dc-c0a6-4a79-91b3-
, says...

On Sep 30, 10:19*am, Jeff Findley wrote:

From the Wikipedia article:

* *The first VASIMR engine model VX-50 proved to be capable of
* *0.5 newtons (0.1 lbf) thrust.[citation needed] Published data
* *on the VX-50 engine, capable of processing 50 kW of total
* *radio frequency power, showed thruster efficiency to be 59%
* *calculated as: 90% NA coupling efficiency × 65% NB ion speed
* *boosting efficiency. It was hoped that the overall efficiency
* *of the engine could be increased by scaling up power levels.
* *[citation needed]

That is enough thrust to raise the orbit of ISS if you assume the vast
majority of ISS's solar array output is fed to the VASMIR engine. *

But this WILL NOT WORK for the purpose of moving ISS to an orbit above
GEO, which is what Bob is advocating. *The relatively low power
available from the ISS solar panels means a very low thrust VASMIR
engine is all you could realistically install. *This would mean a very
slow traversal of the van-Allen radiation belts, which would fry the
ISS's solar panels. *Reducing power means less VASMIR thrust, which
means an even longer traversal which means more radiation damage which
means less power...

In other words, the reduced power from the solar panels means the VASMIR
engine eventually quits working and all of the electronics on ISS fry
since it's now stuck in the van-Allen radiation belt. *I don't think
high radiation is going to be a selling point for a commercial tourist
wanting to visit ISS.

The *only* way VASMIR could work for this task would be using a big
honking nuclear reactor to produce orders of magnitude more electricity
than the ISS solar arrays produce. *And it means using several big
VASMIR engines in order to traverse the van-Allen belts quick enough
that ISS's solar panels and electronics don't fry. *

This is obviously going to be far too expensive to be practical. *Yes
you could do it in theory, but it would cost tens of billions of dollars
to develop the reactor and the big VASMIR engines.

a out of box thought, add more solar panels to increase output, then
once the station arrives in its higher orbit the panels can be
undocked and reused elsewhere..

it could also be a good reason for a space tug

What part of "this won't work" don't you understand?

The VX-200 VASIMR engine (the "big" engine which might eventually be
tested on ISS) has a thrust of only about 5 N (only 1.1 lbs of force)
with a power requirement of 200 kW, which is less than ISS solar arrays
provide (tests on ISS would require extra batteries to test the engine
in relatively short bursts). Even if you bolt on enough solar arrays to
generate 200+ kW, 5 N of thrust means that it's going to take a *long
time* to go through the van-Allen belts.

Slow passage through the van-Allen radiation belts will fry the solar
arrays (and any people on board). This is a fact of physics that you
cannot avoid. You simply cannot move ISS through the van-Allen
radiation belts on solar power and VASIMR engines.

For some reason, supporters of VASIMR don't bother to bring up the whole
van-Allen radiation belt issue, but it's a very real issue. It's easy
to deal with though. You just need a high energy LOX/LH2 upper stage to
quickly traverse the van-Allen radiation belts before your solar powered
vehicle can use its VASIMR engine.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker

In article 1260c865-cc8b-40c5-a40e-
, says...

a space tug and universal docking mechasim on all sats could be very
useful......

If wishes were horses, beggars would ride.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker

Did SMART-1 get through the belts comparatively quickly compared to
what ISS would, or was it specially hardened, or both?

http://en.wikipedia.org/wiki/SMART-1

rick
--
The glass is neither half-empty nor half-full. The glass has a leak.
The real question is "Can it be patched?"
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...