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  #21  
Old February 2nd 04, 02:57 PM
Greg D. Moore \(Strider\)
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Default Hubble Question...


"Starlord" wrote in message
...
That's the idea I've been pushing, not only could it be serviced but also
controled from the ISS, have it maybe about a mile from it in same orbit.


And what happens the first time you reboost ISS?

And not only that, except on a perfect sphere, with a separation of 1 mile
or so, that will gradually change over time.



  #22  
Old February 2nd 04, 03:03 PM
Roger Balettie
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Default Hubble Question...

"Greg D. Moore (Strider)" wrote:
"Starlord" wrote in message
...
That's the idea I've been pushing, not only could it be serviced but

also
controled from the ISS, have it maybe about a mile from it in same

orbit.


And what happens the first time you reboost ISS?

And not only that, except on a perfect sphere, with a separation of 1 mile
or so, that will gradually change over time.


Even over a "perfect sphere", the differential drag would move ISS and HST
apart rapidly.

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/


  #23  
Old February 2nd 04, 03:06 PM
Hallerb
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Default Hubble Question...


Even over a "perfect sphere", the differential drag would move ISS and HST
apart rapidly.

Roger


Would they not slowly depart one another but eventually end up close again?
  #24  
Old February 2nd 04, 03:07 PM
Chuck
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Default Hubble Question...

Boost it into Geo, it can still crosslink to Tedris, be further out of the
atmosphere and won't need fuel to keep from re-entering ...

"Greg D. Moore (Strider)" wrote in message
...

"Starlord" wrote in message
...
That's the idea I've been pushing, not only could it be serviced but

also
controled from the ISS, have it maybe about a mile from it in same

orbit.


And what happens the first time you reboost ISS?

And not only that, except on a perfect sphere, with a separation of 1 mile
or so, that will gradually change over time.





  #25  
Old February 2nd 04, 03:11 PM
Roger Balettie
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Default Hubble Question...

"Chuck" wrote:
Boost it into Geo, it can still crosslink to Tedris, be further out of

the
atmosphere and won't need fuel to keep from re-entering ...


That won't work for four basic reasons (and I'm sure there are more...) --

1) No booster attachment on HST available
2) HST is too fragile to withstand that sort of translational acceleration
3) VERY expensive to boost something that heavy from 300 miles to over
22,000 miles altitude
4) "TDRS" wouldn't be able to see it easily if it were at the same altitude

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/


  #26  
Old February 2nd 04, 03:12 PM
Jorge R. Frank
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Default Hubble Question...

"Brian Gaff" wrote in
:

Ancillary question...
Why was the Hubble placed in the orbit it is in. Pity nobody thought
about access when it was put up. I'd have thought that there could
have been orbits that would be reachable from ISS without the huge
thrust requirements that the current one requires. Or is it just a
case of nobody knew which orbit Iss would use at the time, so then the
question could be asked about the orbit chosen for the ISS??


HST was placed in a 28.45 degree orbit back in the days when that was the
planned orbit for Space Station Freedom, though there was no plan to keep
them in-plane. When SSF became ISS, it was moved to 51.6 degrees to
accommodate the Russians.

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  #27  
Old February 2nd 04, 03:37 PM
Chuck
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Default Hubble Question...

Hi Roger, sorry about the spelling, I knew it was wrong, but it was
pre-coffee and didn't look it up. The attachment and acceleration are the
killers, with the sunk cost in the Hubble, I don't think cost is such a
driver, what is it about $250 million to boost to Geo?
"Roger Balettie" wrote in message
...
"Chuck" wrote:
Boost it into Geo, it can still crosslink to Tedris, be further out of

the
atmosphere and won't need fuel to keep from re-entering ...


That won't work for four basic reasons (and I'm sure there are

ore...) --

1) No booster attachment on HST available
2) HST is too fragile to withstand that sort of translational

acceleration
3) VERY expensive to boost something that heavy from 300 miles to over
22,000 miles altitude
4) "TDRS" wouldn't be able to see it easily if it were at the same

altitude

Roger
--
Roger Balettie
former Flight Dynamics Officer
Space Shuttle Mission Control
http://www.balettie.com/




  #28  
Old February 2nd 04, 03:47 PM
Greg D. Moore \(Strider\)
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Posts: n/a
Default Hubble Question...


"Roger Balettie" wrote in message
news
"Greg D. Moore (Strider)" wrote:
"Starlord" wrote in message
...
That's the idea I've been pushing, not only could it be serviced but

also
controled from the ISS, have it maybe about a mile from it in same

orbit.


And what happens the first time you reboost ISS?

And not only that, except on a perfect sphere, with a separation of 1

mile
or so, that will gradually change over time.


Even over a "perfect sphere", the differential drag would move ISS and HST
apart rapidly.


Fair enough. Ok, perfect sphere in a vacuum. :-)



  #29  
Old February 2nd 04, 05:41 PM
Del Palmer
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Default Hubble Question...


"Roger Balettie" wrote:

"Chuck" wrote:
Boost it into Geo, it can still crosslink to Tedris, be further out of
the atmosphere and won't need fuel to keep from re-entering ...


That won't work for four basic reasons (and I'm sure there are more...) --

1) No booster attachment on HST available
2) HST is too fragile to withstand that sort of translational acceleration
3) VERY expensive to boost something that heavy from 300 miles to over
22,000 miles altitude
4) "TDRS" wouldn't be able to see it easily if it were at the same altitude


Oh boy, are there more! ;-) Most importantly, HST's thermal system
was specifically designed for LEO. Hubble isn't "dressed" appropriately
for any other orbit -- some parts would either be too cold or too hot, and
the heaters would necessarily be on longer away from the warm Earth.

Then again, if it was at GEO, you could just bolt on a high-gain antenna
and transmit direct to Earth -- that would actually simplify communications
and permit a higher data volume.

Frankly, we have the money for SM4, and NASA has every intention of
returning the Shuttle to flight. All that needs to happen for Hubble to
continue operations to 2010 and beyond is for O'Keefe to give the nod.



  #30  
Old February 2nd 04, 06:51 PM
Derek Lyons
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Default Hubble Question...

"Roger Balettie" wrote:

"Chuck" wrote:
Boost it into Geo, it can still crosslink to Tedris, be further out of

the
atmosphere and won't need fuel to keep from re-entering ...


That won't work for four basic reasons (and I'm sure there are more...) --

1) No booster attachment on HST available
2) HST is too fragile to withstand that sort of translational acceleration


The two snipped are real, but the first two can be somewhat overcome
(in theory anyhow).

In *theory* one could a frame that would mimic the Shuttle's cargo
bay, replace deployed items with deployable items, install the Hubble
in the frame, and then boost the whole thing to GEO.

Tain't anywhere near *practical*, but it's not *impossible*.

D.
--
The STS-107 Columbia Loss FAQ can be found
at the following URLs:

Text-Only Version:
http://www.io.com/~o_m/columbia_loss_faq.html

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