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/

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.

"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/

"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.

--
JRF

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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/

"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. :-)

"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.

"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.
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Corrections, comments, and additions should be
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discussion.

"Bruce Kille" wrote in message ...
With or without any future service the Hubble will some day go offline.
There have been a lot of ideas floating around as to what to do then.
I was wondering if it could be possible to boost it to a LaGrange Point,
rather than de-orbit it? Is an earth-moon point stable? I know the
earth-sun point can be used as the SOHO satellite is there, but it
would require a lot more fuel to reach. Apparently, recovery of the
Hubble for placement in the Smithsonian is not possible, so I wanted
to put an alternative idea out for discussion.
Bruce



Apologies if I am missing something obvious - but consider the following:

The main reason for not servicing the Hubble AIUI is there is no safe haven or
tile repair system if the orbiter were to be damaged during take off.

The shuttle payload bay has dimensions 15x60ft (4.6x18.3m)
and has a maximum payload weight of approx 50,000lbs (22,680kg)

A Soyuz TM is 7m long, 2.7m diameter and weighs about 7 tons.

So.... on a mission to replace Hubble gyros or add new instruments
why not just load up 2 x Soyuz into the orbiter payload bay? In the
unlikely event of the shuttle being damaged on the way to orbit
you have a bail out facilty for 6 astronauts.

If transfer from the orbiter to 2 different Soyuz's is a problem then fly a
skeleton crew of 3 and engineer a docking adapter directly from the
shuttle payload bay to the Soyuz.



Andy

In article , Greg D. Moore
(Strider) wrote:
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. :-)

This is rapidly turning into an exam question. Assuming a point satellite...

--
-Andrew Gray