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Sat launches



 
 
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  #1  
Old March 19th 06, 02:55 AM posted to sci.space.station
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Default Sat launches

Considering the number of research satellites that fail or partially fail
due to instrument or other presumably fixable problem, why aren't satellites
(whose mission profiles permit) launched to a near enough vicinity of the
ISS so that astronouts can go out and fix 'em

Surely the sats could also be made fixable?

How many 100 Million to Billion dollars sats could have been salvaged this
way.

Could this be a way to make space colonisation pay?

Hey, maybe the sats could be constructed in orbit?

It could be a good excuse for geosynchronous and Lagrangian stations too


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  #2  
Old March 19th 06, 06:54 AM posted to sci.space.station
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Default Sat launches

On Sun, 19 Mar 2006 13:55:38 +1100, "BlagooBlanaa"
wrote:

Considering the number of research satellites that fail or partially fail
due to instrument or other presumably fixable problem, why aren't satellites
(whose mission profiles permit) launched to a near enough vicinity of the
ISS so that astronouts can go out and fix 'em


Does it really strike you as being a good idea to try to send possibly
malfunctioning satellites as close to ISS as possible? Are you a curling
fan?

How many 100 Million to Billion dollars sats could have been salvaged this
way.


How many 100 Million to Billion dollars extra would it cost to send satellites to
ISS orbit, check the oil, then send them to where they need to be?

Could this be a way to make space colonisation pay?


Only if you can find a mathematically challenged satellite owner to pay the bill

Dale
  #3  
Old March 19th 06, 10:12 AM posted to sci.space.station
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Default Sat launches

Dale wrote:

Does it really strike you as being a good idea to try to send possibly
malfunctioning satellites as close to ISS as possible? Are you a curling
fan?


" 'Close' counts only for horseshoes and hand grenades."
  #4  
Old March 19th 06, 10:57 AM posted to sci.space.station
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Default Sat launches

On Sun, 19 Mar 2006 10:12:35 GMT, Monte Davis wrote:

" 'Close' counts only for horseshoes and hand grenades."


Perhaps that should be amended to mention something
about possibly uncontrolled satellites and space stations

Dale
  #5  
Old March 19th 06, 05:31 PM posted to sci.space.station
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Default Sat launches

On Sun, 19 Mar 2006 13:55:38 +1100, "BlagooBlanaa"
wrote:

Considering the number of research satellites that fail or partially fail
due to instrument or other presumably fixable problem, why aren't satellites
(whose mission profiles permit) launched to a near enough vicinity of the
ISS so that astronouts can go out and fix 'em


Because different satellites need to be in different orbits.
Observation satellites are in orbits that pass over (or nearly over)
the poles, so that they overfly all of the Earth's surface over a
given period of time as the Earth rotates beneath the orbit. They also
like to be down low to get as sharp a view as possible. But down low,
you need a lot of fuel to counteract the drag of the tenuous upper
atmosphere, so if you don't have to be down that low, you don't want
to be. Meanwhile, most relay satellites need to be perfectly aligned
with the equator and way up high, where one orbit of the Earth takes
24 hours and the satellite appears to be stationary in the sky, which
in turn makes pointing antenna on the ground easier. But it takes a
larger rocket and a more fuel to get a satellite up to that altitude
and change its inclination to match the equator. And for satellites
where the exact orbit is not critical, such as some astronomy
missions, the sponsoring agency tends to choose the most efficient
orbit its rocket can reach. For NASA, that's a 28.5 degree inclination
orbit due east out of Cape Canaveral. For Russia, its a 51 degree
orbit more or less due east out of Baikonour. Due east launches take
most advantage of Earth's rotational velocity, meaning a heavier
satellite can be launched on a given rocket, or a smaller, cheaper
rocket can be used. That results in satellites being launched in
numerous, incompatible orbits. Building one Space Station that can
service all orbits is more or less impossible.

Brian
  #6  
Old March 19th 06, 11:06 PM posted to sci.space.station
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Default Sat launches

Thanks for the replies

they don't hold water though, heres why

1) ISS to be moved via electromagnetic tether (google it)

2) Different orbits, schmorbits - what dictates energetics of mission
parameters?
If sats are assembled on orbit then you don't need to worry about this so
much

3) Geosynchronous IS a different matter, hence I posited that it may be a
good enough reason to have Geosynchronous habitats

4) ISS is resupplied via Russian cargo rockets...
So not scared of misses, hmmmm?

also payloads could be sent to rendezvous with tether, then to on-orbit
assembly

5) ISS is stupidly expensive, not all habitats/factories have to be so.

such a system of orbital habitats/factories/sat service stations can easily
pay for itself




  #7  
Old March 20th 06, 01:24 AM posted to sci.space.station
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Default Sat launches

On Mon, 20 Mar 2006 10:06:30 +1100, "BlagooBlanaa"
wrote:

Thanks for the replies

they don't hold water though, heres why

1) ISS to be moved via electromagnetic tether (google it)


Then it can no longer be supplied or crewed by the Russians. They're
stuck launching to 51.6 deg. orbits. Any do you might have noticed, no
one else is supplying or crewing ISS lately.

2) Different orbits, schmorbits - what dictates energetics of mission
parameters?


Objective of the mission, of course. You still can't expect the same
results from an Earth Observation satellite at 28.5 degrees just
because that's where the Orbital MRO Depot is.

If sats are assembled on orbit then you don't need to worry about this so
much


Yes, you do. Where they're built has little impact on where they're
going. (No one builds satellites at Kourou.)

3) Geosynchronous IS a different matter, hence I posited that it may be a
good enough reason to have Geosynchronous habitats


Better to have a Maneuvering Vehicle that can go up there and get
them. You don't want to be sending crews back and forth through the
van Allen belts willy nilly.

4) ISS is resupplied via Russian cargo rockets...


Which can get no lower than 51.6 deg. inclination. (why ISS is there
instead of the Shuttle's optimal 28.5 deg orbit.)

5) ISS is stupidly expensive, not all habitats/factories have to be so.


True, but to handle satellite servicing, ISS is probably close to the
size you'll need. Fewer lab modules, but more spare parts and tool
depots and at least two servicing hangars. Probably need more people,
too. In the end, the Orbital MRO Depot is going to be a beast.

Brian
 




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