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Trying to double-up?



 
 
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  #1  
Old February 2nd 17, 02:13 AM posted to sci.space.policy
Rick Jones[_6_]
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Default Trying to double-up?

http://www.theverge.com/2017/1/31/14...llite-contract

Suggests that a quintet of Iridium Next satellites will be lauched in
conjunction with a pair of NASA satellites. It isn't entirely clear,
but it appears the Iridium satellites are the hitchhikers. Given that
SpaceX have launched 10 of the Iridium satellites in a single shot
before, is this perhaps trying to squeeze things into a smaller number
of launches? Schedule issues?

rick jones
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  #2  
Old February 2nd 17, 03:46 AM posted to sci.space.policy
Vaughn Simon
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Default Trying to double-up?

On 2/1/2017 8:13 PM, Rick Jones wrote:
is this perhaps trying to squeeze things into a smaller number
of launches?


It could have just been a bargain. Perhaps Iridium got a good price on
the excess capability of that one launch?

One thing though, ten identical birds at one time, with all of them
belonging to the same company, sounds like a huge crap shot to me. They
could all be lost in a single launch failure, or (being identical) they
could all share the same technical problem. Putting up a few at a time
via shared launches sounds a whole lot safer.
  #3  
Old February 2nd 17, 03:51 AM posted to sci.space.policy
Sylvia Else
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Default Trying to double-up?

On 2/02/2017 1:46 PM, Vaughn Simon wrote:
On 2/1/2017 8:13 PM, Rick Jones wrote:
is this perhaps trying to squeeze things into a smaller number
of launches?


It could have just been a bargain. Perhaps Iridium got a good price on
the excess capability of that one launch?

One thing though, ten identical birds at one time, with all of them
belonging to the same company, sounds like a huge crap shot to me. They
could all be lost in a single launch failure, or (being identical) they
could all share the same technical problem. Putting up a few at a time
via shared launches sounds a whole lot safer.


Putting them up over several launches increases the chance that some are
lost, so it's swings and roundabouts.

Sylvia.
  #4  
Old February 2nd 17, 07:00 AM posted to sci.space.policy
Fred J. McCall[_3_]
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Default Trying to double-up?

JF Mezei wrote:

On 2017-02-01 21:46, Vaughn Simon wrote:

One thing though, ten identical birds at one time, with all of them
belonging to the same company, sounds like a huge crap shot to me. They
could all be lost in a single launch failure, or (being identical) they
could all share the same technical problem. Putting up a few at a time
via shared launches sounds a whole lot safer.


Iridium is launching a whole bunch of satellites on a limited number of
orbital planes. The 10 were launched on an 86° orbital plane (aka polar
orbit) and would be spaced out on the same plane. So it makes sense to
launch them at same time.


Right. Iridium has gone through and optimized the number of launches
they need to replace their constellation. It turns out to be a number
of 'sets of 10' launches with some 'sets of 4' launches to fill in the
gaps.

The idea is to have enough 'spares' in the build pipeline to be able
to slot them in for a bad launch and be able to use the insurance
money to build replacement birds for later in the launch sequence. So
as long as you stay 10 birds ahead in construction, you're good as
gold.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw
 




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