Author Topic: SpaceX Falcon 9 - Iridium NEXT Flight 1 DISCUSSION (Jan. 14 2017)  (Read 286795 times)

Offline Jim

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If S2 needs a power source for longer endurance, why not attach solar panels to the surface if the stage, like on the trunk of Dragon2?

Because:
the upper stage can't point to ensure illumination of the panels.
the S2 mission is so short, batteries are actually lighter than panels (which still need batteries)
The mission is seldom longer than one orbit and there may be little to no sunlight for any part of the mission

Offline rsdavis9

so add more batteries if you need longer s2 mission.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
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Online Robotbeat

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What's the point of all this again?
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Offline envy887

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Direct GEO insertion, probably.

Offline rpapo

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Direct GEO insertion, probably.
Which is off-topic for Iridium.
An Apollo fanboy . . . fifty years ago.

Offline meekGee

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Also contingency deployment in case of an off-nominal LEO orbit.  Might want the second stage to live long enough to enable the customer to think about it and command a new sequence.   Or even another burn, if S2 shut down wrongly, but is not terminally ill.
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Offline Jim

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There is no commanding of the second stage and no need for it.
The spacecraft are going to be released in the off nominal orbit. The customer has their assets set up for release at a scheduled time.   There isn't enough time to react to those type of issues.   A S2 shut down "wrongly" is because it is terminally ill.  There is no reason for a commanded shutdown other than meeting the burn parameters.  If the stage shuts down earlier, it is due to propellant depletion or engine failure.
The vehicle does not check to see if it is in the right orbit before releasing the spacecraft.  It releases the spacecraft based on a time from the end of the last burn.
« Last Edit: 01/27/2017 05:17 PM by Jim »

Offline gongora

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The vehicle does not check to see if it is in the right orbit before releasing the spacecraft.  It releases the spacecraft based on a time from the end of the last burn.

For the Formosat/SHERPA mission they are supposed to make sure it's in the right orbit before releasing the SHERPA.  Maybe that will just come down to seeing if the final burn is full duration and not necessarily knowing the orbit.

Offline Lar

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There is no commanding of the second stage and no need for it.
The spacecraft are going to be released in the off nominal orbit. The customer has their assets set up for release at a scheduled time.   There isn't enough time to react to those type of issues.   A S2 shut down "wrongly" is because it is terminally ill.  There is no reason for a commanded shutdown other than meeting the burn parameters.  If the stage shuts down earlier, it is due to propellant depletion or engine failure.
The vehicle does not check to see if it is in the right orbit before releasing the spacecraft.  It releases the spacecraft based on a time from the end of the last burn.


let's do better at staying on topic, this is a discussion thread for a specific flight.  Longer term S2 restart/retry options etc belong elsewhere on NSF. Arguing with Jim for the sake of arguing with Jim? Buy him a beer sometime and see. But not here.
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Offline gongora

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I split off the mission simulation discussion into a new thread:
SpaceX Falcon Mission Simulations

If anyone has a problem with where I split the thread let me know.

Online FutureSpaceTourist

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Quote
IRDM CEO(2): The 1st Iridium Next sat is now in full service, filling a hole in our coverage. 8 more to be in service by mid-April.

https://twitter.com/pbdes/status/834759988115603457

Offline Norm38

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So this will be the next reused booster.  From the video it looked to have a very gentle reentry/landing.  I wonder how much refurbishment this one needed?

If BulgariaSat is coming up soon, they're under 6 months at least to get it flying again.


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