Author Topic: SpaceX Falcon 9 : Iridium NEXT Flight 4 : December 22/23, 2017  (Read 24773 times)

Offline swervin

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Putting myself in Iridium's shoes: why do this?

Again, I'm all for it, just curious on the business case / motivation to do so.
Iridium is doing this so they can fly sooner than if they waited for new cores.  That saves them money, rather than having birds on the ground longer waiting to go on orbit.  That is the business case and motivation.

Valid point. If Iridium has a couple dozen satellites fueled and waiting for launch I think this rings true. I can't find it, but believe Iridium said they have X-number of satellites either ready or in construction?

Thx!

Offline Ben the Space Brit

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Maybe Project Zuma has requested a fresh core. Given the tight schedule, SpaceX had to reallocate the Iridium-N4 core but were able to talk Iridium into accepting a reused core.

The 'needs' of the Zuma customer do not make a business case for Iridium, in my opinion. Putting myself in Iridium's shoes: why do this?

It depends on how... insistent USG were over the timing of Project Zuma's launch. The term 'requestion' may have come into the discussions between Grumman and SpaceX. Basically Iridium may have found themselves choosing a launch on a reconditioned rocket or a schedule delay because of some USG launch priority clause in the launch contract.

I have no special insight as to whether this scenario is possible or likely but I would point out that governments can be somewhat unreasonable with their private-sector suppliers when they want something and want it now.
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Online abaddon

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The other thing to keep in mind is that SpaceX is trying to navigate a (likely unique) transition from being a fully expendable launch provider to a fully reliable launch provider.  They've talked about increasing production capacity for some time beyond what they have now, but it seems clear that they've been slow-rolling that for a while.  And it makes sense: why spend money to increase production capacity only to have to scale it back once their reuse plans reach fruition?  The flip side of that is it constrains their ability to catch up on their backlog and they have lots of customers waiting patiently for their ride to orbit.  The Amos incident really hurt in that regard as it set them back right when they were starting to gain some momentum.

It's hard to say what SpaceX is offering right now, but I think it wouldn't be surprising if they are offering some minor sweeteners (discounts) for those who were on the fence to get them on the reuse train sooner than later, and prevent further slippage in their future launch timelines.  This allows them to catch up on that backlog without having to build out capacity on their production line that they will soon not require.  It is a delicate balancing act to be sure.

The accelerated use of previously flown boosters will also help accelerate the adoption of reused boosters by industry as a normal thing and not exceptional.

Offline meberbs

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The accelerated use of previously flown boosters will also help accelerate the adoption of reused boosters by industry as a normal thing and not exceptional.
This is somewhat circular logic - not wrong, just circular in a way that implies self fueling exponential growth in fraction of reuse missions. Although it has to s-curve and level out somewhere short of 100% since at least some boosters have to be new.

Online abaddon

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The accelerated use of previously flown boosters will also help accelerate the adoption of reused boosters by industry as a normal thing and not exceptional.
This is somewhat circular logic - not wrong, just circular in a way that implies self fueling exponential growth in fraction of reuse missions. Although it has to s-curve and level out somewhere short of 100% since at least some boosters have to be new.
What I was driving at with my statement is first, the combination of a large backlog and insufficient production capacity to meet that backlog in a timely manner is pushing both SpaceX and their customers to accelerate adoption of reused boosters.  Although in reality SpaceX is also driving this, by choosing not to expand their production capacity and offer reused boosters in lieu of doing so.  (My interpretation, but I'm not offering any unique insights here).

Second, there is a very short flight curve due to how the rocket business normally operates, where very few operational flights are required before a rocket is considered to be viable as compared to most other industries.  Historically, three successful flights of a rocket is usually sufficient for it to be considered operational.  A reused booster is a new wrinkle but I think a lot of those benchmarks still apply.  So you can get an avalanche affect here where pretty quickly a lot of customers on the commercial side will become comfortable with reuse very rapidly, as demonstrated just now by Iridium.  We're only eight months since the first orbital reuse!  Quite remarkable really.
« Last Edit: 10/19/2017 04:53 PM by abaddon »

Offline DecoLV

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Still confused about RTLS thing. Wasn't RTLS to the new pad planned up until this booster change? I thought it was ready to go. New mfg v. flight-proven should make no difference.

Would this S1 now go to a drone ship?

Online abaddon

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Still confused about RTLS thing. Wasn't RTLS to the new pad planned up until this booster change? I thought it was ready to go. New mfg v. flight-proven should make no difference.
Block 4 can RTLS given this payload and orbit, Block 3 cannot.  The reused booster is Block 3, so switching to it has taken RTLS off the table.
Quote
Would this S1 now go to a drone ship?
Yes.
« Last Edit: 10/19/2017 04:55 PM by abaddon »

Online gongora

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Comfort that risk <= than new and more schedule certainty to complete 5 more launches over next 8 months.  Cost is better, but not driver.

Online gongora

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FCC permit applications filed today, mission 1340 with droneship landing, NET Dec 22.  Iridium flights 2-4 are missions 1338-1340.  It will be interesting to see what number is used for flight 6.

Offline Raul

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It's interesting that there will be apparently no boostback burn during the booster landing of this mission.
Planned ASDS recovery position is as far as 513km downrange, similarly like in Cassiope water landing attempt.

Iridium-1 block 3 B1029.1 had landing position 372km downrange. Iridium-2 326km and Iridium-3 244km.

In the Map

Online ZachS09

It's interesting that there will be apparently no boostback burn during the booster landing of this mission.
Planned ASDS recovery position is as far as 513km downrange, similarly like in Cassiope water landing attempt.

Iridium-1 block 3 B1029.1 had landing position 372km downrange. Iridium-2 326km and Iridium-3 244km.

In the Map

Are you sure there's no boostback burn during Iridium-NEXT F4?

I thought all previous Iridium-NEXT missions used a partial boostback burn.
"Liftoff of Falcon 9: the world's first reflight of an orbital-class rocket."

It's interesting that there will be apparently no boostback burn during the booster landing of this mission.
Planned ASDS recovery position is as far as 513km downrange, similarly like in Cassiope water landing attempt.

Iridium-1 block 3 B1029.1 had landing position 372km downrange. Iridium-2 326km and Iridium-3 244km.

In the Map

Are you sure there's no boostback burn during Iridium-NEXT F4?

I thought all previous Iridium-NEXT missions used a partial boostback burn.

They did, I wonder why there's no boostback.
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Offline MarekCyzio

It's interesting that there will be apparently no boostback burn during the booster landing of this mission.
Planned ASDS recovery position is as far as 513km downrange, similarly like in Cassiope water landing attempt.

Iridium-1 block 3 B1029.1 had landing position 372km downrange. Iridium-2 326km and Iridium-3 244km.

In the Map

My theory  - this is Block 4 - will be reused more than once - reduce unnecessary wear on the rocket.

Offline Barrie

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They decided the fuel they would use for partial boostback is better used for a beefed-up re-entry burn? ie more likely to get a re-usable booster back that way?

Offline ChrisGebhardt

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It's interesting that there will be apparently no boostback burn during the booster landing of this mission.
Planned ASDS recovery position is as far as 513km downrange, similarly like in Cassiope water landing attempt.

Iridium-1 block 3 B1029.1 had landing position 372km downrange. Iridium-2 326km and Iridium-3 244km.

In the Map

My theory  - this is Block 4 - will be reused more than once - reduce unnecessary wear on the rocket.

Iridium-4 is reusing a flight-proven Block 3 at present.  It will likely be the same booster that launched Iridium-2 in June.

Online SweetWater

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They decided the fuel they would use for partial boostback is better used for a beefed-up re-entry burn? ie more likely to get a re-usable booster back that way?

Hard to say, but it certainly seems like a possibility. I think we're all starting to feel that successful F9 stage 1 landings are, if not routine, certainly becoming expected (provided the landing is attempted at all); however, we should bear in mind that SpaceX has only recovered 18 (by my count) stages at this point. They're likely still learning how the stages fare after different types of missions (LEO vs. GTO) and and recovery locations (downrange vs. on land).

I would expect to see some variety in recovery strategies with the continued use of Block 4 and the introduction of Block 5 vehicles, if only to see how those vehicles (and the materials used on them) compare to SpaceX's expectations for a given mission and type of recovery.

Offline ATPTourFan

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My first thought was that SpaceX is giving Iridium as much margin as possible to get their payload to the proper orbit. Iridium and SpaceX worked out the arrangement to utilize the flight-proven core to help schedule this launch, but SpaceX really doesn't need to be gentle to this core as much as they MUST get Iridium-4 payload where it needs to go - maximum margins to make customer happy.

Offline gth871r

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It's interesting that there will be apparently no boostback burn during the booster landing of this mission.
Planned ASDS recovery position is as far as 513km downrange, similarly like in Cassiope water landing attempt.

Iridium-1 block 3 B1029.1 had landing position 372km downrange. Iridium-2 326km and Iridium-3 244km.

In the Map

Iridium 2 was the flew with the Titanium grid fins.  (I think it's the only booster, to date that has done so.)  They may be interested in pushing those a little harder to see what happens.

Online ZachS09

It's interesting that there will be apparently no boostback burn during the booster landing of this mission.
Planned ASDS recovery position is as far as 513km downrange, similarly like in Cassiope water landing attempt.

Iridium-1 block 3 B1029.1 had landing position 372km downrange. Iridium-2 326km and Iridium-3 244km.

In the Map

Iridium 2 was the flew with the Titanium grid fins.  (I think it's the only booster, to date that has done so.)  They may be interested in pushing those a little harder to see what happens.

That's if SpaceX decides to keep the titanium fins on B1036. For the past five missions after Iridium-NEXT F2 (excluding Intelsat 35e), they've been using the aluminum fins, so there's a chance that the latter will be used during Iridium-NEXT F4.
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Offline cambrianera

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It's interesting that there will be apparently no boostback burn during the booster landing of this mission.
Planned ASDS recovery position is as far as 513km downrange, similarly like in Cassiope water landing attempt.

Iridium-1 block 3 B1029.1 had landing position 372km downrange. Iridium-2 326km and Iridium-3 244km.

In the Map

Iridium 2 was the flew with the Titanium grid fins.  (I think it's the only booster, to date that has done so.)  They may be interested in pushing those a little harder to see what happens.

May be that the enhanced attitude control and capabilities of Ti grid fins enables Spacex to try a lifting reentry, keeping the stage "afloat" in the upper layers of the atmosphere.
This would reduce the heat rate and the peak heating, avoiding the reentry burn and saving lot of propellant.
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