Author Topic: SpaceX Falcon 9 : Iridium NEXT Flight 4 : December 22/23, 2017 : Discussion  (Read 93407 times)

Offline JamesH65

  • Full Member
  • ****
  • Posts: 737
  • Liked: 451
  • Likes Given: 8
I donít see SpaceX tossing away a booster just because they donít need it. That runs exactly opposite of the mindset theyíre trying to establish. A few $100k to recover a core is absolutely nothing in the larger framework of mission cost - compare that to the value of underscoring the important of recovery and reuse to their customers.

If I understand you correctly, you're saying that SpaceX would spend a few 100k recovering a booster they don't need so that customers don't think they're going soft on re-use? After 20 previous successful recoveries, including the last 16 consecutive attempts? And on a flight using a flight proven booster?

I think we'll have to agree to disagree on that one.
Feel free. But I suppose with your mindset you see zero value in the returned booster. That's fine - but I see value in:

- Post flight examination of entire system
- Reuse of sub systems such as gimbal control system, hydraulic systems, grid fin actuators and the fins themselves (even if AL), engine control modules, Merlin components (at $1,000,000 for each M1D you say that getting parts off even a few engines won't cover the cost of recovery?)
- Maintaining the path that SpaceX has worked so hard to establish.


Again - disagree all you want, but I maintain it's fatally shortsighted...

Well, they have already examined many returned stages thoroughly, so I am not sure that is a valid argument.

If not reusing the whole booster, reuse of returned subsystems might have merit, if they are of use in block 5. If not, they are just so much scrap, that needs storage. Or do they just leave them out in the car park?

Maintain the path is irrelevant, Musk knows how to count and they already have an impressive track record. If the value return from bringing it back is less than dumping it, which do you think they will do?



Online Comga

  • Senior Member
  • *****
  • Posts: 4076
  • Liked: 1378
  • Likes Given: 1135
According the original plans mentioned in FCC permit, planned booster recovery position should be so far on the south, that boostback burn would be completely skipped compare to previous flight of this booster with Iridium-2 or other IridiumNEXT missions. This also implies like no enough fuel margin for normal landing by some reason.
Change of plan to expedable booster would be comprehensible in this case.

SpaceXís track record and magic ingredient is to make progress, like developing first stage recovery, at extremely low marginal cost by piggybacking on paid launches. If they are forgoing the boostback or braking burn they will get an extremely energetic entry. A perfect opportunity to expand the envelope, from which they can best learn by recovering the first stage.

Wouldnít we expect to see titanium grid fins if they are planning on a high speed reentry?
Either way, we will know in a few days.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 9935
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 6747
  • Likes Given: 4531
I think SpaceX are driven by cost, more than anything else. We don't have visibility to their cost numbers or the exact decision process (although maybe a tweet to Elon is in order?).

But whenever someone starts out with (in essence) "I think SpaceX made the wrong decision" I tend to start out disagreeing. Once in a while (AMOS-6) they flub. But not that often.

If this booster is not being recovered, there is surely a cost driven reason for it that made sense when they worked the trades. As AbuSimbel outlines.

These engines don't have the new impellers. That means they  may not be as valuable (it would be a big teardown to retrofit I would think) as some might suspect.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Online Comga

  • Senior Member
  • *****
  • Posts: 4076
  • Liked: 1378
  • Likes Given: 1135
And then this from Twitter (via the UPDATES thread):

Quote
HŲchstErbaulich. @HochstErbaulich
Hey @IridiumBoss will the Falcon 9 core for Iridium-4 be recovered? There are rumors that the first stage has no recovery equipment installed.

Matt Desch @IridiumBoss
Replying to @HochstErbaulich
No, I understand it won't be

Interesting wording that supports the idea that the decision to recover or not is solely SpaceXís and even their customers sometimes donít know until right before launch.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online Kansan52

  • Full Member
  • ****
  • Posts: 1029
  • Hutchinson, KS
  • Liked: 312
  • Likes Given: 362
IMO, Job One is doing the customer's mission. Sounds like this was the way they could accomplish this for Iridium.

Offline pb2000

  • Full Member
  • *
  • Posts: 190
  • Calgary, AB/Mesquite, NV
  • Liked: 127
  • Likes Given: 67
With regards to reusability being a core part of SpaceX corporate culture; that really only works until they become too efficient and need to start laying off staff on the first stage production line. I'm sure the idea was to have BFR production needing staff before this became a problem, but who would have guessed the attempted recovery success would go to 100%?
Launches attended: Worldview-4 (Atlas V 401), Iridium NEXT Flight 1 (Falcon 9 FT), PAZ+Starlink (Falcon 9 FT)

Online FutureSpaceTourist

  • Senior Member
  • *****
  • Posts: 5684
  • UK
    • Plan 28
  • Liked: 4965
  • Likes Given: 1392
Interesting wording that supports the idea that the decision to recover or not is solely SpaceXís and even their customers sometimes donít know until right before launch.

I agree the decision must be SpaceX's, but I think he does know for sure about recovery it's just that he's careful not to tread onSpaceX's toes and say anything definitive that relates to them rather than the mission.

BTW his response to being asked why no recovery on this mission is:

Quote
Can't answer that.

https://twitter.com/IridiumBoss/status/943161784994811904

Offline saliva_sweet

  • Full Member
  • ****
  • Posts: 544
  • Liked: 415
  • Likes Given: 1309
If this booster is not being recovered, there is surely a cost driven reason for it that made sense when they worked the trades.

In that case we can infer that the marginal cost of ASDS recovery is greater than the value of 20 tons of space grade metals and alloys.

Offline woods170

  • IRAS fan
  • Senior Member
  • *****
  • Posts: 7922
  • IRAS fan
  • The Netherlands
  • Liked: 3899
  • Likes Given: 1188
If this booster is not being recovered, there is surely a cost driven reason for it that made sense when they worked the trades.

In that case we can infer that the marginal cost of ASDS recovery is greater than the SCRAP-value of 20 tons of space grade metals and alloys.

There, fixed that for ya.

Online cscott

  • Senior Member
  • *****
  • Posts: 2848
  • Liked: 1971
  • Likes Given: 664
Interesting wording that supports the idea that the decision to recover or not is solely SpaceXís and even their customers sometimes donít know until right before launch.

I agree the decision must be SpaceX's, but I think he does know for sure about recovery it's just that he's careful not to tread onSpaceX's toes and say anything definitive that relates to them rather than the mission.

BTW his response to being asked why no recovery on this mission is:

Quote
Can't answer that.

https://twitter.com/IridiumBoss/status/943161784994811904
My theory is that there is a significant fairing recovery experiment planned, and he is being careful not to step on SpaceX toes and let them announce that.  The reason for no S1 recovery is to enable the not-for-me-to-announce fairing recovery experiment.

Offline zubenelgenubi

  • Full Member
  • ****
  • Posts: 1400
  • Arc to Arcturus, then Spike to Spica
  • Commonwealth of Virginia
  • Liked: 345
  • Likes Given: 941
If this booster is not being recovered, there is surely a cost driven reason for it that made sense when they worked the trades.

In that case we can infer that the marginal cost of ASDS recovery is greater than the SCRAP-value of 20 tons of space grade metals and alloys.

There, fixed that for ya.

Or the value of another "rocket garden" artifact.  (Either for public display in a museum or such, or for private display in or near a SpaceX facility.)

(If there is discussion on SpaceX donating equipment for display, could someone point to it?)

On the flip side, Davy Jones gets a treasure for his locker that is becoming ever rarer--an expended Falcon 9 first stage! :D
« Last Edit: 12/19/2017 06:46 PM by zubenelgenubi »
Support your local planetarium!

Online cppetrie

  • Full Member
  • ****
  • Posts: 560
  • Liked: 318
  • Likes Given: 3
I can totally understand the economical reasons for foregoing booster recovery along with not wanting to add to the stockpile of 'old' block boosters. I'm honestly more disappointed from an environmental standpoint. Given the ability to recover, it seems a bit irresponsible to just throw the trash into the sea so to speak. I don't really know what hazards might be on board when it goes in the drink, so maybe it's just mostly stuff that doesn't matter/polute. Can they purge/consume any liquid contaminants prior to impact with the water?

Offline Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 9935
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 6747
  • Likes Given: 4531
I can totally understand the economical reasons for foregoing booster recovery along with not wanting to add to the stockpile of 'old' block boosters. I'm honestly more disappointed from an environmental standpoint. Given the ability to recover, it seems a bit irresponsible to just throw the trash into the sea so to speak. I don't really know what hazards might be on board when it goes in the drink, so maybe it's just mostly stuff that doesn't matter/polute. Can they purge/consume any liquid contaminants prior to impact with the water?

What kind of wastrel throws a perfectly good rocket in the drink... :)

As for your questions, I can give you Tory Bruno's twitter ID, you can ask him what ULA is doing to mitigate this....  more seriously, purging contaminants? wouldn't those just end up in exactly the same place anyway? (or in the atmosphere)
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Online cppetrie

  • Full Member
  • ****
  • Posts: 560
  • Liked: 318
  • Likes Given: 3
I can totally understand the economical reasons for foregoing booster recovery along with not wanting to add to the stockpile of 'old' block boosters. I'm honestly more disappointed from an environmental standpoint. Given the ability to recover, it seems a bit irresponsible to just throw the trash into the sea so to speak. I don't really know what hazards might be on board when it goes in the drink, so maybe it's just mostly stuff that doesn't matter/polute. Can they purge/consume any liquid contaminants prior to impact with the water?

What kind of wastrel throws a perfectly good rocket in the drink... :)

As for your questions, I can give you Tory Bruno's twitter ID, you can ask him what ULA is doing to mitigate this....  more seriously, purging contaminants? wouldn't those just end up in exactly the same place anyway? (or in the atmosphere)
I was specifically thinking of TEA/TEB. By purging them together they ignite and burn off rather than leaking individually into the water. I donít know what else is on the booster. Residual helium, N2 and LOx donít really matter. Theyíre inert and/or naturally occurring. The kerosene isnít great. You could burn it to empty before impact? Any other hazardous materials onboard? Probably some heavy metals in the electronics but the amount compared to volume of ocean probably makes inconsequential. Thatís likely the argument any of the launch providers use. Tiny amounts in huge oceans...therefore doesnít matter. Probably true but that logic has been used before to justify doing things that eventually turned out to be problems.

Offline kevinof

  • Full Member
  • ****
  • Posts: 534
  • Dublin/London
  • Liked: 324
  • Likes Given: 366
There is another side to the decision - they don't need the stage, they probably won't reuse it and therefore it has little or no value. However in trying to recover it, there is always a risk that the landing will fail, do a lot of damage to the barge and cost Space X a lot of money and time to repair.

If there's a risk (however small)  vs the zero value of the stage then splash it?

Offline Wolfram66

There is another side to the decision - they don't need the stage, they probably won't reuse it and therefore it has little or no value. However in trying to recover it, there is always a risk that the landing will fail, do a lot of damage to the barge and cost Space X a lot of money and time to repair.

If there's a risk (however small)  vs the zero value of the stage then splash it?

Or possibly testing the FH Side booster engine gimbal separation sequence? IDK... throwing stuff at the wall here

Offline Greg Hullender

  • Member
  • Posts: 60
  • Seattle
    • Rocket Stack Rank
  • Liked: 60
  • Likes Given: 72
I would guess that they learn a lot from each recovered stage. Information that could help them further reduce the cost of reuse, for example, or give them a better idea of how many times they can refly the same stage.

Offline whatever11235

  • Member
  • Posts: 34
  • Liked: 6
  • Likes Given: 30
I would guess that they learn a lot from each recovered stage. Information that could help them further reduce the cost of reuse, for example, or give them a better idea of how many times they can refly the same stage.

After 20 times I think they learned all they could.

Offline UKobserver

  • Member
  • Posts: 9
  • Liked: 51
  • Likes Given: 10
I think we are being too absolute in our arguments;

If Elon/SpaceX have shown anything, it is that they are very pragmatic in their decision making. They are constantly weighing their wish to push on with their experimentation and evolution of their technologies against the need to do a good job for their customers and build up those relationships. Several times they have chosen to sacrifice recovery margins (making for a hotter and more damaging re-entry) or even the recovery itself in order to boost the customer into a better orbit than contractually agreed, particularly where those customers have been waiting a long time and potentially have lost income as a result.

In a similarly pragmatic way, for Iridium 4 they have traded their wish to get a first west coast RTLS under their belt for their equally strong wish to get an important, high-profile, customer to start using pre-flown boosters and get as much use as they can out of their already built and paid-for inventory.

Therefore when we hear that this mission is going to be flown expendable, and we simultaneously hear that the filed ASDS landing location shifted a long way south when they opted to switch to a re-used block 3 booster, our immediate thought out to be that they are making some sort of engineering/customer support trade here.

I think both of the two theories that have been postulated above in this vein could be true, which were;

1. That in return for re-using a pre-flown booster they have promised Matt Desch delivery to a slightly higher initial orbit, so as to reduce the time needed to raise the satellites into their final orbits, and;

2. That they may indeed have traded some or all of the recovery margin to test out something else which requires adding mass to the stage, such as a further evolution of the fairing recovery, as cscott postulated, and which is made more likely by the fairing recovery ship having been switched to the west coast. It could be that they have accepted a heavier recoverable fairing design for Block 5, but want to test it now, and can only do so on a less-powerful block 3 booster by sacrificing margin somewhere else, such as removing the weight of the landing legs and grid fins.

What I don't think we can yet conclude is that;

a) the marginal cost of recovery is greater that the scrap value of the materials in the booster. I suspect that recovery costs are actually pretty low, given how SpaceX never spends any more than they need to on their equipment. As an example compare the size and spec of their tugboats and the fairly rudimentary (simple but effective) design of their ASDS barges, compared to the gold-plated designs planned by Blue Origin. I would certainly guess that recovery is just a small fraction of the cost of actually building the booster, hence why it makes sense to recover it in the first place, but what the actual value of the materials contained within the rocket is would be hard to guess. It's not impossible that it might be less than the cost of recovery, but I don't think we can conclude that much solely from the fact that they are expending this booster. Not without further information.

b) they don't need or want to recover any more boosters. We're lacking some important information here as to how many times they wish or intend to use these older recovered boosters, and it might even be that SpaceX themselves haven't decided yet, and that it might depend on how successful their block 5 design proves to be, and how quickly they can reduce the refurbishment time of that booster. A few things to think about in that regard;

i) they have obviously felt it worthwhile to try to recover all of the boosters that have made a second flight so far. This might be just so that they could inspect them and learn more lessons about re-usability, but it might also mean that they would consider using these boosters a third time, perhaps for the initial launches of their own satellite constellation, to really reduce the capital outlay required for that.

ii) they haven't yet reflown a booster that has performed a GTO profile, but note that they have converted one of these into one of their first Falcon Heavy side boosters. We don't know how much refurbishment that required, but given the risk to LC-39A if that launch goes wrong, I think we can assume that they are completely confident in that booster being safe to refly. And if it's safe to refly that means their other landed GTO boosters might also be available for re-use, even if that has to just be for launching their own satellites, if their customers aren't comfortable with flying on them. Which means they are building up quite a stockpile of boosters, unless they have already quietly started scrapping some of them. So it's possible that in Adelaide when Elon talked about building up a stock of boosters, he may have also meant some of the older block 3 and 4 stages, which they could use to loft some of their Starlink constellation.

iii) As AbuSimbel points out; they wont want to waste precious time and resources refurbishing more demanding older boosters if they think they have more block 5 flight lifetimes available than they could ever use, but given that they can't be certain exactly when BFR/BFS will be ready to assume the full launch workload it's also possible that they will choose to eke out every last flight they can get out of the block 3 and 4 boosters, in order to be keep as many block 5 flights in reserve as they can. It could also simply be good business, if the cost of those refurbishments is sufficiently low.

So taking all the above into account, it's possible that SpaceX are still keen to recover and stockpile even more boosters, and that the decision not to this time is simply a trade to allow them to achieve something else instead.

Offline Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 9935
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 6747
  • Likes Given: 4531
welcome to the forum, UKobserver.  Great first post. I think you nicely synthesized a lot of the previous speculation into one nice easy to digest package of analysis.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Tags: