Author Topic: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION  (Read 566514 times)

Online Chris Bergin

This thread has run its course and needs locking and archiving given there's obviously not going to be any more information and that leads to a diluted conversation.

The above posts have been left on the thread to prove the point. ;)

I think someone said there were a few last checks to confirm no Zuma via those tracking guys, but we could use the update thread if something turns up (we all know that's doubtful) and the update thread could be used if by some chance NG or one of the official entities says something.

If there is a big update posted on there, we can always start a new discussion thread, linking back to this one, so nothing is lost.

"Read 429097 times" <---Heh, just noticed that. Poor Zuma. We hardly knew you, but we won't forget you.

Anyway, let's move on.

Offline su27k

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1661 on: 04/09/2018 04:44 AM »
Found article today by Mr Pasztor that wasn't critical of SpaceX. 

https://www.wsj.com/articles/probes-point-to-northrop-grumman-errors-in-january-spy-satellite-failure-1523220500?mod=searchresults&page=1&pos=1

Looks like the data is pointing towards a issue with the payload adapter.

Quote
But now, these people said, two separate teams of federal and industry investigators have pinpointed reasons for the high-profile loss to problems with a Northrop-modified part -- called a payload adapter -- that failed to operate properly in space.

Hopefully this quote doesn't violate any rules, it's too interesting to pass up:

Quote
Sensors on board failed to immediately report what happened, this person said, so officials tracking the launch werenít aware of the major malfunction until the satellite was dragged back into the atmosphere by the returning second stage. The satellite ultimately broke free, but by then had dropped to an altitude that was too low for a rescue.

I wonder if they'll reconsider putting a camera up there to show payload separation.

Offline woods170

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1662 on: 04/09/2018 07:05 AM »
Found article today by Mr Pasztor that wasn't critical of SpaceX. 

Well, I suppose there is a first for everything...

Offline CorvusCorax

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1663 on: 04/09/2018 07:07 AM »
Google found this non-paywalled copy of above quote here edit: link went dead :(
« Last Edit: 04/10/2018 05:12 AM by CorvusCorax »

Offline woods170

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1664 on: 04/09/2018 08:57 AM »
Basic run-down of the article (for what it's worth):

- NG bought a payload adapter from a third party.
- NG modified the payload adapter to suit Zuma.
- NG tested the modified payload adapter with positive results
- Modified adapter however failed to function properly in zero-G
- Both government and industry investigation teams have reached same conclusion: NG is to blame for loss of Zuma

Online Semmel

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1665 on: 04/09/2018 09:11 AM »
Basic run-down of the article (for what it's worth):

- NG bought a payload adapter from a third party.
- NG modified the payload adapter to suit Zuma.
- NG tested the modified payload adapter with positive results
- Modified adapter however failed to function properly in zero-G
- Both government and industry investigation teams have reached same conclusion: NG is to blame for loss of Zuma

Thanks for the rundown. The non-paywall article also speculates that Zuma costs $3.5B to develop and build, which is a number that I have not seen around before. Maybe I missed it.

Offline Frogstar_Robot

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1666 on: 04/09/2018 10:35 AM »
If the problem had been detected at the time, could the sat have been saved before deorbiting the second stage?

Also, I guess they would only have video on the payload if the video data was sent via secure encrypted link.

Offline CorvusCorax

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1667 on: 04/09/2018 10:55 AM »
If the problem had been detected at the time, could the sat have been saved before deorbiting the second stage?

Also, I guess they would only have video on the payload if the video data was sent via secure encrypted link.

Answering that (speculatively) would require to reopen the Discussion thread. Maybe mods can move some stuff there later :)

The article suggests that the sat broke free in the early phases of reentry, that in turn suggests the sat only needed a small nudge. It also suggests the sat thought it was released, when it was in reality still attached. As such, maybe it could have supplied that "nudge" with a bit of thruster firing. (Considering the error only ever occurred in zero g but not when ground testing also suggests a relatively small force would have sufficed to get them apart, but in zero-g that wasn't present)

On the other hand, it did not come free yet, when the F9 US reoriented for de-orbitting and did its retro-burn (but then again that were likely compressive loads on the adapter, while pulling it off required shear loads)

I guess with detailed enough design specs of the adapter one could attempt to re-produce the fault-case on the ground by more accurately simulating the zero-g environment. Maybe NG already did that. When you have that you could also run simulations what could have possibly mitigated the issue in flight.

All that are could have / would have 's that don't help this mission. But it might help in future missions to solve 2 falt-scenarios:

1. The payload should have some means to detect a situation where it gets signalled a release has/should have happened but is in fact still physically attached. Cross-checking IMU sensor signature during payload release could give some heuristic indications. Double-checks are possible by actuating thrusters or reaction wheels and sensing the incorrect COG/mass fingerprint

2.  With 1 in place a payload could try some desperate active separation measures, such a thruster pulses. This of course should only happen if theres a clear indication that a) the payload is in orbit, b) separation should have occured, and c) it didn't

Last but not least the question is if this failure case is common enough to justify these counter-measures for future payloads.

Its just a bit like the contingency parachute release in Dragon in case of launch abort/premature separation. Noone thinks thats a likely enough scenario to justify it - until it actually happens.

It might be worth it if you combine
a) high value science/natsec payloads
b) unreliable, untested or first-of-a-kind hardware involved in payload separation

both of which was the case in Zuma.

Offline AncientU

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1668 on: 04/09/2018 10:57 AM »
If the problem had been detected at the time, could the sat have been saved before deorbiting the second stage?

Also, I guess they would only have video on the payload if the video data was sent via secure encrypted link.

The $200 GoPro feeds would have told them the $3.5B satellite was still attached... They may have been able to dislodge it with a payload or stage maneuver.

Ironic, isn't it.
« Last Edit: 04/09/2018 11:02 AM by AncientU »
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Offline Nomadd

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1669 on: 04/09/2018 11:12 AM »
 It really fills me with confidence that they'll ever manage to get the JWST sorted.

Offline DistantTemple

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1670 on: 04/09/2018 11:27 AM »
Sounds like SX were not allowed any video of the adaptor or payload even for cleared individuals. If it was just jammed, SX would have 1. Delayed reentry, 2. Shook it about a bit!!! (main engine + thrusters) ...despite the hint that it needed extra vibration protection. Seems criminal that NG didn't know enough about what was going on to at least ask SX to delay reentry!
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Online jjyach

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1671 on: 04/09/2018 11:32 AM »
There is no way to delay reentry.  It flies a preprogramed course flight profile regardless of what they may see.

Offline DistantTemple

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1672 on: 04/09/2018 11:47 AM »
There is no way to delay reentry.  It flies a preprogramed course flight profile regardless of what they may see.
Oh... now you say it , I remember I heard that before... so also that invalidates the rest of my statement, as they could not do additional burns, or thruster firings, if its preprogrammed/on autopilot.

However this scenario is an argument for having the ability to interrupt/override/update program, before deorbit begins. It does seem limiting. Is it because of regulations? I would expect SX to (want to) maintain an intervention channel if at all possible!
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Offline AncientU

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1673 on: 04/09/2018 12:06 PM »
It really fills me with confidence that they'll ever manage to get the JWST sorted.

Would be interesting to know if there was/is any commonality with the JWST adaptor NG is using...
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Online ugordan

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1674 on: 04/09/2018 12:17 PM »
However this scenario is an argument for having the ability to interrupt/override/update program, before deorbit begins.

I would say it's more of an argument toward ensuring that your payload adapter actually... works.

Offline rpapo

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1675 on: 04/09/2018 12:36 PM »
There is no way to delay reentry.  It flies a preprogramed course flight profile regardless of what they may see.
Then what happened on CRS-1?  The second burn for Orbcomm was cancelled from the ground.  That tells me the programming can be preempted from the ground.

EDIT: Woods170 says the decision was made automatically, and I have a strong tendency to believe him.  I simply took the rhetoric of the time as indicating that NASA had made the call then and there.
« Last Edit: 04/09/2018 09:33 PM by rpapo »
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Offline JBF

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1676 on: 04/09/2018 12:39 PM »
There is no way to delay reentry.  It flies a preprogramed course flight profile regardless of what they may see.
Then what happened on CRS-1?  The second burn for Orbcomm was cancelled from the ground.  That tells me the programming can be preempted from the ground.

We can't assume that; it was probably a preprogramed limit.  If < X amount of fuel is present switch to program B.
« Last Edit: 04/09/2018 03:01 PM by JBF »
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Offline DistantTemple

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1677 on: 04/09/2018 12:48 PM »
There is no way to delay reentry.  It flies a preprogramed course flight profile regardless of what they may see.
Then what happened on CRS-1?  The second burn for Orbcomm was cancelled from the ground.  That tells me the programming can be preempted from the ground.

We can't assume that it was probably a preprogramed limit.  If < X amount of fuel is present switch to program B.
A wild guess... NASA required the ability to make this decision, and two (or so) choices of flight profile were programmed in. Sending a command to choose "abort second payload" would be easier than detailed intervention. Also on a NASA mission are more resources deployed to keep in more continuous contact with the spacecraft? AIUI SX routinely has gaps in communication during orbit.  I have just noticed this is not a discussion thread!
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Offline woods170

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1678 on: 04/09/2018 01:20 PM »
There is no way to delay reentry.  It flies a preprogramed course flight profile regardless of what they may see.
Then what happened on CRS-1?  The second burn for Orbcomm was cancelled from the ground.  That tells me the programming can be preempted from the ground.
Incorrect. The burn was not cancelled from the ground. It was cancelled by the on-board flight computer, based on pre-programmed instructions to NOT initiate the second burn if there is insufficient propellant to complete the mission.

The on-board computer keeps track of how long the first burn was for completion of the primary mission (getting Cargo Dragon on its way to ISS). Orbcomm was the secondary mission. Based on the extended burn required to get the target delta-V for Cargo Dragon it was clear to the onboard-computer that there was insufficient propellant left for the second burn. And thus that second burn was not initiated.

Offline woods170

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Re: SpaceX F9 : Zuma : January 7/8, 2018, CCAFS : DISCUSSION
« Reply #1679 on: 04/09/2018 01:29 PM »
It really fills me with confidence that they'll ever manage to get the JWST sorted.

Would be interesting to know if there was/is any commonality with the JWST adaptor NG is using...

No commonality whatsoever. For JWST both the cone 3936 and the PAS (Payload Adapter System) 2624VS are supplied as stock items from Arianespace.

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