Failure: Vega-C VV22 - Pléiades Neo 5 and 6 - 21 December 2022 (01:47 UTC)

[GWR64]

Are there already indications of the cause of failure?
Could there be a connection to this change?

Just a few facts on the Vega C 2nd stage Zefiro Z-40 solid rocket motor, and how it compares to Z-23. This might help with the upcoming discussions.

Another change is in the nozzle joints, respectively their thermal protection.

From "Technological and programmatic development of Zefiro 40 Solid Rocket Motor":

I have been seeing repeated claims in french and Italian spaceflight communities from AS/Kourou workers  that the new Flexible joint, which is supposed to bring down cost and complexity and subcontracted by a new company, is the main suspect of the failure

The design is similar to that on the P80 FW nozzle, or am I wrong?

https://www.eucass-proceedings.eu/articles/eucass/pdf/2009/01/eucass1p141.pdf

[TheKutKu]

Are there already indications of the cause of failure?
Could there be a connection to this change?

Just a few facts on the Vega C 2nd stage Zefiro Z-40 solid rocket motor, and how it compares to Z-23. This might help with the upcoming discussions.

Another change is in the nozzle joints, respectively their thermal protection.

From "Technological and programmatic development of Zefiro 40 Solid Rocket Motor":

I have been seeing repeated claims in french and Italian spaceflight communities from AS/Kourou workers  that the new Flexible joint, which is supposed to bring down cost and complexity and subcontracted by a new company, is the main suspect of the failure

The design is similar to that on the P80 FW nozzle, or am I wrong?

https://www.eucass-proceedings.eu/articles/eucass/pdf/2009/01/eucass1p141.pdf

I think yes, P120C has a similar one  too


It's made near Bordeaux, i'm not sure it's the same company that makes both, the Zefiro autoprotected flexible joint may be made in Italy

[GWR64]

A pdf from 2015 about the Zefiro-40.
There seem to be some differences to the older Zefiro versions.
https://www.eucass.eu/component/docindexer/?task=download&id=3560

[FutureSpaceTourist]

https://twitter.com/jeff_foust/status/1617439104836190209

ESA Director General Josef Aschbacher says he expects the investigation into last month's Vega C launch failure to wrap up on the second half of February. Return to flight as soon as possible but acknowledges need for deep analysis of quality issues with vehicle.

https://twitter.com/jeff_foust/status/1617441919721676805

Daniel Neuenschwander, ESA director of space transportation, says that because the Vega C failure involves it second stage, it may be possible to return to flight first with Vega (which uses a different second stage) before Vega C.

[eeergo]

https://mobile.twitter.com/jeff_foust/status/1623129301582327813

[eeergo]

ESA's independent review of the failure is expected to be publicly released two Fridays from now, on March 3rd.

[bolun]

N° 6–2023: Media invitation: Findings of the Independent Inquiry Commission on VV22 failure

17 February 2023

The Independent Inquiry Commission tasked with analysing the loss of the Vega-C Flight VV22 mission, will share its findings on Friday 3 March 2023 at ESA’s Headquarters in Paris.

Josef Aschbacher, ESA Director General and Stéphane Israël, CEO of Arianespace, will jointly present the results of the investigation at 10:00 CET, in the presence of:

- Giovanni Colangelo, ESA Inspector General and co-chair of the Independent Inquiry Commission;

- Pierre-Yves Tissier, Chief Technical Officer of Arianespace and co-chair of the Independent Inquiry Commission;

- Giulio Ranzo, CEO of Avio

- Daniel Neuenschwander, ESA Director of Space Transportation.

The failure of Vega-C Flight VV22, which was carrying Pléiades Neo 5 and 6 satellites, was announced shortly after its launch on 20 December 2022 at 22:47 local time in French Guiana (03:47 CET/02:47 GMT, 21 December 2022).

Arianespace and ESA immediately set up an independent inquiry commission to analyse the reasons for the loss of the mission, and to define the measures to be taken to ensure all requisite safety and reliability conditions are met for the resumption of Vega-C flights.

Programme (times in CET)

Friday, 3 March 2023

09:30   Doors open

10:00   Beginning of the press conference and presentation of the Independent Inquiry Commission’s findings.
Question-and-answer session.

10:45   End

https://www.esa.int/Newsroom/Press_Releases/Media_invitation_Findings_of_the_Independent_Inquiry_Commission_on_VV22_failure

[TheKutKu]

A day before the results of the investigation, La Tribune reports that a defect in the Zefiro 40 nozzle throat Causes the failure, the article suggests the blame has been put on Yuzhnoye, its provider, and Avio For selecting the Ukrainian manufacturer.

https://www.latribune.fr/entreprises-finance/industrie/aeronautique-defense/vega-c-le-col-de-tuyere-fabrique-en-ukraine-est-a-l-origine-du-crash-du-lanceur-italien-953754.html

[eeergo]

A day before the results of the investigation, La Tribune reports that a defect in the Zefiro 40 nozzle throat Causes the failure, the article suggests the blame has been put on Yuzhnoye, its provider, and Avio For selecting the Ukrainian manufacturer.

https://www.latribune.fr/entreprises-finance/industrie/aeronautique-defense/vega-c-le-col-de-tuyere-fabrique-en-ukraine-est-a-l-origine-du-crash-du-lanceur-italien-953754.html

Interesting, I thought the main Ukranian contribution was through the AVUM, not in the Zefiros themselves. Apparently it was chosen as a cost-saving measure, but it's unclear how that fit with the geographical return policy in ESA and why it was (exceptionally?) allowed given ArianeSpace was supplying Vega's nozzles and is actively producing them for missiles.

The nozzle was reportedly shipped (together with 2 others, of which one was already used in Vega-C's maiden flight, so only one spare should remain) before the current hostilities began and production had to be halted/diverted. The fabrication is now again in ArianeSpace's hands, so the fix should already be implemented.

[Galactic Penguin SST]

https://www.esa.int/Newsroom/Press_Releases/Loss_of_flight_VV22_Independent_Enquiry_Commission_announces_conclusions

N° 7–2023: Loss of flight VV22: Independent Enquiry Commission announces conclusions

3 March 2023

On Tuesday 20 December 2022, Arianespace announced the loss of the Vega-C VV22 mission after its launch at 22h47 local time in French Guiana (2h47 CET/1h47 GMT on 21 December 2022). The mission was carrying two payloads, Pléiades Neo 5 and 6 Earth observation satellites for Airbus Defence and Space.

Arianespace (the launch service provider) and the European Space Agency (ESA – the launch system development authority) immediately set up an Independent Enquiry Commission, which concluded that after the nominal functioning of the Vega-C first stage P120C and nominal ignition of the second stage (Zefiro 40), a progressive decrease in the chamber pressure was observed 151 seconds after lift-off, leading to the loss of the mission.

Initial investigations, conducted right after the launch with the available flight data, confirmed that the launcher’s sub-systems reacted to the events as designed, and that the cause of the failure was a gradual deterioration of the Zefiro 40’s nozzle. More precisely, the Commission confirmed that the cause was an unexpected thermo-mechanical over-erosion of the carbon-carbon (C-C) throat insert of the nozzle, procured by Avio in Ukraine. Additional investigations led to the conclusion that this was likely due to a flaw in the homogeneity of the material.

The anomaly also revealed that the criteria used to accept the C-C throat insert were not sufficient to demonstrate its flightworthiness. The Commission has therefore concluded that this specific C-C material can no longer be used for flight. No weakness in the design of Zefiro 40 has been revealed. Avio is implementing an immediate alternative solution for the Zefiro 40’s nozzle with another C-C material, manufactured by ArianeGroup, already in use for Vega’s Zefiro 23 and Zefiro 9 nozzles.

Considering the nature of the VV22 anomaly, the Commission emphasizes that its conclusions on Zefiro 40 do not affect the Vega launcher which is relying on the Zefiro 23 and Zefiro 9 motors. In this context, Arianespace decided to adapt its launch schedule to reassign a mission to one of its two remaining Vega launchers with a targeted launch date before the end of summer 2023.

The Independent Enquiry Commission has formulated a series of recommendations aiming at restoring confidence in the Vega and Vega-C launcher systems through the establishment of robust recovery plans to ensure a reliable return to flight and robust commercial exploitation.

The main strands of work based on the recommendations are:

* To complement the findings of the Commission with additional testing and analysis in order to ensure the robustness of the qualification of the alternative C-C material selected for Zefiro 40;

* To implement an additional qualification phase of the Zefiro 40 engine with the alternative C-C material;

* To implement a set of actions, aiming at guaranteeing a long-term reliable and sustainable launcher production.

A task force steered by ESA and Arianespace has started implementing the roadmap proposed by the Commission and will thoroughly follow the implementation of the actions by Vega’s prime contractor Avio, in order to ensure a reliable and robust return to flight of Vega-C. The targeted launch date is end of 2023.

ESA, as launch system qualification authority, Arianespace, as launch service provider and Avio, as design authority and prime contractor of the Vega launcher, will join their efforts to achieve the common objective of a robust exploitation of the Vega launch system, for the benefit of their institutional and commercial customers.

Josef Aschbacher, ESA Director General, said: "The Independent Enquiry Commission stands for ESA’s commitment to the highest safety standards. It has drawn a set of recommendations that once implemented should ensure a robust, reliable return to flight of the Vega-C launcher.

ESA will fully engage its engineering and project management expertise to support Avio in the implementation of actions required to regain confidence in the launcher system. Restoring Europe’s independent access to space is ESA’s priority, and I am therefore glad that we can proceed with Vega launch campaigns while preparing Vega-C to safely return to flight."

“Thanks to their hard work, the members of the Commission have identified the immediate cause of the loss of the mission VV22 and of its lessons learnt, and proposed the relevant corrective actions,” said Stéphane Israël, CEO of Arianespace. “Their recommendations already are under implementation by Avio, under the supervision of Arianespace and ESA, in order to allow a successful return to flight of Vega-C and to guarantee its continuous reliability.”

[FutureSpaceTourist]

https://twitter.com/jeff_foust/status/1631582266102038528

ESA's briefing of the Vega C investigation is underway. ESA Director General Josef Aschbacher says he expects a Vega (not Vega C) launch before the end of the summer, as the older version is not affected. Vega C return to flight before the end of the year.

[Galactic Penguin SST]

Briefing mentioned above is here: https://www.esa.int/ESA_Multimedia/ESA_Web_TV

[FutureSpaceTourist]

twitter.com/jeff_foust/status/1631590674679070721

Avio’s Giulio Ranzo says the company selected the carbon-carbon material from Ukraine during the Vega C design effort (2015-17) after concluding existing European suppliers could not provide material in sufficient quantities. "Substantial" testing found no inadequacy with it.

https://twitter.com/jeff_foust/status/1631592506562363392

Giovanni Colangelo, co-chair of the independent inquiry, said the carbon-carbon material used in Vega C qualification testing and inaugural flight was better than required, so no erosion issues. Material for failed VV22 material was "exactly in line" with specs; it failed.

Oops, so spec wasn’t stringent enough but that was missed because material on initial flights was better than spec?

Also:

https://twitter.com/dutchsatellites/status/1631593074135638016

Ranzo's statement is only partially correct. There were European suppliers that could provide C-C in sufficient quantities. Just not at the price level sought by Avio.

[eeergo]

Oops, so spec wasn’t stringent enough but that was missed because material on initial flights was better than spec?

Coincidentally reminiscent, although certainly stemming from different contributing factors, of Astra's root cause for their latest failure: too thin margins on an engine component that certain modes of operation masked in prior flights (for Vega-C, fabrication variance leading to better component margins on first flight article; for Rocket 3.3, environmental variance leading to better operating margins in tests/prior flights).

[mn]

It is entirely not out of the question that this could be intentional on the part of the supplier.

I have no idea who they are and the history of manufacturing in Ukraine, but if you take Chinese manufacturers as an example, you can easily spec a product, get a sample, do extensive testing and approve the product, and then take delivery of the final product only to find (either before or after it's too late) that it is inferior to the sample you approved. (first hand experience not just guessing - albeit on a tiny scale compared to this).

[GWR64]

Here is the recording of the press briefing.

https://www.esa.int/ESA_Multimedia/Videos/2023/03/Media_briefing_on_the_loss_of_the_Vega-C_Flight_VV22_mission

twitter.com/jeff_foust/status/1631590674679070721

https://twitter.com/jeff_foust/status/1631592506562363392

Giovanni Colangelo, co-chair of the independent inquiry, said the carbon-carbon material used in Vega C qualification testing and inaugural flight was better than required, so no erosion issues. Material for failed VV22 material was "exactly in line" with specs; it failed.

...

I wonder if the better material at the two Z-40 ground qualification tests and the qualification flight VV21 was known at that time? Wouldn't the qualification then be invalid?

[Steven Pietrobon]

Seems the testing procedure was flawed. You want to test at both worst and best case materials and conditions. A pass at best case does not mean that it will work at worst case or vice versa!

[GWR64]

The combustion time of the Zefiro-40 is 92.9 sec. (avio homepage)
In 3 tests, the nozzles of the Zefiro-40 apparently survived this period of time without damage.
After the ground tests in 2018 and 2019, the nozzles were inspected, I suspect.
At the VV22 launch, started  just 7 sec. after ignition, a significant unexpected pressure drop in the Z-40.
Can this be explained by small differences in quality?
In addition, the material passed the quality test at Avio (tomography?).

[freda]

I do see the other recent posts related to my question in this thread.

I will add to the thread to reference an article available on SpaceNews: https://spacenews.com/nozzle-erosion-blamed-for-vega-c-launch-failure/

Note: The author of the SpaceNews article might not be clear on something.  The SpaceNews article uses VV21 throughout the writeup on the failure of the 2022 December 20 Vega-C.  The VV22 identifier of the actual failed Vega never appears in the article.  Hence my confusion.

From the article, Giovanni Colangelo, ESA inspector general and the other co-chair of the investigation is quoted as:
>> “The acceptance criteria (the throat ring) were not the right ones”
>> “The one (the throat ring provided by the supplier) for VV21 was exactly in line with the specification, so were not as good as the previous one, so that is the reason why there was a failure”.

Regardless if the SpaceNews article is correctly indicating VV21 or VV22, as a low-contributing NSF forum lurker, here is my question for this discussion thread - I already guess the answer    - If a product supplier delivers a product (such as a throat ring) that meets or exceeds specification, and the product fails, who is at fault?
>> The product supplier, for not knowing that the requirements will be exceeded?
>> The organization that wrote the specification and failed to properly test for acceptance?

And the follow-up question:  Is the SpaceNews article correct in the VV21 vs VV22 reference, or incorrect?  Can anyone here help clarify? 

Does the NSF forum have a feature to insert a "bulleted list"?  Sorry... too many questions in one forum post.

[Rik ISS-fan]

...
From the article, Giovanni Colangelo, ESA inspector general and the other co-chair of the investigation is quoted as:
>> “The acceptance criteria (the throat ring) were not the right ones” (That's the conclusion of the investigation)
>> “The one (the throat ring provided by the supplier) for VV21 VV22 was exactly in line with the specification, so were not as good as the previous one, so that is the reason why there was a failure”.

Regardless if the SpaceNews article is correctly indicating VV21 or VV22, as a low-contributing NSF forum lurker, here is my question for this discussion thread - I already guess the answer    - If a product supplier delivers a product (such as a throat ring) that meets or exceeds specification, and the product fails, who is at fault?
>> The product supplier, for not knowing that the requirements will be exceeded?
>> The organization that wrote the specification and failed to properly test for acceptance?

And the follow-up question:  Is the SpaceNews article correct in the VV21 vs VV22 reference, or incorrect?  Can anyone here help clarify? 

Does the NSF forum have a feature to insert a "bulleted list"?  Sorry... too many questions in one forum post.

The SpaceNews article was incorrect. The throat insert for the Z40 for VV22 was (just) in line with specifications. The throat insert for the two static fired Z40 and the Z40 used on VV21 exceeded minimum product requirements. So the manufactures delivered what was requested.
So Avio, the company that's main design autority for the Vega C launcher is at fault, by setting the desired requirements wrong. There was also criticism about the product quality verification. Because the throat insurt is a dual purpose (Solid rocket motor for orbital launch or ICBM's) product, details about production method are classified. Avio entrusted the manufactured to check the quality of the throat, and without sharing the test data.
I assume this won't happen any longer with ArianeGroup (France) supplying the new throat inserts.

Avio already contracted ArianeGroup early last year to produce several throat inserts, as ensurance for the event the Ukranian supply would be disrupted. Now fully switch towards ArianeGroup supplied throat inserts.
Avio went for a bargain, and that resulted in a unreliable launcher. They might have learned their lesson now.