Author Topic: FAILURE : Epsilon F6 with RAISE-3 + 7 satellites - 12 October 2022 (00:50 UTC)  (Read 13418 times)

Offline Rondaz

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[Aerial video] Epsilon 6 launch failure, destruction order 10 minutes later, JAXA investigates
https://asahi.com/articles/ASQBD3H82QBCULBH001.html


JAXA has announced that it has abandoned the plan. About 10 minutes after launch, he sent an order to destroy the rocket. This is the first rocket launch failure since 2003's H2A No. 6.

https://twitter.com/asahicom/status/1580038780257710082

Offline Rondaz

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The part about whether the rocket was really in an incorrect attitude is not confirmed BTW, JAXA says they are looking at the telemetry.

(Which of course leads to another plausible scenario where the rocket was in correct attitude but the IMU/flight computer thought it wasn’t)

https://twitter.com/Cosmic_Penguin/status/1580058385042767872

Offline Rondaz

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Epsilon rocket No. 6 entering the clouds. (From 2022/10/12 Miyahara news desk)

https://twitter.com/koumeiShibata/status/1580046690412687361

Offline Rondaz

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Everyone who supported the launch of Epsilon Rocket No. 6. I failed. very sorry. I can't talk about the details at the moment, but after the two-stage burn, the third stage failed to ignite, and the altitude began to fall despite the lack of control. Destruction is a tough decision, but losing 8 precious satellites is really frustrating and painful. For a while, I will walk with needle mats.

https://twitter.com/Ishide_Taka/status/1580042691542323200

Offline Rondaz

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Epsilon Rocket No. 6. It looks normal at this stage. Or is there something (9:50:43 on October 12, 2022 (JST))

https://twitter.com/koumeiShibata/status/1580039809254293505

Offline Rondaz

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Offline Steven Pietrobon

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[Aerial video] Epsilon 6 launch failure, destruction order 10 minutes later, JAXA investigates

The part about whether the rocket was really in an incorrect attitude is not confirmed BTW, JAXA says they are looking at the telemetry.

The above contradicts the information posted on the JAXA website.

https://forum.nasaspaceflight.com/index.php?topic=56911.msg2418375#msg2418375
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline FutureSpaceTourist

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Archived webcast:


Online eeergo

Failure mode identified: the second stage's RCS had an attitude control problem. From the two RCS systems in the 2nd stage, the pressure on the +Y manifold did not reach appropriate pressures to function as RCS, as seen in the first attached figure.

As context, the 2nd stage's attitude control is actuated by the TVC (directing the thrust from the main motor on the stage) and RCS (on the 2nd stage, it's a set of eight pressure-fed hypergolic thrusters activated by pyrovalves: each pod is located on the Y axis, at symmetric + and - locations).

In particular, while the 2nd stage is firing, the TVC is responsible for the pitch and yaw, while the RCS is responsible for the roll. Conversely, the RCS is responsible for the three axes after 2nd stage burnout. It should not be confused with the spin motors, which are small spin-up solid motors used to provide spin stabilization to the LV for 2-3 separation during coasting.

During this flight, the error in attitude immediately went out of bounds on yaw after burnout, reaching up to 21º after a minute (nominal is up to 0.91º, 3 sigma). After that, the +Y RCS actually went back to working nominally and stabilized that 21º error, but didn't bring the LV back to the nominal orientation.

Root cause narrowed down to "clogging of the RCS +Y line" or "Pyrovalve malfunction", along with "PSDB [redundant computer responsible for the operation of that fluid leg] failure". Crucially, the pyrovalve operation was NOT monitored as telemetry, so it's not possible to determine whether it actually fired or not.

Presentation from the Ministry of Education and Science:

https://www.mext.go.jp/kaigisiryo/content/221018-mxt_uchukai01-000025514_1.pdf (translated version attached).
-DaviD-

Offline Rondaz

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Both RCS propellant feed lines should pressurize at T+~2:32, post 1st stage separation. The -Y side did work nominally with the line's pressure up to tank pressure levels at receiving channel A's signals, but the +Y never did even w/ both signals sent.

As an event that occurred this time, it is known that the downstream piping pressure on the RCS + Y side, which is the red line in the graph, did not rise. The blue line in the graph is the tank pressure, and you can see that hydrazine is pressurized to about 1.9 MPa with nitrogen gas. The -Y side of the left graph shows normal operation, and the +Y side on the right shows an abnormal pressure history.

https://twitter.com/Cosmic_Penguin/status/1582320903076990977

Offline Rondaz

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The spin-motor fired as planned at T+6:10 prior to planned 3rd stage separation, which stabilised the stack at an attitude 21 degrees off the planned direction.

Due to the RCS + Y (pitch) anomaly, the attitude of the aircraft deviated from the target attitude as shown in the graph, and finally an error of 21° with respect to the target angle occurred. After that, the spin motor started burning as planned, and it seems that the spin stabilized with a 21° deviation.

https://twitter.com/Cosmic_Penguin/status/1582288063522549761

Offline Rondaz

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JAXA is currently investigating 3 possible failure causes:

* Electric/Wiring failure from the Power and Sequence Distribution Boxes to the pyro-valve
* Pyro-valve failed to fire or open properly
* Pyro-valve opened properly but the propellant feed line was blocked

https://twitter.com/Cosmic_Penguin/status/1582350491538710529

Offline Galactic Penguin SST

Update as of October 28: The “Electric/Wiring failure from the Power and Sequence Distribution Boxes to the pyro-valve” scenario has been eliminated, investigations are focusing on the other 2 possible reasons.
Astronomy & spaceflight geek penguin. In a relationship w/ Space Shuttle Discovery. Current Priority: Chasing the Chinese Spaceflight Wonder Egg & A Certain Chinese Mars Rover

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