Author Topic: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)  (Read 59511 times)

Offline gemmy0I

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #260 on: 11/09/2022 11:47 pm »
Quote
In a press release, Northrop Grumman says the Cygnus spacecraft’s solar array deployment failure on NG-18 stemmed from a problem during a stage separation event on launch.

An acoustic blanket from the Antares rocket lodged in one of the Cygnus solar array mechanisms.

Quote
"During a rocket stage separation event, debris from an Antares acoustic blanket became lodged in one of the Cygnus solar array mechanisms, preventing it from opening," said Cyrus Dhalla, vice president and general manager, Tactical Space Systems, Northrop Grumman. "Successful berthing was achieved thanks to Cygnus's robust design and the resilience and ingenuity of the NASA and Northrop Grumman teams."
This could lend support to the theory that there may have been recontact between Cygnus and one of the fairings post-separation (due to the attitude excursion). Given that the insides of the fairings are lined with acoustic blankets, they're exactly the sort of thing that could get snagged on a pointy bit of the spacecraft if there were momentary recontact.

Or the cause/effect could be the other way around: perhaps the pointy end of the folded-up solar array got snagged on the fairing's acoustic blanketing (perhaps during ground handling), and this kept the fairing from separating cleanly (because it would remain physically coupled to the spacecraft until the snagged blanket tore free) - in turn causing the attitude excursion due to the center of mass being thrown off by having a fairing hanging off the spacecraft via a shred of floppy blanket. This feels like the most likely explanation to me, since it could account for the entirety of the weirdness we've seen on this launch with a simple, plausible ground-handling root cause.

Offline mn

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #261 on: 11/10/2022 02:01 am »
Quote
In a press release, Northrop Grumman says the Cygnus spacecraft’s solar array deployment failure on NG-18 stemmed from a problem during a stage separation event on launch.

An acoustic blanket from the Antares rocket lodged in one of the Cygnus solar array mechanisms.

Quote
"During a rocket stage separation event, debris from an Antares acoustic blanket became lodged in one of the Cygnus solar array mechanisms, preventing it from opening," said Cyrus Dhalla, vice president and general manager, Tactical Space Systems, Northrop Grumman. "Successful berthing was achieved thanks to Cygnus's robust design and the resilience and ingenuity of the NASA and Northrop Grumman teams."
This could lend support to the theory that there may have been recontact between Cygnus and one of the fairings post-separation (due to the attitude excursion). Given that the insides of the fairings are lined with acoustic blankets, they're exactly the sort of thing that could get snagged on a pointy bit of the spacecraft if there were momentary recontact.

Or the cause/effect could be the other way around: perhaps the pointy end of the folded-up solar array got snagged on the fairing's acoustic blanketing (perhaps during ground handling), and this kept the fairing from separating cleanly (because it would remain physically coupled to the spacecraft until the snagged blanket tore free) - in turn causing the attitude excursion due to the center of mass being thrown off by having a fairing hanging off the spacecraft via a shred of floppy blanket. This feels like the most likely explanation to me, since it could account for the entirety of the weirdness we've seen on this launch with a simple, plausible ground-handling root cause.

The attitude excursion seems to have begun before the fairings would be expected separate (when comparing the time from meco to fairing separation on ng 17)

Offline Jeff Lerner

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #262 on: 11/10/2022 02:22 am »
Would DEXTRE be able to remove the debris and free the array ??

Offline Bob Niland

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #263 on: 11/10/2022 02:53 am »
Would DEXTRE be able to remove the debris and free the array ??
Is there any mission benefit in doing so at this point? Any payloads damaged by the power loss remain damaged. The Cygnus can probably undock and re-enter as is. Array deployment on station may not be risk-free.

What the arm might be really useful for is a detailed inspection of the entire Cygnus, seeking clues as to what happened & why.
Working for SX could be exhilarating, as long as the job description doesn't include Master PERT Chart.

Offline Robotbeat

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #264 on: 11/10/2022 03:02 am »
Would DEXTRE be able to remove the debris and free the array ??
Is there any mission benefit in doing so at this point? Any payloads damaged by the power loss remain damaged. The Cygnus can probably undock and re-enter as is. Array deployment on station may not be risk-free.

What the arm might be really useful for is a detailed inspection of the entire Cygnus, seeking clues as to what happened & why.
They may be doing experiments after undocking that really benefit from the greater power. Cygnus often has post-undocking mission elements.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Fmedici

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #265 on: 11/10/2022 09:17 am »
Maybe I didn't notice it, but I didn't see it mentioned here or in the ISS thread so here's about a fourth cubesat launched with NG-18. Nicknamed SpaceTuna1, it was developed by the Japanese Kindai University and its launch was contracted with Spaceflight Inc. You can find info about the payload in the link below, together with the Spaceflight tweet confirming its launch:

https://spaceflight.com/kindai-universitys-spacetuna1-headed-to-iss-onboard-ng-18-the-s-s-sally-ride/

https://twitter.com/SpaceflightInc/status/1590425321114726400

Offline woods170

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #266 on: 11/10/2022 10:59 am »
Your conclusion is premature. The only thing that has been determined is that there was negligent risk of sudden deploy of the array during approach, capture and berthing. Everything else, including the cause of the failure, is still being looked into.

You mean, a negligible risk?  A negligent risk rather changes the meaning...

You are quite correct. Indeed I meant negligible. Corrected in my original post.

Offline edzieba

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #267 on: 11/10/2022 12:31 pm »
Best views (so far) of the stuck array. Wad of material just visible around the hinge joint.

Offline eeergo

Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #268 on: 11/10/2022 01:15 pm »
Very clear views of the down-pointing S2 ignition followed by along-track reorientation, from ground observers:

https://twitter.com/Cosmic_Penguin/status/1590704688475045888
-DaviD-

Offline mn

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #269 on: 11/10/2022 05:38 pm »
Very clear views of the down-pointing S2 ignition followed by along-track reorientation, from ground observers:

https://twitter.com/Cosmic_Penguin/status/1590704688475045888

I'm not seeing what you are seeing.

The entire video is one continuous burn. The supposed off-nonimal attitude was at S2 ignition, roughly 45s after MECO.

I don't know what happens at 22s in this video but I don't see how that can be S2 ignition.

Edit: I would assume the entire video is of S1 and what you are seeing at 22s is cloud interaction.
« Last Edit: 11/10/2022 05:42 pm by mn »

Offline edzieba

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #270 on: 11/10/2022 05:42 pm »
Very clear views of the down-pointing S2 ignition followed by along-track reorientation, from ground observers:

https://twitter.com/Cosmic_Penguin/status/1590704688475045888

I'm not seeing what you are seeing.

The entire video is one continuous burn. The supposed off-nonimal attitude was at S2 ignition, roughly 45s after MECO.

I don't know what happens at 22s in this video but I don't see how that can be S2 ignition.
22s is S2 ignition. The 'burn' from the start of the video is not the main engines, but ullage release.

Offline Orbiter

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #271 on: 11/10/2022 05:44 pm »
Very clear views of the down-pointing S2 ignition followed by along-track reorientation, from ground observers:

https://twitter.com/Cosmic_Penguin/status/1590704688475045888

I'm not seeing what you are seeing.

The entire video is one continuous burn. The supposed off-nonimal attitude was at S2 ignition, roughly 45s after MECO.

I don't know what happens at 22s in this video but I don't see how that can be S2 ignition.

I see it. The second stage has already separated by the start of the video. We're probably seeing some of the residual exhaust coming out of the first stage in the video, giving the illusion that it's still burning (red). The second stage (green) is pointed way offset from the velocity vector.
« Last Edit: 11/10/2022 05:45 pm by Orbiter »
Astronomer & launch photographer

Offline mn

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #272 on: 11/10/2022 05:49 pm »
Very clear views of the down-pointing S2 ignition followed by along-track reorientation, from ground observers:

https://twitter.com/Cosmic_Penguin/status/1590704688475045888

I'm not seeing what you are seeing.

The entire video is one continuous burn. The supposed off-nonimal attitude was at S2 ignition, roughly 45s after MECO.

I don't know what happens at 22s in this video but I don't see how that can be S2 ignition.
22s is S2 ignition. The 'burn' from the start of the video is not the main engines, but ullage release.

ullage release on a solid rocket motor?

Offline mn

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #273 on: 11/10/2022 05:56 pm »

... trimmed quotes to save scrolling.

I see it. The second stage has already separated by the start of the video. We're probably seeing some of the residual exhaust coming out of the first stage in the video, giving the illusion that it's still burning (red). The second stage (green) is pointed way offset from the velocity vector.

Exhaust would not be illuminated if the engine is off.

Offline edzieba

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #274 on: 11/10/2022 06:01 pm »
Very clear views of the down-pointing S2 ignition followed by along-track reorientation, from ground observers:

https://twitter.com/Cosmic_Penguin/status/1590704688475045888

I'm not seeing what you are seeing.

The entire video is one continuous burn. The supposed off-nonimal attitude was at S2 ignition, roughly 45s after MECO.

I don't know what happens at 22s in this video but I don't see how that can be S2 ignition.
22s is S2 ignition. The 'burn' from the start of the video is not the main engines, but ullage release.

ullage release on a solid rocket motor?
Antares stage 1 is Kerolox.

Offline Orbiter

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #275 on: 11/10/2022 06:10 pm »

... trimmed quotes to save scrolling.

I see it. The second stage has already separated by the start of the video. We're probably seeing some of the residual exhaust coming out of the first stage in the video, giving the illusion that it's still burning (red). The second stage (green) is pointed way offset from the velocity vector.

Exhaust would not be illuminated if the engine is off.

I have seen this effect for myself in person with a Falcon 9 first stage. During Crew-2, there was a similar "kerolox jellyfish" and I could clearly see exhaust from the first stage after separation, despite the engines being off. Along with the nitrogen thrusters. The jellyfish effect isn't quite as sudden as in this video too, it's a gradual illumination of the plume. I am almost 100% certain this was second stage ignition.
« Last Edit: 11/10/2022 06:13 pm by Orbiter »
Astronomer & launch photographer

Offline eeergo

Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #276 on: 11/10/2022 06:14 pm »

... trimmed quotes to save scrolling.

I see it. The second stage has already separated by the start of the video. We're probably seeing some of the residual exhaust coming out of the first stage in the video, giving the illusion that it's still burning (red). The second stage (green) is pointed way offset from the velocity vector.

Exhaust would not be illuminated if the engine is off.

Yes it would, when the rocket actually passed to orbital dawn (as evidenced also by the warm color), although to be precise the gases seen wouldn't be exhaust, but rather unburnt venting. Prior to that, the contrail was in darkness. The vehicle was already in two pieces at the start of the video.


It's also evident from the fact the jellyfish effect continues to be visible long after the burning engine moves off far away.
-DaviD-

Offline mn

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #277 on: 11/10/2022 06:58 pm »

... trimmed

I'm not seeing what you are seeing.

The entire video is one continuous burn. The supposed off-nonimal attitude was at S2 ignition, roughly 45s after MECO.

I don't know what happens at 22s in this video but I don't see how that can be S2 ignition.
22s is S2 ignition. The 'burn' from the start of the video is not the main engines, but ullage release.

ullage release on a solid rocket motor?
Antares stage 1 is Kerolox.

Yes of course, I mistook what you wrote as referring to fuel settlement before ignition. NVM.

But anyway that sure looks like an engine firing not pressure release.

Offline FutureSpaceTourist

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #278 on: 11/10/2022 07:15 pm »
Couple of photos posted by NASA Johnson

Offline Rondaz

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Re: Antares : Cygnus NG-18 : 7 Nov 2022 (10:32 UTC)
« Reply #279 on: 11/10/2022 08:05 pm »
More than a million students have participated in the Sally Ride EarthKAM investigation aboard the @Space_Station!

https://twitter.com/ISS_Research/status/1590803439906611200

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