Author Topic: FAILURE: Astra Rocket 3.1 - Kodiak - September 12, 2020 (03:19 UTC)  (Read 56615 times)

Offline jcm

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Bear in mind he left/was pushed out of Astra a few weeks ago.

Yeeerp.

So what we learned? Because I'm still clueless about what he's trying to say...

I think previous posters are trying to say that this particular (tweeter?), Ben, actually worked inside Astra, and has some sense of what's going on inside. You can debate whether or not he's trustworthy after leaving, of course. If you follow his previous posts you can get an idea of his feelings about the company.

If he's to be believed, though, what Ben is implying (I think he actually alluded to this in his previous posts, as well) was that Astra may have not actually included a functional second stage in this launch, so there was no chance it'd go to orbit and it wasn't actually an orbital launch "attempt." No idea if that's because their second stage isn't done, or if they have production issues, etc.

One might argue that this is a good idea for a risky new rocket - make sure stage 1 works before wasting any more money on second stage hardware?

Hmm, ok, I wasn't exactly sure if he meant that, or he just didn't believe that even a functional second stage in the current
design iteration had enough oomph to make it.
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Offline ringsider

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I wish I knew for sure where those two twitter filmers were. Then, I could easily figure out a trajectory.

The closer videographer has posted he was at the complex entrance, which gives us this:

[zubenelgenubi: Please attach images to post.  Do not embed them.]
« Last Edit: 09/18/2020 10:24 pm by zubenelgenubi »

Offline Skyrocket

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Bear in mind he left/was pushed out of Astra a few weeks ago.

Yeeerp.

So what we learned? Because I'm still clueless about what he's trying to say...

I think previous posters are trying to say that this particular (tweeter?), Ben, actually worked inside Astra, and has some sense of what's going on inside. You can debate whether or not he's trustworthy after leaving, of course. If you follow his previous posts you can get an idea of his feelings about the company.

If he's to be believed, though, what Ben is implying (I think he actually alluded to this in his previous posts, as well) was that Astra may have not actually included a functional second stage in this launch, so there was no chance it'd go to orbit and it wasn't actually an orbital launch "attempt." No idea if that's because their second stage isn't done, or if they have production issues, etc.

One might argue that this is a good idea for a risky new rocket - make sure stage 1 works before wasting any more money on second stage hardware?

Hmm, ok, I wasn't exactly sure if he meant that, or he just didn't believe that even a functional second stage in the current
design iteration had enough oomph to make it.

My impression was, that he thought, the current design has inherent unsolved issues. Perhaps we should simply ask him?

Offline CJ

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I wish I knew for sure where those two twitter filmers were. Then, I could easily figure out a trajectory.

The closer videographer has posted he was at the complex entrance, which gives us this:

Ringsider, thank you for this info, and the map and wind info!

The time from impact to shockwave arrival indicates about a mile, maybe a little less, which is a very close fit to where you have the impact points.

I tried to find those light polls (I thought they were antennas) and didn't - though now I do see them there in a sat view.

Looks like we have, thanks to your info, confirmation - Astra 3.1 was way off course. This is not the "slight oscillation" they claimed, or, they have a radically different definition of "slight". 

 I can't see any sign of a significant course change in the final seconds of powered flight, so I think the rocket was off course since leaving the pad, and did a range safety shutoff once its IP got close the the range's boundary line.

« Last Edit: 09/18/2020 10:24 pm by zubenelgenubi »

Offline Frogstar_Robot

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What puzzled me was the statement the problem was due to "roll oscillation". However, if the rocket pitched but did not roll correctly, then that might explain the course deviation.
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Offline ringsider

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The time from impact to shockwave arrival indicates about a mile, maybe a little less, which is a very close fit to where you have the impact points.

You are right, the sound data is useful as well:

[zubenelgenubi: Embedded image deleted and attached.]
« Last Edit: 09/18/2020 10:25 pm by zubenelgenubi »

Online FutureSpaceTourist

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Quote
Astra finally launches its first orbital rocket, and it flew for 30 seconds
“For us, what's expensive is not learning.”

ERIC BERGER - 9/14/2020, 1:22 PM

After months of technical and weather delays, Astra launched its first orbital rocket on Friday night from a spaceport in southern Alaska.

https://arstechnica.com/science/2020/09/astra-finally-launches-its-first-orbital-rocket-and-it-flew-for-30-seconds/

Offline Pueo

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I wish I knew for sure where those two twitter filmers were. Then, I could easily figure out a trajectory.

The closer videographer has posted he was at the complex entrance, which gives us this:

https://i.imgur.com/0TWGMZT.png
Ringsider, thank you for this info, and the map and wind info!

The time from impact to shockwave arrival indicates about a mile, maybe a little less, which is a very close fit to where you have the impact points.

I tried to find those light polls (I thought they were antennas) and didn't - though now I do see them there in a sat view.

Looks like we have, thanks to your info, confirmation - Astra 3.1 was way off course. This is not the "slight oscillation" they claimed, or, they have a radically different definition of "slight". 

 I can't see any sign of a significant course change in the final seconds of powered flight, so I think the rocket was off course since leaving the pad, and did a range safety shutoff once its IP got close the the range's boundary line.

In the video Astra posted the camera is aimed south-southeast, and there's a slight movement to the right of frame as would be expected from the planned trajectory.  Small rockets tend to fly comparatively lofted trajectories because they suffer more from drag (thanks square-cube law) and Rocket Lab's quite shallow pitch-over doesn't even begin until T+ 20 s, so a very slight movement in the frame is also expected.  Of course this doesn't tell us what we really want to know, the trajectory to the north west, but it does tell us that the trajectory wasn't so off as to overfly the Astra camera.

The vehicle also completely lost stability after the FTS cut the engines, and the first stage could easily have found itself significantly off course thanks to its unexpected new career as a lifting body.  The second stage crash site appears to the right of that of the first stage in the twitter video, and to its left in the facebook video, suggesting that the two actually landed rather far apart, which in turn implies a very non-ballistic trajectory.

Annoyingly the most recent Landsat-2 images of Kodiak Island were taken 5 hours prior to launch, so we can't even snoop on the burn scars yet.  >:(
« Last Edit: 09/15/2020 01:27 am by Pueo »
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Offline FlattestEarth

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Quote
Astra finally launches its first orbital rocket, and it flew for 30 seconds
“For us, what's expensive is not learning.”

ERIC BERGER - 9/14/2020, 1:22 PM

After months of technical and weather delays, Astra launched its first orbital rocket on Friday night from a spaceport in southern Alaska.

https://arstechnica.com/science/2020/09/astra-finally-launches-its-first-orbital-rocket-and-it-flew-for-30-seconds/

Quote
The first stage for Rocket 3.2 is similar to its predecessor, but the company has upgraded its second stage to give it a better chance of reaching orbit.

So maybe something to the claim that the second stage on this launch was not capable of achieving orbit.

Offline QuantumG

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You can debate whether or not he's trustworthy after leaving, of course.

One can always trust Ben to say precisely what he believes.
Human spaceflight is basically just LARPing now.

Offline harrystranger

Thanks to the help in this thread I was able to find the impact site using Sentinel-2 imagery in true colour and near infrared  :)
https://twitter.com/HarryStrangerPG/status/1305702391723905025?s
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Offline Davidthefat

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Offline Comga

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I wish I knew for sure where those two twitter filmers were. Then, I could easily figure out a trajectory.

The closer videographer has posted he was at the complex entrance, which gives us this:


Assume that the rocket went straight up.
Assume constant acceleration while the engines are burning.
Ignore air resistance.
Use the times from launch to engine cut-off and impact, and the previously derived altitude and velocity.
Can we estimate the turn angle the flight path would have had to make to impact at the distance from the launch site derived above?
Is that reasonable or can we conclude that the rocket was off course?
« Last Edit: 09/18/2020 10:26 pm by zubenelgenubi »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline russianhalo117

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I wish I knew for sure where those two twitter filmers were. Then, I could easily figure out a trajectory.

The closer videographer has posted he was at the complex entrance, which gives us this:


Assume that the rocket went straight up.
Assume constant acceleration while the engines are burning.
Ignore air resistance.
Use the times from launch to engine cut-off and impact, and the previously derived altitude and velocity.
Can we estimate the turn angle the flight path would have had to make to impact at the distance from the launch site derived above?
Is that reasonable or can we conclude that the rocket was off course?
Astra stated they cut the engines as it was heading off course and couldn't be recovered because of the guidance software issue. This implies that trajectory deviated in an arc and they terminated the flight to stay on the range and not land on the inhabited parts of Kodiak which it would have ended over. The wind was to weak to account for the deviation thus the guidance system and residual thrust and shutdown venting is fully responsible for the deviation to the impact site as winds were negligible in contributions.
« Last Edit: 09/18/2020 10:27 pm by zubenelgenubi »

Offline Comga

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Didn’t they say there was an instability/oscillation in the guidance, not wholesale misdirection?

The calculation remains doable.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Celeste_El

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Topics a little old but better late than never. KMXT, a Kodiak radio station, reported on the crash and shared a good photo of the crash site.
https://kmxt.org/2020/09/rocket-crash-site-remediation-underway/

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