FAILURE: Astra Rocket 3.3 – STP-27AD1 – Kodiak – August 28, 2021 (22:35 UTC)

[LouScheffer]

Plenty resilient on the TVC front. In principle you could lose 3 engines and still have total control in every axis. The programming would be a nightmare, and your control margins will still be tiny, but in terms of the physics it's an option.

The programming should be much easier then the all-engines available case.  You have two vectors you can choose, and they need to sum to a third vector.  There's no ambiguity - it's two equations in two unknowns.   In the regular case, you have many more variables than you need, and you have to pick one solution among many, optimizing for other constraints.  It's a much harder math problem.

[FlatFootShift]

Any update on when a next launch is being planned for?

[TrevorMonty]

Its little details that matter, like engines that run till MECO.

https://twitter.com/Astra/status/1435987623902842883?s=19

Sent from my SM-G570Y using Tapatalk

[edkyle99]

Firefly has kept the public informed about the broad path of its early-engine-shut-down investigation.  Anything from Astra on its somewhat similar issue?

 - Ed Kyle

[harrystranger]

Imagery from Sentinel-2 shows the scar left by Rocket 3.3 as it did it's slide off of the pad. Comparison in the gif attached below 
Measured to be ~80m long.

[Comga]

So Firefly got up 50,000 ft without getting offshore and Astra got offshore without gaining any altitude.

We could suggest they collaborate but the combination might be a pad explosion.

[Chris Bergin]

https://twitter.com/ChrisG_NSF/status/1447910039751208962

[lightleviathan]

An interesting tidbit about lv0006's launch, it was terminated by the range because they had the wrong trajectory loaded (rocket 3.2), it could've actually made it to orbit and was on its way too!
https://twitter.com/Kemp/status/1849906891310420030

Fun fact: This rocket returned to its  planned trajectory and was on its way to orbit when, to our surprise, it was terminated by the range because the trajectory of our previous launch was loaded into their computer, and they thought it was flying off course.

Would it have had the performance to reach the target orbit? Surely spending a lot of time at a near 1:1 TWR wasted a lot of propellant.

https://twitter.com/Kemp/status/1849923162034884816

Yes

[zubenelgenubi: edit/split/merge]

[cpushack]

The Range's error certainly cost shareholders a bit LOL

[pilottim]

The range did not make a mistake. The updated azimuth was never given to the range. They were also already extremely off any planned trajectory incorrect or correct by 2:30. This is purely the company. If they wanted to 1) fly with incorrect range data and 2) being allowed to fly despite anomalies then they should have flown under a government launch license.

[brussell]

The range did not make a mistake. The updated azimuth was never given to the range.

Source? You are suggesting that Chris (and other insiders) are lying?

They were also already extremely off any planned trajectory incorrect or correct by 2:30.

So what? If it was inside the flight termination bounds it should have continued flying, and the point of terminal guidance is to fix that.

[brussell]

Plenty resilient on the TVC front. In principle you could lose 3 engines and still have total control in every axis. The programming would be a nightmare, and your control margins will still be tiny, but in terms of the physics it's an option.

The programming should be much easier then the all-engines available case.  You have two vectors you can choose, and they need to sum to a third vector.  There's no ambiguity - it's two equations in two unknowns.   In the regular case, you have many more variables than you need, and you have to pick one solution among many, optimizing for other constraints.  It's a much harder math problem.

(I know this is very old but) This is a simple matrix pseudoinverse. Unless you are trying to do something funny it makes little difference if it's 5, 3 or 2.

[pilottim]

Source? You are suggesting that Chris (and other insiders) are lying?

So what? If it was inside the flight termination bounds it should have continued flying, and the point of terminal guidance is to fix that.

Kemp didn't lie ofc, he's always careful about this. It was indeed the previous azimuth but not because the range made a mistake uploading something. The company should have double checked. The range, with their responsibility to the public, saw a rocket clearly missing one of its engines and dumping prop for 15 seconds, not even reaching MECO by that time, so they terminate it because at that point it is unclear if being allowed to continue would not damage public safety.

[mn]

Source? You are suggesting that Chris (and other insiders) are lying?

So what? If it was inside the flight termination bounds it should have continued flying, and the point of terminal guidance is to fix that.

Kemp didn't lie ofc, he's always careful about this. It was indeed the previous azimuth but not because the range made a mistake uploading something. The company should have double checked. The range, with their responsibility to the public, saw a rocket clearly missing one of its engines and dumping prop for 15 seconds, not even reaching MECO by that time, so they terminate it because at that point it is unclear if being allowed to continue would not damage public safety.

Ignore all that happened, just answer one simple question: WHERE WAS THE VEHICLE AND WHAT WAS IT DOING at the time the terminate command was sent. Just one simple question, which should probably be the only criteria the range would be looking at. was it out of bounds? or was it going in a direction which will momentarily take it out of bounds? YES or NO

[pilottim]

Ignore all that happened, just answer one simple question: WHERE WAS THE VEHICLE AND WHAT WAS IT DOING at the time the terminate command was sent. Just one simple question, which should probably be the only criteria the range would be looking at. was it out of bounds? or was it going in a direction which will momentarily take it out of bounds? YES or NO

The vehicle was at least 15 seconds late to hitting its planned trajectory. So, by definition, it was out of allowed bounds and the range could not confirm it was able to hit its planned trajectory even if it was momentary in its planned trajectory due to an anomaly. That is their responsibility to public safety. This is a very simple yes to that question.

[edzieba]

Ignore all that happened, just answer one simple question: WHERE WAS THE VEHICLE AND WHAT WAS IT DOING at the time the terminate command was sent. Just one simple question, which should probably be the only criteria the range would be looking at. was it out of bounds? or was it going in a direction which will momentarily take it out of bounds? YES or NO

The vehicle was at least 15 seconds late to hitting its planned trajectory. So, by definition, it was out of allowed bounds and the range could not confirm it was able to hit its planned trajectory even if it was momentary in its planned trajectory due to an anomaly. That is their responsibility to public safety. This is a very simple yes to that question.

That depends on what criteria the range uses for the safety corridor. Just position and vector? Position and vector and rates for both? Position and vector and rates and proposed vs. actual timeline? Instantaneous IIP? Different combinations for different phases of flight?
It is not a 'simple' yes.

::EDIT:: 'Engine goes pop, vehicle completes mission anyway' is not without precedence. e.g. Vulcan Cert-2, CRS-1. Just being off timeline does not mean an unsafe ascent.

[brussell]

Ignore all that happened, just answer one simple question: WHERE WAS THE VEHICLE AND WHAT WAS IT DOING at the time the terminate command was sent. Just one simple question, which should probably be the only criteria the range would be looking at. was it out of bounds? or was it going in a direction which will momentarily take it out of bounds? YES or NO

The vehicle was at least 15 seconds late to hitting its planned trajectory. So, by definition, it was out of allowed bounds and the range could not confirm it was able to hit its planned trajectory even if it was momentary in its planned trajectory due to an anomaly. That is their responsibility to public safety. This is a very simple yes to that question.

No. This is just not true. The range is looking for:
- Rocket not tumbling
- IIP within azimuth bounds (what triggered in this flight)
- High altitude limit vs downrange (so it doesn't fly back)

There can be a few other things that are a bit more complicated, like low altitude limits vs downrange or other types of gates, and I am not sure if Astra used those. An engine off is likely to alert them to be ready for the other criteria, but by itself it's not ground for flight termination. There is no such thing as "being 15 seconds late".

I'll give you that perhaps Astra dropped the ball giving the updated trajectory to the range, or there was some miscommunication there. Certainly Kemp's wording leaves that open.

But you are wrong that the range should have shut down the rocket anyway just because it was underperforming.