SpaceX F9 : Starlink 5 (v1.0 L4) : Feb. 17, 2020 : Master Thread

[EspenU]

They should develop an AI algorithm to drive the fairing catch boats, I think its too many variables to instinctively predict. Maybe a crazy idea.

Or just train the crew on simulators between missions (my company makes ship simulators ).

[mme]

They should develop an AI algorithm to drive the fairing catch boats, I think its too many variables to instinctively predict. Maybe a crazy idea.

I'd fall out of my chair if it turns out they are not already heavily leveraging machine learning. I mean his other company designed their own hardware specifically optimized for processing neural networks.

This is just a hard problem that will take time to get reliable.

[lesumsi]

They should develop an AI algorithm to drive the fairing catch boats, I think its too many variables to instinctively predict. Maybe a crazy idea.

AFAIK, they're already controlled by a computer and not a human during the catch attempt. You don't need AI for this, there's control software out there. They just have to figure out the settings 

[mme]

They should develop an AI algorithm to drive the fairing catch boats, I think its too many variables to instinctively predict. Maybe a crazy idea.

Or just train the crew on simulators between missions (my company makes ship simulators ).

Am I missing some article stating that a human is controlling the vessel during the catch? That would be the shock of the century to me.

[trryhin]

Was that an aircraft in the S1 feed around 3:43 elapsed time lasting ~10 seconds?

I believe that may have been a fairing half.

[thirtyone]

Is the new black paint/coating at the fairing tip new for this flight? Given the lack of circular symmetry, I'm pretty sure it's somehow related to re-entry of the fairing halves.

I've always thought Starlink was actually an opportunity for SpaceX to experiment with things that most normal customers wouldn't let them do. This effectively makes them even cheaper than normal launches. I have this sneaking suspicion, particularly for this flight, that they were playing around with some parameters for their booster that may have resulted in the landing failure...

[rpapo]

Is the new black paint/coating at the fairing tip new for this flight? Given the lack of circular symmetry, I'm pretty sure it's somehow related to re-entry of the fairing halves.

They've had that special coating on the fairing tip for quite a few flights now.

[mn]

They should develop an AI algorithm to drive the fairing catch boats, I think its too many variables to instinctively predict. Maybe a crazy idea.

AFAIK, they're already controlled by a computer and not a human during the catch attempt. You don't need AI for this, there's control software out there. They just have to figure out the settings 

Or perhaps the variables exceed the capabilities of the ship (can't move/change course fast enough to react to conditions). I'm sure a VR ship driven by AI would have no problem catching a fairing, problem is getting a physical boat to do that, perhaps they need a hovercraft.

I'm sure this fairing catching does not belong in this thread, but I can't seem to find the correct thread.

Edit: And I see that a hovercraft idea was already floated and shot down way back here: https://forum.nasaspaceflight.com/index.php?topic=37727.msg1898379#msg1898379

[jak Kennedy]

They should develop an AI algorithm to drive the fairing catch boats, I think its too many variables to instinctively predict. Maybe a crazy idea.

AFAIK, they're already controlled by a computer and not a human during the catch attempt. You don't need AI for this, there's control software out there. They just have to figure out the settings 

Or perhaps the variables exceed the capabilities of the ship (can't move/change course fast enough to react to conditions). I'm sure a VR ship driven by AI would have no problem catching a fairing, problem is getting a physical boat to do that, perhaps they need a hovercraft.

I'm sure this fairing catching does not belong in this thread, but I can't seem to find the correct thread.

Edit: And I see that a hovercraft idea was already floated and shot down way back here: https://forum.nasaspaceflight.com/index.php?topic=37727.msg1898379#msg1898379

A normal hovercraft yes. But I think a hovercraft with azimuth thrusters (hanging down into the water) would be nimbal enough.

[JamesH65]

Seems to me that that first stage landed quite close to the booster, and it was a soft landing; that pretty much means that the harder profile was successful - seem more likely to be a navigation problem than something causes by the difficult profile. e.g. drifting of the barge and unable to station keep for some reason, rather than running out of fuel or coming in too hot.

[whitelancer64]

Seems to me that that first stage landed quite close to the booster, and it was a soft landing; that pretty much means that the harder profile was successful - seem more likely to be a navigation problem than something causes by the difficult profile. e.g. drifting of the barge and unable to station keep for some reason, rather than running out of fuel or coming in too hot.

The booster targets its ballistic descent to miss the ASDS. It corrects to land on the ship during the landing burn. If anything is off nominal, then it will not correct its course so as to intentionally miss the landing.

[Alexphysics]

Was that an aircraft in the S1 feed around 3:43 elapsed time lasting ~10 seconds?

I believe that may have been a fairing half.

It is a chunk of ice coming off the LOX tank. The fairings are very far away from the booster to be seen, let alone the fact they wouldn't be under the booster but over it.

[clongton]

The booster targets its ballistic descent to miss the ASDS. It corrects to land on the ship during the landing burn. If anything is off nominal, then it will not correct its course so as to intentionally miss the landing.

Correct. I don't think anything actually went wrong however. When you couple what whitelancer64 said together with the fact that the Merlin engines cannot hover, and the very hot ballistic reentry trajectory, it is my opinion that the most likely scenario is that the flight computer decided that it had missed the zero target by too much to correct in time for the landing translation and so aborted the translation maneuver, soft landing in the sea instead. It was simply too large a delta from zero to correct in time. To it's credit, Falcon 9 knew that and executed the appropriate action.

[Comga]

Was that an aircraft in the S1 feed around 3:43 elapsed time lasting ~10 seconds?

I believe that may have been a fairing half.

It is a chunk of ice coming off the LOX tank.
The fairings are very far away from the booster to be seen, let alone the fact they wouldn't be under the booster but over it.

The relative direction is a good point, but I don't know about the distance.
It's too small to make out a clear shape, and the motion is smooth.
Frozen LOX is a likely candidate.

[matthewkantar]

I think the new flight plan and the missed landing are evidence the sats are getting heavier. launching 59 or 54 is apparently not an option.

[AndrewRG10]

It would be interesting to find out why it missed the drone ship. We have to remember though the booster/core always aims for the water before dog legging to the drone ship or LZ-1/LZ-2. Hardware could have been fine, but maybe booster velocity was too hot where damage to OCISLY could occur from impact and it decided to abort or any other criteria that needed to be met for that dog leg to occur wasn't met. Remember the last FH launch, the center core was seen aborting away from the drone ship.

I think it is silly to speculate that there was a hardware failure every time we see ice fall off the booster, sparks coming from the engine, etc.

Though LZ landing divert much sooner than droneship landing. RTLS landings begin the dogleg once re-entry burn has finished. I didn't realise this till Scott Manely pointed it out but they don't dogleg to the droneship till the legs are extended, obviously after Jason-3.

[sferrin]

I think the new flight plan and the missed landing are evidence the sats are getting heavier. launching 59 or 54 is apparently not an option.

I'd wager satellite weight had exactly zero to do with the missed landing.

[alienmike]

I think the new flight plan and the missed landing are evidence the sats are getting heavier. launching 59 or 54 is apparently not an option.

I'd wager satellite weight had exactly zero to do with the missed landing.

I'm going to wager you are wrong. I think they gave the satellites a little extra boost for the new orbital insertion, using just a little more fuel. My guess is, they ran out of fuel on the landing burn. I'm sure we will know something soon.

[su27k]

I think the new flight plan and the missed landing are evidence the sats are getting heavier. launching 59 or 54 is apparently not an option.

You can take a look at the side by side comparison of this launch and previous Starlink launch:

This side-by side comparison shows the difference in profile between the last two Starlink launches - most obvious from +- 10 km up - and also highlights how much they read from script in the webcast :-D

http://www.youtubemultiplier.com/5e4ad79dab043-starlink-side-by-side.php

This launch's MECO is early and at a lower speed (7840 km/h vs 8078 km/s), so they're taking it easy with this booster, the landing issue is not caused by them pushing it too hard.

[Pete]

It is a chunk of ice coming off the LOX tank.
The fairings are very far away from the booster to be seen, let alone the fact they wouldn't be under the booster but over it.

The relative direction is a good point, but I don't know about the distance.
It's too small to make out a clear shape, and the motion is smooth.
Frozen LOX is a likely candidate.

The fairings are separated some 30 seconds after S2 ignition.
That is 30 seconds of just about 1g of acceleration. The fairings will be about 4km ahead, and moving at 270m/s faster on a very similar trajectory, i.e. ahead and above S1, at separation. At 3:45, another 30 seconds later, the fairings will have coasted on to a distance of about 12km from S1.


Frozen LOX:...
It is definitely frozen something, that blip at 3:45 seems to originate from the same location as the later spiral extrusion will form. I say "seems", because the linear position matches. Scale is impossible to know, thus distance and relative velocity are impossible to know. Color and origin seems to match though.