# From which direction was the Falcon 9 1st stage's landing approach (BulgariaSat-1)?

Looking at this cropped section of the screenshot described below, this is what I think I see:

• A: Shadow from the leg support on the right, but not the left.
• B: Scorch marks?
• C: Scorch marks?
• D: Shadow of the Falcon 9 first stage?

At an estimated time of UTC 2017-06-23 19:19 and a roughly estimated location of 29°N, 76°W, the sun would have had an elevation of about 60° above the horizon, and an azimuth of about 267°, or nearly due West.

Considering that the seas look incredibly calm, and the engines (nacelles?) should be well below the surface, the sudden appearance of rough water and spray on the left side moments before landing is probably the result of exhaust from the rocket just outside the camera's view.

I can imagine two possibilities.

1. The last few seconds of the final approach was roughly from the East, not the West. If so, was this a planned maneuver or is this just a tiny overshoot in an otherwise heroic three engine landing?
2. The last few seconds of the final approach was indeed roughly from the West as one might expect, or was vertical, but the stage was tilted substantially so that the bottom swung out towards the west and stirred up the water and scorched the west side of the landing surface.

Is it known which is a better understanding of the last few seconds, or if a different description is needed?

above: cropped/annotated sections from screen shots below from the SpaceX BulgariaSat-1 Launch Webcast.

• I'm voting to close because complete footage of the landing should be available in a matter of days, and anything prior to that would be guesswork. – Russell Borogove Jun 24 '17 at 17:40
• And also, Comic Sans. – Russell Borogove Jun 24 '17 at 17:40
• @RussellBorogove I'm not sure why you would sell all 12,000 users short and pre-decide nobody could possibly know the answer. Just because you don't see a clear path to an answer, does not mean there is none. Why not give this 24 hours and see? Why the insta-close? Is it the font of the four letters that set you off? I hadn't noticed, but that's easy to fix. I'll take care of that right now. Further what basis is there really for closing a question because you feel it can't be answered for a matter of days? I've never heard of that. Why not give people a heads up? Why must it be prevented? – uhoh Jun 24 '17 at 18:04
• @RussellBorogove the problem is that now you know that the question is asked, and want close it but leave the door open to re-opening in a few days when more footage is available, it looks a little bit like this. Of course I am sure in this case you aren't doing that, but wow, it fits the description to a "T". To reiterate, that question is not about you; and I've seen first hand and appreciated your careful curation of posts. – uhoh Jun 24 '17 at 18:12
• – Russell Borogove Jun 24 '17 at 18:52

## 1 Answer

The landing had tighter timing than usual (see Why were three engines used for the F9 1st stage landing burn (BulgariaSat-1)?), which means less room for corrections.

Elon Musk tweeted: Rocket was suddenly slammed sideways right before landing. Heavy gust or something malfunctioned onboard. Reviewing telemetry.

Assuming the booster did work correctly, it seems the first stage was offset in the last moments of landing by a wind gust and due to the faster landing there was less room to compensate.

• I'm wondering if there has been any further information about this landing. Do you know if footage was ever released, or if SpaceX has made any further comment? Thanks! – uhoh Jul 14 '17 at 5:28
• Have you heard anything further? – uhoh Jul 24 '17 at 14:09
• @uhoh: The only thing I was able to find is the report on Spaceflight 101 but while it does have a lot of information it also doesn't tell whether it was a wind gust or something else. Haven't been able to find a tweet by Elon or some other information. – DarkDust Jul 24 '17 at 18:09
• OK since nothing seems imminently forthcoming, and the prediction that "complete footage of the landing should be available in a matter of days" seems to "have been greatly exaggerated", I'll just accept. Thank you very much for your help with this question! – uhoh Jul 24 '17 at 18:34