The glow on the Kestrel engine was very similar to the glow - in colour and texture, to that on a Delta II second stage - I didn't see anything there I would consider unusual, and indeed upper stage nozzles seem to be very flexible - certainly the Delta II upper stage engine wobbles around quite a lot.

Sloshing sounds like a very convincing scenario. Hopefully Elon will continue his applaudable record of reporting events quite regularly and honestly and we'll soon know what actually happened.

Doug

For a test flight, it was certainly not a complete failure. They demonstrated a lot of good things, and the test of the first stage seems to have been almost completely successful.

If this was an opreational launch, though, it would have been a complete failure, no matter how well the first stage worked. The paying customer would have had his/her expensive satellite dumped into the ocean. That's the real definition of success or failure -- did you deliver the package where the customer wanted it to go?

As tempting as SpaceX's pricing seems to be, I know that if I had a payload that I really needed to place into orbit, I would definitely wait until the Falcons started flying successfully before I spent any money on them. Then again, I wouldn't buy the first model year of, say, a fuel-cell-powered car or a car with a hydrogen engine, either. I'd wait to see how well they work and what the service and maintenance issues *really* are, not just what the salespeople want me to believe they are...

-the other Doug

Quite agree - but if I had a cheap mission that was cash limited to the point of launching on a cheap Falcon in Q1-08, or not launching at all...I'd go for the Falcon.

Doug

Doug - is there something you want to tell us about Q1-08? Are you planning a UMSF microsat or perhaps another shed in LEO?

I wish DougSat is still a pipe dream.

I vote for a sail-powered package to Titan. Sail doubles as aero-capture device/parachute on arrival.

Maybe we should all pitch in for a pongsat ad....

Imagine the UMSF logo up here!

The video I recorded is about 150 mb. It starts half an hour or so (out of 45 minutes total) before the second countdown, so it could probably be trimmed down quite a bit. It seems to be pretty much identical in quality to the high quality wmv on this page, so unless someone wants the full countdown, there's probably not much point in trying to get it out there.

I grabbed this point-of-impact image from the hi-res video

Oooh - that would be very, very cool.

Back to the topic in question. SpaceX explicitly say that the second stage engine nozzle\bell is designed to take a bit of impact debris at separation but that was quite a smack, maybe they designed it to deal with such events but it sure looks dodgy as hell to me.

Looks to me their biggest problem was attitude control. Engines performed well, which is great news. The staging sequence introduced some big attitude disturbance that was probably the culprint causing recontact with the first stage.

A big part of the second stage burn also exhibited wobbly attitude and the engine nozzle was jittering noticeably the whole time. Things started to get very rough at T+04:42 and obviously soon after the thrust vector control reached its maximum authority with the nozzle making rough circles. It managed to keep the heading pretty well, though. It's even possible the oscillations would have died down after a peak, but we'll never know.

At T+04:55 the vehicle started to roll and that's probably what lead to LOS and automatic engine shutdown. Whether the attitude drift and roll problems were linked is the big question, I understand roll control is maintained via cold helium gas jets and it was speculated there could have been a leak somewhere.
That still leaves the question why engine pitch/yaw gimbal was having such a hard time keeping the vehicle steady.

Well, they don't call it an 'Hourman' Missle. The fastest turn around is an always loaded motor. The US has a lot of those.

If the bouncy seperation did not cause the control anomally, they have at least two problems...three if you include a credibility problem (great outcome?).

As an outside observer I agree with their assesment. As for credibility, I'm not sure where you are getting that.

I agree with ugordan's observations re control system difficulties. Given the impact, I have to wonder if one of the nozzle position sensors was affected (perhaps knocked out of calibration?) Oscillating control commands are usually caused by insufficient position feedback or rate sensing if the system itself is malfunctioning. I assume that they used linear variable differential transformers (LVDTs) or something else with high reliability and hopefully redundant channels; if they used feedback potentiometers or rely on single sensors, that could be bad...

Another possibility is that the rate sensors for the second stage aren't located in exactly the right place on the vehicle, I guess, but this seems unlikely.

The fuel sloshing scenario sounds plausible as well, but I can't imagine that they wouldn't have baffles in the tanks to prevent this sort of thing. Unpredictable center of gravity shifts are hard to compensate for...

http://www.youtube.com/watch?v=NE4HkniM3Vc...ted&search=

This video on youtube goes a bit longer than the live webcast and the video posted on the SpaceX site.

The last frame shows a time of +5 min, 14 sec, compared with the 5:01 "official version"

The sequence shows the slow roll that is visible in the last few "official" seconds of video rapidly increases in speed, together with the probable start of a tumbling motion. When the video cuts off, the total roll is somewhere around 3/4 of a turn and the speed is rapidly increasing. The last oscillation of the nozzle seems to be almost violent (the oscillation amplitude steadily increases with time) and rather out of step with the previous oscillations.

In addition, something nobody's noted here or on the Nasaspaceflight.com forum (that I can see)

http://forum.nasaspaceflight.com/forums/forum-view.asp?fid=6

is that at T+4:44, there is a long recangular, square-ended piece of white debris (like a segment of a window blind) falls past the camera and is visible for a few frames. The oscillations of the engine and vehicle get stronger rapidly starting maybe 3 seconds after this event, and more debris, most looking perhaps like shredded insolation or irregular shed ice pieces fall past the camera, the overall abundance of visible debris generally increases in the last 30 seconds. Other pieces are not clearly identifiable as discrete objects like the "slat" at 4:44, but it's clear things are being shaken nearly to bits.

I would not be surprised if at or just after the end of the youtube video, the vehicle had a major structural failure, as suggested by the extra-violent irregular motion in the last 1/2 second of video.

Beyond all this post-mortem analysis, the fact remains that they had a test flight that was a mission failure, but achieved some 90% of "detailed test objectives". In that, it resembles the flights of Saturn 502 (Apollo 6, which made orbit but had multiple problems and failed S-IVB restart) or the Delta IV Heavy (which didn't make the proper orbit and dropped secondary payloads into atmosphere-intercepting orbits.)

They have made a major step toward orbit with a totally new vehicle and should be congratulated.