"Looks like thrust was low on 1 of 3 landing engines. High g landings v sensitive to all engines operating at max."
Lovely understatement ! That's the risk of the hover slam. It's a finesse* thing. In the end it winds up being the most efficient use of fuel ( to basically do a 'reverse launch' ) but the margin for error is slight.
Of extra interest would be which engine ? If not in the centre slot then you have a nastier additional problem of nett torque about wherever is the centre of mass ( which changes rapidly at that time ). These are high thrust engines and even a slight asymmetry would rotate it in pitch/yaw. If that is re-actively attended to by the vanes/thrusters then any translation is going to be of crab-wise nature. Not good and could give an ugly/skew attitude on first contact.
Cheers, Mike.
* This is a seriously like sliding a 300 + km/hr car nicely into a supermarket car park space while in full brake lock ! Brake rotors glowing, passengers screaming, tyres alight ...... pulls up two inches short of the shopping trolley full of eggs. :-)
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Here's the relevant consecutive frames ( RowVid reference ) as presented from the same camera :
looks upright and close to middle at least ! Seems it then fell over due to a landing leg(s) injury ??
Plus the left side is well alight, presumably the source of all the smoke :
Within the limits of what one can estimate* based on the mission clock overlay ( upper right hand screen corner ) this spans 'about' six seconds ( T +8:41 to 8:47 ) or more of appearing to be upright ....
Cheers, Mike.
* This is the longest continuous segment I could find without any repeat frames : 1600.80 to 1606.61 on the frame counter.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Elon Musk made a post on Twitter asserting that the stage ran out of LOX just before touching down, thus hit too hard and did major damage to both the structure and the engines.
There is a landing video in the post that appears to be taken from near sea surface level a fair distance away. Here is a direct link to the video.
Better yet, someone posted a stabilized version to youtube. This makes the barge motionless, which really helps clarify the final movement of the stage, which quite obviously speeds downward very late in the game.
That's a so very close but no cigar ... for want of a nail a shoe is lost ... the final un-powered drop is only of several metres. So the engine damage explains the fire and smoke then. Well they certainly seem to be exploring the parameter space. :-)
FWIW : I count four distinct gimbal corrections after the outer two engines were shutdown. If anything it appeared to stuff about a bit at around ~10+ metres before descending. But we only have one view point so who can say, again, was happening along line of sight.
Cheers, Mike.
( edit ) I understand a PR/business argument for losing the video feed 'accidentally' when mishaps occur, but I reckon SpaceX need not be so sensitive. It's unlike to change the opinion of either supporters or detractors, if anything such transparency is laudable. But it is probably not that simple eg. disclosing extra detail on failure modes may give clues to propriety design aspects. Who can say ?
( edit ) Sorry, let's not forget they punted two satellites at once to GSTO ! :-)))
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
( edit ) I understand a PR/business argument for losing the video feed 'accidentally' when mishaps occur, but I reckon SpaceX need not be so sensitive. It's unlike to change the opinion of either supporters or detractors, if anything such transparency is laudable. But it is probably not that simple eg. disclosing extra detail on failure modes may give clues to propriety design aspects. Who can say ?
I feel fairly certain that the goal of cutting video feeds when things go wrong is to provide SpaceX the opportunity to review the mishap and be sure that nothing is being revealed/given away that might help the competition. Once that is determined by reviewing the full video SpaceX will share the video - even if parts have been cut. I don't believe that Musk worries about mistakes. They happen. But he and his company have put a lot of $s into this effort and want to protect it.
On July 16 SpaceX will launch the Dragon Spacecraft to ISS but I don't know and the NASA site does not speak of any landing attempt. But the Falcon9 is carrying payloads to orbit, no matter what happens to its first stage.
Tullio
Elon Musk made a post on Twitter asserting that the stage ran out of LOX just before touching down, thus hit too hard and did major damage to both the structure and the engines.
Quote:
That's a so very close but no cigar ... for want of a nail a shoe is lost ... the final un-powered drop is only of several metres. So the engine damage explains the fire and smoke then. Well they certainly seem to be exploring the parameter space. :-)
Brings to mind a couple of non-space anecdotes.
1. A number of years ago, I drove my father to Baltimore to pick up a car he'd bought on eBay. Coming back on the Ohio Turnpike, I ran out of gas just as we were approaching a rest stop. I coasted right in and up to the gas pump... except I had to stop short because there was a line, and he had to push me the last few feet.
2. A larger number of years ago, an Amtrak train that ran south from Washington, DC, sat overnight, and returned the next morning, started running out of fuel before it got back. The big question was why, since it was being refueled at the layover by a local contractor. Finally, someone came down from headquarters and got together with the local trainmaster. They staked out the layover point and watched the contractor come and pump fuel into the locomotive. Then he climbed up on top of his truck and pumped more fuel right back into it. When he got to the proper total amount pumped, he printed out the slip for billing... and was arrested. He admitted he'd been gradually increasing the amount of his theft, looking for the amount with which the train would just barely make it. Amtrak found a new contractor.
[/irrelevance]
David
Miserable old git
Patiently waiting for the asteroid with my name on it.
On July 16 SpaceX will launch the Dragon Spacecraft to ISS but I don't know and the NASA site does not speak of any landing attempt
Apparently someone at SpaceX told the Verge in mid-May that CRS-9 was planned for an attempted RTLS recovery. (Return to Launch Site). So that would be a second try at using the recovery pad at the Cape.
While Dragon is fairly heavy, the desired orbit is far less energetic than the ones generally given to stuff on the way to geostationery orbit, so the first stage can have lots more spare delta-V.
Folks posting at the NSF site think that at landing weight the single engine is not spec'd to throttle back far enough to give less than one g acceleration. Close, but not below. They further think they see the stage in the video appearing to converge toward "landing" a good bit too high, then only speeding up in the downward direction as thrust tails off from the LOX depletion (one asserts this is a controlled sequence, not just letting the fluids do their thing).
If this is all true it makes a yet stronger case for how tight the trajectory management has to be in order to succeed, and it also suggests (to my mind) that they had enough fuel/oxidizer aboard to succeed this time had the trajectory gone a bit better in the approach to the end game. To defend my case on the "had enough" thought I'll observe that they seem to have had enough spare oomph to fuel more than two seconds of near-hovering flight, all pure loss from a useful outcome point of view.
RE: "Looks like thrust was
)
Lovely understatement ! That's the risk of the hover slam. It's a finesse* thing. In the end it winds up being the most efficient use of fuel ( to basically do a 'reverse launch' ) but the margin for error is slight.
Of extra interest would be which engine ? If not in the centre slot then you have a nastier additional problem of nett torque about wherever is the centre of mass ( which changes rapidly at that time ). These are high thrust engines and even a slight asymmetry would rotate it in pitch/yaw. If that is re-actively attended to by the vanes/thrusters then any translation is going to be of crab-wise nature. Not good and could give an ugly/skew attitude on first contact.
Cheers, Mike.
* This is a seriously like sliding a 300 + km/hr car nicely into a supermarket car park space while in full brake lock ! Brake rotors glowing, passengers screaming, tyres alight ...... pulls up two inches short of the shopping trolley full of eggs. :-)
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Here's the relevant
)
Here's the relevant consecutive frames ( RowVid reference ) as presented from the same camera :
looks upright and close to middle at least ! Seems it then fell over due to a landing leg(s) injury ??
Plus the left side is well alight, presumably the source of all the smoke :
Within the limits of what one can estimate* based on the mission clock overlay ( upper right hand screen corner ) this spans 'about' six seconds ( T +8:41 to 8:47 ) or more of appearing to be upright ....
Cheers, Mike.
* This is the longest continuous segment I could find without any repeat frames : 1600.80 to 1606.61 on the frame counter.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Elon Musk made a post on
)
Elon Musk made a post on Twitter asserting that the stage ran out of LOX just before touching down, thus hit too hard and did major damage to both the structure and the engines.
There is a landing video in the post that appears to be taken from near sea surface level a fair distance away. Here is a direct link to the video.
Better yet, someone posted a stabilized version to youtube. This makes the barge motionless, which really helps clarify the final movement of the stage, which quite obviously speeds downward very late in the game.
That's a so very close but no
)
That's a so very close but no cigar ... for want of a nail a shoe is lost ... the final un-powered drop is only of several metres. So the engine damage explains the fire and smoke then. Well they certainly seem to be exploring the parameter space. :-)
FWIW : I count four distinct gimbal corrections after the outer two engines were shutdown. If anything it appeared to stuff about a bit at around ~10+ metres before descending. But we only have one view point so who can say, again, was happening along line of sight.
Cheers, Mike.
( edit ) I understand a PR/business argument for losing the video feed 'accidentally' when mishaps occur, but I reckon SpaceX need not be so sensitive. It's unlike to change the opinion of either supporters or detractors, if anything such transparency is laudable. But it is probably not that simple eg. disclosing extra detail on failure modes may give clues to propriety design aspects. Who can say ?
( edit ) Sorry, let's not forget they punted two satellites at once to GSTO ! :-)))
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
RE: Cheers, Mike. ( edit
)
I feel fairly certain that the goal of cutting video feeds when things go wrong is to provide SpaceX the opportunity to review the mishap and be sure that nothing is being revealed/given away that might help the competition. Once that is determined by reviewing the full video SpaceX will share the video - even if parts have been cut. I don't believe that Musk worries about mistakes. They happen. But he and his company have put a lot of $s into this effort and want to protect it.
double post removed by author
)
double post removed by author
On July 16 SpaceX will launch
)
On July 16 SpaceX will launch the Dragon Spacecraft to ISS but I don't know and the NASA site does not speak of any landing attempt. But the Falcon9 is carrying payloads to orbit, no matter what happens to its first stage.
Tullio
RE: Elon Musk made a post
)
Brings to mind a couple of non-space anecdotes.
1. A number of years ago, I drove my father to Baltimore to pick up a car he'd bought on eBay. Coming back on the Ohio Turnpike, I ran out of gas just as we were approaching a rest stop. I coasted right in and up to the gas pump... except I had to stop short because there was a line, and he had to push me the last few feet.
2. A larger number of years ago, an Amtrak train that ran south from Washington, DC, sat overnight, and returned the next morning, started running out of fuel before it got back. The big question was why, since it was being refueled at the layover by a local contractor. Finally, someone came down from headquarters and got together with the local trainmaster. They staked out the layover point and watched the contractor come and pump fuel into the locomotive. Then he climbed up on top of his truck and pumped more fuel right back into it. When he got to the proper total amount pumped, he printed out the slip for billing... and was arrested. He admitted he'd been gradually increasing the amount of his theft, looking for the amount with which the train would just barely make it. Amtrak found a new contractor.
[/irrelevance]
David
Miserable old git
Patiently waiting for the asteroid with my name on it.
Tullio wrote:On July 16
)
Apparently someone at SpaceX told the Verge in mid-May that CRS-9 was planned for an attempted RTLS recovery. (Return to Launch Site). So that would be a second try at using the recovery pad at the Cape.
While Dragon is fairly heavy, the desired orbit is far less energetic than the ones generally given to stuff on the way to geostationery orbit, so the first stage can have lots more spare delta-V.
Folks posting at the NSF site
)
Folks posting at the NSF site think that at landing weight the single engine is not spec'd to throttle back far enough to give less than one g acceleration. Close, but not below. They further think they see the stage in the video appearing to converge toward "landing" a good bit too high, then only speeding up in the downward direction as thrust tails off from the LOX depletion (one asserts this is a controlled sequence, not just letting the fluids do their thing).
If this is all true it makes a yet stronger case for how tight the trajectory management has to be in order to succeed, and it also suggests (to my mind) that they had enough fuel/oxidizer aboard to succeed this time had the trajectory gone a bit better in the approach to the end game. To defend my case on the "had enough" thought I'll observe that they seem to have had enough spare oomph to fuel more than two seconds of near-hovering flight, all pure loss from a useful outcome point of view.