SpaceX And/Or Rocketry In General

robl
robl
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About 8.5 minutes from

About 8.5 minutes from ignition to 1st stage recovery.  Wow!!!!!

Mike Hewson
Mike Hewson
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I have been looking, again &

I have been looking, again & again, at the epic footage from the first stage during its descent from orbit right down to landing on the barge. You can see all control elements in play - thrusters, main engines and the waffle irons - directly producing all of the dynamic changes : roll, pitch, yaw and centre-of-mass accelerations. For instance it is now quite obvious why the barrel burn marks have been asymmetric, that vane on the uprange/lower side of the rocket sticking out when the downrange/upper one isn't*, causing pitch toward vertical ie. get it to point down. SpaceX has effectively written a brand new textbook on real-time control systems. I suggest the title :

How To Land A Thirty Tonne Chimney On A Dime From Orbit With A Cluster Of High Performance Rocket Engines Sitting Up Its A*** 

{ Maybe with a version For Dummies }

Plus the ( presumably thermal ) imaging of the stage separation was awesome.

And I saw it all live ! I am blessed ....

BTW : I think the video feed is line-of-sight and we miss the last few metres because it dips into surface clutter from whatever is relaying ie. the stage merges with some local horizon. After all everybody is standing off during the descent ! :-))

Cheers, Mike.

* Ditto for the unseen vanes on the other side.

( edit ) I think that SpaceX as a corporation is going to be 'OK' from now on. They will have failures again, but I reckon they'll rise to that. I wouldn't call it 'a start-up' any more. Their ability to problem solve many things, that could have otherwise been show-stoppers, is becoming legendary. It's probably time, or overdue, to neither blame nor credit Elon alone for this enterprise.

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

archae86
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Mike Hewson wrote:I think the

Mike Hewson wrote:
I think the video feed is line-of-sight and we miss the last few metres because it dips into surface clutter from whatever is relaying ie. the stage merges with some local horizon.

My pet theory is that there is a satellite uplink on the barge itself, and that the landing rocket shakes it enough to cause loss of signal on the link.  I think I read somewhere a while back that they had an idea or two of how to tinker with it to make it more tolerant.  It did seem to come back to life pretty quickly this time.

The big surprise, however, was seeing the rocket-eye view in real time very nearly down to contact.

Mike Hewson
Mike Hewson
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archae86 wrote:Mike Hewson

archae86 wrote:
Mike Hewson wrote:
I think the video feed is line-of-sight and we miss the last few metres because it dips into surface clutter from whatever is relaying ie. the stage merges with some local horizon.

My pet theory is that there is a satellite uplink on the barge itself, and that the landing rocket shakes it enough to cause loss of signal on the link.  I think I read somewhere a while back that they had an idea or two of how to tinker with it to make it more tolerant.  It did seem to come back to life pretty quickly this time.

Fair call. Speaking of the barge, the ocean swell I estimate at one or two metres. I mention that as the surface weather conditions at sea have to be OK in addition to at the launch pad for complete mission success. This is an interesting extra bound that the competitors of SpaceX don't ( normally ) have as a routine matter.

Cheers, Mike.

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

Gary Charpentier
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Not sure why, but all of a

Not sure why, but all of a sudden I had a thought about the first stage and what came before.  X-15.  About the same speed, and down range.  Obviously recovery is very different.

 

Mike Hewson
Mike Hewson
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Ah, here it is : Cheers,

Ah, here it is :

spacex_manual1.jpg

Cheers, Mike.

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

Mike Hewson
Mike Hewson
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This is modern publishing for

This is modern publishing for you :

spacex_manual2.jpg

Cheers, Mike.

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

Gary Charpentier
Gary Charpentier
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Mike Hewson
Mike Hewson
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Another foto from this fanboy

Another foto from this fanboy :

spacex_epic_landing1.jpg

... how good a shot is that ? The shadow cone, by happenstance, demonstrates nicely the accurate positioning of the stage just before landing. :-)

Cheers, Mike.

( edit ) Spaceflightnow is quoting the following :

Jan. 26 Falcon 9 • EchoStar 23 : Launch time: Approx. 0500-0730 GMT (12:00-2:30 a.m. EST) Launch site: LC-39A, Kennedy Space Center, Florida. A SpaceX Falcon 9 rocket will launch EchoStar 23 communications satellite for EchoStar Corp. EchoStar 23, based on a spare platform from the canceled CMBStar 1 satellite program, will provide direct-to-home television broadcast services over Brazil. Delayed from 3rd quarter, 4th quarter and Jan. 8. [Jan. 10]

Feb. 8 Falcon 9 • SpaceX CRS 10 : Launch time: 1855 GMT (1:55 p.m. EST) Launch site: LC-39A, Kennedy Space Center, Florida. A SpaceX Falcon 9 rocket will launch the 12th Dragon spacecraft on the 10th operational cargo delivery mission to the International Space Station. The flight is being conducted under the Commercial Resupply Services contract with NASA. Delayed from Feb. 13, June 10 and Aug. 1. Moved up from Nov. 21. Delayed from Nov. 11 and Jan. 22. [Jan. 13]
 
.... this being consistent with other statements signalling their desire to be clearing the backlog by launching every few weeks.

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

archae86
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Mike Hewson wrote:... how

Mike Hewson wrote:
... how good a shot is that ? The shadow cone, by happenstance, demonstrates nicely the accurate positioning of the stage just before landing. :-)

In addition to showing remarkably centered positioning, the three photos posted in that set:

Landing photo 1
Landing photo 2
Landing photo 3 

collectively suggest strongly that this was a single-engine landing.  Also someone posting elsewhere said that.

Since the three engine landing by simple physics is more fuel-efficient, this means they had a little bit of spare gusto on this mission.  But the fullest commitment to checking the toughest cases would seem to call for another 3-engine landing.  I wonder if they biased their choices toward improving the chances of visible success.  Another picture of a rocket blowing up was not just what their PR needs valued at this moment.

 

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