SpaceX And/Or Rocketry In General

archae86
archae86
Joined: 6 Dec 05
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All's well that ends

All's well that ends well.

While if not expected the booster going kablooey a while after Dragon pulled away might seem disconcerting, it was actually predicted that it would not survive "dragon fire" as Elon put it.  It actually lasted longer than I personally had guessed from that statement.

So far I've not seen or heard of any anomalies--though I'm sure that deep enough in the data there are things not quite as wished or expected.

This is a very big milestone on the way to US hardware once again carrying crew to ISS.  Maybe our purchases of Soyuz flights will finally end someday.  Though I suspect NASA would like two different systems up and running before they burn that bridge completely.

 

archae86
archae86
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On the Dragon abort test,

On the Dragon abort test, there had been some discussion on whether the escape rockets would fire before or after the mains had finished shutting down.  This amateur photo at just the right moment pretty clearly shows both burning at once:

Anonymous

The amateur says it all. 

The amateur photo says it all.  Incredible shot!!  Cant imagine what the g-forces are like.  

archae86
archae86
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While the amateur photo makes

While the amateur photo makes the point, SpaceX has published (by Twitter) a five second video centered on the separation which really shows the sequencing of the engines well, and is also pretty.

SpaceX video of Dragon separation

The latest version of the sequencing, still subject to some discussion:

1. the flight software had at least one parameter tweaked deliberately to trigger an abort sequence at the desired time.

2. The abort sequence commanded main engine shutdown on the booster stage

3. (very) shortly later the abort sequence commanded the Super Draco engines on Dragon to pull Dragon away.

 

 

Gary Charpentier
Gary Charpentier
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archae86 wrote:While the

archae86 wrote:

While the amateur photo makes the point, SpaceX has published (by Twitter) a five second video centered on the separation which really shows the sequencing of the engines well, and is also pretty.

SpaceX video of Dragon separation

The latest version of the sequencing, still subject to some discussion:

1. the flight software had at least one parameter tweaked deliberately to trigger an abort sequence at the desired time.

2. The abort sequence commanded main engine shutdown on the booster stage

3. (very) shortly later the abort sequence commanded the Super Draco engines on Dragon to pull Dragon away.

No one has told us how long it takes from command of shutdown until the fuel lines are empty to the merlin engines.  Obviously that isn't going to be milliseconds and could be in the whole seconds.  So it looks like the abort engines were starting before merlin stop, even if they were not.  You can see a nice brown nitrogen tetroxide cloud from the super dragos right before you see flame.

Anonymous

You are right.  I had seen

You are right.  I had seen this video that you reference or one similar to it which put the separation sequence into proper perspective.  The videos I had viewed locally seem to imply that there was an explosion of the top of the first stage with capsule separation following.  The videos were quite confusing especially with the accompanying narrative from the local anchors etc.  It made no sense.  

Anonymous

Just viewed the launch from

Just viewed the launch from my back window.  I have a small viewing window i.e., horizon to roof line but the night launches put out a few lumens.  The windows in this old house are now beginning to rattle now that the launch has  move south east.  

cecht
cecht
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There is a 6 Feb New York

There is a 6 Feb New York Times article about plans by SpaceX for 42,000 satellites and by OneWeb for 650 satellites, plus similar plans by Amazon, Facebook, and Telesat. This seems like a brewing Tragedy of the Commons and not good for the future of ground-based astronomy. Or will it all work out well for everyone?

Ideas are not fixed, nor should they be; we live in model-dependent reality.

archae86
archae86
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SpaceX launched another batch

SpaceX launched another batch of 60 StarLink satellites by Falcon 9 today.  The booster missed the landing barge, I'd guess by something in the few hundred yards or less range.  There was a camera transmitting from the barge at the moment of landing failure, and one could see something like a cloud of mist off to the right appear, probably a result of the rocket engine blast touching the ocean, and just a little later some water drops appeared over the view--probably spray tossed up from the water impact, which I suppose to have been gentle.  There was no visible ball of fire, so if it caught fire it was after the transmission dropped out.

solling2
solling2
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cecht schrieb:There is a 6

cecht wrote:
There is a 6 Feb New York Times article about plans by SpaceX for 42,000 satellites and by OneWeb for 650 satellites, plus similar plans by Amazon, Facebook, and Telesat. This seems like a brewing Tragedy of the Commons and not good for the future of ground-based astronomy. Or will it all work out well for everyone?

There was a Forbes article about those plans as well.

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