SpaceX Falcon 9 FT - CRS-11 - LC-39A

[Bobfitz1]

The current answer is no. What they did say is that they would consider it and that reusability is also something that they promote. There is no question that NASA would want to see many successful powered landings before they would ever risk astronauts lives.

Thanks for confirming. SpaceX will want to see at least several test landings before they are as sure as possible nothing can go wrong.
However, .... once SpaceX is satisfied Dragon2 powered landing is safe, I can imagine them making the following point. Or the NASA engineering getting there at the same time. I.e., soft landing a small capsule with a double set of landing thrusters and the usual triple redundant control systems must be 'easier' than landing a 140' booster using gimbaled Merlin engines and nitrogen thrusters. That SpaceX has refined first stage soft landings to where success is to be expected and is highly likely, should mean something to NASA as they decide how many actual tests of Dragon 2 provide the level of risk assurance they want.
I'll inch further out on this limb and speculate that with some number of parachute aided water landings planned, SpaceX is not going to throw out the parachutes system. Since returns from orbit will soft land at the Cape, there can be a window to abort a powered landing and
bring capsule down to a soft enough water landing in the Atlantic off the Cape. IMO, that doesn't need to be quite as bullet proof as a planned water landing to be worthwhile as a not likely to be needed Plan B.

 

[Grendal]

Dragon capture successful about 8 hours ago.

 

[Electroman]

Nice animation and explanation on the first stage landing:

 

[alseTrick]

I enjoyed those youtube videos.

 

[Grendal]

I enjoyed those youtube videos.

Well here's another one to get you excited:

 

[swaltner]

Do not compete against a SpaceX engineer in a game of darts. They get bullseye after bullseye.

 

[alseTrick]

On these landed rockets, the bottom third-ish is black from the engine burns upon reentry and landing. But above that there is a clear demarcation line running the circumference of the rocket where it goes from black to nearly pristine white. What causes that?

 

[ecarfan]

Awesome view! I don't see how an F9 stage can be landed more smoothly than that. I noticed that up to a fraction of a second before touchdown the cold gas thrusters were still firing to ensure the stage was perfectly vertical?

Well here's another one to get you excited:

 

[dhanson865]

On these landed rockets, the bottom third-ish is black from the engine burns upon reentry and landing. But above that there is a clear demarcation line running the circumference of the rocket where it goes from black to nearly pristine white. What causes that?

Temperature difference? Maybe a cold storage fuel tank starts at that line? I'm totally guessing on that one.

 

[Grendal]

Awesome view! I don't see how an F9 stage can be landed more smoothly than that. I noticed that up to a fraction of a second before touchdown the cold gas thrusters were still firing to ensure the stage was perfectly vertical?

Exactly. This was one of the more straight in landings. It's easy to forget that the booster is 15 stories tall and nearly empty of fuel. Even a slight breeze has a huge effect on that large a surface area. The fact that it is almost empty means that it is very easy to push around. It is incredibly obvious how difficult this is on the original CRS-8 landing on the ASDS. Look at the angle the booster came in on:

That's because there was a really big crosswind that the booster was fighting and maneuvering against. In this case there had to be almost no wind but, at the last second, the landing algorithm sensed an adjustment was needed. Smooth as it was, some of the crumple zone was used in one of the legs. Later pictures of the landed booster show a small tilt to it.

On these landed rockets, the bottom third-ish is black from the engine burns upon reentry and landing. But above that there is a clear demarcation line running the circumference of the rocket where it goes from black to nearly pristine white. What causes that?

The clear line is where the supercooled LOX tank begins. The soot doesn't build up there due to condensation. The new block 5 F9 is supposed to have better flame protection. We'll see if that means we'll have less soot build up. Elon wants a 24 hour turn around for boosters. I don't think you can re-paint the stage in 24 hours. Just a quick rinse to get the soot off maybe?

 

[macpacheco]

Its true that any little wind has substantial effect on the nearly empty booster, but inertial systems directly measure accelerations, which means corrective action is taken to directly counteract forces rather than wait until the booster has already moved. On board computers can easily calculate this 100x per second, the delay will be mostly dictated by the speed that TVC can accutuate. What seems hard for a human pilot, isn't nearly as hard for the computer on the helm.
GPS directly measures position, INS directly measures accelerations. Without INS it would actually be nearly impossible to react that quickly.

 

[Grendal]

Its true that any little wind has substantial effect on the nearly empty booster, but inertial systems directly measure accelerations, which means corrective action is taken to directly counteract forces rather than wait until the booster has already moved. On board computers can easily calculate this 100x per second, the delay will be mostly dictated by the speed that TVC can accutuate. What seems hard for a human pilot, isn't nearly as hard for the computer on the helm.
GPS directly measures position, INS directly measures accelerations. Without INS it would actually be nearly impossible to react that quickly.

So you're saying the on board computers act like an.....autopilot. Hmm.

 

[MacGreiner]

On these landed rockets, the bottom third-ish is black from the engine burns upon reentry and landing. But above that there is a clear demarcation line running the circumference of the rocket where it goes from black to nearly pristine white. What causes that?

Yes - wondered exactly the same.

 

[JeffK]

Yes - wondered exactly the same.

Top is probably marks from the second stage.... it's not pristine all the way up. There is a clear line though.

It might be where the liquid oxygen is kept... would have been coated in ice.

 

[Grendal]

Top is probably marks from the second stage.... it's not pristine all the way up. There is a clear line though.

Some of it yes. Watch the Technical video from the last launch and you can clearly see the second stage light up almost immediately following MECO. However the flip happens very fast. In fact, the camera on the first stage looking down shows a bunch of flames for a second. Those flames are from the second stage, not the boostback burn.

 

[Grendal]

SpaceX posted a couple cool photos from CRS-11. They have pictures of stage 2 with Dragon in the background and a picture of Dragon with stage 2 in the background.

SpaceX (@SpaceX) | Twitter

 

[macpacheco]

So you're saying the on board computers act like an.....autopilot. Hmm.

Funny joke... But...
Rockets don't have autopilots, because they don't have human pilots. They have guidance and control systems instead... Computers all the same, but rockets don't have the human to take over, which make them more demanding than aircraft autopilots.

 

[jkn]

Funny joke... But...
Rockets don't have autopilots, because they don't have human pilots. They have guidance and control systems instead... Computers all the same, but rockets don't have the human to take over, which make them more demanding than aircraft autopilots.

Human could not control F9 landing. Things (must) happen too fast. For a computer this is not a problem. Interaction of changing wind and wings of airplane is much more complex than wind pushing a rocket. I think it is easier to write computer program controlling rocket landing than airplane landing.

 

[Cosmacelf]

Human could not control F9 landing. Things (must) happen too fast. For a computer this is not a problem. Interaction of changing wind and wings of airplane is much more complex than wind pushing a rocket. I think it is easier to write computer program controlling rocket landing than airplane landing.

Uh, maybe, but realize that the rockets land on a moving platform at sea...

 

[ecarfan]

Uh, maybe, but realize that the rockets land on a moving platform at sea...

Yes, some of the F9 first stages do, but some return to LZ1.

The ASDSs can hold position to within a meter according to Elon. The deck can pitch, of course, but so far that hasn't been a big issue. And SpaceX has now developed a robot that can move beneath the stage after touchdown and secure it very quickly.