Longer Video Shows How Incredibly Close Falcon Stage Came To Successful Landing

Bruce Perens writes In the video here, the Falcon 9 first stage is shown landing with a tilt, and then a thruster keeps the rocket vertical on the barge for a few seconds before it quits, followed by Kabooom with obvious significant damage to the barge. It looks like this attempt was incredibly close to success. Given fixes, a successful first-stage recovery seems likely.

Comments

Larger landing area

[Dan East]

It sure seems that if a larger landing area was available, so that the rocket didn't have to lean so far to adjust to a very small target and thus could prioritize staying vertical, it would be able to land successfully. What's it going to take for NASA or the FAA or whatever to give them permission to land on, um, land.

Re:Larger landing area

[Bruce Perens]

The ship is 300 feet long. It's a big rocket :-)

The pad area they have at KSC is made for F9 Heavy, and multiple stages are supposed to land there, the neighbors are sensitive about having other rockets come down in their yard, and there's a big building you really don't want to hit :-) . So, they probably do need the precision. There was an odd tweet from Musk, later deleted, that said there was actually a process control problem and a phase delay.

Re:Larger landing area

[farble1670]

Now that I see the video, it looks like it was coming down really well until that last moment.

no way. for a gigantic fragile rocket it came in extremely hot. it was probably moving at 50+ MPH when reached 50 feet of the platform. it didn't slow down much until it was less than 10 feet away. it was also wobbling as it came in.

as much as i'd like to say that was close, it wasn't.

Re: Larger landing area

[D.McG.]

The full tweet was as follows:
@elonmusk: @ID_AA_Carmack Looks like the issue was stiction in the biprop throttle valve, resulting in control system phase lag. Should be easy to fix.

Re:Larger landing area

[He Who Has No Name]

That's exactly what it is, since they don't have the throttle authority to burn lower, longer.

With that approach profile, they're aiming to have dV hit zero the same exact instant that the rocket settles into a 1g static load on its landing gear - same as if it was just sitting on the ground.

There's a good reason it's called a suicide burn.

Re:Larger landing area

[Sardaukar86]

Thanks Bruce, it's often in these little nuances that I catch myself staring into space, contemplating the sheer enormity of what has been achieved here. The skills of these people - to do what they're doing with the budget at their disposal - almost completely wrecks my personal 'scale of difficulty'. I thought I understood what they meant by 'It really IS rocket science,' but I'm really not even close.

We really must be living in the future: small, agile, private enterprises taking the reigns of progress from state-level actors. NASA are by no means obsolete, if anything they've adapted rather well for a bureaucracy of their size and are continuing to do amazing science.

Budgets might be tighter than we'd like but I can't help feeling like we're entering a golden era of space exploration and related technologies.

Ooooh.. uh, does this make me a Space Nutter?

Re: Larger landing area

[michelcolman]

Certainly looked that way to me. On the last oscillation before touchdown, with the tail end moving towards the left, the thrusters keep pointing the same way as the rocket goes through vertical and only change direction a little bit afterwards. This increased the amplitude of the oscillation rather than decreasing it. The thrusters should have changed direction before passing through vertical, not afterwards. I can't imagine them getting this wrong in software, it's basic dynamic stability 101, so a sticky valve seems likely.

The rocket ended up landing almost perfectly vertical, but still rotating so the base was traveling sideways over the landing pad. No way they could stay upright like that.

Re:Larger landing area

[anegg]

Not necessarily. Too much money can be just as much of a problem as too little. Budget constraints can promote clearer thinking and more clever innovations.

Re:Landing vs splashdown

[Bruce Perens]

They have talked about refueling on the barge and flying the booster to land! That's really difficult to do after a salt-water dip :-)

I Disagree with the Summary

[cruff]

Looking at the video, it appears the booster does not come close to ever having anywhere near a true vertical orientation, and this attempt was not, in fact, "incredibly close to success". Granted, it came closer than ever in history to achieving the goal, but the thruster appeared to not have enough thrust to push the rocket to a vertical position once the booster touched down on the barge. I hope Space-X has a successful next test! The world needs a dose of rockets landing on large flames in the style of those old campy movies.

Re:I Disagree with the Summary

[Michael Woodhams]

Someone in the Youtube comments says "The flight profile veers the booster off to the side on purpose so the exhaust from the final burn isn't directed at the barge where it could do damage"

If this was a planned manoeuvre, I'm much happier. Can anyone confirm this statement?

Alternative Idea for Landing

[PeteJanda]

Kindergarten Question for SpaceX: why not simply put the equivalent of a safety net on the barge, cut the rocket's engines at an altitude of ~10m and let the rocket fall safely into the net? Less fuel, less complexity and less cost.

Re:Landing vs splashdown

[AaronW]

A couple of months ago I was having a discussion with a fellow from Space X who designs the hydraulic systems and we spoke about a number of issues. This was right after the failed landing due to it running out of hydraulic fluid. I asked about how reusable the engines are and he said that they run test burns lasting hours. The launch is only a few minutes. According to what he said, it should just be a simple matter of refueling and adding more hydraulic fluid and probably some other simple things without having to do a major overhaul. The engines are very reliable.

I asked about why they don't reuse the hydraulic fluid and he said that it was cheaper and lighter to not reuse it. He also said that they knew it could run out and that the next version would have more.

New product

[SuperKendall]

Musk's claim is that the barge didn't sustain any serious damage.

Screw self-landing boosters. What I want is a house made out of whatever the barge is made of, easily shrugging off what are essentially two direct rocket hits complete with massive explosion.

Re:"Close" Only Counts

[garyisabusyguy]

Armstrong was an exceptional pilot, I read on old NASA report about him regaining control of a space capsule that started spinning before it could kill them. Something to do with a malfunctioning thruster rocket.

Here it is:
"And, make a decision he did. In a rule-breaking move, Armstrong manually disabled the OAMS thrusters and activated the re-entry control system (RCS) thrusters to stabilize the spacecraft. With hand controllers aboard the spacecraft now functioning properly, correct motion of the capsule was restored."
http://www.spaceline.org/fligh...

Yeah, they were 'hands on'