SpaceX Lands a rocket on a barge!

[coppice]

Basically, you are hitting a golf ball (then immediately dive in the sea, and go for a swim), and it gets a hole in one, every time. Then bounces out again, and comes back and lands in your pocket (or lands perfectly on top of your flat hat), while you are swimming in VERY heavy seas.

That's a pretty poor comparison. You need to hit a gold ball perfectly, as no corrections are possible along the way. Something like a Trident missile is almost the same, as it burns through its fuel as fast as it can, and glides most of the way with little directional control. Orbital launch vehicles burn all the way to orbit, and are steered through the entire burn. The SpaceX ones tightly control the booster all the way to the ground as well.

[SeanB]

Iss simply uses both ground test to weed out early failures, and build to survive.  Stuff that fails ( like the last coolant pump they had to spacewalk a lot to replace) has on orbit or on ground spares that they plug in, and in most cases the old stuff is dropped as garbage in a Progress supply ship when it deorbits. They sent back the coolant pump as the NASA designers of it wanted to do a failure analysis, so there they have to wait for a Dragon which does not get cremated. Small things like laptops and such are simply junked.Experiments that are completed are also treated the same, unless there is another one which can reuse the modules without needing complex tool work or soldering. They do have a soldering iron there and basic tools, to fix things like headsets and replace seals in space suits.

[MK14]

That's a pretty poor comparison. You need to hit a gold ball perfectly, as no corrections are possible along the way. Something like a Trident missile is almost the same, as it burns through its fuel as fast as it can, and glides most of the way with little directional control. Orbital launch vehicles burn all the way to orbit, and are steered through the entire burn. The SpaceX ones tightly control the booster all the way to the ground as well.

I agree, in that my statement, would have been a completely open loop system (after the initial closed loop, hit of the golf ball). It was intended to show the achievement, to people who don't understand the difficulties, rather than being an accurate analogy.
tl;dr
It was not intended to be an accurate analogy.

But simply closing the loop, may not be enough to solve the problem.

A better analogy, would probably be a fighter jet, landing on an aircraft carrier. As far as I am aware, that is beyond current control systems, or at least has not been done yet. EDIT: CORRECTION. I think it has been done, so that automatic drones, can land/takeoff, since they are unmanned, although potentially controlled by human operators.

I would like to think, that I can control things, in real time. Such as riding a bicycle. But I'm pretty sure that if I was to try and land a jet fighter aircraft on a moving aircraft carrier, it would end in disaster. I have probably tried it using PC flight simulator(s) and/or video games. Probably making a huge (virtual) fireball.

I'm not sure if a fighter jet (landing on an aircraft carrier), is similar, harder or easier, than the space thing, landing on the sea based, drone platform.

On the other hand, I guess one could think of the rocket, as a sort of helicopter/drone. So automating it, is not so hard.

I don't know enough about that space program, to really know, how hard it was, or should have been.

Maybe the next thing we hear, is that North Korea buys up that company, for some secret project of theirs ? (joke).
But it is a bit worrying, having such technology, out in the wild (commercial), rather than contained within the secretive military systems.

[MK14]

Iss simply uses both ground test to weed out early failures, and build to survive.  Stuff that fails ( like the last coolant pump they had to spacewalk a lot to replace) has on orbit or on ground spares that they plug in, and in most cases the old stuff is dropped as garbage in a Progress supply ship when it deorbits. They sent back the coolant pump as the NASA designers of it wanted to do a failure analysis, so there they have to wait for a Dragon which does not get cremated. Small things like laptops and such are simply junked.Experiments that are completed are also treated the same, unless there is another one which can reuse the modules without needing complex tool work or soldering. They do have a soldering iron there and basic tools, to fix things like headsets and replace seals in space suits.

What you are saying makes a lot of sense. If the electronics is tiny surface mount parts (presumably), there is not a lot, uneducated (as in hardware/software), non-electrically minded people can do, with a simple 25W (or whatever), soldering iron.

They may have built automatic (and controllable from experts on the ground), monitoring/test/failsafe modes into some of the equipment. Because most satellites and long distant probes, are completely unmanned. So if it breaks, it is tough cookie, unless the ground control can make adjustments (electronically). Sometimes I hear of such stories, where an old satellite, broke. But they sent special signals to it, and fixed it. E.g. By updating the software, so that it could ignore/bypass the faulty stuff.

The stuff is probably very conservatively designed, and as you said, thoroughly tested (etc), before it goes up to the ISS. So hopefully, they have few/no problems. Although I have heard, various stories, about stuff that has gone wrong up there.

[dmills]

6DOF autopilots have been around as open source for a while (IIRC The US military actually published a  code back around year 2,000).
Doing a zero/zero intercept following re entry is new, and it is one hell of an engineering achievement, and some fairly epic development work, but it is development not researching new physics. 

Still one hell of an achievement.

Regards, Dan.

On the electronics thing, the NASA workmanship standards are on line and make very interesting reading.

[MK14]

6DOF autopilots have been around as open source for a while (IIRC The US military actually published a  code back around year 2,000).
Doing a zero/zero intercept following re entry is new, and it is one hell of an engineering achievement, and some fairly epic development work, but it is development not researching new physics. 

Still one hell of an achievement.

Regards, Dan.

On the electronics thing, the NASA workmanship standards are on line and make very interesting reading.

Thanks for the interesting information/post.

This could open up the door, for future moon-probes/moon-landings, by commercial, rather than government/country, entities.

[dr.diesel]

6DOF autopilots have been around as open source for a while (IIRC The US military actually published a  code back around year 2,000).
Doing a zero/zero intercept following re entry is new, and it is one hell of an engineering achievement, and some fairly epic development work, but it is development not researching new physics. 

Still one hell of an achievement.

Yup!  But let's not forget about the epic auto landing done by the curiosity rover.      

[Brumby]

Yup!  But let's not forget about the epic auto landing done by the curiosity rover.      

I still don't get bored watching this...

[rdl]

They probably do have some kind of multimeter on the ISS.
They seem to have soldering equipment and a hammer at least.

  Contingency Maintenance - planned action devised for a specific situation that might occur.
        Soldering (wiring)
        Scavenging (spare parts)
        Jumpering (around failed equipment)
        Fabricating (creating new equipment)
        Banging with hammer (self-explanatory)

(http://isslive.com/secondarysys/index.html#maintenance_and_repair)

[nad007007]

Good effort SpaceX well done. Love those private companies


Nad   

[TerraHertz]

Plenty of interesting follow-up videos being posted.
These are not as gripping as watching a rocket land on a barge, but they are just as important. No use landing on a barge, if someone bingles the rocket on the way back to the factory. So, how do you handle a huge used re-usable rocket? Like this...
   Falcon 9 Lost Her Legs 04-15-2016
   Falcon 9 CRS8 Booster Loaded 4K 04-18-2016
  CRS8 Comes Home - SpaceX Falcon 9 Booster 04-19-2016

[HP-ILnerd]

Some 360 degree footage of the barge landing.  You can PAN AROUND while the video is playing.
Pan up to see the rocket coming down toward the camera POV.

Amazing!

[TerraHertz]

Now they did it again. 2nd successful barge landing.
https://www.rt.com/news/342026-spacex-falcon9-launch-landing/
http://www.space.com/32811-spacex-rocket-landing-jcsat-14-launch.html
https://www.theguardian.com/science/2016/may/06/spacex-lands-reusable-rocket-for-second-time

[ajb]

Once again, the uplink from the landing barge was a little unsteady right at landing (go figure).  Only this time, instead of cutting out entirely as it has in the past we just got the glow from the approaching rocket, the stream froze, then there was a brilliant flash of white, and then darkness, making it look very much like another RUD until the exposure came back up a few seconds later and revealed the landed rocket.  The reaction from the crowd in the background of the hosted webcast is an amazing roller coaster of mob emotion:

(the landing happens at 29:25, in case the below doesn't start at the right spot)

[coppice]

Are there any reports from SpaceX about the condition of the rockets recovered so far?

[ez24]

The whole things live with that really neat mission timeline bargraph down the bottom.

Thanks Dave.  Really enjoyed this video so I re-linked it.  I see this as a monumental moment in history.

[AndreasF]

Once again, the uplink from the landing barge was a little unsteady right at landing (go figure).  Only this time, instead of cutting out entirely as it has in the past we just got the glow from the approaching rocket, the stream froze, then there was a brilliant flash of white, and then darkness, making it look very much like another RUD until the exposure came back up a few seconds later and revealed the landed rocket.  The reaction from the crowd in the background of the hosted webcast is an amazing roller coaster of mob emotion:

I watched the live stream and had the same reactions:

"common common!"

"oh, it's coming!"

"ahh, crap it cut out, probably failed again - bummer"

"wait, what is that? It's standing on the SHIP!!!  HOLY COW!!!!"

I can't imagine what it must have felt like for the people directly involved.

[ajb]

Aaaaand they've just made it 4/4 overall, 3/3 at sea, and 2/2 GTO* launches!

* Getting to geosynchronous orbit requires a much higher velocity than getting to LEO, which means the first stage has a higher reenty velocity and lower fuel margin making for a much more challenging landing.

[HP-ILnerd]

Amazing super-snug margin landing.  The undies were tight on this one!   

The live video showing the entry burn on the first stage was pretty spectacular.  Hopefully they have it recorded all the way from space down on to the barge!

For anyone wondering about the 91,000 km apoapsis on this one, Scott Manley provided an explanation some months for the ThaiCom launch back in January
https://www.youtube.com/watch?v=QXPhQKkOcYM&feature=youtu.be&t=10m

If you aren't interested in the math, it's that going so high allows you trade a higher deltaV to get to that altitude with a much lower plane-change deltaV to compensate for the orbital inclination.  A plane-change from the 28.5 degree North launch site to 0 degree equatorial is progressively  more punishing the lower you do it.  Since the launcher pays for the high apoapsis, it allows the satellite to save a couple hundred meters per second compared to doing it at the target altitude, thus extending it's life.  <-applicable in Kerbal Space Program!   

[HP-ILnerd]

Speak of the devil, Elon just posted a sped-up version.

Freaking amazing!!

[spudboy488]

I give you this...............  

http://www.dailystar.co.uk/news/latest-news/519268/conspiracy-theorists-claim-space-x-rocket-landing-hoax-youtube-video

[ccs46]

Not bad, they are getting better every time. There was that failure not too long ago and they definitely improved.


Sent from my iPhone using Tapatalk

[ebclr]

I guess math was needed to do that

[Kjelt]

another few times and it gets boring