SpaceX Lands a rocket on a barge! - Page 1
Forum section: electronics / general

author: HP-ILnerd
author_rank: Frequent Contributor
timestamp: April 09, 2016, 07:58:18 am
content: Congrats to all involved. Like many of you I've been watching them develop this for closing on 5 years now? Going from not even being able to get the stage back into the atmosphere without the supersonic wind shredding it, to this. I'm impressed, to say the least.4K footage:If you want to watch the whole launch to landing (of the first stage): (scrub to 18:40 if the index doesn't work):https://youtu.be/7pUAydjne5M?t=1121

author: EEVblog
author_rank: Unknown
timestamp: April 09, 2016, 08:02:45 am
content: The whole things live with that really neat mission timeline bargraph down the bottom.

author: EEVblog
author_rank: Unknown
timestamp: April 09, 2016, 08:12:55 am
content: Quote from: HP-ILnerd on April 09, 2016, 07:58:18 amIt's a ridiculously hard thing to do!

author: RobertoLG
author_rank: Frequent Contributor
timestamp: April 09, 2016, 08:25:11 am
content: cool stuff! I always wanted to see something like that in person, maybe some day...

author: dr.diesel
author_rank: Super Contributor
timestamp: April 09, 2016, 12:49:01 pm
content: Nothing short of absolutely spectacular.Gives me the same feeling as a kid watching the Shuttle launch dreaming of a Star Trek society in space. Now where it Data's equivalent?

author: Wytnucls
author_rank: Super Contributor
timestamp: April 09, 2016, 01:52:23 pm
content: Absolutely mind blowing. A spectacular display of scientific and engineering accomplishments. Beats blowing up ancient artifacts in the Syrian desert.

author: Bud
author_rank: Super Contributor
timestamp: April 09, 2016, 03:02:42 pm
content: Yes but why going into that much trouble, what would be a practical use case ?

author: Monkeh
author_rank: Super Contributor
timestamp: April 09, 2016, 03:05:26 pm
content: Quote from: Bud on April 09, 2016, 03:02:42 pmUh.. reusing a stage which costs multi-millions to build?

author: dr.diesel
author_rank: Super Contributor
timestamp: April 09, 2016, 03:06:27 pm
content: Quote from: Bud on April 09, 2016, 03:02:42 pmEventually this research will lead to fancy reusable spacecrafts, which are cheaper. Right now these guys are pioneering new automation, flight controls/logic/code, sensors whatever else it takes to accomplish such a difficult task.Gotta start somewhere.

author: SeanB
author_rank: Super Contributor
timestamp: April 09, 2016, 03:36:24 pm
content: Quote from: Bud on April 09, 2016, 03:02:42 pmHenry, what use is that thing you are making? it breaks down often, uses a stinky fuel which is hard to get, can hardly go anywhere, needs a specialist to fix it when it breaks. Parts have to be sent out regularly as they wear out so fast, and you need so many tools to fix it.

author: TerraHertz
author_rank: Super Contributor
timestamp: April 09, 2016, 05:03:51 pm
content: Excellent!Even more amazing that it could land and stay upright with the barge pitching around so much in the heavy swell. That must have been near the limit, surely?

author: rrinker
author_rank: Super Contributor
timestamp: April 09, 2016, 05:12:19 pm
content: Simply amazing. It's science fiction come to life - think about how many novels and movies have various spacecraft just landing on planets purely on rocket motor power. Now add in the additional difficulty factor of the non-stable landing platform. Elon Musk, the real life Tony Stark.

author: ajb
author_rank: Super Contributor
timestamp: April 09, 2016, 05:30:40 pm
content: Quote from: TerraHertz on April 09, 2016, 05:03:51 pmAs far as the landing process, apparently the bigger challenge for this one was the high wind. If you watch the video from the chase plane you can see the waves are running right-to-left, suggesting the wind is blowing in the same direction. The rocket is tipped towards the right as it approaches, but doesn't seem to have much horizontal velocity, suggesting the attitude is meant to thrust against the wind rather than any residual horizontal momentum from its boostback. Once it rights itself for touchdown, you can see it starts getting blown to the left, and lands a bit to the left of center on the barge. I wonder if they're going to have to start compensating (more?) for wind speed in the terminal guidance algorithm; much more and it would have been blown off the barge entirely.By the time it's sitting on the barge, the first stage has practically no fuel left, so the bulk of its remaining mass (the engines) is in the bottom couple of meters, while the top is mostly lightweight tanks full of inert gas. So it's far more stable after touch down than its proportions would suggest. Even so, apparently one of the first things the recovery crew does is place steel 'shoes' over the rocket's feet and weld them to the deck of the barge as a safety measure--it would really suck to have the rocket stick the landing only to tip over on its way back to port!This clip has great (but NSFW) audio:

author: Howardlong
author_rank: Super Contributor
timestamp: April 09, 2016, 05:48:48 pm
content: From a buddy of mine on FB:Developer: "We went into orbit and landed back again on a barge in very choppy seas"Client: "You didn't make the middle of the target area"

author: dannyf
author_rank: Super Contributor
timestamp: April 09, 2016, 09:26:11 pm
content: QuoteGreat question.A few breakthroughs:1) re-ignitable and thrustable solid fuel rockets;2) reusable rockets.The first is truly revolutionary and quite useful. The 2nd is questionable at this point.The rocket didn't ace the landing - it is off center.

author: sleemanj
author_rank: Super Contributor
timestamp: April 09, 2016, 10:14:47 pm
content: Quote from: Bud on April 09, 2016, 03:02:42 pmThe 1st stage (the bit they landed) construction cost is a massive financial compponent of the entire launch cost, something like 70% i believe. If the stage can be retrieved, and used again, cost reductions happen.For most launches it has no hope of getting back to dry land, it is too far away.and doesn't have sufficient propellant, so a barge is necessary to take the landing point to the rocket.

author: dr.diesel
author_rank: Super Contributor
timestamp: April 09, 2016, 10:35:47 pm
content: Quote from: Howardlong on April 09, 2016, 05:48:48 pmAlthough it appears slightly off target, I wonder at what point the software stops correcting and considers it good enough? After all, it's on the barge, mission accomplished, what point is there in achieving sub Planck length?

author: Howardlong
author_rank: Super Contributor
timestamp: April 09, 2016, 11:14:12 pm
content: Quote from: dr.diesel on April 09, 2016, 10:35:47 pmI don't know but if I were the "developer" I'd be well chuffed. In a gusty/choppy scenario like that, I'd say all bets are off on a spot-on landing. I don't know what the exact weather was but it looked like something a floatplane wouldn't consider safe, looked like about 20G25 at least.

author: RobertoLG
author_rank: Frequent Contributor
timestamp: April 09, 2016, 11:25:04 pm
content: I only can say to all the folks that participated in that projectimpressive!

author: mswhin63
author_rank: Frequent Contributor
timestamp: April 10, 2016, 02:55:13 am
content: Privatisation can only work if there is a real passion for it. Space X is a good example. Even did better than NASA.

author: Brumby
author_rank: Unknown
timestamp: April 10, 2016, 05:24:55 am
content: Quote from: rrinker on April 09, 2016, 05:12:19 pm

author: German_EE
author_rank: Super Contributor
timestamp: April 10, 2016, 09:08:06 am
content: <sigh> My girlfriend saw the video and couldn't see what I was getting so excited about, she then went to YouTube and for the next ten minutes it was 'look at this', 'look at this' as she watched one animal video after another. What SpaceX did is spectacular and amazing, especially when you consider how the barge was behaving in those choppy seas.

author: MK14
author_rank: Super Contributor
timestamp: April 10, 2016, 09:49:47 am
content: 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.The huge (I presume) cost of each launch, makes real life (full scale) testing, rather limited. So they (presumably), used accurate simulations. Which CAN'T be that accurate, because the atmosphere and weather, are NOT 100% fully understood/predictable yet. So they seem to have done, a really good job.I wonder if some weather conditions would make accurate landings impracticable. Because the target area looks somewhat small, so there is little room/tolerance to get it wrong, without falling in the sea.Also Dave should enquire if he can loan/buy some load space on it, and drop the next test meter, from out-space, to make sure that it survives it. Maybe the rocket can make 2 passes. The first, lands the test meter (at FULL terminal velocity), onto solid reinforced concrete. It can then find the landing craft.

author: SeanB
author_rank: Super Contributor
timestamp: April 10, 2016, 10:26:32 am
content: There have been DMM up on the ISS, and quite a few of them have failed ( that pesky radiation thing, or they needed a calibration) so have had a 300km drop test into a soft landing in the South Pacific ocean. So far none have survived, something about 12 kilometers per second being a little on the high side at the beginning of the fall.

author: MK14
author_rank: Super Contributor
timestamp: April 10, 2016, 10:46:53 am
content: Quote from: SeanB on April 10, 2016, 10:26:32 am(Hopefully) Obviously I was joking (about the DMM bit).But on a serous note. With all the (I would expect), electronics up in the ISS. I would have thought they need, quality/reliable/accurate multimeters, up there. So NASA, should/would/have sorted it out, by now.It could be that the multimeters, just need better protective cases, so they can work in space. If radiation etc, is a problem.Or put it another way. Say a vital piece of electronics, became faulty, and they had no idea what was wrong. Electronics experts, on the ground, could guide the astronauts, into using the multimeter, to help diagnose what the fault(s), were. There are presumably experiments going on up there, which also might benefit from multimeters.Since I have never been on the ISS, I have no idea how they fix electrical problems, up there. Maybe they never get their hands dirty. Although I think, I read/heard they fix stuff outside (the space craft), sometimes.In practice, I presume the main issue, would be the DMM burning up as it hits the atmosphere. It would be interesting to drop samples, of the main/best DMMs, and see which survives the longest, as they burn up. (Joke)

author: coppice
author_rank: Super Contributor
timestamp: April 10, 2016, 11:08:59 am
content: Quote from: MK14 on April 10, 2016, 09:49:47 amThat'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.

author: SeanB
author_rank: Super Contributor
timestamp: April 10, 2016, 11:18:02 am
content: 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.

author: MK14
author_rank: Super Contributor
timestamp: April 10, 2016, 11:47:47 am
content: Quote from: coppice on April 10, 2016, 11:08:59 amI 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;drIt 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.

author: MK14
author_rank: Super Contributor
timestamp: April 10, 2016, 12:00:28 pm
content: Quote from: SeanB on April 10, 2016, 11:18:02 amWhat 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.

author: dmills
author_rank: Super Contributor
timestamp: April 10, 2016, 12:02:37 pm
content: 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.

author: MK14
author_rank: Super Contributor
timestamp: April 10, 2016, 12:15:32 pm
content: Quote from: dmills on April 10, 2016, 12:02:37 pmThanks for the interesting information/post.This could open up the door, for future moon-probes/moon-landings, by commercial, rather than government/country, entities.

author: dr.diesel
author_rank: Super Contributor
timestamp: April 10, 2016, 12:22:39 pm
content: Quote from: dmills on April 10, 2016, 12:02:37 pmYup! But let's not forget about the epic auto landing done by the curiosity rover.

author: Brumby
author_rank: Unknown
timestamp: April 10, 2016, 02:02:37 pm
content: Quote from: dr.diesel on April 10, 2016, 12:22:39 pmI still don't get bored watching this...

author: rdl
author_rank: Super Contributor
timestamp: April 10, 2016, 03:02:58 pm
content: They probably do have some kind of multimeter on the ISS.They seem to have soldering equipment and a hammer at least.Quote from: ISSLive(http://isslive.com/secondarysys/index.html#maintenance_and_repair)

author: nad007007
author_rank: Contributor
timestamp: April 16, 2016, 05:25:53 am
content: Good effort SpaceX well done. Love those private companiesNad

author: TerraHertz
author_rank: Super Contributor
timestamp: April 23, 2016, 02:27:39 pm
content: 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 04-15-2016Falcon 9 CRS8 Booster Loaded 4K 04-18-2016CRS8 Comes Home - SpaceX Falcon 9 Booster 04-19-2016

author: HP-ILnerd
author_rank: Frequent Contributor
timestamp: April 30, 2016, 10:27:02 am
content: 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!

author: TerraHertz
author_rank: Super Contributor
timestamp: May 07, 2016, 02:53:28 am
content: 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.htmlhttps://www.theguardian.com/science/2016/may/06/spacex-lands-reusable-rocket-for-second-time

author: ajb
author_rank: Super Contributor
timestamp: May 07, 2016, 03:12:40 am
content: 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)

author: coppice
author_rank: Super Contributor
timestamp: May 07, 2016, 03:49:35 am
content: Are there any reports from SpaceX about the condition of the rockets recovered so far?

author: ez24
author_rank: Super Contributor
timestamp: May 07, 2016, 06:35:43 am
content: Quote from: EEVblog on April 09, 2016, 08:02:45 amThanks Dave. Really enjoyed this video so I re-linked it. I see this as a monumental moment in history.

author: AndreasF
author_rank: Frequent Contributor
timestamp: May 07, 2016, 10:38:19 am
content: Quote from: ajb on May 07, 2016, 03:12:40 amI 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.

author: ajb
author_rank: Super Contributor
timestamp: May 27, 2016, 10:16:08 pm
content: 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.

author: HP-ILnerd
author_rank: Frequent Contributor
timestamp: May 28, 2016, 02:20:52 am
content: 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 Januaryhttps://www.youtube.com/watch?v=QXPhQKkOcYM&feature=youtu.be&t=10mIf 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!

author: HP-ILnerd
author_rank: Frequent Contributor
timestamp: May 28, 2016, 02:34:05 am
content: Speak of the devil, Elon just posted a sped-up version.Freaking amazing!!

author: spudboy488
author_rank: Regular Contributor
timestamp: May 31, 2016, 11:56:16 am
content: I give you this...............http://www.dailystar.co.uk/news/latest-news/519268/conspiracy-theorists-claim-space-x-rocket-landing-hoax-youtube-video

author: ccs46
author_rank: Regular Contributor
timestamp: May 31, 2016, 12:13:41 pm
content: 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

author: ebclr
author_rank: Super Contributor
timestamp: May 31, 2016, 12:28:37 pm
content: I guess math was needed to do that

author: Kjelt
author_rank: Super Contributor
timestamp: May 31, 2016, 12:51:32 pm
content: another few times and it gets boring