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SpaceX nails triple booster landing after satellite delivery
- raehik 7y agoBig fan of making technical spacecraft manoeuvres sound like cool skateboard tricks.
- trollied 7y agoI'm more impressed by the booster landings though :-) Seeing a launch/landing in-person is on my bucket list.
- Joe-Z 7y agoI saw the live stream yesterday and when the two side boosters landed side-by-side synchronously it was almost as if it was out of a movie. We are living in the future!
- qmarchi 7y agoOn this launch, it looks like they offset the timings to reduce the chance of tipping over. If you get time, go look for the first FH booster landings. The timing is almost perfect and the long exposure images looked beautiful.
- isostatic 7y agoThey are supposed to be offset for radar purposes. The fact the first time was so close was a mistake, fortunately it worked.
- pedrocx486 7y ago>On this launch, it looks like they offset the timings to reduce the chance of tipping over. On reddit a lot of people enphasised that it was to avoid interference. Which interference, no one knows.
- that_jojo 7y agoIncorrect. Gift that you give to me, no one knows,
- Teknoman117 7y agoIt's certainly very cool. I saw the night launch/landing of Falcon 9 out of Vandenberg a few months back. Certainly worth the overnight trip. Most impressive part for me was that you see the booster make it's landing burn and touchdown BEFORE you hear the landing at the observation site.
- stackola 7y agoHoverslam!
- Timpy 7y agoThe way the text appears with a downward-drawing red line really steals my attention. There are rockets on screen and I kept having my eyes avert to the fragmented text in the bottom left corner. I had to watch the video twice to keep my eyes on the rockets. I'm thinking of the UI/UX implications, subtle and effective.
- usermac 7y agoI wonder what emergency procedure is in place in case the landing is off-course. Does it blow itself up?
- andrewcchen 7y agoThe booster's trajectory targets offshore or away from droneship in case landing burn fails. The landing burn brings the booster onto the landing pad. See CRS-16 where the booster landed in the water when the booster lost roll control when the grid fins failed.
- Klathmon 7y agoThey've had a few "on purposes misses" over the years. The Falcon Heavy demo launch had the center core purposely miss the droneship as it was coming in way too fast since 2 of the engines didn't light. IIRC it purposely missed the droneship by only a few hundred meters, but it was going something like 300 miles per hour!
- inflatableDodo 7y agoAs an addendum to that, if one accidentally lands in my back yard, can I keep it?
- agumonkey 7y agoyou can, as long as SpaceX recovery truck has not reached your door
- inflatableDodo 7y agoI'll swap the house numbers with next door. They'll never find it.
- bloopernova 7y agoI know this is increasingly off-topic for hn, but the mental image of being woken up by loud booster noises, then seeing a huge booster sitting in your now-ruined garden is hilarious to me. We certainly do live in the future.
- plutonorm 7y agoI wonder how they do the booster landings? Is it precise modelling and standard control algorithms, or something more exotic like neural networks?
- sonium 7y agoIt's done using convex optimization https://www.nap.edu/read/23659/chapter/10#39 https://www.nap.edu/read/23659/chapter/10#39
- amelius 7y agoHow is "booster landing" mapped to a convex optimization problem?
- theoh 7y agoLars Blackmore, who works for SpaceX, has a page about the techniques that are used here: http://www.larsblackmore.com/losslessconvexification.htm http://www.larsblackmore.com/losslessconvexification.htm See also: https://www.aa.washington.edu/facultyfinder/behcet-acikmese https://www.aa.washington.edu/facultyfinder/behcet-acikmese
- dom96 7y agoCan anyone give a ELI5 (for developers) of how this technique works?
- theoh 7y agoThe control parameter space for the rocket is non-convex because, for one thing, it can't be throttled down close to zero thrust. You can think of the parameter space as having a hole in it. An optimal control algorithm might want to make very delicate low-thrust corrections, but that's not possible. This technique is based on "the idea of relaxing the nonconvex control constraints to a convex set in such a way that the optimal solution to the relaxed problem is guaranteed to be the optimal solution to the original problem." By "relaxing", what they mean is that the new model (the convex set) actually contains some parameter values that aren't achievable, but OTOH it is geometrically susceptible to being analyzed by an efficient optimization technique. So it's a clever replacement of a hard problem with an easier one. The complex bit, which I don't understand, is how they show that this replacement will always give the same value as if they had solved the (real) hard problem, i.e. that the solution will never actually use the "illegal" parameter values. Maybe someone else can give more insight.
- joeblau 7y agoEvery single time I watch a successful SpaceX launch I get chills and also get so excited. Congrats to everyone who has worked on this.
- maxerickson 7y agoLarge existing discussion at https://news.ycombinator.com/item?id=19639965 https://news.ycombinator.com/item?id=19639965
- oska 7y agoFor some reason the discussion in this thread is far better than the earlier one you linked.
- deleted 7y ago[deleted]
- bbojan 7y agoNot only that, but apparently they recovered both fairings: https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.teslarati.com/spacex-falcon-heavy-fairing-recovery-starlink/amp/&ved=2ahUKEwjojrSJwsrhAhVkiOAKHdmCDVYQyM8BMAB6BAgFEAQ&usg=AOvVaw1M3yDSNH7xzYKQG9Hcdd1Z&cf=1 https://www.google.com/url?sa=t&source=web&rct=j&url=https:/... So 5 out of 5...
- qmarchi 7y agoIt's an interesting issue with the fairings, and I'm interested to see what (or if) they're going to solve the issue with the saltwater contaminated fairings. Being a SpaceX launcher, as the article indicates, means they can accept higher risks, but in turn has a greater financial risk to the company. It's times like this where I'm glad SpaceX is a private company.
- pedrocr 7y agoAccording to a reddit thread they've saltwater hardened the fairings and now they can reuse them: https://www.reddit.com/r/spacex/comments/bc8105/arabsat6a_elon_musk_on_twitter_both_fairing/ https://www.reddit.com/r/spacex/comments/bc8105/arabsat6a_el... The first reuse mission seems to be an internal one though.
- Ajedi32 7y agoThat's just speculation, I wouldn't cite it as an authoritative source.
- azernik 7y agoThe part that says they're able to reuse these ones is a tweet directly from Elon Musk; he also confirms they were recovered from in the water, not caught in the air.
- Ajedi32 7y agoThat information was already covered by the news article linked in the root comment above. The additional suggestion by a commenter in the Reddit thread that "they've saltwater hardened the fairings" is speculation.
- hoorayimhelping 7y agoHere's the video cued up to the booster landings: https://youtu.be/TXMGu2d8c8g?t=1643 https://youtu.be/TXMGu2d8c8g?t=1643 with the main core landing a few minutes later. If it's not obvious, the main core landing was much harder this time around, because of how fast it was going due to the two boosters imparting a lot of extra speed on it before they separated. If you think about it, it'll have somewhere between 1x and 3x the velocity of a normal Falcon 9 core
- gnode 7y agoIt doesn't necessarily make it harder. There's a burn to slow the booster down for re-entry, and having the side boosters do a lot of the work means more fuel / delta-v can be saved to slow the core booster. The FH is apparently capable of 8,000kg in a reusable GTO launch ( https://en.wikipedia.org/wiki/Falcon_Heavy#Capabilities https://en.wikipedia.org/wiki/Falcon_Heavy#Capabilities ), and this satellite was only 6,000kg. So it looks like there would be plenty of fuel available to slow the core down well below the survivable maximum.
- ravedave5 7y agoIt's the same steps but it is harder, the center booster was going faster than any other core that has been recovered. The recovery itself was ~300 miles further out than any other recovery. Swinging a bat at a 10mph ball is the same technology as swinging at a 90mph one. I don't think anyone would say that they were equally as easy.
- gnode 7y agoMy point is that it's less a question of technical difficulty / tolerance, but more fuel / delta-v / mass cost. In the case of a bat swing, to bat the ball faster, your muscles need to be stronger, and the ball and bat need to withstand greater pressures. In the case of a vehicle travelling through space / thin atmosphere, it only needs more fuel to burn to slow it down. Analogously, you don't parallel park a car from 70mph, having travelled somewhere on a highway. Here's a graph a booster's speed over time, showing the reentry burn: https://i.stack.imgur.com/xFYIh.png https://i.stack.imgur.com/xFYIh.png ( from https://space.stackexchange.com/questions/20246/what-is-this-debris-on-the-crs-10-reentry-at-t630 https://space.stackexchange.com/questions/20246/what-is-this... )
- martythemaniak 7y agoThere's a great media thread on reddit where people post their own photos and videos: https://www.reddit.com/r/spacex/comments/bbhz9a/rspacex_arabsat6a_media_thread_videos_images_gifs/ https://www.reddit.com/r/spacex/comments/bbhz9a/rspacex_arab... Here's a great video of the entire flight and landing of the side boosters in one shot, made with custom tracking software: https://www.youtube.com/watch?v=cEZZkEXAD6Q https://www.youtube.com/watch?v=cEZZkEXAD6Q
- hcrisp 7y agoThe boostback burns in that video are amazing. Lots of dynamics in what looks like a shock-induced interface of the rocket exhaust and hypersonic atmosphere.
- jessriedel 7y agoFor those interested, booster separation is just after the 3:00 mark. The whole separation, flip, and boost-back dance is incredible to watch.
- xfitm3 7y agoI never realized there were launch observers in the water - what a great idea!
- deleted 7y ago[deleted]
- andy_ppp 7y agoAm I going mad I only see two booster landing in the video?
- benplumley 7y agoOn the live stream, the video feed cut out for the landing of the third (middle) booster.
- deleted 7y ago[deleted]
- ben_bai 7y agoThis almost always happens. It's really hard to keep a stable satellite connection, while a 150ft. booster is blasting the deck with the exhaust from 3 firing rocket engines.
- JshWright 7y agoIt doesn't fire all three engines down to the deck. The landing burn starts with one engine (in order to have more control authority when the two outboard engines start up), then two more engines get lit, then they shut down shortly before the actual landing (reducing the TWR makes the landing a bit easier).
- gnode 7y agoThe two side boosters were landed close together on dry land. The core third booster was landed down-range on a sea platform.
- DennisP 7y agoThis really looks good for launch costs long-term. The Heavy costs $90 million per reusable launch with a 64,000 kg payload, or $1400 per kilogram.[1] Current versions of the Falcon 9 and Heavy can fly ten times with virtually no refurbishment between flights.[2] The only part they throw away is the $7.5 million upper stage.[3] Their expendable cost is $150M and they haven't really started reusing yet, so if they actually reuse each rocket ten times, they have a lot of room to lower prices; ten launches would be $($150M - $7.5M) + ($7.5M * 10) = $21.75M per launch, or $334/kg for the rocket itself. Launch cost won't be quite that low because they also have labor, fuel, and so on, but it looks like they can get well under $1000/kg just with the Falcon Heavy. The larger and fully-reusable BFR should do even better. [1] https://en.wikipedia.org/wiki/Falcon_Heavy https://en.wikipedia.org/wiki/Falcon_Heavy [2] https://www.space.com/spacex-falcon-heavy-triple-rocket-landing-success.html https://www.space.com/spacex-falcon-heavy-triple-rocket-land... [3] https://www.nextbigfuture.com/2019/04/spacex-recovered-6-million-fairings-so-falcon-heavy-will-be-92-reusable.html#more-155979 https://www.nextbigfuture.com/2019/04/spacex-recovered-6-mil...
- gliptic 7y agoNote that a 64,000 kg payload LEO launch doesn't cost $90 million because it would have to fly expendable.
- baq 7y agothe fully reusable falcon heavy can IIRC only lift about 8000kg to LEO. expendable is volume-limited but if you want to lift a concrete block, you can :)
- JshWright 7y agoReusable is 8000kg to GTO, not LEO. LEO performance in fully reusable configurations is 30+ tons.
- DennisP 7y agoSo assuming 32 tonnes it's $668/kg for the hardware (assuming full payloads). Probably also have to build in enough slack for occasional failed landings, but we don't know yet what the failure rate will be after the kinks are worked out.
- narrator 7y agoCan we finally stop having sci-fi films in which the whole outcome of the movie is solely determined on some heroic manual flying of a spaceship while simultaneously using manually aimed weapons like it's World War II?
- hwc 7y agoAlso, can we start seeing this kind of re-usable multi-stage rocket used for achieving orbit in fiction?
- bergoid 7y agoThe Apollo 13 astronauts would like to share a couple of anecdotes with you.
- jniedrauer 7y agoApollo 13 (the movie) had plenty of careful checklist readbacks and minimal explosions or shaky cameras. Most scifi is more like Michael Bay in space. See Gravity for a more egregious example of a movie that tries to play itself off as "hard scifi" but ends up just being an over the top action movie.
- TremendousJudge 7y agoYeah, The Martian is like, the hardest sci-fi book I've ever read, but I found the film adaptation... lacking
- deleted 7y ago[deleted]
- clarkmoody 7y agoMy favorite sci-fi anticipates increased autonomy of technology and incorporates that smoothly into the narrative.
- timdiggerm 7y agoIf you're talking about Star Wars, definitely not, because it's intentionally unrealistic. Other sci-fi, maybe.
- goshx 7y agoI was at Kennedy Space Center's Apollo/Saturn V viewing site for this launch and it was amazing. If you ever have the opportunity to be there for a Falcon Heavy launch, do yourself a favor and go. It's quite an experience and totally worth the money.
- WhompingWindows 7y agoWhat was amazing about it? Tell us the story.
- goshx 7y agoAside from the whole historical factors of the location itself (for instance: the humans sent to the moon were launched from that same launch pad), watching the launch from a video or live stream does not tell the entire story. To hear the roar of those 27 engines and feel it vibrating on your chest and the bleachers is an emotional experience. Then you can see the boosters coming back, and their entry burn and you can follow them down to their landing zones. A few seconds later you hear the sonic booms. While all this is happening, you also have the energy of the happy crowd cheering and celebrating what humans are capable of doing. It gives you hope and an exciting future to look forward.
- ravedave5 7y agoIt's definitely the sound that most can't be reproduced at home. It really sounds like the air itself is being ripped apart. That's why I want to go back and see another launch. Also, the flame is SO BRIGHT, video doesn't do it justice. It's miles and miles away and it's almost like looking at a welding flare.
- jostmey 7y agoI've seen a falcon launch (not the falcon heavy). It is indeed amazing
- ambicapter 7y agoYeah, if you have a week of free time. I planned to go this weekend but chickened out at the last second-turned out in my favor since they launched yesterday, four days after the original date.
- mhandley 7y agoNice video capturing the sonic booms from the booster landings here: https://twitter.com/jefffwilliams/status/1116486329284595717 https://twitter.com/jefffwilliams/status/1116486329284595717
- jcims 7y agoI’m always surprised at how loud the single engine landing burns are.
- misterprime 7y agoYep, shared that with the office and family. That's amazing. It really does feel like the future.
- ineedasername 7y agoCan someone explain why reusable mode can't lift as much?
- JshWright 7y agoBecause it has to reserve fuel for landing.
- rjf72 7y agoI find this, and SpaceX, so inspiring. It's easy to feel that technology just moves itself forward. After all there are billions of people on Earth with people working on a countless array of different problems. And each day things seem to move forward, almost inexorably so. And so it's easy to feel that the value of the individual is really relatively low. Yet imagine a world where Elon did not exist and thus SpaceX did not. Much of what he's done is stuff that we could have been working on decades ago. For some time we were. NASA as early as the 70s had already laid out plans for a Mars expedition including a tremendous space ship that would be assembled and fueled in orbit to take 5 man crew on a 600 day manned expedition to Mars, including landing of rovers similar to the moon. Those plans got canned by Nixon, and space never really recovered. Not only did we not "inexorably advance" in space, we regressed. Today we're struggling to do a manned flyby of the Moon - when we went to having barely put a man in orbit in 1962, to putting a man on the moon in 1969. The point of this is that technology does not advance by itself, let alone inexorably so. I think it's extremely likely that had SpaceX not come to exist, it's entirely possible that we would still be effectively where we were at near the turn of the century. Progress of our species, in spite of there being billions of us, is still dependent upon the individual. And SpaceX's plans have very much followed the old quote of Gandhi, "First they ignore you, then they laugh at you, then they fight you, then you win." But of course we've not yet won. As remarkable as this achievement is, it's but the starting line for where we need to be. And that line will not move forward unless we move it forward. But "we" does not mean waiting for somebody else to do so. As SpaceX and Musk have demonstrated, it's ultimately up to the individual to get up and move that line forward -- for the betterment of all.
- chasd00 7y agoif you want to talk inspiring, consider Gwynne Shotwell. She's tasked with turning Musk's crazy ideas and timelines into reality. I can't imagine a tougher job and she's killing it.
- TremendousJudge 7y agoI always read about Musk like he does the whole thing on his own. Never read about all the engineers that work their asses off to achieve these results