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Giant SpaceX Spiral Appears Amid the Aurora Lights in Alaska's Night Sky
- adzm 4y agoWhy is there so much excess fuel to begin with?
- tuatoru 4y agoContingency planning.
- Symmetry 4y agoPhysical systems aren't perfectly predictable, and so require feedback. You include a little more fuel than you think you need so that if you use more than expected, say because solar conditions make the atmospheric drag a bit higher, you won't run out with the payload just shy of the intended orbit. But during re-entry there's no reason to keep that with you and if by some chance your stage arrives intactish at the ground it might cause a fire. Hence the venting before re-entry.
- pixl97 4y agoIn case something doesn't work as efficiently as possible. Since these rockets are not specialty designed for each launch you only save a very tiny amount of money/weight by not filling it all the way up.
- LeonM 4y agoTo add to the other (good) answers: it is also because this makes (re)starting the engines in zero gravity easier. Liquids behave very weird in 0g, trying to suck fuel from a nearly empty tank in 0g can be challenging. Leaving more fuel in the tanks makes this less of a challenge.
- Tuna-Fish 4y agoThat's not all that much fuel. There's always some margin in the tanks to make sure that the turbopump won't ingest a bubble, and probably a little more so that if the rocket underperforms slightly on ascent they won't lose the mission because they skimped on 50kg of fuel.
- 0xDEF 4y agoThere isn't that much excess fuel. The reason it looks so big and dramatic is because of water vapor and fumes reflecting sunlight.
- BenoitP 4y agoI wouldn't say there is a lot of excess fuel as a percentage of the mix in exhaust gases, but there is some, by design. Maybe a few percents. Why do we want some fuel in the exhaust? Burning an oxydizer-rich mix is not a good idea, especially with a reusable rocket. You'll have a very hot gas that is going to burn-corrode your engine. Metals can burn in an oxygen-rich air. Now imagine that mix at 3,600 K and 300 atm pressure. You'll have what is called in the industry an 'engine-rich' burn. You don't want that. Also, I don't know about this rocket but sometimes you want to cool down your nozzle and you can do that with unburnt fuel that you inject from the side. Running a stochiometric mix puts you also at risk of damaging your engine (some parts of your mix might be oxygen-rich), on top of combustion temperature being higher. Now, burning a fuel-rich mix make these problems go away. And does not decrease much your thrust: heated at very high temperatures, this residual fuel will expand and contribute to some part in the force generated. Last, a fun fact: you can detect when then rocket leaves the upper atmosphere with the flame color! That's when the flame goes from being orange (high temp residual fuel meets oxygen from the atmosphere and burns) to being grey (flame meets the atmosphere but not enough oxygen to relight it, and soot is grey). You can clearly see it happen around 40km altitude here: https://youtu.be/xY96v0OIcK4?t=15881 https://youtu.be/xY96v0OIcK4?t=15881
- corbulo 4y agoThanks for making HN awesome
- cs702 4y agoCool visual effect, apparently created by emission of excess fuel by SpaceX rockets with Starlink payloads. Great photo. Make sure to watch the video too, taken by an all-sky camera run by the University of Alaska. The video shows the spiral as it starts forming at ~1:30. The spiral expands to cover much of the sky, and then dissipates -- all in just a few seconds.
- aardvarkr 4y agoThanks for including the time stamp. That’s a pretty amazing sight to witness
- tqkxzugoaupvwqr 4y agoIn 6–7 minutes real time (see timestamp bottom right). The video is sped up.
- cs702 4y agoSorry, yes. That's what I meant. Thanks! :-)
- yread 4y agoI find the northern lights captured by the camera much more interesting than the rocket spiral
- dmix 4y agoAnother example https://youtube.com/shorts/9SZY_QEozWw?feature=share https://youtube.com/shorts/9SZY_QEozWw?feature=share
- Uptrenda 4y agoWe really are living in the future... and it happened so fast. It's like on one of those empire games where you research the space age and get access to crazy tech. We are now capable of so many advanced feats. It feels like only a few years ago were primitive compared to today. What will tomorrow have? Personal space ships? Underwater houses? Houses for sale on other planets? Service robots? It's mind blowing...
- dylan604 4y agoThe 1950s called and wants it's meme back. Seriously, though, the 50s promised flying cars, personal jet packs, moon bases, etc. They were so convinced cars would fly, they all came with wings on them =) Houses underwater was a thing they thought were right around the corner as well. It really reads like you just picked up a Scientific American magazine issue from your doctor's office lobby that's from the 50s.
- ben_w 4y ago> Seriously, though, the 50s promised flying cars, personal jet packs, You can buy those, they're just expensive to buy, to run, to insure, and to learn how to operate. But you can buy them.
- snovv_crash 4y agoThe future has arrived, it just isn't evenly distributed yet. - William Gibson
- mholm 4y agoAnd soon, it'll be smeared out into a broad global layer of what a Pakistani brickmaker would consider to be prosperity - Neal Stephenson
- jjulius 4y agoThey're also, more often than not, far more limited in scope and capabilities than their imaginative 50's counterparts.
- zzzeek 4y ago"SpaceX rockets are designed to land back on Earth but the second stage of the Falcon 9 does not parachute down to the ground. Instead, it burns up in the atmosphere but before doing so it vents its unused fuel which will often take the form of a stunning spiral. " so...we are marveling at how awesome it looks to dump rocket fuel into the atmosphere? cool, cool
- arprocter 4y agoThe article contradicts itself about what happens to the second stage "it burns up in the atmosphere" and "deorbit and eventually splash down in the Pacific" Seems like the latter is correct (if it was going to 'burn up' why would you need to dump fuel?) - https://en.wikipedia.org/wiki/Falcon_9#Recovery_of_second_stages_and_fairings https://en.wikipedia.org/wiki/Falcon_9#Recovery_of_second_st... I guess they figure it's better to let the fuel diffuse in the atmosphere than poison the ocean, or less weight to be recovered/sink
- ceejayoz 4y agoThe fuel dump is to prevent explosions before reentry that could damage the spacecraft it just delivered or create unnecessary space debris. https://sattrackcam.blogspot.com/2018/01/fuel-dump-of-zumas-falcon-9-upper-stage.html https://sattrackcam.blogspot.com/2018/01/fuel-dump-of-zumas-... > Rocket stages always carry excess fuel, as you don't want the engine to cut out prematurely by running out of fuel. So it always has a sufficient fuel margin. Once its work is done, this excess fuel is often vented, also known as "depressurization". > Depressurization and fuel venting avoids the risk of the rocket stage blowing up, for example as a result of static electricity building up in the rocket stage. You do not want your rocket stage to blow up, as it creates an uncontrolable swarm of debris and includes the risk that particles are ejected into orbits where they do not decay quickly, adding to the space debris risk. As for burning up, it's a bit of both. Some material burns up, some larger chunks splash into the ocean. Same thing happened a while back when the US dropped bits of Skylab on Australia. https://www.abc.net.au/news/2020-05-31/nasa-skylab-fell-to-earth-esperance-retrofocus/12282468 https://www.abc.net.au/news/2020-05-31/nasa-skylab-fell-to-e...
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- samstave 4y agoSo van Gogh's Starry Night was showing how CERN and SpaceX sent multiple rockets back through his time?
- MisterTea 4y agoLooks like they missed an opportunity to visit the Black Lodge and say hi to the Arm.
- shadowgovt 4y agoWhen people complain about the effects rocketry and space colonization will have on astronomy, this is what I think about. Like... How many people complaining about the effects of Starlink satellites have ever actually seen a Starlink chain drift by, like beads on an invisible string? It's mesmerizing.
- femiagbabiaka 4y agoIt's mesmerizing now at small scale, at anything resembling the kind of scale I think SpaceX wants to target it'll just be noise, like contrails.
- subpixel 4y agoI saw one once and my immediate thought was that I hope such an aberration of my natural view of the sky doesn't become common. I would describe it as eery.
- pjot 4y agoI think we’re already past that point. I can hardly see stars now given the amount of light pollution my city puts off. Little dots zipping around won’t change much.
- philwelch 4y agoI think we're in an in-between stage--at some point, it'll be within reach for people who want an uninterrupted view of the night sky to catch a ride into orbit and just look out the window up there.
- JohnFen 4y ago> it'll be within reach for people who want an uninterrupted view of the night sky to catch a ride into orbit The thought that would be necessary just to see the night sky depresses me beyond belief.
- qikInNdOutReply 4y agoReminds me of the sords in crest of the stars.
- andsens 4y ago> Those were the best hours of blissful bewilderment. What a fantastic alliteration to describe his state of mind :-)
- rolph 4y agono joke intended, that rocket flew over my cabin and knocked stuff off the shelves. one earthquake did that about three years ago, had it not been for the subsequent hardening , i would have lost my preserves to a rocket.
- mlindner 4y agoI'm not sure what you're claiming. Rockets cannot cause shockwaves on the ground by flying over you in space. You experienced something else and misattributed it.
- deleted 4y ago[deleted]
- rolph 4y agoyou are quite wrong about that, and im sure it wasnt "in space". i live in a place between two major installations, and see uncommon things often. [such as X-45 variants https://en.wikipedia.org/wiki/Boeing_X-45 https://en.wikipedia.org/wiki/Boeing_X-45] this happened a little before 2:00 hours saturday morning, and was the loudest thing ive ever heard and felt in my life, and was definately not an earthquake, or a hurricane, i saw the spiral.
- dabluecaboose 4y agoI'm sorry, but you're definitely misattributing this. The rocket in question was launched from Vandenburg SFB in California. It was not close enough to you by the time it reached Alaska to have knocked anything off a shelf.
- rolph 4y agoso it didnt fly over central matsu valley, denali range and delta junction? https://www.theguardian.com/us-news/2023/apr/18/northern-lights-spiral-alaska-night-sky-blue-light-spirals-spacex-rocket-fuel https://www.theguardian.com/us-news/2023/apr/18/northern-lig... perhaps you could enlighten me with a trajectory during launch, and during stage recovery. im not the only one that saw the spiral, and i had nieghbours on the next ridge that were disturbed by it as well, they thought the noise was my fuel exploding.
- deleted 4y ago[deleted]
- rurp 4y agoI'm torn on this. On the one hand it's a really cool visual, coming from some impressive engineering. On the other hand, I am absolutely not looking forward to the night sky becoming filled with light pollution.
- agloe_dreams 4y agoI think you might be mixing up this with the actual Starlink sats, which yeah, def pollution. This is from the second stage reentry and only happens for a few minutes in a specific area. Theoretically, Starship will not do this as both stages are reusable...buuuut I imagine they will end up trashing a few stages on the way to get there.
- stronglikedan 4y agoIt looks really cool. And it's fleeting. And it looks really cool. I'd love to see it in person some time. And it looks really cool. And to think it's man made, and on a level with the awe of nature. I'd love to travel all that way to see the Aurora, and then get treated to that as well. I don't see the problem.
- HenrikB 4y agoIn the video on https://vimeo.com/818040730?embedded=true&source=video_title&owner=73339908 https://vimeo.com/818040730?embedded=true&source=video_title..., it appears around the 1m29s for a few seconds corresponding to 08:46:54 - 09:57:09 UTC in real time.
- jtode 4y agoAhh, maybe that's why my service has been spotty lately - sattelites diverted to light shows.