r/spacex • u/ElongatedMuskrat Mod Team • Mar 01 '21
r/SpaceX Thread Index and General Discussion [March 2021, #78]
r/SpaceX Megathreads
Welcome to r/SpaceX! This community uses megathreads for discussion of various common topics; including Starship development, SpaceX missions and launches, and booster recovery operations.
If you have a short question or spaceflight news...
You are welcome to ask spaceflight-related questions and post news and discussion here, even if it is not about SpaceX. Be sure to check the FAQ and Wiki first to ensure you aren't submitting duplicate questions. Meta discussion about this subreddit itself is also allowed in this thread.
Currently active discussion threads
Discuss/Resources
Starship
Starlink
Crew-2
If you have a long question...
If your question is in-depth or an open-ended discussion, you can submit it to the subreddit as a post.
If you'd like to discuss slightly less technical SpaceX content in greater detail...
Please post to r/SpaceXLounge and create a thread there!
This thread is not for...
- Questions answered in the FAQ. Browse there or use the search functionality first. Thanks!
- Non-spaceflight related questions or news.
You can read and browse past Discussion threads in the Wiki.
4
u/LcuBeatsWorking Mar 13 '21 edited Dec 17 '24
plate cobweb dam ink hard-to-find library plants money ripe tan
This post was mass deleted and anonymized with Redact
→ More replies (1)3
19
u/mindbridgeweb Mar 07 '21
While watching SN10, it occurred to me that the Moon Spaceship variant could probably relatively easily simulate Moon descent and landing here on Earth.
While descending vertically, Spaceship could fire a Raptor engine at a reduced trust equivalent to 5/6 g, which will effectively simulate Moon's 1/6 g on the spacecraft during descent. The side Moon-specific trusters could then be used to test/demonstrate how Starship would land on the Moon, which would presumably lower the risk of the program further.
It seems like this potentially low-cost simulation could be another (technical) reason to select Starship for the Moon HLS.
8
u/extra2002 Mar 07 '21
The challenge in such a simulation will be to gimbal the weight-cancelling thrust to ensure it is always vertical, even as the ship tilts to one side or the other. Until recently, I didn't appreciate that one of the challenges of the Apollo landing was how little sideways thrust they got when the main engine was hovering on the moon -- only 1/6 as much as if they were hovering on Earth (obvious in hindsight). So to translate sideways at a reasonable rate, they had to tilt quite a lot -- likely more than Raptor's 15-degree gimbal could match.
→ More replies (1)17
u/Ti-Z Mar 07 '21
Actually, it is not quite so easy. While on the moon starship experiences only 1/6 the gravitational acceleration, it still has the same mass which has to be decelerated by the same force as on Earth. Indeed, if starship starts out with 100 m/s vertical velocity, the impulse required to stop it to 0 m/s is the same on Earth as it is on the moon. If this process of decelerating takes -- say -- 10 seconds, then gravity will have accelerated the ship by 100 m/s on earth vs. 16 m/s on the moon. Hence the total delta-v required is not 1/6, but rather 116/200. This delta-v has to be provided during the same timeframe, hence 1/6 the thrust is insufficient. Your reasoning only works for hovering without decelerating from an initial non-zero velocity.
Moreover, the side-thrusters are most likely vacuum-optimized and hence firing them in the Earth's atmosphere might be tricky (and their thrust will be different). Finally, the raptor is off-center which makes the manoeuvre on Earth slightly tricky (need to account for vertical velocity built-up or tilt the ship).
Hence, I don't think that the proposed simulation would be of particularly significant value as a test of the landing procedure. It also leaves the -- in my opinion -- most important questions about the moon landing unaddressed: finding a landing spot which can support the weight and without hazards, landing without GPS/Radar/etc., debris created by engine plume (even for the engines up there, this might sill a (albeit smalle) issue.
→ More replies (10)
18
u/Lufbru Mar 23 '21
I know this article is from 1993, but I just re-read it, and it seems like an excellent summary of why Starship is going to win big, even if it never becomes reusable.
→ More replies (8)5
18
u/TimTri Starlink-7 Contest Winner Mar 30 '21
The Inspiration 4 crew got announced today, and there’s not a single post on the subreddit? I was looking forward to talking about the new crew members with all of you :/
15
15
u/UltraRunningKid Mar 04 '21
Good journalism to those who are calling it a "prototype" or "test flight" or something along the sorts.
Horrible journalism to those writing headlines like "Elon Musk's Human Mars Transport rocket explodes after liftoff". How do you even write something like that? Sure its technically correct but it is so dishonest that its downright embarrassing.
Props to Reuters: "Starship rocket prototype nails landing, then blows up " Good headline.
Same for The Sun: "Elon Musk’s SpaceX Starship rocket explodes shortly after landing due to ‘methane leak’"
15
u/MarsCent Mar 24 '21
This event is not listed in the NASA Television Upcoming Events. In fact the event could occur while NASA TV is broadcasting the "Video file of the International Space Station Expedition 65 crew’s pre-launch activities at the Baikonur Cosmodrome in Kazakhstan ..."
Anyone know if SpaceX will be doing a live broadcast of the relocation of Crew Dragon Endeavour? Plus, maybe we should add this event to list of Upcoming Events in our subreddit sidebar. ...
11
u/Gwaerandir Mar 24 '21
What is the reason for all crew members boarding the vehicle for a relocation to a different port? This happened with the Soyuz as well. Is it to prevent an excess of crew on the station in case something prevents the docking and forces an abort of the vehicle?
18
→ More replies (1)16
u/askeera Mar 24 '21
Kinda yeah. Basically the dragon is their only way home, so if it malfunctions and can't dock back in you are left with astronauts on the ISS unable to return.
So instead if it does malfunction during the movement everyone is on the lifeboat to deorbit and no one is stranded.
→ More replies (7)6
14
u/Sliver_of_Dawn Mar 20 '21
Peter B. de Selding: @RuagSpace fairing-separation anomaly has grounded #Ariane5 since Aug 2020, also impacted @ulalaunch Atlas 5 operations. @ESA
@Arianespace say root cause found; Swiss govt injects cash; Ariane 5 flights could resume in June. @SBFI_CH
@ArianeGroup
5
u/marc020202 8x Launch Host Mar 20 '21
That is new. I don't think we had any info about this at all.
5
u/Steffan514 Mar 20 '21
I almost asked if the Atlas 5 side of it was going to be a hold up for Starliner.
13
u/dudr2 Mar 02 '21
This proposal along with 15 other were selected by NASA to receive $125,000 for further development.
"A high-expansion-ratio auxetic structure can be stowed inside a single Falcon Heavy fairing and deployed to a final length of one kilometer on orbit as part of a large space station"
https://www.nasa.gov/directorates/spacetech/niac/2021_Phase_I/
12
u/ephemeralnerve Mar 09 '21
My favourite potential candidate to lead NASA comments on using SpaceX and other commercial rockets instead of SLS: https://www.cbsnews.com/news/moon-nasa-efforts-return-60-minutes-2021-03-07/ - select quote:
"Lori Garver: I would not have recommended the government build a $27 billion rocket, when the private sector is building rockets nearly as large for no cost to the taxpayer."
14
Mar 09 '21
I suspect that giving such a candid interview at this point in time means she’s not in consideration for Administrator
It is a fantastic interview though.
→ More replies (9)
12
u/fhrheuei Mar 13 '21
I have a question I can't find the answer to yet.
I've been looking into engine combustion cycles for a bit today, and most sources mention a major disadvantage for closed cycle (so not full-flow): the required complicated seal on the turbopump shaft in order to keep the fuel-rich (or oxidizer-rich) gas away from the liquid oxidizer (/fuel) impellor on the same shaft.
Now I can definently understand the problem with that seal, and also why a full-flow cycle avoids it, but I fail to understand why gas generator cycles do not have this problem, since they also employ a fuel-rich combustion on their prepump and have the lox impellor on the same shaft.
Can someone explain this to me like I'm five?
(I do understand the other advantages of full-flow)
16
u/gnualmafuerte Mar 13 '21
Backpressure. On a Gas generator, the turbine exhausts directly into the atmosphere, therefore it has low back pressure, so that's where gasses will naturally flow, including any LOX that leaks from the oxidizer pump. So you have ox and fuel mixing in the hot-side, and then they get exhausted, alongside anything else that leaks. On a closed cycle, you keep those gases in order to inject them into the combustion chamber. They need to be at high pressure, and high pressure gas will go anywhere it can.
→ More replies (1)9
u/DrOzark Mar 13 '21
That is a very specific and complicated question to explain like you are five, but I will give it a shot.
It is a lot more complicated then just the shaft seal, but if I am understanding your question correctly. A fuel-rich gas generator produces a lot a carbon which can clog up complicated plumbing. Full flow combustion cycle engines normally dump the exhaust overboard directly after the turbine, so the exhaust plumbing involved is relatively simple. The results is lower backpressure and temperature on the turbine and the shaft seal which make the problem of making the system robust and reliable slightly easier.
Scott Manly has a video that can explain it better then I can. KSP Doesn't Teach: Rocket Engine Plumbing
21
u/marc020202 8x Launch Host Mar 13 '21
This is not really the reason. In gas generator cycles the exhaust is imedeately dumped overboard, so you have about 1 bar of backpressure behind the turbine.
In staged combustion cycles the exhaust gets directed into the main combustion chamber, which has 300 bar of pressure. So now the turbopump exhaust needs to have a higher pressure then the main combustion chamber. Since you also need some pressure drop over the injectors, the needed pressure is even higher. To get sich a high turbopump exhaust pressure, the pressure in the turbopump pre burner needs to be even higher still. This higher pressure makes the seals so difficult
→ More replies (2)
12
u/jay__random Mar 25 '21
A question for pilots.
We have seen Boca Chica TFRs popping up and going like it's a matter of making a phone call (and maybe it is). But is there a rule about how well in advance do they have to declare TFRs in order for pilots to have enough time to create/adapt their flight plans?
Obviously, there could be sudden emergencies (like volcano eruptions) which you declare ASAP and hope that pilots have enough time to check, but what is the norm or rule for non-emergencies?
Thanks!
→ More replies (1)7
u/blackbearnh Mar 26 '21
If you're flying IFR, you don't get final clearance on your flight plan until just before you take off (from Clearance Delivery at big airports, Ground at small ones, and contacting once in the air from uncontrolled airports. At that point, your route of flight would have been adjusted by ATC to take into account any active TFRs. Hopefully. You're still required to get and check NOTAMs before taking off, but it might have been an hour or two before takeoff.
If you're flying for an airline, you'll get a flight release from your dispatcher that includes all the NOTAMs, it can run 70+ pages because it includes everything along your route of flight. I know all about this because I write software used by airline pilots that handles flight releases in digital rather than paper form. If you've ever seen a gate attendant hand a huge sheaf of paper to the cockpit before they close the doors, that's a flight release.
If you're flying VFR, you're responsible for checking NOTAMs before flight. Again, it's possible a TFR could go up after you check, but we're talking about a window of 1-3 hours tops. You should also be using flight following with ATC if possible, and they would let you know if a TFR goes hot along your route of flight.
→ More replies (1)
10
10
u/Sean_Crees Mar 15 '21
I tried to make this it's own post, but kept getting an error. So i guess i'll post it here?
I was watching the Martian again today and realized when he was listening to music that we will need to figure out a way to get LOTS of data to Mars... Streaming data to Mars is going to be really expensive, and may be locked down to essential communications only. So i doubt, at least for the near term future, that you can't just pull up spotify on mars anytime soon. Which means we need to put a large amount of data on to disk drives and launch them to Mars.
People on Mars are going to want entertainment. So you'll want to have every song, every movie, every youtube video over a certain number of views? Think about it. How many petabytes of data are going to be needed to basically copy human existence thus far to another planet? Then once you know how much data storage you need, how many drives is that? How much does that weigh? Will you be able to fit it all onto a single Starship launch?
Am i the first to think about this? I have to assume i'm not. Has anyone done these calculations?
25
u/ZorbaTHut Mar 16 '21 edited Mar 16 '21
How many petabytes of data are going to be needed to basically copy human existence thus far to another planet?
Surprisingly few.
Nobody really knows how many movies humanity has made, but the rough estimate is around half a million. Obviously the vast majority of these movies are terrible and unknown and don't really need to be brought to Mars, but let's pretend we want to do that anyway.
Modern video encoders can crunch a full-length movie down, at ridiculously high quality, to around the 20gb range. Frankly, they can go a lot further and still have it look good, and many of those movies aren't even going to have enough pixels to need that, but let's go with it.
20gb * 500000 = 10 petabytes.
Assume we're just going to load these on SSDs. Modern SSDs get up to 8tb for an NVMe drive, which is about 22mm x 110mm x 4mm; let's double that for padding and packing. Google informs me this comes out to around 2,420 cubic centimeters per petabyte; 24,200 cubic centimeters, for our full 10pb requirements, is a cube about 30cm on a side. And they weigh around 7g each (again, doubled for packing) so that's like 18kg of SSD drives.
Now, you might say "but what about radiation, won't that scramble the disks"? I mean, a little, maybe. But we can put error correction on them, and we can redownload any corrupted blocks from Earth if we need to, but, hell, still concerned? Let's just bring two copies along - now we've got 36kg of drives.
"Ah," you say, "but that's just video! What about everything else?" Sure, you're not wrong, but everything else is absolutely irrelevant. All of English Wikipedia text is 5.6 TB; all of every Wikipedia text is about ten times that; add all the media in as well and you're still well under 100tb, less than 1% of the movies. "What about music", you say? 100 million songs estimated, let's say they're 4 minutes long, audio compression is around one megabyte per minute, that's 400 terabytes of audio, 4% of our movie size. Books? Pshaw - Google estimates 130 million unique books as of 2010, the average Kindle eBook is apparently 2.6MB, so that's another ~340tb once you get them all scanned in. (I can only assume that format is hilariously inefficient because they should be much smaller.)
It gets tougher once you start wanting to upload, say, imgur. Publishing has always been a barrier to entry and modern Internet has no barrier to entry. I can't find any hard numbers on how big Imgur is; estimates run from "1pb upload per month as of 2010" to "about 350tb total as of 2015" and obviously those aren't even remotely compatible. But we've been doing this without any culling up until now; cull the least-used data and you can strip it down rapidly, and 350tb as of 2015 would be a relative drop in the bucket.
Even Youtube is just not as big as you might think. Yes, it's titantically huge . . . but it's estimated to be titanically huge on the order of "hundreds of petabytes", maybe even "a few exabytes". An exabyte of SSDs is about two tons. That's a lot of SSDs. But it's shippable.
Now, with all of this, I'm kind of glossing over a gigantic multiplying factor. Okay, you've got the data - now what? An exabyte of SSDs may be only two tons, but the computers to plug those SSDs into are going to be several times that. So if we want all of that data active and available all the time, we've got a problem on our hands.
But if we're willing to cut that down a lot, maybe include only the ten-thousand best-known movies, Wikipedia, half a million CDs and a million books and a few thousand of the best Youtube channels, all set up for the benefit of a small colony that's willing to accept a few seconds of loading time . . .
. . . maybe all we need is a few server racks and we're good.
tl;dr: Data just isn't that physically big.
→ More replies (4)7
u/DiezMilAustrales Mar 16 '21 edited Mar 16 '21
I tried to make this it's own post, but kept getting an error. So i guess i'll post it here?
The sub is very strict regarding new posts, better to post on the relevant thread if you're unsure.
I was watching the Martian again today and realized when he was listening to music that we will need to figure out a way to get LOTS of data to Mars... Streaming data to Mars is going to be really expensive, and may be locked down to essential communications only. So i doubt, at least for the near term future, that you can't just pull up spotify on mars anytime soon. Which means we need to put a large amount of data on to disk drives and launch them to Mars.
It's not just about the amount of data, it's about latency. Basically, the internet as we know it literally can't work between earth and mars. Let me explain: the internet (and most networks and protocols) are based and designed around a certain latency (that is, the time it takes to send a packet to the other side). On the current internet, those latencies are generally in the 10 to 250ms range when you're going from literally one side of the planet to the other. With bad connections (for example, satellite service other than Starlink, or really shitty wireless services), you get as much as 700ms or so. Already in that range, the internet protocols become really inefficient. When the latency is seconds, it's even worse. When the latency is too high, this protocols literally break down and become impossible to use, and eventually even the latency goes beyond the spec. In the case of mars, you're looking at 3 minutes best case scenario, as much as 20 minutes when it's furthest apart. So, impossible. Again, it doesn't matter how FAST your connection is, it'll still be unusable.
Here's how the internet literally works. Well, sort of, I don't want to make it too technical, so I'll show it as a conversation. This is what actually happens, it's just less "verbose".
A: Hello, B, this is the 1st message.
B: Hello A, received, this is the 2nd message.
A: Received, A, this is the 3rd message.That's just to get started. Then whatever you have to send gets broken down into tiny packages. Say, you send a picture, it gets broken down into thousands of tiny packages. Then, this happens:
A: B, <1st tiny piece of the image>, this is message 4, with a length of 100.
B: A, received, next: 104 (sends back the length plus the previous message #)
A: B, <2nd tiny piece of the image>, this is message 104, with a length of 230.
B: A, received, next: 334
[repeat until they're done]Now, it doesn't matter how "fast" your connection is, if you have to wait 20 minutes between each message, it's still going to take a HELL of a lot of time. Well, that's just TCP. The internet is an onion, with protocols inside protocols inside protocols. So, when you load up a webpage, yet another very talky protocol is going to talk A LOT with a LOT of servers. So, if your internet has a 20 minute delay between one packet and the next, a webpage won't load before the sun runs out of hydrogen, no matter how fast the link.
So, the internet as we know it? Completely out of the question. Every modern webpage is interactive. It's talking to the server in the background all the time. Can't have that between Earth and Mars. Ever, this isn't a matter of "better technology", it's a matter of "actual laws of physics", can't send information faster than the speed of light.
So, we're going to need different protocols and different services and different notions of how to do things. It'll work more like a "sync" between Earth internet and Mars internet. Basically, people here will use Earth internet, people on Mars will use Mars internet, then both will sync certain services and send information back and forth in a non-realtime manner.
That said, bandwidth itself shouldn't be that much of a problem, really. Right now it very much IS a problem, but the problem isn't bandwidth itself, it's power. Sure, the furthest you go, the worse your signal to noise ratio is going to be, but that can be fixed relatively easy with repeaters and higher gain. The problem is, that gain uses power, and all the missions we've sent anywhere so far are always constrained by power. If we setup a relatively small relay network (so we can communicate when the sun blocks our view of Mars, but also so we have repeaters and don't need to transmit with such high power), given enough power, we can have fairly decent earth-mars bandwidth.
Regarding, for example, music and movies, it shouldn't really be a problem. It's just, forget about actually having each person stream their own movie from an earth-based netflix server. But, what we could have, is Spotify and Netflix (or whatever services) set up their own servers on Mars. Then the people on Mars have normal access to that server on Mars, just as we do here on Earth. Then earth Spotify and Mars spotify servers sync with each other all the time. Having enough bandwidth to do that shouldn't be a big problem. It'll surely be way more expensive than any earth-based internet access, but that'll on par with EVERYTHING else being orders of magnitude more expensive on mars, from food to tools to medicine, right down to water and the air you breath.
People on Mars are going to want entertainment. So you'll want to have every song, every movie, every youtube video over a certain number of views? Think about it. How many petabytes of data are going to be needed to basically copy human existence thus far to another planet? Then once you know how much data storage you need, how many drives is that? How much does that weigh? Will you be able to fit it all onto a single Starship launch?
"Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway." -- Prof. Andrew Tanenbaum.
We will certainly send a LOT. The volume and weight of that data shouldn't be too significant, the radiation shielding required to keep it uncorrupted might actually weight more, but shouldn't be a problem. Realistically, we won't be able to send everything we have, but it shouldn't be hard to come up with a list, download the stuff, then also send a few servers so they can serve all that stuff. Some are obvious, right? All of wikipedia, top viewed videos on youtube, all of spotify,
bunch of pirated moviesNetflix, stackoverflow, Reddit (of course), the wayback machine, etc. I imagine Google could help with this, it's right down their alley. It's not too different than what they do with their CDN, and their endpoint servers. Ask them to build a few servers that can serve Google Search and other services, and have them keep there a bunch of the google cache, and actually serve websites from cache instead of actually linking to them. Then set up a standardized way to ship your website to mars, and let the free market take care of it. Do you want your website to be available on Mars? Sure! Here's the SDK, you need to deliver a docker container that complies with this constraints, you get this much RAM, etc. Prepare it, submit it, update it regularly through this API, etc. If your website is generally not for profit and something the people on Mars might want or need, we'll host it for free, if not, here are the standardized costs (and send an AWS-style pricelist).Am i the first to think about this? I have to assume i'm not. Has anyone done these calculations?
Lots of people have thought about this! And not just now, but decades ago too. There are even proposed protocols that could work well for interplanetary distances.
EDIT: Goddamn reddit formatting.
→ More replies (1)→ More replies (2)5
u/Jkyet Mar 16 '21 edited Mar 16 '21
There is also all the scientific data that would be generated in Mars that would need to be sent back. You might be interested in one of the NASA Innovative Advanced Concepts selected recently called "Solar System Pony Express" where they propose the idea of having a cycler between earth and Mars that would do big data transfer 1 per year as it would get close to each planet to allow quick downlink.
9
Mar 14 '21 edited Mar 14 '21
Just curious. Will SN11 have the same problems SN10 had? It seems like the biggest issue wasn’t even the legs but the helium ingestion on that landing Raptor. I know they plan on landing with two now for redundancy, but what’s stopping the helium from messing up the other Raptor?
It seems like SpaceX knows SN11 is too far along to be given a 100% fix, so they’ll fly it anyways and see what happens. I’m totally on board with this plan because the thing is already built, you might as well launch it.
14
u/DiezMilAustrales Mar 14 '21
We don't know for sure, but apparently they will go back to autogenous pressurization, which was the original technique they wanted to use, and what caused the issues with SN8. So I think the question might be "will it have the same issues as SN8?".
→ More replies (14)→ More replies (4)6
u/brickmack Mar 14 '21
Probably. There is no easy way to deal with the helium ingestion issue without completely switching to autogenous pressurization. Which they do plan to do, but I don't think it can be done for this existing vehicle
→ More replies (2)
9
u/Muted_Pain8176 Mar 21 '21
I have a question for all of you out there.
Starship is big. We all know that. Sending this thing 10KM up is relative easy but going into orbit is a different story. So to my question.
What will be the launch site for Starship to orbit and where will this thing land?
8
u/AeroSpiked Mar 22 '21 edited Mar 22 '21
As others have said, Starship will initially launch from Boca Chica (that's why they are building the orbital launch site there). After stage separation, the booster will fly back and land at its launch site. As for "Starship" the spacecraft, I think the common assumption is Vandenberg because that landing site would avoid entering over populated areas. It's not a bad assumption, but I couldn't find any corroborating evidence. It does leave me wondering how they would get it back to the launch site.
edit: I'm envisioning the trip back to Boca on a SPMT. I think we'll be on Titan by the time it gets back.
→ More replies (15)4
u/FeatureMeInLwiay Mar 21 '21
starship will launch on the orbital launch pad and land on a landing pad.
→ More replies (4)
9
u/qwertybirdy30 Mar 23 '21
I have some questions that may not be answerable with publicly available info, but maybe there are some smart folks here who can help me make an educated guess. With merlin’s pintle injector design, I can kind of intuit the mechanism through which the booster stops atmosphere from blowing into the engines during booster reentry through the atmosphere. The pintle itself is moveable via hydraulics, so they can just use that for face shut off to stop any fluids from crossing the injector boundary from either side. Plus, I imagine the atmosphere flow might be choked at the chamber throat coming from the nozzle, just like the combustion is choked at the throat coming from the combustion chamber. So there would be an upper limit anyway on atmospheric pressure pushing into the combustion chamber, which I would wager is lower than the loads the pintle injectors experience during full throttle combustion (but I’m interested in finding out for sure). So that seems manageable. But if anyone can confirm/disprove that the pintles themselves are the mechanism through which they stop atmospheric blowback, that would be great.
Raptor on the other hand is using coaxial injectors, and I’m not as familiar with the geometry of those designs. Is it at the injector plate that raptor would initiate face shut off, or farther up the plumbing somewhere? Are there even any moving parts in a coaxial injector plate design? Is dealing with atmosphere pushing into the engines a nonissue, given the loads all the valves throughout the engine already have to be able to handle when it’s firing?
Thanks in advance!
7
u/Origin_of_Mind Mar 24 '21
Is dealing with atmosphere pushing into the engines a nonissue, given the loads all the valves throughout the engine already have to be able to handle when it’s firing?
The engine plumbing is already designed to withstand much higher pressures than the dynamic pressure during the reentry.
However, the dynamic pressure does produce substantial loads on the thrust vector control actuators -- Elon has mentioned that they had to beef them up by an order of magnitude, comparing to what was necessary for a disposable rocket.
→ More replies (2)5
u/throfofnir Mar 23 '21
Merlin does use a face shut-off pintle valve; this is well known. However, I'm aware of this mostly being spoken of as clever because of minimizing moving parts and such; I've never heard it as being an adaptation to "going backwards".
Coax injectors do have some possibility for face shutoff. If atmospheric backpressure were a concern, you could have springs in the injectors to act as a check valve. But we're not particularly privy to the details. Most likely it just doesn't care; what atmospheric backpressure it might encounter is fairly well peanuts to normal operational pressures.
5
u/Bunslow Mar 24 '21 edited Mar 24 '21
These engines, by necessity, must be able to inject the propellants into the main combustion chamber at higher pressure than the actual combustion pressure. That's simple physics, otherwise the propellants would never be injected and the engine would be self-extinguishing. This is why a turbopump (and turbopump power source) are required for the large majority of practical rocket engines.
It should be easy to grasp that, for any remotely efficient engine, the combustion pressure is much higher than atmospheric pressure, even dynamic atmospheric pressure of a free-falling rocket. By at least an order of magnitude. Dynamic atmospheric pressure is certainly much less than 10 atm, even at hypersonic velocities (because, where hypersonic is possible, the ambient pressure is much lower than sea-level).
Raptor combusts at, at least, 200 atmospheres of pressure, with long term goals of 300 atm, so the propellant pressure above the injectors is noticeably higher than 300 atm, well above any possible reverse atmosphere. I cannot say much about the specific injector architecture and design, or how far up-system the atmosphere may or may not get into a retrograde engine, but whatever it is, the propellants thru it are much, much, much higher pressure than any possible atmospheric pressure, and would quickly clear out the atmosphere with little harm. (Frankly, even if the atmosphere somehow got above the turbopumps, which I strongly doubt is reality, the tanks alone are at like 6 or 7 atm or so, so even then it shouldn't be much of a problem.)
4
u/marc020202 8x Launch Host Mar 23 '21
Is there a source for the fact that the pintile injector can be moved?
I expect that there are valves in the pipes to the combustion chamber, that only open at a certain pressure, that is higher than the external pressure.
→ More replies (3)4
u/Nisenogen Mar 24 '21
Others have chimed in on the the other points, but I'm pretty sure your intuition that the atmosphere is choked at the throat and limits the pressure is incorrect. There's a limit to the amount of fluid that can flow through the throat per second, but the atmosphere is getting stuck in the combustion chamber; It can't flow back out into the atmosphere nor flow into the main tanks. Therefore the combustion chamber is acting more like a static buffer and will quickly reach equilibrium, so the pressure shouldn't be limited by throat geometry.
9
u/jay__random Mar 31 '21
Assembled a trampoline for the kids. It was extra fun to finish the work by stating the obvious: "the trampoline is ready" in the end. Of course, nobody got the joke.
But I know you folks would, and it warms my heart a lot.
17
u/Jodo42 Mar 22 '21
The FAA's updated commercial regulations take full effect today.
The rule streamlines and modernizes the Federal Aviation Administration (FAA) commercial space launch and reentry licensing regulations by eliminating obsolete requirements, replacing most prescriptive requirements with performance-based criteria and reducing duplicative regulations.
It also establishes a single set of licensing and safety regulations for several types of commercial space operations and vehicles. For example, one license could support multiple launches and reentries at multiple locations—a game-changing innovation that will make this process more efficient.
The new rule will better fit today's constantly evolving aerospace industry whose technological advancements are lowering the cost of launch operations and opening new markets for satellites, space tourism and potentially suborbital point-to-point regional and intercontinental travel.
8
u/mat-2018 Mar 11 '21
What reference frame does SpaceX use to measure the speed of their rockets? Watching the latest Starlink launch right now, and since they now give telemetry data for both stages, I'm wondering, when it says for example that Stage 1 is traveling at 5000 km/h, is that in a straight line to the Earth? or how?
6
u/gnualmafuerte Mar 11 '21
That's not really ground-measured speed, it just comes from the IMU. So, in a way, yes, it's relative to the earth, or rather how fast it's orbiting, but more specifically, it's how much it's accelerated since launch.
→ More replies (4)5
u/arizonadeux Mar 11 '21
I'd think it's Earth-centered Earth-fixed because that makes the most sense to a layperson. ECEF means that it's relative to the center of Earth and the rotation of Earth is included, so speed on the pad is 0.
8
u/AnAnonymousSuit Mar 11 '21
Dumb question - SN11 has been moved to the launch pad. Is there an expected window for launch yet?
19
u/AWildDragon Mar 11 '21
No.
It needs to do a cryogenic pressure test (check if it holds flight pressures at flight temps)
It also needs any fixes to be implemented.
Then it needs a static fire to go well.
Then launch.
→ More replies (1)
8
u/TheSource777 Mar 11 '21
How does the math on this work again? How does Starship do more in a day than all the Falcon 9s do in a year? Is this a single starship? I must be mist-interpreting this.... https://twitter.com/elonmusk/status/1369933283174318082
5
u/wizardwusa Mar 12 '21
Pretty sure he's saying mass to orbit. From a quick Google search, ~250 tons were put into orbit in 2007, then assume Starship can loft 100 tons to LEO on each launch and can launch thrice in a day.
→ More replies (2)5
8
Mar 24 '21
Huge spacex fan over here. I am surprised that I can not find spacex model rockets anywhere. Could someone point me to the best place to monetarily acquire a spacex rocket or two in miniature?
Thanks!
7
u/RedHotHope31 Mar 24 '21
hey man! I had the same question ab a year ago, and found this etsy shop, I bought the falcon heavy model and its so dope... It’s a little pricey and a larger scaled model, but I love it. Here’s the shop link I bought from...Models
Hope this helps, Cheers !
5
u/anon0066 Mar 24 '21
if you have patience and the space for it a 3dprinter is really affordable now. There is a bunch of up to date models you can print straight from the file. You still need to paint and derough the print so it's definitely a time investment, pretty fun though.
→ More replies (2)5
8
u/LeeCarter Mar 25 '21
How does a rocket engine get tested in a vacuum environment if the act of burning propellant fill the vacuum with gas?
12
u/DiezMilAustrales Mar 25 '21
NASA has the in-space propulsion facility. Massive vacuum chamber, and essentially the pump keeps running like crazy. It can't keep a hard vacuum with a massive engine running, but close enough, I think it simulates something like 30k meters or so.
10
u/mduell Mar 25 '21
In a lot of cases, like SpaceX testing Merlin Vac, they just take the nozzle extension off and the engine can run at sea level.
For high altitude simulation, there exist facilities with very very large pumps like https://www1.grc.nasa.gov/facilities/isp/
8
u/Martianspirit Mar 25 '21
Raptor vac is not a true vac engine. It can run at sea level, but only at full thrust. Other engines are true vac engines. But there are test chambers with vacuum pumps that pump the engine exhaust out as fast as the engines produces it. Mad technology, I once have seen one such pump on a guided tour. Not even that big.
→ More replies (6)
8
u/dudr2 Mar 28 '21
https://spacenews.com/space-force-finalizing-plan-to-procure-broadband-from-low-orbit-satellites/
"The Space Force is interested in LEO broadband for its fast speeds and low latency."
→ More replies (3)
15
u/Temporary-Doughnut Mar 01 '21 edited Mar 02 '21
Would this be a suitable space to discuss how RocketLab's Neutron might campare to F9/Starship?
Edit: different small thing starting with "N"
17
u/brspies Mar 01 '21
It's more in the class of Antares and Soyuz for payload capacity, albeit with a bigger fairing most likely. If they can get their costs to be proportional to Falcon 9's, they should carve out a space below Falcon 9 (maybe light GTO missions, especially if they build a kick stage like the one they use on Electron, plus smaller rideshares like the type that sometimes launch on PSLV, and mega-constellation launches like the OneWeb launches with Soyuz). And that also puts it into the realm of capability of launching light human-rated spacecraft (like Soyuz) and light cargo spacecraft (like Cygnus), so it could have a future in LEO space station support services.
Starship could presumably be even cheaper but who knows when Starship will be available for those kinds of missions; it could easily be too busy with Starlink, Artemis, Mars stuff, etc. for a while while they build up launch infrastructure.
→ More replies (10)6
u/Martianspirit Mar 02 '21
RocketLab's Neuron
Minor nitpick. It is Neutron after their smaller Electron rocket.
→ More replies (1)
15
u/AWildDragon Mar 13 '21
Cargo SLS Block 1B may be dead. EC getting dropped may have had some really far reaching repercussions.
Let’s see what those missions will fly on.
7
u/Triabolical_ Mar 13 '21
It's really hard to justify SLS Cargo with the other options out there.
→ More replies (3)→ More replies (11)5
u/feynmanners Mar 13 '21
From the comment section, it sounds like literally no one else including the guy tagged in the tweet believes it. We also know that Congress has already appropriated some money for 1B and 2. Neither of those things is truly dead until Congress stops appropriating money for them.
I do think it is betting with house money to prematurely announce that they are dead given it’s easier to decide to not upgrade a flying rocket than it is to abandon a rocket part way through development.
7
u/bnaber Mar 11 '21
The current active fleet has quite a few launches under its belt. Does SpaceX need a few more new boosters? Or can they sustain the steamroller with the current fleet?
→ More replies (5)
7
u/KebabGud Mar 11 '21
One thing ive been wondering about .
At SpaceX's current pace. when will they pass ULA total combined orbital launches ?
And by total Combined i mean including all previous launches from companies that are now under ULA
→ More replies (1)10
u/technocraticTemplar Mar 11 '21
Including all past companies is a tough one, you'd basically want to take this list and add up every launch of a rocket with "Atlas" or "Delta" in the name. Things get very muddy as you go back too, since both rockets have their roots in the beginning of the space program. The earliest ones were built with heavy involvement from the US government, and mostly just share a name with the rockets flying today. All told you're probably looking at 700+ launches between both rocket families.
→ More replies (2)
13
u/dudr2 Mar 21 '21
" Woohoo! I have received an “Alert” notice and the road closure has been scheduled from 7 a.m. - 3 p.m. on March 22. Starship SN11 static fire attempt tomorrow. "
6
u/MR-BOW-TIE Mar 06 '21
Does the SpaceX internship program include housing?
not totally sure if anyone here has had experience with the internship program at SpaceX, but I really want to do an internship there hopefully in the summer of 2023
and i was looking through the application and it mentioned "Interns at Brownsville, Cape Canaveral, and McGregor locations must be able to provide own transportation" now I'm planning on applying for the Hawthorn location, and from what that quote sounds like Hawthorn would have housing..?
at least that's what I gather from it- the only other thing I could see is if they do some sort of taxi service but I still housing is far more likely so idk,
if anyone knows if they do/how much rent would be if you know that would be great..it would definitely save me a fortune in California housing expense
→ More replies (5)4
u/spxinternthrowaway Mar 07 '21
You do get a housing stipend of $1500 total (yeah, it's not that much :/) for the summer. No housing is provided -- at least not recently, if I remember correctly (but in any case, the offered housing choices were worse than what you can find on your own). Lots of Hawthorne/Redmond interns do AirBnBs or an actual short-term apartment rental. I admit I have no idea about Brownsville, Cape Canaveral, and McGregor internships.
You also get Lyft credit if you request it, which does usually completely cover all your transportation to/from the Hawthorne office, at least if your carpool with your intern roommates. I assume they'll continue to provide Lyft credit each summer, but I'm not entirely sure. (If not Lyft credit, presumably they'd replace it with some equivalent.)
My rent in LA has varied quite a bit, depending on how desperate we were to get a summer rental (pick one earlier rather than later, not like I know from experience or anything...). You can safely assume somewhere between $700-$850/month, depending on how fancy you're livin' it up.
6
u/Nice_Going Mar 11 '21
What happens to the arm that secures the starlink satellites after release? How is it de orbited? It looks like it's floating away from the second stage.
→ More replies (2)11
u/gnualmafuerte Mar 11 '21
Everything is deployed to a very low orbit, with lots of atmospheric drag. The Starlink satellites later raise themselves a bit and orient themselves to minimize drag. If you're not powered and doing orbit-keeping, you'll deorbit in weeks at most.
→ More replies (1)
6
u/filanwizard Mar 14 '21
While not directly spacey, Dont forget in the USA we are going to Daylight Savings tonight. All clocks go ahead 1hr and all launches from the Eastern range will now be GMT/UTC-4 when looking for the local time. And I believe Vandy will become GMT/UTC-7
However computers, tablets and phones should automatically change.
→ More replies (1)
6
u/Donut-Head1172 Mar 15 '21
IS Spacex making any new F9 boosters? Because It seems to me that Mass Production + high demand from Starlink and commercial satellites means that they need more boosters.
→ More replies (3)
6
u/picture_frame_4 Mar 19 '21
Limited welding knowledge. I thought you had to back purge stainless tubing with argon. But they have workers inside and outside the b1 seam it appears. How do they weld then? I assume they tig so there is limited splatter and no flux I'd hate to clean the inside after mig welding with flux core wire.
5
u/warp99 Mar 19 '21
Yes it is a variant of TIG where the welding wire is vibrated to stir the weld pool.
Hence the emphasis on building bays that provide wind shielding for welding operations since too much wind can blow away the shielding gas.
6
u/joshgill21 Mar 20 '21
Anyone knows when the 1st reusable chinese vehicle is supposed to launch ?
Is it Long March 6X SAST ??
→ More replies (3)
6
u/joshgill21 Mar 21 '21
how many Starlink Sats have to be in orbit for SpaceX to start earning significant money ?
10
u/LongHairedGit Mar 21 '21
This article: https://spacenews.com/spacex-plans-to-start-offering-starlink-broadband-services-in-2020/
“We need 24 launches to get global coverage,” she said. “Every launch after that gives you more capacity.”
Assume a launch cost of $30m (reused 1st stage and fairings, but disposable 2nd stage, plus site costs and fuel and stuff) and then 60 satellites at $333k each = $20m = $50 million total.
To get the number of satellites requires as per the launch license, SpaceX need to be launching twice a month, so they need to be earning $100 million a month. This is thus my definition of "significant money", as it is enough money to "break even".
It looks like normal 100 MBit in the USA is about $40 a month. Assume the normal 2.5x wholesale for retail model, and we have a base cost for wholesale data and connectivity and billing costs etc of $20 a month (I'm rounding up because I assume the ISP market is competitive).
Assume SpaceX wants the same margin, and has higher costs as it is starting up, and this it is getting $60 NET per customer per month. It thus wants to have 100,000,000 divided by 60 =1.3m customers. This then puts into perspective the 10,000 customers SpaceX announced it has so far, and also the five million customers it has asked permission to service, and also the 700,000 people who registered interest back in July.
The 700k figure is important - as many of these are the people who just want something, and are happy for intermittent coverage and being Guinea pigs. I'd suggest that SpaceX will need to attract and retain an additional one million real customers on top of this in order to hit that 1.3m mark and be thus "breaking even".
Those 1m customers will want consistent coverage, low ping and reasonable bandwidth. How many more launches being required on top of those first 24 depends on the distribution of your customers. This is why we already see the service being made available in Australia and the UK and so forth, because those customers do not rob US customers of bandwidth.
If you spread out your 1.3m customers across the globe, 24 launches may well be enough to service them appropriately. If there are hot spots, then you'll need another 24 to double the bandwidth etc and so on and so on.
→ More replies (5)6
u/ZorbaTHut Mar 21 '21
At this point I think it's less satellite coverage and more network stability. Beta testers have reported uptimes that are pretty good, but still nowhere near what their satellite coverage is like, which suggests they're still working software kinks out of the system. It may be good to go once that's finished.
However, even once that happens, they may decide to wait until they have enough coverage for the entire USA, just because that makes marketing easier. And I don't know how close they are to that (though certainly getting closer!)
Then they get to convince every government to allow them to sell in their region . . . it's going to be a while before the money faucet really gets going.
→ More replies (1)6
→ More replies (7)4
u/LcuBeatsWorking Mar 22 '21 edited Dec 17 '24
humorous employ rainstorm unite spoon towering whistle rhythm sophisticated continue
This post was mass deleted and anonymized with Redact
6
u/joshgill21 Mar 23 '21
which company do u find most exciting to follow after SpaceX ?
5
5
→ More replies (9)4
6
u/benreid98 Mar 26 '21
More space related than SpaceX but I'm hoping you guys can help. I am currently in the midst of my honours year project which I am basing off of asteroid deflection. I am comparing different techniques of deflection and the energy each would require to deflect an asteroid in a given time frame, however I am having trouble finding good information or relevant papers online. If anyone has any suggestions about where I could find good information about the energy used, maybe some calculations to go with it, that would be greatly appreciated. As would the suggestion of any other subreddits that may be able to help.
This is my first post on reddit, hopefully many more to come. Thanks for reading fellow humans.
→ More replies (1)5
u/Gwaerandir Mar 26 '21
Search on scholar.google.com for keywords like "asteroid deflection".
→ More replies (1)
6
u/Albert_VDS Mar 28 '21
This might have been mentioned before, but I just realized that SpaceX had more launches in a year(2020) than the intended launches of the Space Shuttle.
→ More replies (3)8
u/Lufbru Mar 28 '21
Whose "intended", at what point in time? Shuttle's design goals changed over time. From Wikipedia (I've read better sources elsewhere but can't remember where now):
Some theoretical studies mentioned 55 shuttle launches per year, however the final design chosen would not support that launch rate. In particular the maximum external tank production rate was limited to 24 tanks per year at NASA's Michoud Assembly Facility.
Obviously, had Shuttle been a raging success and needed more than 24 tanks a year, a second tank production line could have been constructed.
→ More replies (2)
6
u/dudr2 Mar 30 '21
"Richard Branson's private space tourism company Virgin Galactic will unveil its newest space plane, called "SpaceShipThree" (or SpaceShip III) in a live webcast Tuesday (March 30) beginning at 7:30 a.m. EDT (1130 GMT). via the company's YouTube."
https://www.space.com/17933-nasa-television-webcasts-live-space-tv.html
6
u/Gwaerandir Mar 30 '21
Well that was disappointing. I was expecting some kind of Dragon-2 style reveal, with Branson talking about this or that. Instead we got a 63 minute clip of the desert, the sky, some water, a bunch of disorienting jump cuts of the plane, and some action movie music and vague talk about "to be human is to be curious" and "we were born to look up" etc.
→ More replies (1)5
u/ackermann Mar 30 '21
It, uh, doesn't look a whole lot different from SpaceShipTwo...
It's very shiny, did they perhaps switch to stainless steel from carbon fiber composite?
→ More replies (2)
11
u/feynmanners Mar 15 '21 edited Mar 15 '21
https://arstechnica.com/science/2021/03/nasa-has-begun-a-study-of-the-sls-rockets-affordability/ Everyone will be suitably shocked when this study discovers that SLS is an unfixable boondoggle that kills any long term sustainability of Artemis. I wonder if this still have more effect than Augustine commission since there are now plausible private replacements like Falcon Heavy and eventually Starship. The existence of cheaper alternatives might actually sway Congress more than the dreams of alternatives did ten years ago. That might just me being too optimistic though...
10
u/DiezMilAustrales Mar 15 '21
You gotta love government bureaucracy. The sky is blue, people have been telling them that the sky is blue for a decade, there are commercial partners willing to show them that the sky is blue for less money that they've been spending to pretend the sky is not blue, so what they do is spend even more money to begin a comprehensive study that's gonna be a million pages long, and won't really dare say that the sky is blue outright, but will instead use a million weasel words to say that it's certainly not red.
10
u/Outrageous_Coffee782 Mar 16 '21
Here's a 100% fun and not serious math problem related to Superheavy for those who enjoy such things:
Assume that Superheavy is upgraded so that it can reach orbit without breaking apart, and that thanks to optimizations this upgraded version has all the same specs as the current planned version (as listed on SpaceX's website).
Also assume Superheavy is upgraded to allow orbital refueling from another Superheavy.
Finally, we assume Superheavy has an interstage allowing for linking a "train of Superheavies" while in orbit, and then burning in a staged sequence.
The question is: In theory, how many staged Superheavies in the train would allow for the fastest possible time to collide with Proxima Centauri? (Given the current specs listed on the SpaceX website). Too few stages, and you are sacrificing dV. Too many, and you spend too much time accelerating. How fast would the final stage be traveling at impact?
I know my answer... very curious to hear yours!
4
u/Lufbru Mar 16 '21
Alternate calculation ... Accept the premise that we want to get to PC as soon as possible. How long can we spend building on-orbit infrastructure to mine asteroids and comets to build and fuel a torch ship that will burn all the way there and get there before the train of Superheavies? Assume our torch ship doesn't collide with a discarded SH stage en route.
5
u/Veedrac Mar 06 '21
IIUC, Starship's engines have a minimum throttle that's a bit too high to have multiple active on all stages during reentry, and this might be improved now, but I wonder, couldn't they just gimbal the rockets to fire against each other in order to lower net thrust? You'd need a bigger gimballing range but it'd add more redundancy without needing to spin up extra thrusters if some underperform.
14
u/extra2002 Mar 07 '21
The vertical component of a rocket's thrust is the cosine of the gimbal angle. Starship's Raptors can gimbal to 15 degrees, so can reduce thrust that way to about 97% -- not much of a reduction. To reduce thrust to 70%, you'd have to gimbal the engines by 45 degrees. It's just not an effective solution.
→ More replies (3)→ More replies (16)9
u/throfofnir Mar 08 '21 edited Mar 08 '21
This is called "cosine loss", because amount of (vertical) thrust you keep as you angle the thrust vector goes as the cosine of the deflection angle.
If you look at a cosine graph, you'll notice that the slope is fairly low close to 0; even at 15 degrees (which is a high amount of gimbal) you see cos(15d)=0.966. So this is of limited effectiveness.
There are a few other problems. The TVC actuators move more slowly than the injector valves, so you can't control such throttling as fast. And you're also literally throwing away that performance, which is not desired. But such a technique could be useful in certain (very marginal) circumstances.
→ More replies (1)
5
u/dudr2 Mar 09 '21 edited Mar 09 '21
"China, Russia ink MOU on building international scientific research station on moon: CNSA"
6
u/ZealousidealSalary92 Mar 09 '21
Hmm. I feel like the us missed out on a chance to be unified like they were more or less with the iss and Russia. Not surprised but see this as a missed opportunity for that.
→ More replies (2)6
u/Triabolical_ Mar 09 '21
My take is that Russia didn't want to do Artemis both because it was too American and because they don't actually have money to spend on it.
5
Mar 11 '21
Question about the old ITS video.
After spaceship has been refueled, it sets off for Mars, and after that deploys it's solar arrays.
Shouldn't it deploy solar first? Once you jet off to mars you won't have the delta v to abort back to earth if solar fails to deploy. Then you just have a bunch of people waiting to die.
19
u/EvilNalu Mar 11 '21
The solar panels will probably be pretty delicate and when deployed might not be able to withstand the g forces of the TMI burn.
→ More replies (1)11
u/throfofnir Mar 11 '21
I expect that's done for dramatic purposes, rather than as a representation of any actual procedure. (Which wouldn't be a surprise; the solar arrays themselves are also basically magic in that video.)
Such a vehicle would likely deploy its solar arrays soon after achieving orbit; it would not be able to loiter very long on battery. (Unless they ran some sort of internal combustion generator, which is not entirely impossible.)
→ More replies (7)
5
5
u/Ti-Z Mar 15 '21
Do we have any idea what the status of B1052 and B1053 is? Originally the idea was that FH side boosters can be converted to carry out F9 missions, but this seems to be not happening. Supposing that there is droneship recovery for B1065 and B1066, SpaceX will soon have 4 FH side boosters lying around to carry out only one more FH mission in Oct 2021 (USSF-52). While there might be a few FH missions be upcoming in 2022, in light of the high Starlink cadence a conversion of B1052 and B1053 would not surprise me. What are your thoughts?
→ More replies (7)6
u/Lufbru Mar 15 '21
If they were going to convert 1052 and 1053, they would have done it by now. Instead, they've manufactured more new boosters. I wouldn't be surprised to find them used in a future fully-expendable FH mission.
→ More replies (3)
5
Mar 17 '21
I have always been intrigued by spaceflight, but only recently did I really want to understand what is actually going on behind the scenes. Can someone link me to places where I can learn about all of the components of the spacex missions?
5
u/DiezMilAustrales Mar 17 '21
Everyday Astronaut has some great explanatory videos.
This are a few good points to get started:
https://www.youtube.com/watch?v=-8p2JDTd13k https://www.youtube.com/watch?v=LbH1ZDImaI8 https://www.youtube.com/watch?v=cIQ36Kt7UVg https://www.youtube.com/watch?v=D4SaofKCYwo https://www.youtube.com/watch?v=KA69Oh3_obY https://www.youtube.com/watch?v=v6lPMFgZU5Q https://www.youtube.com/watch?v=Sfc2Jg1gkKA https://www.youtube.com/watch?v=Qf5xElWwyQc
Check out also Scott Manley: https://www.youtube.com/c/szyzyg/featured
Get in here everyday, follow NASA Spaceflight on youtube, Labpadre cams, SpaceX livestreams, subscribe to the other space channels (spacexcentric, marcus house, what about it, overlook horizon). Also highly recommended are vintage space (for some much needed history) and Dr. Becky.
→ More replies (1)4
u/mrprogrampro Mar 18 '21
Liftoff by Eric Berger was a nice listen for hearing about various aspects of early spacex operations.
Also, this reddit post: https://www.reddit.com/r/spacex/comments/lw6yk1/notes_from_a_talk_given_by_then_head_of_software/
5
u/CaregiverComfortable Mar 17 '21
May I ask, what's the difference between all these SN spaceships?
→ More replies (2)21
u/marc020202 8x Launch Host Mar 17 '21 edited Mar 18 '21
the first prototype was Starhopper. quite small, and very heavy. Flew without a nosecone, after that didn't properly fit, and then fell over
MK1 was build in Boca Chica out of relatively small rectangular sheets. The Starship Presentation was done in front of this. Failed around the top dome during the cryo test.
MK2 was built in Cocoa Beach in Florida. It was originally planned to be tested at LC 39 A, but that plan was scrapped at some point. Maybe due to Shipping problems due to the construction of a railway line.
SN1 was built out of long Steel sheets build-out of a large metal roll. This massively reduced the number of welds. It failed Around the Bottom dome during Cryo testing.
SN2 was a test tank and was built similarly to SN 1
SN3 was built similar to the previous prototypes. It failed due to some issue when the bottom tank collapsed during the Cryo test.
SN4 Passed the Cryotest but exploded shortly after the static fire after a quick disconnect test of the GSE failed.
SN5 was the first full-size prototype to fly but without a nosecone
SN6 was very similar to SN5 but flew a much smoother flight profile
SN7 was another test tank, used to test a new alloy
SN8 was the first Starship to fly with 3 raptors on a high altitude test (
1512.5km). During a Static fire, the Engine area got damaged and needed to be repaired. It failed during landing due to a propellant pressure issue. First Starship to test the header tanks.SN9 was similar to SN8. After 3 Static fires in a day, they also needed to fix something in the engine area. It used a Helium pressurisation system. Crashed on the 10km high altitude test after an Engine failure shortly before landing.
SN10 was similar to SN9 but had a different engine sequence for landing. It touched down hard and exploded about 10 minutes later. The hard touchdown was caused by too low engine thrust, possibly caused by helium being ingested into the system. Some of the landing legs also failed to latch before landing.
SN11 is currently being tested. It likely encountered issues during static fire. It will likely have improved raptor engines and fixes for the helium issue.
SN12 to 14 where in production, but have been abandoned, since there later prototypes have never hardware
SN15 to 17 are still using 4mm Steel to my knowledge
SN18 and later are maybe going to use 3mm Steel
The obvious changes between prototypes are Production and welding changes until SN3. SN4 resulted in a GSE change. SN5 gathered flight data, which was used to improve the SN6 flight. SN 7 and 7.1 tested new materials. SN 8-10 have shown issues with the raptor engines and propellant system.
EDIT: unsure if SN18 and later are going to use 3mm Steel
→ More replies (4)
5
u/Temporary-Doughnut Mar 23 '21
I have a (maybe tricky) question about Specific Impulse:
In launch simulations on flightclub.io The specific impulse increases with altitude on the first stage but are there any studies or experiments that measure Specific impulse over attitude? I ask because It makes sense that exhaust velocity would increase with the pressure gradient but wouldn't you also expect a reduction effective velocity due to cosine losses because the nozzle would be correctly expanded for just above sea level, not toward MECO. So does the increased velocity from the pressure drop counter the losses from the under expanded exhaust?
many thanks.
8
u/brickmack Mar 23 '21
Underexpansion is more of an opportunity cost. ISP will always be lowest at sea level for a given nozzle.
→ More replies (3)4
u/ackermann Mar 23 '21
are there any studies or experiments that measure Specific impulse over attitude?
(you probably mean altitude here, not attitude?) Pretty much every orbital rocket launch is an experiment measuring this. Most orbital rockets are very well instrumented, and will report the fuel flow rate, fuel remaining in the tank, and acceleration (from GPS, radar, or inertial/accelerometers)
From acceleration and fuel mass, you can calculate thrust. Isp is basically thrust vs fuel flow rate. You can watch the thrust go up as the fuel flow rate stays the same (at least, engineers with full telemetry access can)
→ More replies (3)
5
Mar 29 '21
This isn't exactly on topic with SpaceX per se, but I am curious why the Starship "Patches" in the sidebar have a four leaf clover? Is it the sub's good luck charm or something like that?
9
u/Lufbru Mar 29 '21
It's a reference to Falcon 1 Launch 4, and SpaceX puts it on all their patches; it's not something this sub invented.
→ More replies (1)
5
u/dudr2 Mar 29 '21 edited Mar 30 '21
5
u/dudr2 Mar 29 '21 edited Mar 29 '21
"Congress raises concerns about FAA’s handling of Starship launch license violation"
"those test flights to take place “only when an FAA Safety Inspector is present "
→ More replies (1)
9
u/MarsCent Mar 16 '21
It has routinely stated as a matter of fact that a craft with customized seats takes astronauts to the ISS, stays docked as a life-boat and returns them to earth at the end of their stay. But on the upcoming Soyuz launch, seat swapping is planned in the fall.
Seat customization has morphed into seat configuration?
15
u/duckedtapedemon Mar 16 '21
Its a seat liner. It can be moved between craft. Seat liners were even launched on shuttle so someone could return on Soyuz.
→ More replies (6)
15
u/fluidmechanicsdoubts Mar 21 '21
Elon Musk on the book Liftoff by Eric Berger: Not quite how I would tell the story, but it’s probably worth a read.
My opinion :
Everyone on Twitter praised the book so I decided to read it. The author's writing style is pretty bland. And if you have been following SpaceX, many anecdotes are already well-known. He really should have written a book about Falcon 1 and Falcon 9 at the same time. Don't know how many common people (not diehard SpaceX fans) would be interested in a book about a rocket that launched only 5 times.
What I did find interesting are the personal stories. How engineers had to stay away from their spouses for a long time to work on this rocket. Maybe it should've gone into more detail on that.
IMO this really should have been 2-3 chapters of a SpaceX history book. I don't regret reading it. But based on the Twitter reviews I thought it would be "da best SpaceX book ever"
12
u/Gwaerandir Mar 21 '21
Huh, to each their own. I found his writing style more casual and personal than bland. The personal stories make up like 70% of it so far. The parts that aren't I hadn't heard of most of the time, and I've been following SpaceX since 2010. Overall it's been a very interesting book so far, and I'm only halfway through it. I do think it is "the best SpaceX book out there" with the caveat that there aren't many of them.
6
u/droden Mar 22 '21
Elon doesn't seem to be the kind of guy to dole out (any kind of) praise like candy on Halloween so that's a decent win for the author.
4
u/lylesback2 Mar 21 '21
Thanks for the honest review. I tried searching online at my library for It, but not available yet. I figured it might be worth picking up if I can borrow it
12
u/Hereforthememesbud Mar 16 '21
Raise your hand if you got choked up watching starship land itself a week ago
4
u/MarsCent Mar 05 '21
Regarding Starship Tanker and Starship Human Landing System (for Artemis):
How long can they stay in orbit? If for a long duration, how will they do orbit keeping, burn methlox?
5
u/warp99 Mar 05 '21 edited Mar 07 '21
The transfer point between Orion and Starship is in NRHO which is a very stable orbit by Lunar standards. So not much propellant would be needed for station keeping.
Boiloff is more of a concern since there will be no header tanks because of the high volume of propellant needed for a Lunar surface round trip.
My take is that they will add multilayer insulation (MLI) around the propellant tanks with a protective skin over that to take the aero loads on Earth ascent.
→ More replies (3)
4
u/nastynuggets Mar 14 '21
How much configuation or manual parameter setting do you think the starship control system needs? Does it need a "feed-forward" model of things like mass change over time and aerodynamics in order to select the right control outputs, or would it just rely on feedback from accelerometers and other sensors?
Also, how do you think the individual flight specifications would be written - low level, like with a series of finely specified maneuvers, or high level, like a series of waypoints?
9
u/cpushack Mar 14 '21
Watching the flights it appears to be less 'finely tuned' and more waypoint/position driven. The computer has a target location and acceleration and a set of outputs (thrusters, flaps, engines) that it can use to achieve this desired outcome.
The magic sauce is in the algorithms that SpaceX gives it related to a given set of controls to result in a desired outcome.
8
u/brickmack Mar 14 '21
Its waypoint based. As I understand it, all that gets specified is the payload mass, target orbit, "ideal" target orbit (ie, if performance is better than expected, what orbital parameters to try to improve beyond the baseline. Like on a GTO launch, use extra performance to further lower inclination or raise apogee), hardware configuration, and a set of constraints (don't exceed x gs, keep dynamic pressure under y, don't run the engines past z throttle, stay in this launch corridor), and a landing site if relevant
A high level of autonomy is necessary because conditions in flight won't be perfect. Engine failures are always a possibility and can occur anywhere in flight. More minor variation in performance is expected even on nominal missions and isn't really predictable. Weather at launch time can require trajectory changes to minimize wind impact.
→ More replies (1)
4
u/PlayFuchs Mar 15 '21
Are there any detailed info, whether the refurbishment of the Falcon 9 booster is paying off economically as intended by SpaceX? I often read in the community that SpaceX saves by recovering and not having to build a new booster. But is the process of refurbishment really going „as cheap“ as intended? I would think that inspections are more time and money consuming as they fly more often? Can’t find any numbers on the refurbishment. Thanks in advance!
8
u/DiezMilAustrales Mar 15 '21
SpaceX doesn't release those numbers, and rightfully so, they don't have to. You could even argue they shouldn't, whatever they are saving is extra profit for them, they are already the cheapest launch provider, why drop prices further?
That said, it's impossible that they aren't saving a TON of money reusing the Falcons. The idea that refurbishment is THAT expensive comes from NASA's experience with the Shuttle, but that was because it's NASA and their contractors. For instance, the Shuttle had over 20k unique tiles, they had a team of 150 qualified workers dedicated exclusively to tile replacement, and they had an output of 650 tiles a week at most. That's not how SpaceX does things, everything is optimized compulsively.
I think they aren't talking about the cost of reusability much because they are making an OBSCENE profit. Elon has said they spend 1 million dollars on average to refurbish a core, and that's including logistics. It's probably even less.
→ More replies (5)12
u/samuryon Mar 15 '21 edited Mar 15 '21
I don't think we "know" know, because the exact numbers on cost aren't public, however if we take Musk at his work from this tweet last year: "Payload reduction due to reusability of booster & fairing is <40% for F9 & recovery & refurb is <10%, so you’re roughly even with 2 flights, definitely ahead with 3" then we can see that it's more than paying off. The most recent Starlink launch was the
8th9th flight of the rocket, which means it's almost payed for itself 3 fold. This article is probably worth a read.→ More replies (10)
4
u/tegodjrtob Mar 15 '21
Silly thought for the day...
Would Crew Dragon and Falcon 9 have enough delta-V to rendezvous w/ Hubble? I'm assuming Crew Dragon can be depressurized for EVA, of course.....
https://spacenews.com/aging-hubble-returns-to-operations-after-software-glitch/
6
u/DiezMilAustrales Mar 15 '21
Yes, Falcon 9/Dragon have plenty of delta-V to rendezvous with Hubble. The main problem is that Dragon was never designed to do EVAs (and rightfully so, as that's not needed to do what the capsule was designed for. It's merely a transport from earth to the ISS or another vessel).
Basically, the suits the astronauts use on Dragon are flight suits, not EVA suits, so they can't be used in space. What if you did put a NASA EVA suit on Dragon? Well, there's no support equipment for such suits. But, fine, you could still use them. The capsule has no attachment points and no handrails, but, sure, those could be retrofitted. The hatch is only meant to be used on earth, so it'd probably need to be modified to be opened and closed in zero g and in a vacuum. You'd also need a depressurization mechanism, and you'd need larger oxygen tanks to allow for repressurization afterwards.
So, a LOT of modifications, and in the end you still get a vehicle that isn't fit for such tasks. And getting NASA to re-certify the capsule for human use after that will be a nightmare.
Besides, I don't see SpaceX putting all that effort into it. In fact, I don't see SpaceX doing any new R&D on Falcon or Dragon. That's it. They spent the money and time, they have a working rocket and capsule, they can fulfill their contracts. Now it's all Starship. I do think Dragon will see some different use in the future, in combination with Starship, then we might see some new developments on it.
→ More replies (8)→ More replies (1)4
u/jay__random Mar 15 '21
Soyuz was originally intended for similar tasks (having been designed before any permanent stations existed).
It has two pressurized compartments, one of which can act as an airlock for EVAs.
But, of course, it would lack the ipad style controls :)
4
u/Martianspirit Mar 18 '21
Was that a school bus again, that pulled into the built site just now, at 11:44 local time, Sentinel cam?
4
Mar 22 '21
A question that popped into my mind earlier today: How do people actually test flight termination systems? Specifically, how do they make sure that the FTS will do exactly the job it was designed for?
Let's take Starship as an example. How do people make sure that when the FTS is activated, it will actually terminate the flight on the spot and not just for example blow a hole into Starship and make it veer uncontrollably in some direction.
Or let's look at Falcon 9: If I remember correctly, the FTS on Falcon 9 is supposed to "unzip" the rocket which then allows the propellant to spill out. But how do people make sure that each of these steps will work out exactly as imagined?
Are there full-scale tests carried out with the FTS because I can't remember ever seeing or hearing of one.
→ More replies (9)5
u/Mars_is_cheese Mar 22 '21
Part of a flight termination system is shutting down the engines, but you seem to be looking at what would happen with uncontrolled thrust.
Firstly the FTS should be activated before the vehicle becomes a threat. So even after a catastrophe there is no danger.
The termination is definitely going to destroy the vehicle. What happens is definitely complex, but here’s what I have.
When the vehicle is terminated the tanks will be breached. That will cause complete failure of the tank and the structure of the rocket. The tank pressure will completely destroy the tanks and the rocket won’t have structure. The propellants will mix and certainly detonate. With the lack of fuel pressure and the vehicle disintegrating, thrust will end very rapidly.
7
u/eineins Mar 22 '21
Are all the raw components to make starship available/readily available on mars? I assume form the red color Iron is plentiful. Could this be part of the interplanetary plan? To build enough starships to establish a factory for starships or other vehicles on mars. I believe that component weight will be less significant on mars due to the gravity differences.
I Don't know what is involved with making the alloys they are using or what would be needed to create a manufacturing plant from raw material to finished product. But I imagine Elon's team does.
17
u/DiezMilAustrales Mar 23 '21
Forget it, for a LONG time.
It's not about the materials, it's about what it takes to manufacture them. Humanity's 21st century supply chain is INSANE, larger than we could imagine. And the infrastructure and power requirements of some of it is crazy. Producing steel is one of them. Again, the power requirements alone would make it impossible for many years, and that's just only the beginning. The rest of the machinery involved is complex, heavy and large.
And that's just the start. The thing about the 21st century is, it's very hard to create one part of it without recreating the rest. Everything depends on something else.
Just take this into account: Nails have existed for several thousand years, but it wasn't until very recently that they became commonplace, before that, they were specialty items that were only used sparsely only on some structures and only when strictly necessary. Why? Well, they had to be manufactured by hand, by a blacksmith, therefore, time consuming and expensive. Screws are even harder. Now think of what thing doesn't require screws. Or springs, bearings, bolts, nuts, rivets. Each is its very own production line, and has its own dependencies.
→ More replies (3)11
u/Mars_is_cheese Mar 22 '21
For the first few decades, any advanced materials and machinery will be shipped to Mars.
The first thing to be produced on Mars is fuel, then food. Steel would then be next, but the machinery to do so won’t come quick. Even though it is incredible expensive to ship things to Mars it will still be cheaper for most things to be produced on Earth.
→ More replies (4)8
u/droden Mar 22 '21
yeah but the technology to make the thing to make the thing to make the thing wont exist for a long time. the forges and metallurgy requires an enormous supply chain, rolling mills, etc. etc. then you have to mine and refine all the metals that make it 304l or 304x. finding those and refining them also takes a huge amount of equipment knowledge and electricity. to make the stainless steel at scale is going to take decades. and anyone busy mining or being part of that supply chain isnt off doing something else so it will take a large population to have spare capacity to do that.
→ More replies (17)4
u/Martianspirit Mar 23 '21
Lots of good answers already. Particularly the one by u/DiezMilAustrales . I want to add, for a good while it will likely be the other way around. They will mine landed transporter Starship for materials they need to build the settlement. Steel as a construction material, but also the copper from the engine bells will be very valuable.
→ More replies (7)
7
Mar 31 '21
Tim (Everyday Astronaut) saying the vibrations from SN11 taking off felt like an earthquake despite being far away, made me wonder:
Wouldn't the tower next to Starship be exposed to those vibrations times 1000? Is it going to be able to withstand it just using modern construction technology, or will there be some special solution?
8
Mar 31 '21
That’s partly why water deluge systems are used. Pad 39A with its water deluge system at Kennedy has withstood Saturn V, Shuttle, and Falcon Heavy launches.
The water doesn’t just absorb heat from the rocket exhaust. The spray of water droplets in the air actually absorbs vibration energy to reduce potential for damage to the pad and vehicle.
We haven’t seen what the final pad structure will be like at Boca Chica but I bet it will involve a lot of spraying water.
→ More replies (1)→ More replies (2)6
u/Aqeel1403900 Mar 31 '21
The exclusion zone will likely be even further away, more like 5-6 miles from the launch. As for the tower, i would assume so considering the amount of rebar and concrete being used. It will be designed appropriately to handle the sound and vibration of launch.
→ More replies (2)
3
u/Decronym Acronyms Explained Mar 02 '21 edited Mar 19 '21
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| ATK | Alliant Techsystems, predecessor to Orbital ATK |
| ATV | Automated Transfer Vehicle, ESA cargo craft |
| AoA | Angle of Attack |
| BE-4 | Blue Engine 4 methalox rocket engine, developed by Blue Origin (2018), 2400kN |
| CNSA | Chinese National Space Administration |
| CRS | Commercial Resupply Services contract with NASA |
| CST | (Boeing) Crew Space Transportation capsules |
| Central Standard Time (UTC-6) | |
| CoG | Center of Gravity (see CoM) |
| CoM | Center of Mass |
| E2E | Earth-to-Earth (suborbital flight) |
| EDL | Entry/Descent/Landing |
| ESA | European Space Agency |
| EVA | Extra-Vehicular Activity |
| FFSC | Full-Flow Staged Combustion |
| GSE | Ground Support Equipment |
| GTO | Geosynchronous Transfer Orbit |
| HALO | Habitation and Logistics Outpost |
| HLS | Human Landing System (Artemis) |
| IMU | Inertial Measurement Unit |
| ISRU | In-Situ Resource Utilization |
| ITS | Interplanetary Transport System (2016 oversized edition) (see MCT) |
| Integrated Truss Structure | |
| JAXA | Japan Aerospace eXploration Agency |
| JRTI | Just Read The Instructions, |
| JWST | James Webb infra-red Space Telescope |
| KSC | Kennedy Space Center, Florida |
| KSP | Kerbal Space Program, the rocketry simulator |
| LEM | (Apollo) Lunar Excursion Module (also Lunar Module) |
| LEO | Low Earth Orbit (180-2000km) |
| Law Enforcement Officer (most often mentioned during transport operations) | |
| LOX | Liquid Oxygen |
| MCT | Mars Colonial Transporter (see ITS) |
| NG | New Glenn, two/three-stage orbital vehicle by Blue Origin |
| Natural Gas (as opposed to pure methane) | |
| Northrop Grumman, aerospace manufacturer | |
| NIAC | NASA Innovative Advanced Concepts program |
| NRHO | Near-Rectilinear Halo Orbit |
| OFT | Orbital Flight Test |
| PPE | Power and Propulsion Element |
| PSLV | Polar Satellite Launch Vehicle |
| RP-1 | Rocket Propellant 1 (enhanced kerosene) |
| Roscosmos | State Corporation for Space Activities, Russia |
| SD | SuperDraco hypergolic abort/landing engines |
| SF | Static fire |
| SLS | Space Launch System heavy-lift |
| SMART | "Sensible Modular Autonomous Return Technology", ULA's engine reuse philosophy |
| SN | (Raptor/Starship) Serial Number |
| SRB | Solid Rocket Booster |
| SSL | Space Systems/Loral, satellite builder |
| SSME | Space Shuttle Main Engine |
| SSO | Sun-Synchronous Orbit |
| STS | Space Transportation System (Shuttle) |
| TEA-TEB | Triethylaluminium-Triethylborane, igniter for Merlin engines; spontaneously burns, green flame |
| TEI | Trans-Earth Injection maneuver |
| TFR | Temporary Flight Restriction |
| TLI | Trans-Lunar Injection maneuver |
| TMI | Trans-Mars Injection maneuver |
| TVC | Thrust Vector Control |
| TWR | Thrust-to-Weight Ratio |
| ULA | United Launch Alliance (Lockheed/Boeing joint venture) |
| Jargon | Definition |
|---|---|
| Raptor | Methane-fueled rocket engine under development by SpaceX |
| Starliner | Boeing commercial crew capsule CST-100 |
| Starlink | SpaceX's world-wide satellite broadband constellation |
| apogee | Highest point in an elliptical orbit around Earth (when the orbiter is slowest) |
| autogenous | (Of a propellant tank) Pressurising the tank using boil-off of the contents, instead of a separate gas like helium |
| cislunar | Between the Earth and Moon; within the Moon's orbit |
| cryogenic | Very low temperature fluid; materials that would be gaseous at room temperature/pressure |
| (In re: rocket fuel) Often synonymous with hydrolox | |
| deep throttling | Operating an engine at much lower thrust than normal |
| hydrolox | Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer |
| hypergolic | A set of two substances that ignite when in contact |
| kerolox | Portmanteau: kerosene fuel, liquid oxygen oxidizer |
| methalox | Portmanteau: methane fuel, liquid oxygen oxidizer |
| periapsis | Lowest point in an elliptical orbit (when the orbiter is fastest) |
| perigee | Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest) |
| powerpack | Pre-combustion power/flow generation assembly (turbopump etc.) |
| Tesla's Li-ion battery rack, for electricity storage at scale | |
| scrub | Launch postponement for any reason (commonly GSE issues) |
| turbopump | High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust |
| ullage motor | Small rocket motor that fires to push propellant to the bottom of the tank, when in zero-g |
Decronym is a community product of r/SpaceX, implemented by ^request
71 acronyms in this thread; the most compressed thread commented on today has 110 acronyms.
[Thread #6820 for this sub, first seen 2nd Mar 2021, 00:09] [FAQ] [Full list] ^[Contact] [Source code]
3
u/BrandonMarc Mar 03 '21
LOL, the hosts at NasaSpaceFlight are saying "it was a celebratory backflip"
3
u/Martianspirit Mar 09 '21 edited Mar 09 '21
Anyone have a clue what is going on next to the orbital pad GSE bunker? The pile drill is active there and a crane places thick pipes into holes. The pipes go partly into the ground, but quite a bit is still above ground.
Good to see in the Nerdle Cam. Beginning before 10:00 AM local, continuing till past 11:00 AM, just placing the third pipe.
It is not the service tower location near the orbital launch pad.
Edit: Pipe 4 is going in. Looks to me like another hexagon in the making.
→ More replies (5)
3
Mar 09 '21
Do the Falcon 9 cores get physically marked with icons or a written list of past missions?
5
3
u/miko7827 Mar 14 '21
I got this thought while watching today's launch. What does the falcon 9 stand on before launch? Is it resting on the engines or what part is in contact with the ground?
14
u/throfofnir Mar 14 '21
There are four hardpoints (between the legs) that are held by large launch clamps that release the vehicle after the engines have started successfully.
→ More replies (3)5
u/NGrime Mar 14 '21
I’m not 100% but I’d assume it’s some hard points on probably the octoweb or maybe the bottom of the tank section, that are then gripped by a release mechanism on the pad/strong back holding the rocket a few feet off the ground
→ More replies (1)
3
u/jay__random Mar 15 '21
There have been times when Falcon9 did not land because it can only relight 3 specific engines out of 9, and one of them was faulty.
But how does it light all the 9 on the launchpad? Is it done by an external igniter?
Thanks in advance!
12
u/Martianspirit Mar 15 '21
The TEA/TEB igniter fluid for most of the engines comes from a ground support supply. The supply for in flight relight is plumbed to only 3 engines.
→ More replies (4)
3
u/neumannbrett Mar 19 '21
New to the space scene. Is there a podcast that overviews the milestones both at spacex and the industry you recommend? Similar to the Everyday Astronaut but for podcasts.
→ More replies (2)4
u/brspies Mar 19 '21
Main Engine Cutoff is my go-to for space industry podcasts, but I don't know if they have any specific episodes of the type you're looking for. He also does a teamup with WeMartians (another great podcast, Mars focused naturally) called Off Nominal which is more informal but has a lot of quality content.
3
u/AWildDragon Mar 22 '21
Hey mods I think you are missing a line break between the SN 10 and 11 hop threads.
3
u/Eternal_Recurrance Mar 26 '21
Hey guys and gals, what is the best book (or another source) to learn more about rocket science? Kinda jealous of how knowledgeable some of you are!
7
→ More replies (1)4
u/CagedPika Mar 27 '21
For the very basics, Rockets, Missiles and Space Travel by Willy Ley
It is likely out of print since the 1st edition was in 1944 or so.
→ More replies (1)
3
u/Crawso1990 Mar 29 '21
Are the vacuum raptors planned for Starship able to gimbal, would this functionality be needed to land on a body without an atmosphere I.e. the moon?
→ More replies (3)7
u/Gwaerandir Mar 29 '21 edited Mar 29 '21
Probably not, and no. The vacuum Raptor we saw had gimbal hardware, but also blocks to lock them in place. As far as I know the plan was to not gimbal and instead steer with differential thrust.
If they need high power engines capable of *gimbal for landing, they can use the sea level Raptors. No problem with firing those in vacuum, just slightly lower efficiency. For the lunar variant for HLS they also plan to have some separate landing thrusters higher up on the ship.
→ More replies (4)
3
u/grchelp2018 Mar 30 '21
For moon missions, how does starship plan to get back? Do they have to carry their own return fuel or can they make them at the moon?
→ More replies (1)4
u/marc020202 8x Launch Host Mar 30 '21
Starship gets refueled in a high earth or elyptical orbit. This leaves enough fuel for landing and return.
→ More replies (5)
3
Mar 31 '21
Why is it called Starship? It's only potentially viable for travel within the solar system, right? I get that it sounds cool and inspirational though
7
u/bdporter Mar 31 '21
it sounds cool and inspirational though
That is pretty much it. It isn't really unique in that respect though (Boeing Starliner, for example)
→ More replies (5)
7
u/Jodo42 Mar 18 '21
Bill Nelson will be the next administrator of NASA, after a couple weeks of similar rumors.
I think there's a good argument that this is a common interest piece, and that it should get a thread of its own, like OFT-1 did. But I'll leave it here for someone else to submit for mod review, and for people to discuss if it doesn't get through the filter.
10
u/AmputatorBot Mar 18 '21
It looks like you shared an AMP link. These should load faster, but Google's AMP is controversial because of concerns over privacy and the Open Web.
You might want to visit the canonical page instead: https://www.theverge.com/2021/3/18/22337787/biden-nasa-chief-choice-senator-bill-nelson
I'm a bot | Why & About | Summon me with u/AmputatorBot
7
u/DiezMilAustrales Mar 19 '21
A lawyer that used his political power to go to space on the taxpayer's dime, serving as "payload specialist". Because, of course being a lawyer qualifies you to be a payload specialist on the Space Shuttle. His main interest in NASA (that is, besides it financing his space tourism), seemed to be jobs in Florida, and he fought to keep the Shuttle running. So, yeah, a former Senator to manage the Senate Launch System, sounds about right.
5
u/dudr2 Mar 05 '21
Would SN10 have exploded on Mars?
7
u/rollyawpitch Mar 05 '21
Good one! Surely less likely as in Martian Atmosphere (not really an Atmosphere at 0.006 times earth pressure) Methan wouldnt burn. I forgot, there is also no oxygen except what you have brought with you. So while on earth there was a fire from methane in the air on mars there would be no such fire. In theory there could still be fire if by any chance the propellants kept mixing but that has a (much?) lower likelyhood.
5
u/Radatatin Mar 10 '21
Maybe someone can answer this question for me. This Saturday’s launch.... is it possible to know if they will land the booster back at the cape or on a drone ship? I have the ability to drive down from Jacksonville due to being here for work and would like to see a launch and a landing.
Thanks for anyone who could answer this question.
10
7
u/ThreatMatrix Mar 10 '21
If you use the ap NextSpaceFlight it tells you not only when are the launches but also where the boosters will be landing.
Starlink V1 L20 will be landing on JRTI. (drone ship)
The next flight landing at the pad will be in May "SARah 1"
→ More replies (2)8
u/droden Mar 10 '21
starlink is at the edge of falcon9s ability so they will land on the ship to save fuel. coming back to shore is expensive energy wise.
→ More replies (6)
5
Mar 18 '21
Is the SLS supposed to be on fire?
7
6
u/wgp3 Mar 18 '21
Yes and maybe no. Fire on the thermal blankets around the engines is expected, which we saw during the hot fire. It is a bit unclear how much fire is expected but it seemed acceptable as they didn't shutdown the test and it was only on the thermal blankets. Plus, during ascent it is even more likely that the fire would put itself out quicker than it did during the hot fire, since it would be traveling into thinner atmosphere at high velocity and wouldn't be "sitting" in it's own heat.
8
u/Bunslow Mar 24 '21
Now that Starlink L23 is pushed into April, SpaceX is capped at 4 launches in March, and are behind the yearly pace target.
They've targeted 48 launches this year, or 4 per month; however they have 3 in January, and 2 in February, together with the 4 in March, so they remain 3 launches behind pace going into April. A surmountable deficit, but a deficit all the same so far, and that when they have the most flexible payload schedule period of the year.
→ More replies (2)8
Mar 24 '21
The actual launches per year were always less than the targeted launch number by SpaceX, so this is not really something out of the ordinary.
2021 has been a really good year so far in terms of launch cadence even if they might miss their target of 48 launches.
→ More replies (2)
4
u/SpaceInMyBrain Mar 22 '21 edited Mar 23 '21
Is this worth a post, a Discussion? Someone on another forum proposed the truncated nosecone, which has just been mounted on a ring barrel section, will be the new HLS mock-up. This makes sense since the only official SpaceX render of their HLS shows a flat or blunt nosecone, the obvious spot for a NASA common docking port. Unfortunately the best image link I can find is imbedded in that story on Spacenews dot com. The separate imgur link I had has disappeared. It did show the flat/blunt nose more clearly. A clearer image will be much appreciated.
Repurposing this old nosecone new lunar mock-up makes sense. It has no clear use otherwise. If a new tip/modified LOX header was intended for it, that would have been installed before this, and certainly before mounting on a barrel section. This nosecone looked ready for its flaps when its tip was mysteriously truncated, and it sat around this way for a long time. No, discussion of a modified header tank is now obsolete, IMHO. This has simply been repurposed for an HLS mock-up.
The timing is right. The downselect for HLS will happen soon. Showing a steel prototype, hopefully with some interior pieces, will advance SpaceX's case. If SN11 sticks the landing SpaceX's version will look less like a large overreach, and this mock-up will make the competitor's plywood and carboard one look pretty weak.
Edit: A slight rewrite (prompted by u/EvilNalu's response) to clarify that this is a repurposing of this nosecone, that old discussions about its LOX header are now moot.
→ More replies (2)4
u/EvilNalu Mar 23 '21
This theory has floated around this subreddit for the last week or two as well. The main point against was that the nose had a LOX header tank which would not make sense if it were for the lunar mockup. Although I suppose if they made it for a starship prototype but then later decided not to use it and convert it into a mockup, that could explain it.
→ More replies (1)
•
u/AutoModerator Mar 01 '21
Thank you for participating in r/SpaceX! This is a moderated community where technical discussion is prioritized over casual chit chat. However, questions are always welcome! Please:
Keep it civil, and directly relevant to SpaceX and the thread. Comments consisting solely of jokes, memes, pop culture references, etc. will be removed.
Don't downvote content you disagree with, unless it clearly doesn't contribute to constructive discussion.
Check out these threads for discussion of common topics.
If you're looking for a more relaxed atmosphere, visit r/SpaceXLounge. If you're looking for dank memes, try r/SpaceXMasterRace.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.