Live feed of Starship SN15 flight test [video] | Hacker News Reader

Live feed of Starship SN15 flight test [video]

spacex.com

315 pointsprtkgpt194 comments

Congrats! Looks like they stuck the landing. Marks the 60th anniversary of first American in space: Alan Shepard's Mercury-Redstone 3 mission ;)

https://en.wikipedia.org/wiki/Mercury-Redstone_3

Also apparently SpaceX’s 21st birthday.

19th, it was founded in 2002.

Happy anniversary!

Wanna work with us? Check out this role on my team - aerospace experience is not required: https://grnh.se/25a344122us

If that's not your flavor, we have others: https://www.spacex.com/careers/index.html?department=Softwar...

The ITAR part is a bummer :-(

How much of the work is on-site? I live in Houston and don't want to move to California for software roles.

They are hiring for software roles in Boca Chica

How’s work/life balance at SpaceX these days?

> ADDITIONAL REQUIREMENTS:

> Must be willing to work extended hours and weekends

I appreciate that they're upfront about that.

Do they hand out good chunks of equity for this at least?

https://www.cnbc.com/2020/03/06/what-elon-musks-early-mornin...

All hand meeting Sunday 1 AM.

>Must be willing to work extended hours and weekends

I'm not completely sure that a web developer doing typical frontend work would consider "being in the same company as people building rockets" to be exciting enough to justify the extended hours and weekends thing. For a mechanical engineer getting to practice the pinnacle of mechanical engineering? Yeah, I get it. For react work? Maybe not so much.

The crew displays of the Dragon 2 are built on web tech.

Hollywood: we're running out of oxygen, we're going to die.

Spacex: the electron app allowing us to control our life support systems via touch screen crashed, we're going to die.

There are physical backups for important controls if touch screen fails.

There’s not many greater missions out there than helping pioneer human space exploration. Realistically whatever your role, it’ll be incredibly small - SpaceX has thousands of employees. But however small, it’s moving the needle forward.

If you’re at the point in your life where you can make major sacrifices to a greater cause I’d say this is a fantastic opportunity.

Disclaimer: I’ve have no affiliation to SpaceX, I just believe in their mission.

Whoah, this comment is dark

> If you’re at the point in your life where you can make major sacrifices to a greater cause

On the flip side, you’re making major sacrifices for the direct benefit of one of the richest men on the planet.

Yeah, I agree

I get it, in Space there are no weekends or nights. People working on Mars missions have to work weird hours etc

But no, I wouldn't work at "infinite crunch" places

Most of the positions are tangibly creating something that will be sent into space. This particular role is likely just for the website.

For a mechanical engineer, working at SpaceX is not making a major sacrifice. You're earning a serious pedigree from a place that is on the cutting edge of your field. If you're a frontend developer, you're going to be paying the cost and not collecting the benefit. It would be nice to hire a React dev from spacex, but we all know they'd be the same as a react dev from any other startup. That is not true for people in engineering career paths. A SpaceX line on their resume will help them for the rest of their career.

Is it just a state of mind? I've been perfectly happy and even proud to do menial work on nights and weekends when it was for a cool cause.

I've said this a few times in other comment threads on HN, but be careful with this mentality. Any hiring manager who sees you as a person who always "watches the clock" downgrades you to someone unreliable for the team, and probably added to a list of "first people to cut" when the opportunity or need arises.

If you are the only person in the world with your skillset, you can maybe get away with this. But "web developer doing frontend work" is one of the more replaceable jobs out there, and it's only getting more competitive.

Don't underestimate the hunger of others in the marketplace. Just because you have a comfortable setup now doesn't mean this will always continue.

I assume you're talking about staying a little late during an emergency, balanced out by leaving a little early when nothing important is going on. SpaceX is talking about 80 hours a week baseline. I understand your platitudes about not being a clock watcher, but if you go to work for spacex expecting to merely not watch the clock, you will find yourself unpleasantly surprised. If we're talking about the average hiring manager, the average hiring manager could not handle SpaceX hours.

Damn. ITAR requirements? Surely with Starlink expanding globally (and focused on functioning in space, rather than the "easily-converted-to-ICBM's" that get it there) there's potential for hiring a more global workforce.

Hit me up when EU nationals can apply for the more interesting positions.

> To conform to U.S. Government space technology export regulations, including the International Traffic in Arms Regulations (ITAR) you must be a U.S. citizen, lawful permanent resident of the U.S., protected individual as defined by 8 U.S.C. 1324b(a)(3), or eligible to obtain the required authorizations from the U.S. Department of State. Learn more about the ITAR here.

If not for this, I would have applied years ago. Your company is changing the world and I just wish I could be part of it.

I feel exactly the same way.

I sometimes wonder what "or eligible to obtain the required authorizations" means. Does that just mean that SpaceX has to sponsor the clearance process for you?

I remember reading another thread where they were talking about one or two non-US people working there, it would be nice if they elaborated more on what the process is for foreigners and maybe had some profiles of non-US people in their employee gallery. Even confirmation from a SpaceX person here that they do have people like that would be nice :)

> I sometimes wonder what "or eligible to obtain the required authorizations"

For stuff that goes beyond just being a US Citizen or Permanent Resident with no criminal record:

If they want you to do an SF-86 with the US OPM for a Secret or better clearance, it really means "if you even THINK you have something negative in your personal background, don't waste our time or yours in applying"

(reference: I'm one of the peoples whose full set of personal data was stolen in the OPM data breach)

https://en.wikipedia.org/wiki/Office_of_Personnel_Management...

Not really in any way SpaceX specific, but this is something you will commonly see if applying with any large defense contractor/US-based aerospace industry firm.

Please don’t spread this sort of FUD. I’ve had cleared colleagues who had nuanced opinions on which pot or acid to use, or who were draft dodgers from their home countries, or who were flamingly out with any kink you could care to name.

They care about blackmail material, oaths to other governments, felonies, and not a lot else.

Not my experience at all - prior clearances and NDAs preclude me from going into detail, but I personally saw a number of people who wasted a lot of time going through the process and getting denied for things in the same category as the first part of your statement.

It's true that almost any randomly chosen member of the DoD can get a regular 'secret' clearance for things that aren't especially super sensitive (I've met some very immature 20 year olds who only had Secret probably by virtue of the fact they were too young to have made any major mistakes in their life yet), but when you go beyond that, the requirements are greater.

Re: being flamingly out and kinky, the key part there is out. This isn't the 1950s were getting blackmailed over being gay is a super high risk to somebody if they're already voluntarily flamingly out.

The issue in this case is not security clearances, but getting authorization to share ITARed data with foreign persons.

There are SpaceX jobs that require security clearance, too, but they're in the minority.

Similar story for me. I was really into model rockets from age 7 to 11, and went to Euro Space Camp.

I studied Engineering, but made the choice to go into electronics rather than aerospace because of my nationality issues (see recent comments).

If they really want you, SpaceX can apply for a license from the government that gives them permission to “export” all the ITAR stuff to you.

Yes. The brain of a non-US person is considered foreign soil for export control purposes.

> If that's not your flavor, we have others: https://www.spacex.com/careers/index.html?department=Softwar...

Many others - made for interesting reading.

Does spacex happen to have fall 2021 software internships?

Do you also allow remote work from outside the US? I have lots of backend en service mesh experience.

As I like to say, "The Soviets may have put the first man in space, but we put the first American in space."

> ”Marks the 60th anniversary of first American in space”

And also 1 day short of the 19th anniversary of SpaceX, which was founded on May 6th, 2002.

This is a huge milestone for the Starship team and SpaceX, so massive congratulations.

This was also fun to watch. Fun in part because while SpaceX had it on "tape delay" the enthusiast channels were showing it live. It will be fun to have them do it without the low cloud cover but I'm guessing that without the disassembly at the end they may have some on-board recordings that are recoverable.

To whomever does telemetry for these things, the frequency bands you are using are blocked by clouds. It makes it hard to keep a live signal. Ask the FCC for a temporary operating permit for 900Mhz or so. You will be much happier with the results.

I was paying close attention to the area of 'heat shield' tiles. That is the next really big hurdle. If you recall getting the grid fins on F9 to survive re-entry was a big challenge. Getting tiles that don't break because the various expansion coefficients don't match is a big challenge as well. That is critical to having enough fuel left over to stop when you get back down inside the gravity well.

It is easy to forget the scale of this thing without visual cues but its like flying skyscrapers around. They are very big. And the booster will be larger still.

Also super curious how the lunar lander version will work. That is awfully high up there, could be a long ladder down to the surface. That, and given its mass, means that when it lands on the moon the dust it kicks up will hit escape velocity[1] which will be interesting.

All in all though, so much progress in space after so much non-progress. Quite the thrill!

[1] https://arxiv.org/pdf/2102.12312

It won’t use the raptors to land on the moon.

The question isn't raptors or something else, the question is mass. In order to decelerate, you throw mass at high speed out the other send. That is typically a small mass (the exhaust gases) hitting the moon at a high velocity.

The larger the mass you are trying to land, the more momentum you are going to transfer to the regolith and dust under the lander. As the referenced paper points out, it is pretty easy to get that stuff up to escape velocity which has it leaving the moon on its own journey into space.

It will use the raptors to decelerate and hot gas trusters to land in the last 10s of metres to avoid this problem. From wiki:

“ The variant will use high‑thrust oxygen- and methane-fueled thrusters located mid‑body on Starship HLS during the final "tens of meters" of the terminal lunar descent and landing to avoid plume impingement problems with the lunar regolith.”

Potentially they could also brake down to 0 velocity when they switch to the thrusters and land at 0.1M/s, but they obviously won’t do that because it’s just a waste of fuel.

Astros on Lunar lander will use elevators to drop people to the surface

In the previous tests Spacex used 2-3 rocket engines for the initial landing burn.

For SN15, the rocket used 2 engines throughout the landing procedure. I wonder if this is a sign of their confidence in the improved design.

The landing was smooth as butter and nothing went noticeably wrong, although I did noticed that the rocket landed dangerous close to the edge of the concrete pad.

There was also quite a bit of fire after the landing, but this time the rocket would not explode from it.

Fire and a few pops/pings/small explosions in the engine area, but didn't appear to destabilize the rocket, which is a good sign.

SN10 blew up from the post-landing fire, because it landed hard, collapsing the landing legs, skirt and damaging/destroying the engine bells and more stuff around them - possibly the thrust bulkhead and bottom of methane tank, leading to significant leaks and eventual explosion. SN15 seems to have landed intact on fully extended landing legs, so the hardware inside the skirt likely survived, and whatever caused the fire was a (relatively) minor leak and not catastrophic.

Man did you notice how close on of the legs came to missing the concrete pad and ending up in the dirt? It looked like just a couple feet to me. It would have probably tipped over.

It slid sideways about a meter on the pad. I believe yesterday had the highest winds in any of their Starship launches.

I think they were supposed to fire all three engines and turn one (or two?) off if they all start fine, but in the video it looks like only two engines started. Not sure if that was intended, or if one of the engines failed to light.

That is what I recall from the prior failures, and what they said they were doing to mitigate. Interesting to see only two lighting.

They actually did it. Lot of work left, but this is the big fence to jump over. The bellyflop and landing is no longer a theory or a hope, it works, with real hardware, in the real world. Rocket go up, rocket come down, rocket still standing. What a thing to see.

Previously as well: Rocket go up, rocket come down. Rocket still standing.

But the difference with Starship is the amount of fuel burned to slow it down.

I think the real success of Starship was proved a few launches ago - flip maneuver, belly flop and coasting on the belly to slow down sufficiently. Landing took a few tries but it was relatively a smaller success compared to the aforementioned aspects demonstrated during failed attempts to land.

Didn't it explode a few moments after the other "successful" landing though? That doesn't really count. My understand is this is the first fully successful landing of Starship with the flop maneuver. Might have missed one though.

Could also be that these Raptors are able to throttle back more deeply. Just a guess though.

Interestingly, the video feed gets corrupted around 11th minute, and neither YouTube under Linux/Firefox, nor VLC, nor mpv can play it: the picture freezes, and error diagnostics are printed.

Youtube player under Windows / Firefox does play it through, forcing its way past some garbage frames with noise and rainbow artifacts.

If you got a snapshot of that corrupted file, I know at least the VLC and Firefox projects would appreciate the bug report, since "freeze + error" is often a short step away from "buffer overflow" — and simply alone the fact that you captured a bytestream under real world circumstances that crashed their players, and have that bytestream for the bug report, is always of maximum interest with such things.

A great idea; will do.

Which video feed? The YouTube stream linked in the submission plays fine under all three players you mentioned for me. SpaceX did have issues with freezing picture around that mark, but that's all on their end (note the clock keeps ticking).

Yea, would guess transmission issues from the rocket to the ground and the clock is added on the ground somewhere. I wouldn't expect the clouds to interfere if the transmission went up to space then back down (would expect them to do something like that at some point). But maybe microwave from ground to rocket could have had clouds interfere with the signal?

Downloading it via youtube-dl for the highest quality version also results in a file that at first glance has many freezes in the video stream, when played in VLC. But I think there's nothing wrong with the youtube stream. The freezes were in the downlink from SN15 to the ground.

If you go to 9:37 in the video, you can see that the overlaid text timestamp in the spacex stream continues to increment (3:06, 3:07, 3:08, etc). It actually is a video that plays normally. Their ground based equipment that was adding the framing and T+ overlay was working normally and sending out a normal stream, it was just receiving frozen video on its input side.

Meaning that they were feeding normally formatted video to youtube at that time.

What i got from youtube-dl looks like the following: https://pastebin.com/1JvVY6s4

The one I've downloaded is a FullHD h264 stream. It freezes at 11:41, with VLC reporting a few lines of errors:

  [h264 @ 0x7f4d35907640] get_buffer() failed
  [h264 @ 0x7f4d35907640] thread_get_buffer() failed
  [h264 @ 0x7f4d35907640] decode_slice_header error
  [h264 @ 0x7f4d35907640] no frame!

It of course freezes completely, with the overlaid clock and all.

VLC version 3.0.13 Vetinari (3.0.12.1-158-g6977abc430), must be pretty fresh.

Not what I'm seeing here with a version of VLC that's slightly older than yours. At 11:41 in the video, the video feed from starship to ground does freeze, but video continues normally with the overlaid time clock counting seconds.

VLC media player 3.0.12 Vetinari (revision 3.0.12-1-0-gd147bb5e7e)

I used the default youtube-dl options which downloaded the video as VP9 codec (See above link to pastebin for ffmpeg's info for the file), not H264, so how it's handling a hiccup in the stream may be part of that.

available formats show as follows

format code extension resolution note

249 webm audio only tiny 51k , opus @ 50k (48000Hz), 5.20MiB

250 webm audio only tiny 66k , opus @ 70k (48000Hz), 5.98MiB

140 m4a audio only tiny 130k , m4a_dash container, mp4a.40.2@128k (44100Hz), 14.90MiB

251 webm audio only tiny 153k , opus @160k (48000Hz), 11.40MiB

278 webm 256x144 144p 73k , webm container, vp9, 30fps, video only, 3.60MiB

160 mp4 256x144 144p 78k , avc1.4d400c, 30fps, video only, 3.57MiB

242 webm 426x240 240p 98k , vp9, 30fps, video only, 4.31MiB

243 webm 640x360 360p 154k , vp9, 30fps, video only, 6.98MiB

133 mp4 426x240 240p 165k , avc1.4d4015, 30fps, video only, 7.32MiB

244 webm 854x480 480p 244k , vp9, 30fps, video only, 10.95MiB

134 mp4 640x360 360p 288k , avc1.4d401e, 30fps, video only, 13.78MiB

247 webm 1280x720 720p 465k , vp9, 30fps, video only, 23.04MiB

135 mp4 854x480 480p 545k , avc1.4d401f, 30fps, video only, 21.75MiB

248 webm 1920x1080 1080p 788k , vp9, 30fps, video only, 26.61MiB

136 mp4 1280x720 720p 1004k , avc1.64001f, 30fps, video only, 39.90MiB

137 mp4 1920x1080 1080p 1985k , avc1.640028, 30fps, video only, 79.93MiB

271 webm 2560x1440 1440p 3509k , vp9, 30fps, video only, 147.72MiB

313 webm 3840x2160 2160p 6214k , vp9, 30fps, video only, 342.33MiB

18 mp4 640x360 360p 210k , avc1.42001E, 30fps, mp4a.40.2@ 96k (44100Hz), 24.25MiB

22 mp4 1280x720 720p 475k , avc1.64001F, 30fps, mp4a.40.2@192k (44100Hz) (best)

How do they get the video stream from the rocket to the ground? Maybe the clouds caused interference?

Rocket exhaust is highly charged and can cause significant interference! It’s easy to loose a com link

Interesting.. how wide of an impact area would the exhaust have? Would it only impact signals traveling directly through it or would there be some bubble of interference around it?

Ionized gas escapes from the exhaust plume and causes interference in general... the actual aerodynamics are... complicated!

"Starship landing nominal!" - @elonmusk

https://twitter.com/elonmusk/status/1390073153347592192

For those looking for more explanation and commentary - I really enjoy the Everyday Astronaut streams of Starship. https://www.youtube.com/watch?v=htnG_mABtSQ is SN15

I love his stream and was watching as well, but decided to also try out NASASpaceFlight (https://www.youtube.com/c/NASASpaceflightVideos) and was pleasantly surprised. They had video feeds from multiple sides so you could really see the landing, as well as integrating the SpaceX live feed. I hope Tim does the same in the future, as they only showed a view of the landing pad and clouds during the entire flight i.e. we only saw 3 seconds of take-off and landing.

That's a standing, upright rocket, which is pretty cool!

More camera angles (unofficial): https://www.youtube.com/watch?v=NPNvB5ComFw

Looks like whatever the small fire was after the landing has been contained.

At 11:08 you can see udp://234.70.253.161:9000

IANA reserved multicast space, often used in peoples' internal networks, not something you could ever access unless you were connected to the same network segment as the video stream source.

Today I learned, thanks for sharing that info!

Thanks a lot! I was almost about to spend couple hours analyzing the ip and ports. Now I know that it’s a reserved multicast ip.

This means the actual IP range should be something in 70.252.0.0/14, which is assigned to AT&T according to whois.arin.net.

Chopping off 234 from head of this IP address, the parts left are the network address and group id.

See: https://tools.ietf.org/html/rfc6034

People have managed to tune into the raw video stream via RTL-SDR. I'm guessing this IP is post this step and internal to their streaming

https://www.rtl-sdr.com/receiving-space-x-falcon-9-telemetry...

https://news.ycombinator.com/item?id=26423406

The font used in the IP address almost looks like something generated as an overlay by VLC or ffmpeg.

Yep, it looks like VLC.

If I had to make a guess they're taking a stream from some embedded system with a camera on board the starship, downlinked to a system running VLC at the test site, and that system is being used to perform some form of on the fly transcoding or resizing, feeding video out to a live editing/mixing setup (how they're accomplishing the picture-in-picture of inside the rocket skirt and exterior camera at the same time).

VLC can do all sorts of stuff that 99% of its users never touch, if they're just playing files.

https://wiki.videolan.org/transcode/

The IP address shown was an multicast address, which provide a crucial hint as to their setup. Most likely after downlink from Starship the camera feeds are distributed from the test site through their network using UDP multicast, probably without any transcoding and resizing, only remuxed. This allows the feeds to be available to mission control, engineering, employees, etc with minimal delay. Then a separate system, possibly not even at the test site, receives that stream, transcodes/resizes it and feeds it into the mixing and streaming setup. This last part is probably want they use VLC for and what generated the overlay we saw.

The engineer at SpaceX responsible for running the webcasts actually used to be active on r/SpaceX, and has shared some details about how they ran it all.

If you find that reddit thread I'd love to see it thanks!

It wasn't an AMA. Their user account is (was) https://www.reddit.com/user/bencredible, but you'd have to hunt through the comments to find the interesting bits. I also think at some point some comments got deleted.

Amazing thanks! I'll have a dig through. I'm incredibly fascinated with video codecs but it does my head in.

Immediately after that post, SpaceX began encrypting the streams from both Falcon 9 and Starship.

The SpaceX engineer who implemented the encryption apologized on Twitter:

https://twitter.com/skiboysteve/status/1375507358814674944

Didn't know that! Kind of disappointing.

Lame. I came for explosions and shrapnel, and all I got was a viable POC of cheap interplanetary flight.

This comment made my day. Looking forward to Starship flights to be as routine as the Falcons.

Downvotes from all the negative people hoping this would fail

I guess they might be downvoted because of “lame” which is now considered ableist.

Meh, probably it happened because of lazy readers who just scan the first 3 or 4 words and then downvote- the joke most likely soared miles above their heads. This is why downvotes should cost karma.

Breaking news!

Most boring Starship flight ever!

You were looking for this video: https://youtu.be/bvim4rsNHkQ

Bezos sues, Musk launches.

Exactly. Still not sure about all of that litigation. At the end of the day, even if the review process gets re-opened for whatever details got changed last second, SpaceX has multiple trips there and back again. That would naturally put them in the lead of any contest.

It's quite routine in defense to sue or protest the contract decision no matter what.

open protests at the GAO: https://www.gao.gov/legal/bid-protests/search?processed=1&cl...

True, but the optics aren’t good.

Only because we like spacex. Remember that they themselves sued the USAF not too long ago in a similar situation: https://spacenews.com/case-closed-california-judge-ends-spac...

"SpaceX challenged the Air Force over contracts the service awarded in October 2018 to United Launch Alliance, Northrop Grumman and Blue Origin."

From that list, which company is actively launching humans to space? Has Blue Origin even been to space yet? Seriously asking, as I thought they kept going to near space for their testing. ULA might be sending satellites up, and Northrup Gruman can knock the dust off of their lunar landers to see if they can retro fit them , but they're not lifting off the ground by themselve either.

Blue Origin has been to space but not orbit if I remember correctly.

Stomps foot on ground, kicks dirt. "awwww! mom!!! it's so not fair. they need to learn to share! whaaaa!"

Those optics? 'cause that how I'm seeing it.

Yes, but typically that goes with an actual ability to deliver. Which Bezos does not have, all he has is a hobby, slightly ahead of where Armadillo Aerospace was at some point in time (another rich person with a hobby, so a good comparison).

Now the next step is high suborbital flight and then real orbital test.

IIRC they don't plan on an orbital test of the standalone second-stage. They'll strap it to a superheavy first.

Yes, you are right. But 100km altitude or so suborbital test is definitely possible with SN prototype alone.

Yes, but 100km isn't very valuable as compared to 10km. Pressure is already low at 10km.

The difference would be supersonic/hypersonic flight during the fall.

Honest question: is it possible that the rocket could already be hitting terminal velocity when falling from 10km?

Yes, it gets to terminal velocity pretty quickly, it's decelerating for most of the fall as the atmosphere gets denser.

Estimated kinematics from a prior flight. https://flightclub.io/result/2d?code=SN91

edit: To clarify, a drop from 100km would not hit terminal velocity quickly, it would accelerate until it got to the thicker lower atmosphere where it would be rapidly slowed.

Hitting a speed and sustaining it throughout the entire re-entry are two different tests?

Terminal velocity is defined as the velocity at which the force of gravity is equal and opposite the drag exerted by the atmosphere. So, yes, I think Starship is hitting terminal velocity at 10 km, but the velocity is smaller than the terminal velocity at 100 km. Less atmospheric drag at 100 km means the velocity is greater than at 10 km, so 100 km flight would be different than a 10 km flight.

I don't think coming up to terminal velocity in atmosphere is really the concern. What's more interesting is getting up out of atmosphere, falling back down at a speed that's many times higher than terminal velocity, slamming into atmosphere at that speed, and then dealing with the reentry heating and other forces that result from that.

The fire looked identical to the SN10 one only it started on the ground instead of in the air. After about 30 seconds I said out loud “someone put out the effing fire!” Haha

The raptor engines seemed much better behaved on re-ignition. Although I can’t help but wonder about the fire.

A question for those in the know: since the landing payload is much lighter, wouldn’t it be possible to use SuperDraco engines (the ones used for emergency escape in the Dragon) attached to the outside to prevent RUD in case the main engines don’t light up?

I am no expert on these things but I think the starship has no tanks or system for the different, hypergolic fuels used for the superdraco and similar type of thrusters.

"SuperDraco engines use a storable propellant mixture of monomethylhydrazine fuel and dinitrogen tetroxide oxidizer"

Hypergolics are very toxic, corrosive and made of the most exquisite molecules of the purest evil. Dealing with them is expensive and complicated and drives cost up.

It was one of the reasons why shuttles were so expensive to refly.

The new hypergolic fuel everybody is actively working on switching to is not (especially) toxic or corrosive. And has better specific impulse. Existing Dragons might never be switched over, because flight-qualifying a crewed vehicle over again is expensive. If they build any new Dragons, it would not be surprising if they still use the old fuel. But anything in design today will use the new fuel, because it's enough better.

Are you thinking of the new viscous liquid monopropellants that replace hydrazine monopropellant, rather than hypergols?

Hypergols are always highly reactive, by very nature of being hypergolic.

Better objective is just to keep testing and tweaking until the main engines do reliably light up

Also, for landing the engines need to be steerable which I think the emergency Superdraco ones aren't.

When you’re carrying a hundred people inside on a weekend trip, what is “reliably”? 99%? five nines? Planes have a much less risky failure mode..

Thats a good point.

But I'm not sure that throwing extra engines into the scenario will help much. It takes very precise control to land a rocket. Those SuperDraco things are for going up fast, not coming down with sub-meter accuracy.

I had an aerodynamics / rocket science professor in grad school who used to say 'planes are as reliable as toasters', and the reason for that is the literal 40 million flights per year. Planes can explode just as easily as rockets can. The reason planes have a much less risky failure mode is because we've flown them for billions of hours, not because we've added a ton of redundancies to them.

In fact many of the structural 'factors of safety' in airplanes are only 1.5, as opposed to a FOS of 8 in your car.

So again, it's not about just tacking on redundant systems, it's about getting the experience required to understand all the failure modes. The only times planes crash these days is when we encounter a new failure mode. Rocketry will get there as well.

Its a tradeoff between complexity and results.

Think of it like this, every kg added to Starship is one kg less to Orbit. And maybe like 10-30kg less to Mars.

For what you are talking about you likely need 16-32 SuperDracos, you need massive tank. A highly complex system of tubes along the vehicle and so on. You would reduce the payload to Orbit and return by a huge margin.

On earth, for a system to be reusable AT ALL, is incredibly hard. Like seriously, super hard. Their margins are already very thin. I'm not even sure what you suggest is possible at all.

And such a system would only prevent some very few cases. You already have engine redundancy. It wouldn't save you in many failure cases either. So its a gigantic increase in complexity for a slight reduction in potential failure.

The extra complexity quite apart from the performance would also lead to many new failure most that must be considered. If in a full risk analysis this would actually be safer is questionable.

If you want to increase safety adding a 4th Raptor would like by safer, as well as starting the flip earlier.

P.S: The fuel would also be highly toxic and would make operations with humans much more complex and much more expensive.

> Think of it like this, every kg added to Starship is one kg less to Orbit. And maybe like 10-30kg less to Mars.

With standard staging this would be correct. With starship it's a bit different:

Every 1kg added to Starship is 1kg less [payload] to Orbit. And 1kg less to Mars. And maybe an extra tanker launch for refueling

That's exactly the thing. I will take more launches. So overall its still true. If you did the exact same flights, overall you would end up with many fewer kg landed on Mars.

But of course that inefficiency is gone be buffered by more refueling.

Still calculate the lost efficiency on the scale on a mars base and 1kg is a major.

Not to mention the system suggest above.

SuperDracos use hypergolic propellants, which can't be sourced on Mars. So SpaceX isn't using them on Starship. The HLS moon lander version will have small methalox hot gas thrusters to avoid kicking up a cloud of debris, but these aren't needed right now, eventually they'll be used in place of the nitrogen RCS thrusters.

The landing was really smooth this time. Very graceful. It seems some progress is being done.

They used the new generation green raptors for SN15.

They need to paint Bezos' face on the side of it and launch it again!

Heck just buy a bunch of doge, paint the rocket with the dog, launch it and sell all the profits when it spikes from the memes.

It didn’t explode!

Let's launch it again!

Any idea why they shutdown some engines during ascent?

Seems efficient as you are fighting gravity with less acceleration and more dead weight.

They’re not trying to go fast. They’re trying to get to the target altitude to test the flip. No need to rush or overshoot.

In “production” it will be atop the booster, so taking off like this from sea level isn’t part of the plan.

They don't want to go to high or to fast. So they start out pretty heavy and as the fuel is consumed they turn of engines in order keep the TWR the same.

They don't want to test supersonic flight profiles with this vehicle.

This flight profile is not at all optimized for fuel use.

> This flight profile is not at all optimized for fuel use.

I suppose you could say it's optimized to use almost all the fuel :)

Each Raptor engine cannot throttle down below about 40% of its maximum thrust [0], so they must completely shut down some of the engines in order to achieve the lower required thrust for hovering or landing.

[0]: https://twitter.com/elonmusk/status/1295553672454311941

It is less efficient. That said, they aren't carrying a payload and they don't have to run it full on fuel, so it doesn't matter. More importantly, they care about testing the landing which requires them to be a certain horizontal distance from the landing site, so it's easier to do that by hovering sideways so they don't get way too much height.

Hey! A no-RUD landing!(Rapid Unplanned Disassembly) I think it did the transition back to vertical at a higher altitude than previous attempts. Too bad there was cloud cover and the video was not working.

That was a fantastic flight! The previous ones were great to watch, too, but seeing them really stick the landing this time was a sight to see.

Congratulations to the entire SpaceX team!

What is the significance of number 61 imprinted on the engine? Anyone?

It's the engine serial number.

What goes into getting that rocket ready to fly again?

It probably won't fly again, certainly not soon. SN20 will be the first one to fly on a Super Heavy. SN15 was built for this test, and as the first to land successfully they'll almost certainly be going over all of its parts looking for potentially problematic wear.

...has landed!

And no big fireball.

And all this from classical mechanics and no fancy ML/AI right?

man I am going of this planet

Excellent launch! Just watched it taking off. And touched down.

Man I'm going of this planet :)

>Shortly after the landing burn started, SN11 experienced a rapid unscheduled disassembly. Teams will continue to review data and work toward our next flight test.

I wonder how many failures SpaceX can fund before the project ends up in trouble.

It's my impression they're printing money, so probably a whole lot.

That impression is incorrect. SpaceX raised ~$2B in August and ~$1B in February [1]. The company is very cashflow negative (operationally), as growing companies typically are.

[1] https://spacenews.com/spacex-adds-to-latest-funding-round/

They are also funding StarLink + the moon landing program. Better to pile cheap money up while investors are knocking at their doors.

Reportedly they turned down many more investors than they accepted in the recent funding round, because they wanted a great proportion of the shares available vs. the funds that were offered. They could have raised way more than $2B + $1B if they'd been willing to go for further dilution.

Musk has been quite open about how starlink will need to go through a deep trough of low revenues and high expenses, before it can become self sustaining from the monthly subscription revenue of millions of customers.

Right now Elon can bankroll SpaceX for decades without even noticing losses, just like Bezos with Blue Origin. The difference is that SpaceX has results and revenue.

Does Elon musk actually have enough liquid assets to do this?

I was under the impression that most of his personal wealth was in the form of Tesla stock.

He gets loans using stock as collateral. billionaires have entirely different resources than the rest of us. AFAIK he has slightly >50% of his Tesla stock pledged as collateral for loans right now.

At tiny interest rates (wouldn't be surprised if he gets even better private bank rates because they want in on his other business or IPO etc).

it's basically free money - until something goes wrong... especially in the crazy dynamic we seem to be in now where fast stock growth = more access to free money = faster stock growth cycle. until pop

In a correction he is facing a nasty margin call.

Which would in turn probably hurt (?crash) the stock. It's a game of chicken. GME again! From an outside who only reads the free bloomberg it feels like there's a lot of this going on right now just boosting everything especially with basically free money; the recent Archegos blow up as an example of the down side

I've heard about 50% stock as collateral when Tesla was 20% of its current value. It does not make sense now - that would mean he took ~90 billion dollars of loans.

Do you have any links that confirm SpaceX is cashflow negative?

"SpaceX needs to pass through a deep chasm of negative cash flow over the next year or so to make Starlink financially viable. Every new satellite constellation in history has gone bankrupt. We hope to be the first that does not." -Elon Musk in February

https://twitter.com/elonmusk/status/1359024384200101888?s=21

I've heard that the Boca Chica operations are currently a really small % of the overall SpaceX budget given how cheap the materials and low the consequences are.

(it's just steel + engines, and since there's no human or customer component, there's much less process than around the commercial launches)

I'd imagine the most complex engine ever to use the full flow staged combustion cycle has a large price tag.

Presumably a vast majority of that cost is in R&D rather than manufacturing.

Its not that high, because its designed from the beginning to be produced in the 100s per year. Its probably being produced faster almost every other rocket engine (outside of SpaceX own) and maybe some much simpler engines from Russia or China.

They are producing SN100ish by now. A while ago they said 2 million $, already cheap for such an engine. Target is more like 200k$.

So likely its between 1-2M. That would make it only about 6M per flight based on the engine.

Even more amazing when you consider a full flow combustion rocket engine is an engineering masterpiece. The design and materials science are priceless.

Well, one of the aims of the Raptor project is good/cheap manufacturability of engines. They do plan to produce them in massive series.

The really costly phase is probably already done - the design work and early experiments.

Roughly $1 million, marginal cost (if Wikipedia is to be believed). Each 3 engine Starship prototype conceivably only costs several million.

Compared to what NASA is paying for the SLS engines (over $140 million each), it’s loose change.

Why are you bringing up #11?

That's what was on the page when I opened it. On my desktop it's talking about #15 though, so I guess I was victim of a weird mobile vs. desktop issue.

Looking at Reddit, more people had the same issue. I would guess the true culprit is caching.

Does the naming bother anyone else? It's even less a Starship than an actual interstellar spacecraft than the Tesla self-driving tech is Autopilot. This type of bullshit branding just rubs me the wrong way.

Edit: Your boos mean nothing, I've seen what makes you cheer. You can disagree as much as you want, it won't make the rocket a starship...

No, I’m just happy people are launching new rockets.

Imagine getting pissed off about the name of a breakthrough rocket.

Not saying I'm not happy people are launching rockets. That's awesome. And I'm not 'pissed'. Just call them rockets, not starships. If tomorrow I write a wrapper on top of grep and call it a 'search engine', half of hackernews is gonna jump at my throat bUt ThAt'sNoT aSeaRchEngInE!!!

And yet people still refer to the orbiter as the Space Shuttle, when it isn't

which orbiter? What?

Presumably he's talking about the Space Transportation System, colloquially known as the "Space Shuttle".

Are q-tips shaped like a Q?

Are Ford Explorers actually used for exploring?

Is the Magic Bullet a type of ammunition that kills magical creatures?

Is Wonderbread really wonderful?

bad analogies all around. My sedan is not called a truck. You're also a CTO, not a CEO. And the Q from Q-tips stands for 'quality'. But they're not called Q-clubs or Q-poles, right?

This is a starship: https://en.wikipedia.org/wiki/Starship. The SpaceX starship is a spacecraft named like an interstellar spacecraft. Like naming the Dodge Dart as Dodge truck.

Next year, Toyota is gonna rename the Camry as Tundra and when people complain, they're gonna say 'Is Wonderbread really wonderful?'

I look forward to the time when the SpaceX Starship is actually an ambiguous name.

You definitely missed my point. Products do not have to be named in a semantically correct, technical and pedantic manner. SpaceX isn't advertising flights to Alpha Centauri, so what's the problem? The entire world knows that actual starships as per your definition don't exist. Nobody's going to get confused or misled by this.

Also I notice you didn't say anything about the Magic Bullet. So at least one of my analogies were ok. If there was one that worked, there exist others. Don't bash the concept just because I couldn't furnish a list of 100 acceptable examples for you off the top of my head.

Also, most people call their SUVs or CUVs "trucks". They are not trucks, yet we call them that.

It's just how language is used, dude. There are so many more important things to get upset about IMO. Or, better yet, life is much happier if you're a leaf on a stream.

> Also I notice you didn't say anything about the Magic Bullet. So at least one of my analogies were ok. If there was one that worked, there exist others. Don't bash the concept just because I couldn't furnish a list of 100 examples for you off the top of my head.

It's not about examples specifically. It's about bullshit marketing. Same as with the Tesla Autopilot, but in this case, you're not the customer so probably that's why you're missing the point. For each analogy you make, I can counter it with one that proves it's bullshit.

> Also, most people call their SUVs or CUVs "trucks". They are not trucks, yet we call them that.

I haven't met anyone on this content to call a SUV a 'truck'. Also, I was saying something about sedans though..

> It's just how language is used, dude.

Not a dude.

> better to just be a leaf on a stream.

You're right. I'll go outside now to unwind and ride my gunboat on the bike trail.

"Dude" has been a genderless term for like a decade now.

> For each analogy you make, I can counter it with one that proves it's bullshit.

This sounds like a fun game, but count me out.

> I haven't met anyone on this content to call a SUV a 'truck'.

Super common around NY/NJ.

I can see that "bullshit marketing" and product naming is a real buggaboo for you. We'll just have to agree to disagree. You did pose the question, after all. You may get responses that disagree with you.

> "Dude" has been a genderless term for like a decade now.

Huh.. TIL Was under the impression that calling a couple of girls 'dudes' was gender neutral but apparently 'dude' itself is. Thanks.

> You may get responses that disagree with you.

And that is ok and expected. Enjoy the rest of your day, stranger!

Well, there's at least one star you can fly it to

I guess that's technically true.

I'm not so sure. Getting to Mars and back is relatively easy delta V-wise relative to even a transfer orbit to the sun.

Not sure if gravity assists could make up the difference or not.

Actually not. That takes way more delta-V than it can do. Even starting fully fueled from Earth orbit.

Wow you’re right, have to slow way down to get there

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