Modern rocketry is somewhere between WWI and WWII aviation. We’re beginning to mass manufacture, but the leading edge advances so quickly that learning curves have limited runtime. Alongside new designs, new materials are being invented and deployed across America and China (and to a limited degree Europe.)
Most importantly, we can tune risk and and reward across the production line; the crewed Falcon 9/Dragon launches are far more conservative than their Starlink + rideshare ones.
> Most importantly, we can tune risk and and reward across the production line; the crewed Falcon 9/Dragon launches are far more conservative than their Starlink + rideshare ones.
Do you have any details about how this is achieved? What changes?
There's a whole bunch of reading you could do on "man rating" of rocket boosters. Nothing SpaceX does is unique in this area (except reusing some of the boosters). I mean, more testing, more QC, more caution and less pushing of limits, etc. I don't think it's something where you'll find a really clear, single answer about specific changes that need to be done to rate a spacecraft. [0]
Russia's Soyuz-U has a long history as a reliable booster. They flew it for over four decades, and some blew up, but they never lost a crew. (They did send one crew downrange on a ballistic flight path after a safe abort, which I bet was exciting for everyone concerned [1])
There’s an interview Tim Dodd did with Elon where they talk about the difference of approach between Falcon and Starship.
Falcon had to be built on simple and proven hardware concepts because private commercial space flight was unproven and considered very risky.
Now that SpaceX has proven the impossible is indeed possible to the world many times with reusable rockets, private manned space flight, and an affordable satellite data network—they can raise the capital and field the team needed to build a proper space launch system, which we now know as Starship.
There are many experimental space startups in Europe experimenting with different engine designs (like hybrid engines, love those) and material (plain steel).
No it’s not, the massive increase in the number of sensors dramatically improves reliability and changes the game more than the appearances would suggest (A rocket may look the same as 100 years ago but the data stream is completely different and invisible to humans at first sight).
The sensors and lightweight compute were not available during World War II.
> sensors and lightweight compute were not available during World War II
Planes came back in WWII. No such luck with upper stages. No Wald hints.
Telemetry doesn’t compensate for the exponential increase in the envelope of relevant parameters in the transition from subsonic flight to orbital mechanics.
Tangentially related: Most journalists - especially in tech these days - seem to be doing practically no original or investigative work and simply rehash what they read on Twitter & co. Are there any decent apps that do the same thing? For example I'd like to say "Follow everything SpaceX-related from these primary sources and give me regular updates/summaries". I don't care to read people's opinions on it, just the aggregated raw info would be nice.
I know also see media like CNBC doing basically a transcript of TikTok videos along with some reactions about the video from Twitter. And then call that “journalism” :D
We’re working toward exactly this with https://www.brief.news! We’ve got the ability to create custom topics in beta (I’m currently using it to follow Starship updates), happy to add you to the beta just shoot me an email (in profile).
> A few minutes after liftoff of SpaceX's Starlink 9-3 mission, veteran observers of SpaceX launches noticed an unusual build-up of ice around the top of the Merlin Vacuum engine, which consumes a propellant mixture of super-chilled kerosene and cryogenic liquid oxygen. [...]
> Numerous chunks of ice fell away from the rocket as the upper stage engine powered into orbit, but the Merlin Vacuum, or M-Vac, engine appeared to complete its first burn as planned. A leak in the oxidizer system or a problem with insulation could lead to ice accumulation, although the exact cause, and its possible link to the engine malfunction later in flight, will be the focus of SpaceX's investigation into the failure.
> A second burn with the upper stage engine was supposed to raise the perigee, or low point, of the rocket's orbit well above the atmosphere before releasing 20 Starlink satellites [...].
> "Upper stage restart to raise perigee resulted in an engine RUD for reasons currently unknown," Musk wrote...
For Falcon 9 manned launches, there are a whole series of abort modes and we-didn't-get-to-orbit splashdown locations:
It'd be interesting to know where in this mission's flight profile, if it had been manned, the launch director would have ordered an abort. That LOX leaks often lead to explosions is Rocket Science 101.
If this were a manned launch, I would guess that unless the telemetry showed something very off, they would most likely have completed the full second stage burn. That would have left Dragon in a 190 x 205 km orbit, which is stable. If I understand correctly, SpaceX doesn't do orbit raising for Dragon by restarting the second stage engine (which is where the RUD happened on this Starlink launch), but rather uses Dragon's own thrusters to raise orbit. So most likely this would have been a successful flight.
On Starlink flights they don't have the margin to reach a full circular orbit on a single burn. It's more efficient to achieve an eliptical orbit initially, then coast and perform a second burn at apogee. It's that second burn that proved problematic this time.
Edit: having watched the videos, it would have been clear to SpaceX that they had an oxygen leak right from the start of the second stage burn. So I guess it depends on whether the pressures and flow rates within the engine looked OK. If the leak was external to the engine, then the main risk would be running of out LoX - engines really really don't like ingesting a gas bubble instead of liquid. If it looked like they were getting low on LoX, I'm sure they would have initiated one of the abort modes. Otherwise it's probably safer to continue to orbit. They do have cameras inside the tanks, in addition to all the telemetry - they have occasionally shown then on the livestream.
I'd argue that going for 0 failures in virtually any domain will lead to inefficiency. You need some failures to get the feedback that you've "under-engineered" something. Without failures, you can guarantee that you've over-engineered it.
In a similar vein, I think proper risk acceptance policies shouldn't say "security/safety is our #1 priority", just like a good SLA doesn't guarantee 100% uptime. When you set a 99.9% uptime SLA, make sure you're actually down sometimes. When you want efficient rockets, you have to see some of them crash.
It doesn’t take rocket science to understand that rockets eventually have a success rate of less than 100% .
(Edited changed failure rate to success from child comment)
That is true, but it is not directly related to this issue. SpaceX doesn't (can't) reuse second stages. (For now.) The one in question which had the anomaly was a "brand new" second stage.
It is more likely that either this is due to a defect which escaped their QA, or a design issue with a very low probability rolling a nat-1 this time, or some change they introduced not working out as they expected. I would not describe any of those as "aging".
Upper stage engines are notoriously difficult, because the operate in a very different environment than we're used to, under annoying mass constraints, and after exposure to the rigors of a rocket launch (high vibrations and acceleration).
Also, they must ignite without any help from the ground, without any felt gravity (which really helps with pumping fuel and oxidizer).
All that makes the previous run of successful missions all the more impressive.
I agree with the reasons you list. Would like to add one more which is somewhat specific to spacex. They are reusing the first stage, but can't reuse the second stage. Which provides complications in two ways:
Every second stage they fire is a brand new one. There are no "flight-proven" second stages. (of course the design is flight proven, but the actual piece of hardware itself is not.)
The other one is since the second stages are not recovered it is much harder to do an after-flight engineering analysis on them. With the first stage SpaceX have most of them back after the flight. That means they can check that all is looking as they expect it. If something with the design is "marginal" in a way they haven't designed them to be marginal they can adjust the design to improve it. With a second stage you can not do that.
Of course this is the default state of every other rocket ever flown. But in spacex's case I would expect the first stage just a tiny bit more reliable than the second stage because of this. (Just a tiny bit, since there is a lot of commonality between the stages)
Oh. Interesting! I haven't thought of that. It sounds super cool, although my gut reaction is that it would be a lot of work for not much bang.
My childish imagination pictures the proposal as the Agena target vehicle from the Gemini IX test flight. There the fairing did not separate correctly leaving the docking target looking like a hungry space alligator:
https://www.nasa.gov/wp-content/uploads/2016/05/5-s66-37966-...
One could imagine the aligator gobling up a drifting second stage. :D It would absolutely not look like that in reality, but if life were a cartoon that is how it would happen. :)
I don't know. Surely it will be a sellable feature of Starship eventually to service and/or return aging sats from orbit. Grabbing an F9 second stage feels like the perfect way to demonstrate that capability. It's not like they're going to have a shortage of Starships returning from orbit in the future.
Low orbits clean themselves up relatively quickly though, and that’s where most of the newest satellites are going.
One of the Shuttle’s selling points was exactly this mission. Apparently it recovered a total of five satellites, three of which were research satellites launched specifically with the expectation of being recovered ahead of time. The other two were mis-launched into the wrong orbit because of a rocket failure. https://space.stackexchange.com/questions/15094/what-satelli...
> IIRC one of the initial animations had a landing second stage
Of Falcon 9?
Yes, they were aiming for that, and put significant engineering effort towards it before it was deemed too difficult, and instead to focus on Starship, which is a second stage design for re-use from the ground up.
(Same story for catching faring halves in a net on a ship.. they tried and tried, and ended up just making them a little tougher and letting them land in the ocean before fishing them out.
For Starlink and Starshield flights, upper stages are generally configured slightly differently than flights for external customers. These flights are used as an opportunity to explore "optimizations" that, if successful, could be used to lower costs and increase performance for future customer flights. If something doesn't work out, the impact to the Starlink and Starshield constellations is relatively modest and a lesson is learned.
Unfortunately second stage has been a business area where there has been considerable employee turnover and a cluster of mental health episodes and harassment and assault allegations. I hope the people there are and remain safe.
Worst part of it is that lower stage engines, in SpaceX's case, have been thoroughly studied after flight, because they return back in working condition, so any quirks in them have been found and fixed long ago. Upper stage engine is based on the lower stage one but all of the delta between them could only be validated through telemetry - there's never a returned article in a recognisable shape to study and fix bugs in - because upper stage is not reusable and mostly burns up upon reentry. It makes hidden, rare bugs very likely.
There's a lot of commonality. Especially as the first stage also needs to relight in a similar environment for the boostback burn. Engine commonality is a real strength of the Falcon 9 architecture, it keeps that delta as small as possible.
Disagree. It means that their streak, which had been running for quite a while, has ended. “streak” here is a noun referring to the specific successful launches.
Much like saying a sports team’s 10-game winning streak is over does not mean they will never win 10 games in a row again.
Most importantly, we can tune risk and and reward across the production line; the crewed Falcon 9/Dragon launches are far more conservative than their Starlink + rideshare ones.