#spacobs

Yeah so uh holy shit. That was definitely a launch that happened. It's such a weird program; extreme by most metrics that it's kinda hard to think about. The main thing that appears to be catching people up here is RUD vs explosion. I mean, RUD been used for a while now and is sort of a tongue in cheek joke, but I could understand why this being the first exposure could catch people.

There's also this post which is cosmically funny. All the complaining about Blue Origin no orbit has come back to bite the SpaceX stans because jokes on them; people are now confusing the two and saying SpaceX no orbit lol. Cheers @greetings-inferiors you gave us a good laugh.

But that's tumblrs reaction, what's mine? Idk, I laughed a fair bit. Schedules were always shot to hell, so I'm not too fussed in that regard. The rocket itself doesn't matter at this stage; it's the OLM damage, which I suppose separates this other launch failures. I still think H3 failure really reduced my expectations of first launches outcomes. If a country that's been doing launches for 30 years can't successfully launch a fairly conservative evolution of an existing rocket; then all bets are off for everyone else.

It's always nice to have a reset of expectations for the entire program so that means when things happen they can be appreciated rather than trodden over. (cough cough Falcon 9)

Launch wise, it was incredibly scuffed. 3 engines out from the get go which resulted in an extended burn at OLM to gain sufficient TTW resulting in that fat crater. The engines out also resulted in a slide that is scuffed and scary for a vehicle of Starship size. But the flight continued. Then more engines out, an hydraulic power unit explosion, some more engines, and oh yeah the tiles. (I don't care about the tiles). And yet the vehicle still flew. It's showed robustness in the scuffed of situations of it's own creation. When you roll around with B9 and the reliability enhancements, it actually is fairly interesting. They took engine explosions or at least flame outs in their stride, but you know; don't have them in the first place am I right.

The question is now when next flight and that really determines the value of this one. Because it's always the next product™. But presumably the Raptor ops and propellant management will be good outcomes. Also not to use HPU, but that was already a learned lesson. This failure just feels unusual because of the scale I suppose.* (I mean it's automatically notable because Musk rocket failure, but that's beside the point). Like we've had RS-1, ZQ-2, Terran 1, LauncherOne, H3 and Vega failures recently; what's different. Well, entirely different classes. But still, nowhere near media circuses. *+the damage to the ground infrastructure.

To summarize, the vehicles job was to gain experience on the performance of the many subsystems that make up this vehicle. Like autogenous pressurization on a vehicle of this scale as it handles many Raptors (failures) is no small feat. The next 2 Starships have given up heat shields and payloads, because they're also now exclusively marked as flight test vehicles as well. There was a lot of things that went wrong, but it still gave a fair bit of insight into the vehicle for SpaceX. And if that was just it; it would be fine because the next vehicle would be rolling to pad in a couple months. But this happened.

And that means a fair bit of work in repairing, upgrading and potential legal issues to grind out, which will cause delays in its own right. This is what pushes the needle in the direction of not worth it. But shit has happened and will continue to happen; the program will just move on.

SpaceX has a lot of good weeks nowadays, but even by those standards this week was pretty radical.

To start off with, IFT-5. Yeah. I'm not sad that I slept through the catch. Not at all. Holy shit it happened what the fuck. This is some bullshit Musk design that actually got to pad and worked what? Aspiring to have no flame diverter my ass. In general I'm pretty happy with the launch. The things that were supposed to happen happened. There are things to improve, but that's what makes following dev of Starship so much fun. SLS is like, yeah we need ~3 year to refurb our pad after that first launch because an elevator door got knocked and different scope. Meanwhile SpaceX pulls this fucking shit and has launched 4 more times in the past 1.5 years and done a catch.

Then Europa Clipper launched on Falcon Heavy. This is SpaceX most important/expensive/performance driving scientific launch yet. The adventure of selecting Europa Clipper's launch vehicle is a journey in it's own right. Very cool and awesome stuff there and definitely not nerve racking giving the second stage issue two launches before.

3 Starlink launches for prosperity. Starlink is borderline misunderstood? People obviously talk about it a lot. What is so good about it is that it's a payload with a relatively steady $/kg in regards to revenue. You can only launch so many Earth observation sats you can launch before you run into diminishing returns, but satellite broadband is a lot more scalable. There are years in which ULA launched less than SpaceX did in this week.

Also SpaceX won $733M worth of Space Force launch contracts for 9 launches. So much for Lane 1 diversifying providers lol. It's not unsurprising per say, it's only between SpaceX and ULA and VC0 is a bad config (0 contracted launches btw).

So Stoke is pretty popular ay. I remember there was this fun time in like 2022 on discord where about once every month somebody would discover Stoke for the first time and it would be this fun little conversation. That boat has well and truly sailed.

Now onto this trade space. I'll begin with engine ISP as that's the easiest to understand. Now despite what this meme and Stoke might have you believe, the engine isn't that efficient in a vacuum at 430s of ISP. Conventional vac optimised expander bleeds can hit 450s, so they're down relative to that. And against a hypothetical FRSC hydrogen upper stage engine which could hit 470s of ISP (and they are capable of building); they're losing 40s. 430s is what open sea level engines achieve.* Essentially, if it was methalox, the ISP would be ~345s, below that of staged sea level engine like Raptor. This is their primary performance loss in the trade space. So what do they gain for that? They get to integrate 3 capabilities into the one engine, effectively decreasing the system complexity and dry mass of the stage.

*Although worth noting that those sea levels need ~100 bar in the chamber to achieve that ISP, Stoke does it with 40 bar. 40 bar means that they get to do things like skip bi metallic jackets on the chambers and can instead just have a copper alloy print. This combines with the 'positively benign' environment that a bleed expander turbine experiences so their engine doesn't experience a lot of stress; it should have a really good lifespan and be easy to reuse.

So it's kinda more of a sea level engine that gets reasonable performance in a vac for how robust and versatile the engine is. Something that restricts the performance of Starship, especially for HLS, is the fact that they need those sea levels in the skirt. Because they can't fit a gimballing Vactor in there, it means they have to deal with the ISP drop that comes with having to use 350s engines alongside your 375-380s vac engines. (not to mention throttling problems).

As a landing engine it’s fairly nice as it’s much easier to deeply throttle the architecture because you don’t have to worry about combustion instability in the pre-burners/gas generators, nor in the combustion chambers themselves as they can just limit the number of chambers that receive propellant. I don’t know what the theoretical limit is, but the renders do show 10% throttling.

Actively cooled heatshields are to ablative heatshields as liquid rocket engines are to solid rocket motors. (don't think about passive tile solutions, they don't fit in the analogy). This is something that people doubt the technical viability of. However, what I think people need to realize is that propulsion engineers already have to deal with thermal fluxes of ~100 MW/m² on the combustion chamber walls in their engines. The ~10 MW/m² of LEO re-entry is actually a breath of fresh air for them. In this case, the Stoke’s ‘aeroplug’ won’t experience that high of a heating due to the relatively low thrust/area of the engine, so re-entry thermal flux will likely be higher in this case. But the point still stands, it’s well within the propulsion engineers experience; get out of here TPS engineers! (just kidding we still need you for the material science of optimizing the alloy for the heat shield).

What does an actively cooled heat shield achieve? It’s no secret that the heat shield is one of the weaker elements of Starship’s design currently, with 18,000 tiles and a secondary ablative heat shield taking a significant portion of the mass and maintenance budget. It’s more robust than I would’ve thought; well at least the vehicle is. However for a fully and immediately reusable orbital heat shield, there’s definitely a lot to be improved upon. Active cooling has a much better shot of getting there, because effectively we’ve already gotten there previously with thrust chambers on reusable rocket engines. Monitoring the heat shield for damage should be easier, given that it’s inherently easier to place sensors and watch the flow of propellant compared to analysing 18,000 tiles. I’m not sure it would be easier to repair per say, but if it is permanently damaged, you could just treat the heat shield as a Line Replaceable Unit (LRU) and slot another one in.

Now comparing Starship flaps to Stokes lifting body heat shield is interesting, because the flaps do provide greater control. The mitigating factor here is that Nova doesn't need the greater control. Because SpaceX has a tile solution and enters on the broad side in an passively unstable state, they need the flaps to provide that flight control during re-entry and landing. Nova is passively stable with its base heatshield, so with the offset to provide a degree of lift they have enough trajectory control.

Chines are just in there for the meme of it (storage space). If they do get rid of the chines on Super Heavy, I’ll definitely miss them. They add so much to the look of that vehicle.

So what about hydrogen? To get something out of the way, I'm tired of people treating hydrolox as a curse on price. Yes the hardware (valves/seals) to support it does cost a % more, but it's not like you're forced into hundred million $ stages as a result. It's like going, 'oh well Shuttle proved reusability could never be cost effective, so Falcon 9 reuse will fail.' You're blaming mixed technical trades when the ultimate driver is managerial and organizational culture.

Hydrogen is fairly important to this architecture. A likely significant reason why methane wasn’t competitive with passive tile solutions for Starship was that by mass, it requires 4.5x as much methane to extract the same amount of heat as hydrogen. Now volumetrically this is less than the hydrogen, but mass is the driver at this stage of the mission. 

I will say that VTVL first stages prefer high mass second stages as staging earlier decreases delta v + thermal flux to get to the landing site. In Falcon 9 case; replacing the current stage with a hydrogen stage of the same proportions would decrease performance to LEO by like ~3 tons for the reusable missions. This is why the higher impulse density propellants like methalox/kerolox are nice in this case and why Starship in particular.

From a long term perspective, hydrolox is better for the Moon, methalox is better for Mars. I will say that in order to produce methalox via ISRU on Mars, you can produce hydrolox. However impulse density and storage conditions make it preferable for methalox on the red planet. 

This is now just another Starship spam channel that's right woo baby all we talk about is this. I mean I am inherently very excited for Starship because it is just a very interesting launch vehicle, although my interests are more broad in space than just that take notes people. Coping I guess. I mean even people who hate the program find it at least very engaging; even more than the things that they like to extent.

Now the question on everyone's minds is how successful was this flight? How does it compare to the previous flight?

Well at a baseline, the pad isn't totalled, so that's nice. The steel plate worked and minimized damage. That side of the infrastructure will presumably no longer be a bottleneck for future flights. Well, ok there will be scrubs and work continues; but presumably it seems like it won't generate month long pauses.

Booster 9 performed it's job as a first stage well; getting to staging with no apparent major issues with it's 33 engines, which would be good enough for most launch vehicles. As a reusable stage however it failed. It appears that relighting one engine failed in the dynamic situation post stage separation for boostback causing a cascade of failures and overall explosion. I'm pretty happy with how it performed; it's not going to inhibit future launches and restrict future flight tests. Falcon 9 first stage recovery took it's time as well; but didn't inhibit Falcon 9 customers as development was happening. The main concern would be that in future, there's not enough Super Heavy's for launches because those are very large and complicated stages with 33 Raptors. And so the associated delays with the recovery effort because of this failure could have longer term schedule impact.

Though recovering early boosters honestly isn't too valuable either. Well ok, it is valuable because you can look at the hardware and see how it performed and some of the most valuable data you can collect in regards launches and reliability. But like; vehicles are inherently going to become less valuable over time given SpaceX rapid iteration and development. Having a vehicle be initially expendable while you figure what is the optimal design points is something I think is reasonable. Even with Falcon 9 Block 5 the later boosters are a fair bit better than the earlier ones.

Starship 25 however less so. A. SpaceX where were the on board views? We were robbed. More to the point though, it failed during the second stage burn which means they have to repeat this flight. Yes you want to test; but you also do want to continuingly expand what your testing if you want a reasonable schedule. If SN10 had of succeeded in landing, SN11 and maybe even SN15 probably wouldn't have flown. Still it did hot stage which was a risk point and burn for a good portion of time; so it would seem like with fixes they would have reasonable odds of going the full way on next launch. To quote Handsome Jack, "that's the sound of progress baby." Tiles fell off but I maintain that tiles aren't important for the reusable launch system while the launch system part isn't working.

Are SpaceX closer to their goals after this flight? Should they be closer? Is this a close to optimal balance of schedule, budget and hardware? Evaluations that I don't really feel like making.

The thing to watch for and baseline as assessment of program execution as I set out in a previous post is turn around time for the next flight.

The current metric to watch for Starship progress will be turn around time from flight 2 to flight 3. Sub 2 months is indicating that the program is going really well, 3-4 months is alright, 5+ months is bad.

You have to be very sneaky like when discussing this topic, because if people understand what you're getting at before you arrive at the topic area, they will form arguments. They will feel less obliged to do so if they're already committed to the idea because it got explained to them in fullness. So you kinda have to pretend to be a little old lady and then bam you hit them with the upper cut of the entire architecture. 

The inspiration for this is the recent OIG report and the reaction to this quote.

Although the SLS is the only launch vehicle currently available that meets Artemis mission needs, in the next 3 to 5 years other human-rated commercial alternatives that are lighter, cheaper, and reusable may become available.

Most people I feel dismissed this instantly, because of the Falcon Heavy historical argument, where Orion could be easily launched on Falcon Heavy, SLS bad. In practicality, Orion can't easily launch on Falcon Heavy; it's a very marginal solution. But there is a question here of, well are there now more solutions on the horizon in 2023 than there was in 2018?

I'll start with the Lockheed pill. So what do Lockheed have, or will have in the next five-ish years. They are the prime contractor for Orion, so they have the most interest in having the most effective version of that vehicle in face of any potential competition and the more it can launch, the more money they could make. Currently SLS has a cap of roughly 1 launch/year on it near term, if they do arrive at effective reuse of Orion, presumably they could do better than that. What else do Lockheed have. Well they gunna have a Cislunar Transporter, a zero boil off hydrolox depot, developed as part of the Blue Moon HLS contract. And if the rumours are correct they are interested in buying ULA out from Boeing, which would give them full ownership of the Vulcan rocket. They also have no stakes in the SLS rocket itself, so if they were able to develop their own launch solution, they would stand to make a fair bit more money per launch from it. 

Vulcan has a hydrolox upper stage called Centaur V, which is planned to be implemented with long duration and refuelling capabilities, which in turn with a ZBO depot in LEO would enable it to be refuelled. Vulcan has about 27.2 tons to LEO (Orion weighs like 27 tons) and is designed to be able to be human rated, it's a glove that fits. Technically Orion weighs more than that with the launch escape system, but there will be performance enhancements to the engines (BE-4 Block upgrades and RL10C-X) that should cover that. Diameter wise, Orion is 5 metres wide, Vulcan Centaur is 5.4m, so there's no weird aero covers required.

So we can launch Orion to LEO on Vulcan, what next? Well we send it to the Cislunar Transporter depot and refuel it there. With a single New Glenn launch worth of propellant to the depot, we can then transfer that propellant to Centaur and launch Orion to NRHO (needs 35 tons of hydrolox propellant, min, so should be margin there). 

The good thing about this architecture is A. there are clear incentive structures for the companies involved to do this. B. it leverages the tools available in such a manner that doesn't require them to go widely outside of their existing operations. C. it does so with contractors that a lot of the SLS fans have a reasonable amount of respect for. Like any Starship proposal is going to be met with eye rolls, but a Lockheed/ULA/Blue one that uses their capabilities in reasonable manners is something they're going to find harder to reject.

The other big thing is that it doesn't require a 2 billion/year overhead, because all aspects (Vulcan, New Glenn and Cislunar Transporter) have existing operations to cover their baseline costs. So it could be like a $200M Vulcan launch, a $100M New Glenn launch and the cost of the depot operations. There's an interesting question of whether the depot can return to LEO from Blue Moon refuelling in time for Orion launch ops, but you could also spend the capex (idk like 0.5-1B) on just building another. The development is human rating Vulcan Orion and Centaur refuelling, which is like a billion $, but nothing too unreasonable (+Blue Moon/Cislunar Transporter work will help out with the latter). In addition, it develops the LEO Orion launch and reduces the cost for adding additional Artemis flights in a year (or just makes it possible in the first place). 

So to summarise this concisely, Lockheed could reasonably leverage their own hardware/IP to develop a cislunar Orion launch solution with solid costs and flight rates. They are also somewhat incentivized to do so from an optimising potential $ perspective. The main additional critical risk is a single docking and refuelling op which is not insignificant, but in the scope of what it offers is reasonable.

Ok there my motivation is gone lets get through the others quickly. Blue Origin refuelling Lunar Clipper and launching Orion. Basically the same as the Lockheed one but probably less popular because of Blue's execution to date. And SpaceX Starship with expendable Starship stage and maybe another stage on top to get a TLI payload of some sort that would be Orion capable. People really don't like this because SLS fans are inherently going to be sceptical of Starship. Also SpaceX isn't interested inherently unless you come with $.

There you have 3 potential options for Orion launch.

Anything like a Relativity Space Terran R option is no good; start ups don't have the program of large scale execution to worry about giving crew cislunar transportation to. There's the skip Orion people, use CCrew vehicles or Starship entirely; if you think the SLS people dislike alternate Orion launch solutions; just you wait until they see alternate Orion solutions. I'm sympathetic, requirements for Cislunar ops are a fair bit different from LEO transport requirements. And Starship crew rating is not something to emphasise right now. There's some thinking that you could add a habitation module to Cislunar Transporter and have it act like a taxi between LEO stations and Gateway. It does appeal to me on a thought basis; the main criticism is required propulsive to LEO and in general LOC/human rating problems.

(I wanna make 1 point about Starship, but if I just make that the post, I would be limiting my visible self unusually)

It's always funny seeing launches get delayed by months. Well not funny, more very sad. So opposite. But it's like, you see the fully built rocket on pad and it's like; just fill er up and go ay fella. Not the case. Every launch campaign is an epic journey with many trials and tribulation that unfortunately will not see the light of day. The reason I'm currently thinking about this is Firefly Alpha with Victus Nox that had what appeared to be a ready vehicle on pad in March and we're now in August.

The current metric to watch for Starship progress will be turn around time from flight 2 to flight 3. Sub 2 months is indicating that the program is going really well, 3-4 months is alright, 5+ months is bad.

The actual time on repairing the OLM and getting ready for flight 2 I think has caught a fair amount of people off guard. Like the gut reaction to that flight was 'oh no shot; next launch is in 2024.' The fact that it looks like the hardware is reasonably setup for September is like damn. Like there was 69 days between the first 33 (31) engine static fire attempt on Booster 7 and the actual launch. This is the next launch, so I expect the process to go a bit smoother than that.

Ok, so I've got a great factoid and I think it has legs to have a little bit of a run.

NASA underestimated radiation doses of certain accidents for the launch of their nuclear Mars rover by a factor of 3,200 (that's a comma not a period)

It think it's got a real grab and clickbait potential. So I'll post it to an anti-nuclear subreddit and see what happens. Will it spread beyond or just stay there and get a couple hundred upvotes or I am overestimating it and it just dies. If it dies, I'll try it again elsewhere just to see whether it was a timing thing.

But anyway, lets talk about memes, and when I say meme, I'm referring to the older definition, not just the current one of funny image. As I understand it, the older definition considers a meme more of an idea; with information on how it spreads and grabs people and it's position in the minds of people.

See I will post these words in this order and then it will spread as an idea as people share it on their own volition. It's an infection of sorts; mind virus is definitely an underwhelming term as it's been restricted to focus on one specific thing when it could be considered in a more general context.

It is very interesting to think about how much power words have and how much possession of someone's brain you can have despite never meeting them.

Putting NASA in their just gives phrases for some reason a certain staying power. NASA does so much in so many things that it sort of has lost meaning to me to say "NASA does something" given how broad the organization is.

For the record, I am not anti-nuclear; in fact I am generically positive as most space people given the engineering links. I think storage and disaster concerns are overblown, but actual implementation and socially acceptable power concerns under. The actual risks in the NASA report are still fairly insignificant and didn't matter in the end; I fully support the launches of Perseverance, Curiosity and Cassini.

Hey so, Artemis is pretty cool. SpaceX bid a modified variant of the Starship upper stage to act as the lander that is currently manifested to take US astronauts back to the Moon. I mean schedule wise it is completely screwed, but that was obviously from the day it was selected. The problem here isn't whether it happens in 2030 instead of 2026, rather how it happens at all.

Now with the protests that followed the sole sourcing of SpaceX, we got a bid launch count of 16 for Starship HLS; 1 depot, 1 lander and 14 tanker (to the depot). This is a large number that has continuingly generated arguments about it's largeness not aided by the napkin math of Musk. It does represent architecture complexity and in currently reasonable world would represent a not small expense (at $2B a year, with 50 launches of Starship, that would still have a cost share of $640M).

But this is just what they bid in 2020 December, how is it going in 2023? Not good. Because of the nature of the architecture; Starship has an extra 3km/s to travel as a single stage; which really tightens the belt on the supposedly large margins it should have as a 1300 ton stage. + Raptor is a large high thrust engine, good for launch vehicles fighting Earth gravity; bad for in space stages where throttling gimps your ISP and thus performance. So launch count hasn't gone down from 16 like people wanna say; it's actually floating even a little up. Now exact launch numbers I don't believe in, because there's a lot of TRL numbers that aren't 7-9.

Launch count isn't only thing; margins are just straight tight. No ZBO + high delta V gives low remaining %s after doing it. Architecturally you can do thing to plug the hole kinda, but fairly large increases launch count and complexity with multiple refillings of Starship in various orbits.

Also reusing a cryogenic stage without zero boiloff in NRHO and which the Gateway people will riot if you leave attached to their station is hard.

Solutions? Innately I just wanna make the lander a bit smaller. That reduces the launch count; although makes the performance hole bigger; meaning more scuffed positions in the architecture to fix reducing the decrease in launch count. To elaborate, performance hole would increase because dry mass ratio increases as the individual components begin taking up more. But if the lander was like 500 tons wet mass instead of 1200 tons that would be nice. Also a smaller engine that Raptor. Closed expanders may be too small at 100 kilonewtons; unlikable burn times without large engine counts. So maybe you do like a 200 kilonewton full flow staged engine?

But like, 8-9 launches and not nail biting margin architecture is nice.

Any custom built lander will also be expensive and increase cost estimates way beyond what 4 bil was bid on. Will SpaceX persevere? Well if Starlink is the money printer they want it to be; expending the resources to develop their lunar capabilities is reasonable. (and also the right thing to do!)

There this thing where like people who dislike SpaceX like their cancelled plans, or at least hypothetical versions of it. I don't think I'm falling into that category.