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Great timing on the tag, it looks like they made orbit tonight. https://x.com/SpaceX/status/1960179929204596907
Thanks for the bet, I have to admit I was sweating a bit by launch 10. Happy to discuss but as I understand it landing in a stable orbit was the main bet.
What? They weren't even attempting to reach orbit with this one.
https://www.spacex.com/launches/starship-flight-10
Ahh ok clearly I am confused on what orbit means. So you want a stable orbit? Idk I don't think spaceships would ever try to get in a completely stable orbit since they're coming down, no?
ETA: Happy to pay the bet if I'm just wrong here, of course.
In practice there's no such thing as a completely stable orbit - we spend like 3 tons a year of propelllant reboosting the International Space Station, and if we ever stopped its orbit would just keep decaying, faster and faster, until it reentered the atmosphere a year and a half or so later.
But you want to release satellites either into their final orbit (which you want to be stable for years or decades) or into an initial "parking" orbit they can gradually raise themselves (so you want it to even initially be stable for weeks or months). So the upper stage of a spacecraft will enter this mostly-stable orbit to release its satellites. From there, ideally you do a deorbit burn to control where you reenter, but either way you tend to have a small light aluminum upper stage that just burns up on reentry.
All the Starship tests have targeted "suborbital, but just barely" orbits like the one in test 10, aimed to reenter the atmosphere over the Indian Ocean without any further maneuvering. From a performance perspective there's not much difference between this and a full orbit, but from a safety perspective the difference is huge, because the Starship is huge.
If they're on a suborbital trajectory that's going to hit atmosphere over the middle of nowhere, then at that point even if the vehicle isn't controllable (which happened on the 3rd and 9th tests) or the engines can't relight in space (which hasn't happened, but they've only tested that twice now) it's still not a danger - even if it can't reenter safely, it'll still break up where nobody can be hurt. If they're on an orbital trajectory, they're not an immediate danger to anybody, but there's no such thing as a completely stable orbit, and the instability of an orbit depends on "space weather" that expands and contracts the upper atmosphere somewhat unpredictably, and so basically anywhere with a latitude as close to the equator as Boca Chica or closer would become a possible target.
China has at least one large rocket stage that basically plays Russian Roulette this way, but an untargeted Starship reentry would be even worse - the Long March 5B stage has at least been designed to use lighter materials that won't survive reentry very well, but Starship is steel and heat shield tiles designed for just the opposite, and it's 100 tons of them instead of 20. So they're not going to even try to get into orbit until they're very confident they can get out of it again.
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Rockets (that fly up to deploy satellites) tend to accelerate until they reach their desired altitude, which should be well outside the atmosphere, then accelerate again to stabilize their orbit. Stable usually means that no point of their orbital trajectory is low enough to be subject to significant atmospheric drag, so that the spaceship in question can remain on its (ciruclar or elliptic) trajectory indefinitely. Then they deploy their payload, which will continue on that orbital path. Reusable spaceships then accelerate again, this time in reverse, to deliberately reduce their orbital velocity and cause their trajectory to dip back into the atmosphere, where drag will slow them down so they can land safely.
Let me know if that made any sense.
Ooh, we just talked about this, kinda!
It would be correct to say "hefting its payload, the rocket accelerated to orbit", because the "gain altitude" part and the "gain horizontal speed" part of a launch trajectory aren't two separate parts. A launch vehicle generally starts angling a little bit away from vertical almost immediately as it leaves the pad, and a launch to low orbit usually doesn't reach its final altitude until at or after the point it turns off its engines. There's a slight break earlier, in between the acceleration phases from different rocket stages, but not much of a break and not much change in direction before vs after.
It's mostly just geosynchronous satellites that have a distinct separate "now we're high enough and we start accelerating again horizontally" phase, but even geosynchronous transfer orbits are stable (and faster than low earth orbits, all horizontally, at perigee) so the final phase is called "circularizing" the orbit, not stabilizing it.
Given that I have a million hours in Kerbal Space Program (ESA hire me already!), I already knew all this and then some, but I wanted to keep it as simple as possible while still getting across what a stable orbit even is and how it relates to getting spaceships back down to Earth.
Still, thanks for the added detail!
Thanks for letting me sperg out on the added detail! I suspected you might know it already, but it's surprising how counter-intuitive it is.
As a kid 30-something years ago I wrote an orbital dynamics simulator (in QBasic, with Explicit Euler time stepping, with nothing but circle sizes to indicate z-dimension position and nothing but animation to indicate velocity; I won a science contest award but I cringe to think back on it), and one of the features I added was user-controllable rockets. Keys to control orientation, another for acceleration, others for speeding/slowing/pausing time. I'd ask people to get from a lower circular orbit to a higher one, and basically everybody I asked would try the same strategy: turn the rocket vertical (perpendicular to its current direction of motion), thrust, then turn horizontal again on the theory that that's what they'd need to do after they'd accomplished "up".
To be fair, at the same time I was struggling to understand why porkchop plots all have those gaps in the middle, and I didn't finally get that until long long afterward, when I first had to make an interplanetary plane change in KSP.
I recall being part of a student group at university (Computer Science) that aimed to explore the Apollo Moon Mission's onboard computer. My job was explaining orbital mechanics to everyone...and I completely overshot and took about an hour to do it in a 20-minute time-slot, giving far too much detail.
Somewhat later, I'd write my own (purely keplerian) orbital simulations, mostly in C#.
To some extent, nerds are all the same, no matter the time and place.
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I mean, you even said "stable orbit" in the post above.
The "coming down" part is actually optional, and most of ships so far have been working without it, that's why reusability is such hype - you make them come back. Even Falcon 9 leaves it's upper stage up there.
OTOH, reaching orbit is mandatory. If you want to launch a satellite, you first have your ship reach the desired orbit, then you deploy the satellite. If you don't do it like that, they'll just come back crashing down. Only then do you start thinking about making the ship come back.
To be fair, I'm pretty sure they could reach orbit if the wanted to. Keeping the engines alight, after you get as far as they did, is the easy part. If my bet was with Elon Musk himself, he'd probably put one in orbit just to prove a point, but luckily for me they probably won't attempt it until they're reasonably sure they got everything right. Which means that you might be sweating for a while yet, and if you win, it might be a lot closer than you expected.
Yeah I may have been confused in making the bet, as @roystgnr mentioned above it seems they may never go “to orbit” and instead do suborbital velocities.
Starship was stable enough to release a dummy payload so I’m assuming that’s as far as they’ll go! Not trying to weasel out of the bet here just genuinely above my pay grade, hah.
Oh, no, they're definitely trying to go to orbit. Basically every use case they have requires it. Starlink satellites use low-acceleration argon ion thrusters to change their orbit after a launch, but they have to start from a low parking orbit that won't decay for weeks or months. (One time a series of solar storms reduced that to "days" and actually brought down a batch of satellites.) Starting from an orbit that reenters within 45 minutes is out of the question. Artemis missions and Mars missions have to refuel in Low Earth Orbit, and that again requires weeks or months of orbital stability, at a minimum, for the propellant depot Starship. These barely-suborbital flights are the best way to test everything, but even barely-suborbital is not suitable for an operational launch.
Their problem is that they're trying to get to orbit with a ridiculously huge payload (which is requiring redesign after redesign to make things more powerful and/or lighter) and then get back from orbit in good enough shape to reuse (which will require redesigns to make things more robust and thus potentially heavier), and so even when they have successful tests (the last version-1 flights, 4 through 6, were awesome) that doesn't guarantee that a major redesign will still be successful (the first version-2 flights, 7 through 9, were awful, and they had one v2 that didn't even make it to flight).
[Edit, to sum up the problem in one sentence: They can't safely go to orbit until they can safely go to orbit, and it's hard to both achieve and verify "safely" with a design that's still a rapidly moving target.]
My guess is that they'll go for a full orbit in the same flight that they attempt their first ship catch, which Musk claims will be 13 if everything goes right with 12 (the first v3 launch). They've got one last v2 launch for flight 11, and if they had a NASA milestone for orbit then I think they'd try to check that box then, but they don't (the next milestone is for ship-to-ship docking and propellant transfer, requiring two launches to orbit) so 11 will probably be another "fix stuff that broke or wore too badly on the previous flight and pick new spots to weaken to see what else they can push to the breaking point" suborbital like 10 was.
If everything goes right with flights 11 and 12 then 13 would probably be around December. I wouldn't bet on that, since even Elon is suggesting that they might end up waiting until 14 or 15 for a catch. And if the first v3 flights are as much of a regression as the first v2 flights were then the catch+orbit attempt would be flight 16 and wouldn't be until next summer. Even that would still win you your bet with months to spare, but the implications for the already-implausible Artemis 3 timeline would be awful.
What's your take on it's performance so far, in that regard? It seems to have taken quite a bit of time for it to pick up speed during launch, just with 16 tonnes of the dummy payload. It's hard to imagine it taking off with double that, let alone the 100 tonnes they're targeting.
Very disappointing out of context, then reasonable with a little context, then worrying with a lot of context.
With their current "v1 booster, v2 ship" stack, they claim max payload to Low Earth Orbit of ~35 tons, basically twice what they can get from a Falcon 9 with a drone ship landing. A new stack and test flight of Starship is something like 4 times the cost of a Falcon 9 flight, so we're looking at twice the price per kg, when they were shooting for 20 times less, so they're off by a factor of 40. Demonstrating booster reuse this early means that ongoing costs would be less than new stack costs, but until they can reuse the ship too or increase the payload they're still at maybe half of the price per kg of Falcon 9, roughly what Blue Origin is trying to hit with New Glenn. They'd be way ahead of Falcon in price per m^3, which for older Starlink designs might have been more important (they were limited by the size of the Falcon 9/H fairing much more than by the payload capacity), but these days they're launching "Starlink 2 mini" and "Starlink 2 mini optimized" satellites that squeeze down more densely and actually use the Falcon 9's mass capability. Regardless, billions of dollars of R&D to save a few hundred million a year on launch costs would be very disappointing in LEO.
Past LEO the current design would be a total failure. Their goal of using at most a dozen refueling launches at full-reuse prices to get a hundred tons out of Earth orbit would be awesome. They'd be able to put dozens of people on the moon more cheaply than they currently send four people to the ISS. But with their current performance, requiring three dozen launches at partial-reuse prices to get 35 tons out would mean they'd eat a loss just fulfilling the HLS contract.
So, TL;DR: very disappointing.
When I watched, it looked like it cleared the pad pretty quickly as soon as it started moving at all, but for some reason it wasn't released from the pad for like 5 seconds. Makes me wonder if some sensor reading almost triggered aborting the launch. They did shut down one booster engine about 2/3 of the way through its flight, and didn't relight it for the boostback burn, but just one problem engine wouldn't have been enough problem to possibly cancel a liftoff.
That's because imagination is an inadequate substitute for math. ;-)
The v1+v2 stack is around 5200 tons. By far most of what any rocket does with its fuel is accelerating the rest of its fuel. If they were to add another 16 tons of payload to that stack, it would not have half as much acceleration at takeoff, it would have 99% as much acceleration at takeoff (about .36 instead of .365 g's). Another 68 tons after that gets you down to around 94%. The rocket equation is a harsh mistress, and one of the consequences of it is that, for any rocket with enough delta-V to get to Earth orbit, the payload mass at liftoff is practically a rounding error.
The extra 200 tons of propellant in the v2 ship does make a bit of a difference to their initial acceleration, though. What their current descriptions call a "v2" Starship would have been in between v1 and v2 in their earlier talks; it's basically "v1.5". It's got the stretched ship from what they previously called a "v2" stack, but not the stretched booster with higher-thrust Raptors. From a performance point of view they've upgraded half the ship so far, and in an imbalanced way. They still think they can get 100 tons to LEO out of what they're now calling "v3" (what was "v2" on their prior timelines) with both ship and booster upgraded. Flying newer ships on older boosters isn't a performance thing, it's a "need to test after major changes" thing, and in hindsight they really needed to test after major changes. The higher-thrust Raptors on the next booster version should give it around .41 g's at liftoff even with both stretches. That also means higher acceleration through most of the trajectory (rockets start accelerating faster and faster as each stage's fuel burns away and the same thrust is lifting less weight; it's common to start at around .25 or .3 g's but throttle down before the end to cap the acceleration at 6 g's to go easy on the payload), which means less nasty gravity losses (imagine a rocket "taking off" at 0 g's acceleration - it's still producing 1 g but only fighting gravity with that and getting no velocity) and more efficiency, which means much more payload makes it to orbit. The payload at liftoff is practically a rounding error compared to the weight of fuel and oxidizer, but when Starship hits orbit with only as much propellant left as is necessary to get back down, the payload should be more than a third of the total mass.
We saw this same sort of growth with Falcon 9. The first "v1.0" stack was around 320 tons at takeoff and could put 8 or 9 tons into orbit, but they kept making the engines more powerful and that let them stretch the fuel tanks and densify the fuel, and today the final "v1.2 Full Thrust Block 5 Why-Cant-SpaceX-Name-Versions-Sanely" stack is around 550 tons at takeoff and can put at least 22 tons into orbit. They typically spend some of that growth on things like earlier staging and landing legs and landing fuel, and now they can put 17 tons into orbit while landing the booster again afterwards. For booster landings, Starship doesn't have to spend anything more than it already has. Earlier staging and landing fuel are already in the current accounting, and they replaced "landing legs" with "giant robot arms on the launch tower" and somehow that's repeatedly worked because I guess we live in some kind of sci-fi anime now.
They could finish up their immediately planned upgrades, and if everything works on upper stage reuse too, hit their original goals. With an additional booster upgrade (and an extra 3 engines on the upper stage), they still think they can double their original (2017, after they scaled down from the 2016 trial balloon) payload goals, and that would be amazing but not a priori impossible.
So, TL;DR: reasonable with a little context.
The trouble, in the long term, is that "if everything works on upper stage reuse too". They could give up on upper stage reuse completely, get to spend a few tens of tons on more payload instead of on heat shielding and flaps and landing propellant, and even with the design they're testing next year they'd be good enough for HLS and for Starlink launches and for continuing to price under their competitors' next generation. But, unless they can do upper stage reuse, that still doesn't put a colony on Mars. Their existing "can reenter and then do a soft touchdown afterwards despite some damage" ships would actually be fine for getting to Mars, since that atmospheric entry isn't inherently as bad as Earth's (less free oxygen in the shock plasma, plus significantly lower speed entry) ... but then to bring people home they need the same upper stage to get back to Earth afterward, with no more refurbishment than they can accomplish in situ, with the reentry at Earth now at a significantly higher speed. With their dream architecture, getting to Mars is (relatively!) cheap and getting back afterward is practically free, but if they can't make upper stage reuse bulletproof then getting to Mars is too expensive to do regularly and getting back is impossible (without some other gimmick like carrying a separate reentry capsule). Part of why their flights 7 through 9 were so awful was that such major regressions on the v2 ship were really embarrassing, part of it was that the flight 7 and 8 failures were at the worst possible part of the trajectory, but part of it was just that they've been trying to do more heat shield robustness tests (removing tiles here, experimental tiles there) since January and they didn't actually get a v2 ship to reenter properly and run a test until August.
So, TLDR; worrying.
Thanks for the detailed response!
Yeah, I take it back. When I was watching a livestream, someone commented on it taking it's time (probably it being held, as you say), but what really gave me the impression was a post-launch commentary video, which, looking at the original stream again, must have shown the takeoff in slowmo.
Eh, it would be awesome, but unless some rabbits get pulled out of several hats, Mars feels like a distant dream.
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I just ran across an Eric Berger article from this morning which agrees that 13 would be "probably the first orbital flight" but predicts a much longer delay before the first v3, putting flight 12 "in early 2026", which would push 13 to something like March. He says to take this "very notional" "informed guesswork and reporting" "with a pinch of salt" but his guess is probably far more accurate than mine.
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No.... Roystgnr was making a rather nuanced point, I assure you SpaceX is planning to send Starship to a proper orbit. They literally say this during the stream from the last test flight, when they were testing the engine relight (around T:+37 minutes, I think). It's just that they're not confident it's safe to do so yet.
That makes no sense. They want to use it to launch satellites. To do so, they need it to go to orbit. The dummy payload was there to test if their deployment mechanism works, and to see how well the ship performs under actual load, but on the current trajectory, it either burned up in the atmosphere, or crashed into the ocean right after the Starship.
I am kinda starting to feel bad for getting you sucked into this. We can downgrade it to a gentlemen's bet, if you want. Honestly, all I wanted was for Elon stans to plant some flags, and tell me what future achievement I should exoect from him, if he's such a genius.
No way man I’m all in on this bet. We’re DOING IT. If it doesn’t go to orbit you’ll get your donation.
Dont worry my friend I can afford the $100 and I’m happy to bet. This is my first online bet and it’s quite fun.
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