We’re getting warmer …
Woohoo! let’s go!!!
I’ll be there at the south tip of South Padre, can’t wait. Monday is looking like a perfect day for a launch too.
The New York Times has a fun article today, with video, showing all of the tests so far, including the failures (gift article):
Bellyflops, Booms and Big Rockets: A Recap of SpaceX’s Starship Tests A Timeline of SpaceX’s Starship Rocket Tests Ahead of Orbital Flight Launch - The New York Times
Fingers crossed. It’s been a while coming! One has to wonder though: if they get the second stage up there OK, why not do at least one or two LEO orbits as a sort of ‘victory lap’?
Of course we don’t know the details of the planning, and it would complicate things with a re-entry burn, I suppose. I guess any launch is better than no launch…
They’re trying to keep things simple for now. If the upper stage fails in some way, it’s on a trajectory guaranteed to deorbit it quickly. No one wants a giant tank in a rapidly-decaying orbit that will come down who-knows-where. The Chinese have been getting plenty of flak for that.
Could they have set up a mission plan to boost it into a real orbit once it looks like things are going smoothly? Sure, but that complicates the mission. They’re here to test that the booster, upper stage, and the staging itself works. They’re focusing on getting that right above all else. Getting to orbital velocity–even if they don’t actually complete a full orbit–is a sufficient test of that.
There are plenty of other vehicles in the pipeline to test all the other stuff.
Apparently they don’t intend to land them, but drop the booster and starship in the sea. That seems rather expensive. I would think that they would at least land the booster.
Neither vehicle has landing legs: they intend to catch them with the launch tower. But the launch tower is expensive, and next to a bunch of other expensive stuff, so I think they want to retire at least a little bit of risk before making that attempt.
I’m mildly surprised that they don’t plan on even testing the bellyflop recovery maneuver for Starship, but it looks like they really want it to break apart and sink immediately. A soft water landing could complicate that. And they tested that reasonably well with previous attempts.
The vehicles aren’t that expensive. They’re producing over an engine a day at their production facility, and the structure is both made from cheap materials and is easy to fabricate. I don’t think they’re worried about expending a fair number of vehicles in the test program.
Are there? It would be nice if so. When are we going to get to the point of routine launches?
There’s a list here which I think is pretty up to date:
The flight tomorrow is with Booster 7 and Starship 24.
Ship 25 and 26 are built and stored offsite, and 27 and 28 are under construction. I believe that 25 and 26 don’t have heat tiles and so won’t be used to test reentry.
Boosters 9 and 10 are already built. 8 got scrapped.
We’ve seen tons of pictures of Raptor 2 engines in storage. No shortage there.
Routine, fully-reused launches are probably a few years away. It’s going to take a while to get right. But I expect that we’ll see at least some real payload–namely, Starlink–this year.
It’s not always easy to grasp the sheer scale of Starship, but I think this image does a pretty good job:
It’s a skyscraper that goes to space.
I would think that barely missing the launch tower and falling into it would fellate with great alacrity.
Stolen transcript from a discussion on that bird site:
“If we don’t destroy the launchpad, it’s a success”
“we’re dying to get [booster 7] launched because there are hundreds of improvements in booster 9”
A: We’re still looking at 39a and building out crew launch capacity at 40. Need redundancy. And need to get past developmental stage at Starbase before we begin launching at the Cape.
“our concerns are similar to what the soviet N1 rocket faced: many high pressure engines, potential for domino effect if a single engine failure cascades”
“If it blows up, it’ll be more of a fireball than an explosion. A very big fireball. It’ll melt the steel and slag the launch pad.”
“we will have a CO2 [engine] purge in flight”
“probably tomorrow will not be successful, if by success one means getting to orbit”
“we’ve got booster 9, ship 26 almost ready to go, and a significant cadence of rockets moving forward. In the long run, meaning 2 or 3 years we should achieve full and rapid reusability”
On orbital refueling: If we’re docking with ourselves it’s much easier than docking with the space station
“In order to pass [this] great filter, Mars must be self sustaining. If ships stop going to Mars, Mars civilization must not die out.”
The 2-3 years to full-and-rapid-reusability fits with what I said earlier.
It sounds like they want to launch B7/S24 if for no other reason than to make space for newer, more advanced vehicles.
What does this mean?
39A and 40 are launch pads in Florida (Kennedy Space Center). SpaceX launches Crew Dragon out of 39A, and also wants to launch Starship there. But if Starship blows up, or there’s some other issue, that means the only US crew launch capability is lost until they can rebuild.
SpaceX also launches from Pad 40, but it’s not yet set up for crew. They’re in the process of building out support for crew launches out of 40 for redundancy.
So, no risky stuff (like Starship) out of 39A until there are at least two pads for crew launches.
ETA: From NASA’s position, they gain redundancy once Starliner starts real flights, which are from Pad 41 (actually “Space Launch Complex 41”, or SLC-41). But that’s not happening yet, and I think SpaceX wants internal redundancy in any case.
Thanks!
Oh well, at least they seem to be getting serious about it. Some months ago I was beginning to wonder if, behind the scenes, they had run into some showstopper technical problem which would call the entire concept into question… and were keeping quiet about it to save face.
But apparently not. Good, here’s hoping for a shot in 48 hours.
Sticky valve causes scrub of brand-new rocket? Pretty much the least surprising outcome possible. Funny part is that Musk specifically mentioned the difficulty in building valves that work from a cryo-to-ambient temperature range on the Twitter thing yesterday. Somehow, no one has quite figured that out yet.
I did manage to wake up at the crack of dawn to watch the stream. It’s a good sign that they made it as far as they did. Though it wouldn’t surprise me if we see a few more scrubs for different reasons. Weather is supposedly looking pretty dicey later this week, too.
IIRC, one test of Starship failed for example because they found that the fuel feed to the engine to restart failed, something about pressure in the fuel tank during the maneuver. These are the details you only find the hard way (sometimes) when trying something new. If you are launching a dozen of these, and build them cheaply, fixing what you find as you go - it’s simpler than Boeing launching its one expensive capsule only to find that they had a software glitch, so wait until another one’s ready a year later and test again.
It seems SpaceX was ready to go with this the moment they got their license, so odds are that was the main holdup.
The issue is ‘ullage collapse’. Ullage is the vapor above the fuel inside a tank which keeps the tank pressurized (‘autogenous pressurization’). In a cryogenic tank, if you slosh or stir the contents the pressure will fall as the vapor gets chilled down by the liquid cryogenic. Even truck drivers of cryogenic fuels will tell you that the pressure in the tank will fall if they brake hard and slosh the contents.
Remember the Apollo 13 disaster? That was the result of a request to ‘stir the cryo tanks’, which keeps the ullage pressure down. An over-voltage in a switch caused the explosion.
In the case of Starship, when it did the ‘flip’ manoever it caused ullage collapse from the sloshing fuel, lowering the pressure in the tank enough to not feed the engines. They then fixed this problem by adding helium pressurization to the header tank (instead of ‘autogenous’ pressurization using Ullage alone). This caused the second landing failure, as helium gas bubbles managed to get into the fuel lines and cause the power in the engines to drop. Rockets are hard.
You’ll be hearing more about ullage when they start trying to refuel in orbit, as ullage issues are a difficult problem in zero g.