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Sn10's nose, complete with its newly installed flaps, has been moved into the High Bay where it's expected that it will be mated to the rest of Sn10 at any time.

And Elon's gone crazy again. (From watching Boston Dynamics dancing robots apparently.) He writes:

"We're going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load."

https://twitter.com/elonmusk/status/1344327757916868608

Viv asks whether he's playing Kerbal, the Real World Edition.

Elon says

"Saves mass & cost of legs & enables immediate repositioning of booster on to launch mount - ready to refly in under an hour."

https://twitter.com/elonmusk/status/1344342598694047744

Lots of skepticism about this. Frankly it sounds crazy. But Elon has a proven track record of successfully doing crazy things so you can't dismiss it.

Then Tim Dodd asked about the Sn8 header tank problems and whether the changes to Sn9 were hardware or software changes. Then Tim asked whether the headers are back pressurized with gaseous CH4 and GOX. Elon chose to answer the second part.

"Sn9 will press CH4 header tank with helium. Long-term solution is under debate. not clear what is lightest/simplest."

If they've gone to helium, that answers the first part of Tim's question too, since it presumably will require plumbing mods, not just software.

https://twitter.com/elonmusk/status/1344344855237992448

Some of the engineers think that what happened in Sn8's CH4 header was something called 'ullage collapse'. It's the counter-intuitive idea that stirring the contents of a partially full tank of cryogenic fluid reduces pressure rather than increases it. And Sn9's radical pitch up flip maneuver obviously sloshed the contents of the fuel header. I'd never heard of ullage collapse until today, but below is an explanation of the phenomenon in cryogenic liquid hydrogen tanks, though I assume that the principles should be the same for liquid methane. Elon suggests that using helium to maintain pressure is just a temporary expedient until a better permanent fix comes along, presumably employing autogeneous pressurization from engine bleeds which is the long-term plan (not without its own challenges though).

Amazing how much information the engineers can squeeze out of a little off-hand twitter post.

https://hydrogen.wsu.edu/2015/03/19/expl...-collapse/

(Dec 30, 2020 10:53 PM)Yazata Wrote: [ -> ][...] Elon's gone crazy again. (From watching Boston Dynamics dancing robots apparently.) He writes:

"We're going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load."

https://twitter.com/elonmusk/status/1344327757916868608

[...] Elon says

"Saves mass & cost of legs & enables immediate repositioning of booster on to launch mount - ready to refly in under an hour."

https://twitter.com/elonmusk/status/1344342598694047744

Lots of skepticism about this. Frankly it sounds crazy. But Elon has a proven track record of successfully doing crazy things so you can't dismiss it...

Sheesh, compared to the cost of a NASA equivalent, I suppose losing a few SH boosters before they get it right won't even faze him. 

Interesting Engineering: "From an engineering viewpoint, while several times more powerful and bigger, the Super Heavy will technically be simpler than Falcon Heavy — since it uses a single core. Built from the same simple rings used to assemble Starship prototypes, the Super Heavy will likely also come at a lower cost to construct than Falcon Heavy."

Rumor seems to be that Sn 9 will perform its static fire on Monday January 4 and is penciled in to fly several days after that. The flight plan is expected to be a redo of Sn8, in hopes of successfully completing the landing and getting more data.

Sn10 and the others are expected to "expand the envelope" as the aeronautical engineers say. Going supersonic is probably first. Then maybe a trip up to and back from the Karman line.

The horizontal sky-diver descent looked rock-solid stable on its first try. The 90-degree pitch-up "flip" worked pretty well, I guess. Apart from the last seconds fuel-feed problem and the loss of thrust, the whole Crazy Elon landing certainly looked feasable. They still need to get it right though.

The biggest remaining challenge will be orbital reentry, hitting the top of the atmosphere at 18,000 mph.

Sn10's nosecone has been installed in the High Bay. So Sn10 is at least superficially complete, though there's probably some final systems integration stuff happening that we don't see, plumbing and electrical cabling to connect. It seems like SpaceX likes to have a backup Starship complete or almost complete when one flies. They had 9 waiting when 8 flew and now they are completing 10 before 9 flies. Maybe it makes them feel better about the possibility of losing one.

Meanwhile 11's tank section is nearing completion in the Midbay and barrels and domes belonging to 12 have joined it for stacking. There are new nosecones taking shape in the nosecone tent while the other two Giant Tents crank out pressure domes and ring barrels. So there are more spaceships following 10 at various stages of completion. It's a Tesla-style spaceship assembly line!

RGV Aerial Photography has posted an extraordinary flyover video of the entire Boca Chica operation. Lots of closeups of mysterious activities.

One mystery is what's happening at the old gas well site just west of the build site. Lots of earthwork, lots of concrete, some big mysterious pieces of chemical refinery style equipment. Speculation is that Elon is building a gas purification refinery to turn natural gas from the well into rocket-grade methane. (Which involves removing the heavier hydrocarbons like butane.) There's even speculation that he wants to build an oxygen liquefaction plant to produce his own LOX. That will require lots of energy. There's also talk of a water desalinization plant since right now all of Boca Chica's water is trucked in. That will require energy too. It all comes together somehow, but it isn't clear how yet. 

But adding intrigue is the presence of big concrete pad thing that looks suspiciously like the hexagonal footprint of the Superheavy test stand a mile down the road at the launch site. Except that there's no way that they would build a Superheavy test stand right next to the build site. Too dangerous if a Superheavy does an Sn4 imitation and blows up. Presumably it's  foundation work for Elon's anticipated fuel/LOX/water/energy plant... or whatever they are doing there.

The build site is positively infested with rings. Some of them are barrels and some of them will have the geeks examining them to see what's inside them. The familiar domes or something new? There's an interesting rectangular dirt area next to the High Bay. Is it reserved for a possible future second High Bay? Right now it seems to be a spot for piling construction materials. The smaller triangular bay where nosecones are stacked has a mysterious vertical machine in it. (Some kind of lift?)

The real activity is down at the launch site. Sn9 is sitting grandly on the second test stand being prepared for its expected static fire test Monday. Sn8's nose is still sitting on the landing pad but it will have to be removed before Sn9 flies to make room for its landing. I think that they are still figuring out where they want to put the Sn8 nose since it's a historical relic. (I don't think Elon wants to cut it up for scrap. Perhaps they should build a rocket garden next to the restaurant.) Meanwhile a big square has been cut out of the landing pad, presumably where the crater was where Sn8 impacted and exploded. Presumably they will have to pour new concrete and let it cure before Sn9 can land there. So maybe its flight won't be next week.

The real mysterious activity at the launch site is over at the SuperHeavy test stand. It's a positive hive of insect-like activity. But paradoxically, nothing seems to be happening with the stand itself. Its six big concrete legs have been there for several months now with nothing more being done to them. Is there something wrong with them? Has SpaceX gone to a different launch pad design that leaves the old legs obsolete? Or (perhaps most likely) they are still designing the platform that will sit atop the legs? (They make it all up as they go.)

The big green prefab building that the SPMTs moved down the road the other day has turned up next to the launch stand, painted white. From the vents and ports on it and a warning sign at the door (hardhat zone), it's speculated that it's filled with some unknown machinery. It's likely temporary whatever it is, since it's so close to the launch stand and a permanent structure a little further away is being constructed with reinforced concrete blast walls. It might house pumps and control gear. The big rectangular space between it and the road is filled with earth moving equipment. Mary has photographed them digging trenches and there are lots of concrete culvert things that will probably be buried and filled with pipes and cables. The best speculation at this point is that this area is to become a new bigger tank farm to serve fuel and LOX to the SuperHeavy launch pad. (There's hints in some permit applications that they eventually plan a second Superheavy test stand as well.)

Check it all out in the video below. Boca Chica isn't just about test flying spaceships, it's about making a spaceship mass production assembly line. And third, it's also a never ceasing construction zone. Amazing to compare what it is now to what it was a couple of years ago. What will it be in another year?

Road is closed, pad is clear and wind-like and occasional hissing noises are coming from the tank farm. (Lab's new remote camera/microphone right across the road is great.) Small amount of venting from the farm. There's a heat-exchanger/condenser thing that's increasingly active.

But... no warning notices have gone out to Boca residents so unlikely that liquid methane is being used. So no static fire today. Speculation is another cryo-test. Dunno why, maybe they want to test that helium pressurization idea in the fuel header.

In other news, they have cut up and hauled off the Sn8 nose to be scrapped. Sadness that they didn't save it like Elon said he wanted to.

And the square cut-out on the landing pad has has had concrete poured. It will take as much a a week to cure. So I'm guessing no flight till next week. But rumors from out of SpaceX are still saying that the plan is later this week. Bottom line is nobody except Elon and his circle really knows.

The sad end of Sn8's heroic nose (photo taken on the ground by RGV Aerial Photography)

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Here's Lab Padre's map of the build area (his labels on a satellite photo from Maxar)

Big news on Sn9's upcoming flight. A new temporary flight restriction has been announced for Friday January 8 from 8 AM to 6 PM Local/CST (2 PM to midnight UTC so our British and European friends can watch too). Altitude extends from the surface up to unlimited (an airplane exclusion column extending from the surface to space). Same boundaries as last time.

Identical tfr's have been issued for Saturday Jan 9 and Sunday Jan 10. Presumably these are backup days in case the schedule slips. Same hours (8 AM to 6 PM local).

https://tfr.faa.gov/save_pages/detail_1_1073.html

Looks like they are really getting ready to try again to land one of these things.

Mary has been handed one of the by-now-familiar "overpressure" warning notices for tomorrow, Wednesday Jan 6. It's believed that this is for the anticipated static fire in preparation for Friday's planned flight.

Sn9 just conducted a short static fire. Looked good to me.

Edit: there is still a lot of tank farm activity and venting from Sn9. Don't know what they are doing. My guess is testing out pressurization of the headers.

Edit 2: now it's spooling down. I suspect they are done for the day.

And Mary says that they handed her another of those "overpressure" warnings for tomorrow (Thursday Jan 7). So they might be resuming whatever it is tomorrow after the sun comes up again. Right now there's a thunderstorm rolling though.

Elon has recently passed Jeff Bezos to become the world's richest person. He's currently estimated to be worth $180 billion. His sky-rocketing wealth is largely the result of Tesla's skyrocketing share-price. At the beginning of 2020 Elon's net worth was "only" $27 billion. TSLA's share price was less than $100. Today TSLA is trading at the equivalent of $800/share (adjusted for a stock split).

https://arstechnica.com/cars/2021/01/elo...st-person/

And everyone knows what Elon likes to spend money on....

Though thanks in some large part to the efforts of Gwynne, SpaceX has revenue and is operating in the black.