RCgothic

Simulator I'll grant.

Potential static fire tomorrow:

They should use Starship to land an entire (Lego) Saturn V on the moon! Go one better than a few minifigures! (^ ω ^)

This is definitely not machined aluminium. It may be extremely badly applied aluminium sheet, but it's definitely not any form of tank structure.

I believe it's fabric over frame. It's at best a full scale mock-up, I'd struggle to dignify this with the term "pathfinder", which implies at least some manufacturing processes have been tested.

But they don't have to be complicated. I personally fly these occasionally. Solid propellant, no moving parts: This is also a complete complete liquid rocket thruster. Not the most efficient or the largest. It's a pressure-fed monopropellant thruster that flew on the Mercury capsules: This next one is slightly more complicated because it's bipropellant and a little larger, but it's still basically two valves, an injector and a nozzle. R-4D used on Apollo. The complexity comes in when you: -Want to use fuels that don't self-ignite (add starters). -Want the chamber pressure to be higher than the tank (add pumps). -Want to use a more advanced engine cycle (add tap-offs, turbos, etc). -Want to operate continuously (add cooling channels for temperature management). -Want to Gimbal (add hydraulics and joints). -Want the engine to pressurised the tanks instead of using bottled helium (add heat exchangers and pipes) -Want a variable throttle (add more complex injector assemblies). -Want better combustion stability in a larger engine (add baffles). -Want a comprehensive engine-management system for all of the above for maximum efficiency, diagnose faults, and have non-catastrophic emergency shut-downs (add a butt-load of sensors and an onboard computer). -Want additional information for engine development purposes (add another butt-load of sensors). It all stacks up quickly.

It's been released: I'm a little disappointed by the headline telescope at first glance. I was hoping for a 15m LUVOIR, or maybe something using distributed launch. But it's not recommending even 8m LUVOIR, but a 6m version merged with an extra-large HabEx.

In case there was any doubt. This spurious lawsuit has done enough damage, happy to see it settled favourably.

Complex as opposed to what?

Cold nitrogen is also heavier than air. Doesn't really help if the rocket leaks both oxidiser and fuel. Also it would need to be filled after landing as the rocket exhaust would empty the berm. I wonder if what is needed is an intermediate density gas. Methane's a lot lighter than oxygen at equivalent temperatures. Use something inert that Methane will float on and Oxygen will sink and that would keep the fuel and oxidiser apart! Probably a lot of practical issues. Wind, for one. Momentum of leaking gasses is probably another.

Is that really $10B worth of benefit (not Inc VAB alterations and ML2) considering the radiation environment is clearly not so bad they don't mind sending at least two crews through it? It'd be a stronger argument if they'd stuck with only Artemis 1 using ICPS. Personally if I were determined to spend $10B extra on Artemis that looks *just* like the extra HLS funding NASA needed for that 2nd lander system that's apparently congressionally popular.

There's a limit to how much mass Orion can push into NRHO and still have enough fuel to return itself. I believe it was calculated up thread at about 16.9t with no margin. So B1B can only manage fractionally more than a FH (~16t after deduction for spacecraft propulsion bus), and B2 can't manage any more than B1B. The idea that SLS will ever launch anything other than Orion is laughably hilarious. Its only dedicated payload, Europa Clipper, was taken off it, and SLS will never win a competitive tender against upcoming more capable launchers. I'd seriously save the $10B EUS dev cost and launch ~65 Falcon Heavies instead. 200 starships? More? $10B is stupid money for this "upgrade", frankly.

Hey, if there's one left over to stick in a rocket garden I won't be complaining.

SLS won't keep launching into the 2050s. It'll be lucky to make the 2030s.

There's also a distinct lack of emergency shutters on those large windows. That'd take up additional external radius.

Yes, the header tanks will be full. But the main tanks won't necessarily be completely empty. As I said, might not be a bad idea to have some cryogenic residuals in the main tanks for the first couple of flights at least. Happy Austin is following his passions, but it'll be a loss to the community if he can't report anymore.

They'll be somewhat empty. For non-high performance missions it might be worth keeping some residual fuel for emergency cryogenic cooling. Deceleration would hold the fuel residuals against the windward tank wall.

Well.

A magnetic monopole in a magnetic field would be analogous to a charged particle in an electric field.

Lunar regolith has a density of ~1500kg/m3, so a Starship buried to 3m would be under 4500kg per m2 or 7360Pa in lunar gravity. Internal air pressure of 1bar or 100kPa easily counterbalances that, though unintentional depressurisations and large unpressurized spaces would need additional consideration.

Yeah, you don't really get shockwaves in a vacuum. It's how Galactica can take getting nuked In an actual orbital launch the heat shield will be very much further from the pad, and reflected energy goes with about r^4 if I remember my Scott Manley. Plus water deluge sound suppression system.

Not latched doesn't necessarily mean it isn't deployed and producing power, but if it isn't secured that may cause issues in manoeuvres as I understand it.

It won't. There's definitively too much still to do. Small chance of December. Far more likely next year.

The way you equalise 4 strands is you equalise two adjacent strands by allowing them to float until the slack is taken up. O O X X By moments about an axis X-O, if the floating legs O and O are made the same then the fixed legs X and X are also the same, because X must equal O. I was doing a spell as an integration engineer on a job and the designers just before a deadline "helpfully" gave us a heavy component we had to cryo-fit flush underneath with no lifting features and refused to let us modify it. Had to lift it into a nitrogen bath with magnets, but the magnets individually weren't very capable (they could have been made stronger, but we'd start damaging the component). I had to do a deep dive into all the "de-rating" factors to see which ones could be made not applicable to the specific process. Other than non-equal legs, the other major de-rating factor for multiple legs is included angle between them. If they're pulling horizontally then capacity is being used on that and not vertical load. It's common for general purpose multi-legged lifting equipment to assume an included angle of 90-120 degrees, which de-rates each leg by the cosine of the half-angle. Magnets in particular do *not* like being pulled sideways though. They'll slide until the pull is mostly vertical, except now that's a smaller lifting footprint so the load probably becomes unstable, the lifting surface angles to the horizontal, and then the magnets slide again until the load is dropped. So if you're only using a very small included angle on the legs anyway to prevent sliding, that de-rating factor also drops out almost completely. Also had to account for cryo-conditions as well. All-stainless steel equipment, and samarium-cobalt magnets that would only lose ~10% of their magnetism unlike neodymium one which become basically useless at LN2 temperatures. Got some beautifully shiny stainless steel D-shackles that became prized office paperweights after fulfilling their function. And then the magnet supplier's courier let us down, so I had to get the magnets taxi'd across the country overnight on my own buck to make the start of testing the next day. Fun little job.