sevenperforce

That's fair. At the same time there is value in optimism. For example, optimism helps keep people from jumping to conclusions about saline.

Godly. Ordinarily I wouldn't support peeking under a skirt with a telephoto lens, but.....

Never gladder to have been wrong

Fortunately, the mutation appears not to have changed the structure of the virus in a way that alters the effectiveness of vaccines on it. Correct. The new strain is more infectious, which means its spike proteins are at least as effective as the original strain at piercing cell walls via the hACES2 receptor. Usually when a vaccine-resistant strain emerges, it is because of some impaired functionality. If the new strain was less infectious but more deadly, then I would be worried. If a strain is more infectious, and the target of the vaccine is the part of the virus which causes the infection, then the vaccine should be just as effective against it.

No Dinosaur Killer required -- I'm talking one of the intermediate-size city-killers. No one would be able to know for sure where it would impact and so everyone would want to work together.

I'm reminded of that old Buddy Davis song from my creationist years... "It's designed to do what it does do; What it does do, it does do well! Doesn't it? Yes it does. I think it does. Do you? I do. Hope you do too. Do you?"

God the pace It's like watching paint dry On an SLS core tank Which isn't even supposed to be painted because they changed the design back in 2015

So you don't actually want to impact the asteroid; rubble pile or not, it's always easier to deal with one object rather than many. No need for an Orion-style tungsten shaped charge. Rather, you want a very big blast, as big as possible so that you can detonate it from a significant distance. The x-ray and gamma flux to the surface of the asteroid will vaporize the first 12-14 centimeters of regolith, causing it to expand in the opposite direction and produce relatively gentle, distributed thrust. Then you rinse and repeat. You'd want to send up 20 or 30 bombs, both to spread out the thrust over time and to give yourself plenty of margin in case a bomb fails to detonate or is lost during launch. Modern nuclear weapons designers could probably produce 100-200 megaton bombs at somewhere between 20 and 30 tonnes each. If the orbital mechanics and rocket scientists decided slightly smaller nukes would be better, you could produce a bunch of 10-megaton weapons at 3-4 tonnes each. The United States no longer maintains its arsenal of W53 thermonuclear warheads, but it retained the casings and some associated parts to allow them to be rebuilt if they were ever needed for planetary defense. Detonated in-atmosphere, the W53 would have created a nuclear fireball up to 5 kilometers in diameter. A refueled, stripped-down Starship would probably be the best delivery system in any event.

Yes. You could, in fact, calculate the required energy to compress the gas by solving for the amount of energy produced during the ascent. Plus efficiency losses. Energy out and energy in (factoring in efficiency losses) are always equal.

And now we have a new strain in the UK that is what, 70% more infectious?

Aliens, living peacefully in a system several lightyears away: WTH are they doing to their own planetary system? Those barbarians must wage truly horrifying war! Nope, we are not going there! TL;DR - "Let's nuke it!" is not the best answer to 95% of problems. Nuking asteroids is, in fact, one of the best ways to deflect them. Sometimes I think that what the Earth really needs is a nice big serious asteroid scare. It would bring us together in a way that the pandemic clearly didn't. You'd have all the best nuclear physicists and rocket scientists in the world coming together. Plus it would be a peaceful reason to build REALLY big nukes...which are exciting for boom boom reasons. And it would force rocket science to improve and expand.

Wow. With the exception of the Crew Dragon IFAT, SpaceX hasn't expended a single booster since AMOS-17. And of the 29 launches they've done since then, only 6 were new boosters. That means 79% of their launches have used flight-proven boosters.

No, because you can just bring more RCS propellant. The whole point of Orion is that you have as much payload as you want. Including as much RCS propellant as you want. These threads remind me of the car I tried to design at age 8 which propelled itself by a gear that attached the steering wheel to the powertrain, so the "driver" would just turn the steering wheel around really fast to go. And then I needed to figure out steerng.

The first blast will liquefy the crew.

Ground-penetrating legs could cause problems if there was lateral velocity on touchdown. You want the legs to prevent tipover, not exacerbate it. I don't want to put a shock absorber in the "toe" for two reasons. First, the shock absorber need to be inline with the vehicle to reduce the bending moment on the skirt. Second, and more importantly, you can fit more shock absorbency and a longer stroke length with less weight in a separate system. You don't want too much complexity in the part of the leg that is already going to have to rotate and lock into place. Stroke length is the most important factor for a shock absorber system. I'm envisioning the "heel" as having nothing more than a spring and an emergency crush core, to bear the primary static load just like the current legs. The dynamic load is borne entirely by the pneumatic piston. And even if you use F9-style legs with a heatshield seam, you end up with the heatshield tiles directly contacting the ground at the toe, which again is something you want to avoid.

Because I apparently cannot stop making these....

There's no way to source carbon on the Moon, so this can't be used to refuel Starship. However, NASA does want to try and source water ice from the moon to refuel hydrolox ships for Mars missions. That's why Artemis is targeting the lunar south pole.

Falcon 9 has too much pressure; Starship has too little pressure -- why can't they make up their mind??

That portion of the leg can point more vertical if needed to avoid exhaust impingement. But if you recall, the existing legs already have a pretty rough time of it on landing: I don't think that bending in vs out is going to make much of a difference there. However, a higher stance with more ground clearance will help because it means less blowback gets trapped in the skirt. I believe it's a weather hold.

Clearance shouldn't be a problem. Depends on piston stroke and stuff, but you can definitely make it fit.

No mass simulator in SN8. The mass sims for SN5 and SN6 were intended to substitute for the COM moment of the fairing and LOX header. They were not simulating a payload. In other news, here's one additional possible render. It has an "ankle", a "heel", a "toe", a "sole", and a "shin". The ankle rotates the shoe, the toe slides through the shoe, the ankle locks against the shin, and the sole makes contact, distributing force between the heel and the toe. The load path goes from the toe to the shin and from the heel to the ankle.

Elon has said they need a wider stance, so evidently he thinks there's a problem. Remember that Elon wants to put people on Starship. So it needs to be able to have every advantage for contingency landings. It needs to be able to land on one engine, on two engines, at an angle, in the wind, on uneven surfaces...everything. So the ability to have a wide, shock-absorbing stance is critical.

Elon said the problem was pressurization, not gas-gulping. Here's a new leg design that I think I really like. It's the only way I can think of to get the clearance that the Raptors need, maximize the extension of the legs, and avoid any heat shield seams. At leg deployment, the leg slides down, guided by a "shoe" that wraps around it. The pneumatic pistons on the outside deploy. Once the leg has reached maximum extension, it is locked in place and the "shoe" rotates outward until the leg contacts the pneumatic pistons. As the tip of the leg touches the ground, it applies upward pressure to the pneumatic pistons, causing them to compress. If the ground is uneven, the pressure setting in each piston can be adjusted to self-level. The "heel" contacts the ground to bear the static load at the same time as the pneumatic pistons absorb all dynamic load and reach minimum stroke. This way you avoid having both a sliding and rotating member. The only challenge is figuring out how to actuate the sliding action within the rotating shoe.

If the header tank is pressed via valves from the main tank, this is what I'm thinking probably happened:

I spammed a few questions at Elon since he's active right now; let's see if he bites. That works if you have a separate press line already. Also, where is the gas coming from? If it's from Raptor's autogen press line then it is going to die when Raptor stops firing. The problem is gas flow velocity. Liquid methane is essentially incompressible, but gaseous methane is extremely compressible. If you're relying on the autogen press line entering the main tank to pressurize the header tank via valves, it will take a moment for the gas entering from the press line to expand enough to reach the valves.