RCgothic

Cats also require soft media in which to toilet. I can't imagine any environment without at least some simulated gravity being suitable.

Where's this 100kN Starship RCS figure come from? Because the Apollo SPS was only 70kN and they aren't using engines remotely that big for thrusters. The Artemis ESM was built to specification. Being underpowered is a problem with the specification, not the manufacturer. It would have sucked just as much built to the same spec in the US. Let's not be unduly unfair to ESA.

Presumably a meatier SM would weigh more. Is SLS even capable of lofting a heavier Orion & SM to the moon? Does it actually gain you anything?

Looks like Gateway just took a step towards not happening?

Is 100kN feasible for hot gas RCS thrusters? Space Shuttle's primary RCS was under 4kN each and the primary OMS engines less than 30kN each.

Can it even land on one engine? Also that's mass without payload. Starship would be delivering a payload to the moon, it wouldn't be landing empty. But even on one engine and with a payload, the payload won't be 5x the dry mass. So yes, starship would have to hoverslam. But at the same time the thrust requirement is approx 1/10 a raptor at full thrust even without payload, so I think it's pretty safe to say starship won't be hovering on RCS hot gas thrusters.

A raptor engine has approximately 2000kN. We're looking for 1/10th that, so agree that even several thrusters together aren't likely to be sufficient. Tipping would require half as much thrust, but would probably utilise half as many thrusters so no net benefit.

How much thrust do the hot gas thrusters have? If the combined translational thrust is over 200kN then a 120kN Starship would be able to hover horizontally on the moon and presumably touch down in that orientation.

I feel sorry for the pad used for a full duration static fire of superheavy!

New Shepherd.

Gets you into orbit. It's clearly not ridiculously hard to install/detach raptors, SpX seemed able to do it in a day for Starhopper. Put a few of SH's SL raptors in starship cargo bays and return to earth... You could even maybe launch with a couple Vac raptors installed. They're dual-belled, and you don't need as much thrust at launch because you're carrying no payload...

Could be they aren't overly concerned with a SH conflagration. It's so large it's likely to not mix particularly well before ignition, so not a detonation. Stainless steel can survive over a thousand 'C and the blast of six raptors would scatter debris away from Starship pretty effectively. Starship could just translate sideways to an abort pad and by the time it touched down you'd be at about a g due to fuel use.

That would be... Weird.

I work in nuclear engineering. It's not actually very good engineering. Very reliable, but as far from cutting edge as you get. You get away with a lot of sins with a safety factor of x10 and no consideration of mass penalties. We can't afford to fail and so we don't learn much. I bet SpaceX learns loads.

Blue origin sure do make it hard to be a fan. A little less graditum please!

The warp drive uses warp nacelles to generate a subspace field to fold space and propel the ship via inertia-less propulsion, generally powered by an antimatter annihilation reaction in the warp core. The impulse engines use the plasma product from a fusion reactor both as conventional rocket exhaust and to energise an "impulse driver coil" (and other ship systems) which reduces the effective mass of the ship and makes the plasma exhaust much more effective. Thrusters are basically evolved current tech. Inertial dampers ensure high accelerations don't squash anyone. I've never really been clear why warp core detonation is the primary risk to a starship however. Containment failure of the antimatter tanks would be far more devastating, and making safe the warp core should just be a case of reducing the antimatter flow. Even if the core injectors froze you should be able to shut off the antimatter flow elsewhere. The only thing I can think of is for containment field instability requiring increasing containment field power that only a full power core can generate. In which case there should be a safety system that can provide a enough power to maintain core containment whilst the core shuts down. It's basically the Chernobyl safety gap all over again.

I would hazard that as you burn through fuel the CoM moves backwards as most of your fuel tanks are ahead of the CoM. Your margin of stability (difference between CoM and CoD) probably isn't high enough to compensate. Empty all the tanks of fuel and see where the CoM goes.

This isn't something that they aim for and would be damaging and inefficient if achieved. Note that the fuel is lighter (CH4 - 16) than the products. As you approach stochiometry the exhaust therefore gets heavier and therefore slower on average. This is inefficient for rocket engines. It also releases more energy which is more difficult to manage, and there's a higher proportion of free oxidiser for longer, which also does bad things to engine internals. 3.8 is the design ratio for good reasons.

What do you mean, optimistically expect stochiometry? 3.8 is deliberately non-stochiometric for ISP reasons.

It's too many moving parts. E.g. if Raptor has a 1% chance of failing in an uncontained way then that's a 30% chance of at least one catastrophic failure on superheavy (35 engines). But on ultraheavy that's a 78% chance of something going catastrophically wrong. That's not even counting additional complexity of plumbing and control systems.

18m would be just wow! But I don't think 150 raptor engines in a booster sounds plausible. They'd need something with at least F1 level thrust. Keep it to ~50 engines!

Looks like a few pieces didn't stay attached, but successful hop!

KSK was joking about the new white vertical assembly tent I believe. The starships, booster and hopper are still shiny stainless.

No, because it's a falcon NINE, and reducing engines is a complete redesign of all the thrust structures, as well as a reduction in length (because you can't lift full tanks anymore) and alteration of all ground support equipment to suit. With 9 you just have reserve capability. Which the current design does and uses when required.

Without re-use Merlins would still have high TWR. Without re-use you'd still have nine merlins on a falcon. Without re-use they'd still be reusable and restartable because that's what's required for the test regimen.