RCgothic

It's official!

And this is how you win a major contract:

Sad Vulcan New Glenn and SLS noises.

Ninja'd by seconds. If they choose only SpaceX I expect it will be primarily because SpaceX bid such a low price and the funding for the project has not been forthcoming. I wonder whether the announcement late on Friday is to let the rage to die down over the weekend. It'd be a hugely unpopular decision, but NASA really given no choice if serious about getting to the moon on current funding. The angry congresspeople will only have themselves to blame.

Fingers crossed for Dynetics and SpaceX!

Will consume power and the fused product would be so large and unstable you'd likely get all the power back instantaneously in some other form along with a shower of decay products.

CNBC has interviewed 50 Starlink beta users about their experiences and have found the early response to be overwhelmingly positive. https://www.cnbc.com/2021/04/15/spacexs-starlink-early-users-review-service-internet-speed-price.htm

Back of an envelope calc suggests that's between 130kg and 1000kg extra LOX depending on whether it's extra inches in the cylindrical part of the tank or right at the top of the dome. On the second stage that would be a 1 to 1 payload increase. Even an extra 200kg is significant. On the first stage that's interesting but not really a huge deal. If the same procedure is used on both tanks it could be an error for both.

I never find April fools very funny tbh, especially not half a month late. Didn't take me very long to find no evidence of the above, but have to filter out enough fake news without also having to contend with it from trusted sources. SN15 is fine.

I suppose this is a way to prevent Artemis III being delayed (more) in the absence of an operational HLS. But it is a delay to the landing.

Iron is the most energetically stable element. To fuse anything to a heavier weight than Iron takes energy rather than releases it. All the elements heavier than Iron were created in Supernovae where fusion of comparatively vast quantities of light elements powered fusion of comparatively tiny traces of heavy elements as byproducts. Dirt is mostly oxygen, silicon and aluminium though. These are all lighter than Iron, so you could perhaps expect to get some power out of fusing dirt. But you wouldn't get any power from, e.g. gold. As alchemy though, transmuting one element into another, sure, go nuts. A civ capable of atomic manipulation and at-will fission/fusion could change anything into anything else. Justkeep in mind transformations towards Iron release power and away from Iron consume power. Vast vast quantities of power.

I assume it will slip a couple weeks, but still a pretty good turn around. I wonder what the FAA has to say about the SN11 Investigation.

Nice. Round up of a few tweets.

It's easy for shorter rockets to look quick. The same speed is more body-lengths which is how we tend to judge speediness.

I did comment that the mystery frame looked like tension members. That's making more and more sense the more of it they build.

I'm having an off day. Think I misplaced a kg for g somewhere, and 1k cm2 to a m2 instead of 10k cm2. Thanks for the corrections. Think a 1cm/s kick would be more noticeable rather than seriously injurious.

Nice to see Falcon Heavy getting more missions. I think we're overdue a few.

The swept distance over a microsecond at 30km/s is 3cm. The average human is ~500cm² frontal area so you'd sweep out 1.5 litres of stellar corona. As a diffuse plasma it would reasonably be expected to penetrate skin rather than be deflected. The density of the Corona at the edge of the photosphere is ~0.0000002g/cm3. The 1.5 litres contain 0.3g of stellar material, 9kgm/s of momentum, 135kJ of kinetic energy, and approximately 15kJ of thermal energy. This would all be transferred to the unfortunate traveller in addition to the radiative effects other people have outlined. A human is about 20cm thick and weighs 60kg, so the wind-facing 3cm would account for about 9kg. Those 9kg would be kicked backwards at 1m/s and heated by ~4 Kelvin near-instantaneously. It wouldn't be a fun kind of 1m/s either. More like hitting a less-friendly concrete wall. Could come with severe deceleration injuries.

Superheavy grid fin spotted.

Sure, but in this instance I was speaking purely in terms of propellant delivery to LEO. In every case a means of transferring propellant would be required, but that's a necessary technology for getting to Mars. Full drop tanks would be harder. It'd be easier structurally to put up the tanks as payload and then transfer the residuals from the upper stage.

The vast majority of what will be required for a Mars mission is fuel, so residual props isn't necessarily the wrong way to go. So long as the booster can put up a lot of them on a reasonable timescale for a reasonable cost. That's not SLS by any measure. It might be FH, or Vulcan, or New Glenn though. Even if Starship never works reusably as intended, there's no serious reason not to think it'll be an enormously cheap way of putting up a lot of propellant cheaply and often.

I made no assertion about Falcon Heavy at all in the section you responded to. I said "Some other Booster". It may indeed be the case that Falcon Heavy can't lift more payload to LEO than Falcon 9. That doesn't change the fact that SLS is never assembling a Mars mission. A reasonably worthwhile Mars mission will take over a thousand tons to LEO. SLS can't do that on any reasonable cost or timescale. If no other booster exists that can do that then we're not going until one does.

Yes, that's the thing that annoys me most. Not that it's a badly designed architecture that can't accomplish any mission by itself, but that it shouldn't be as expensive as it is and it could be flying over four times as often for the same money. The opportunity cost is staggering. If any part of SLS/Orion goes to Mars it'll only be because the vast majority of the work was done by some other boosters. It's completely incapable of constructing any practical mothership in either LEO or at Gateway at any reasonable cost or timescale. "SLS /Orion is how we get to Mars" is one of those statements I classify as *lies to investors*. In which case it'd be somewhat competitive to Falcon Heavy, we could build five times as many for the same price, four cargos for every crewed, and the extra launches would cover Orion's weak points. That'd be the kind of SLS I could get along with. Well they have to pretend Gateway is useful for something. Even with full ISRU I'm not convinced fuelling a Mars mission at Gateway (LLO would be better) is worth it compared to assembling in LEO.

SLS / Orion are the least essential bits of Artemis, tbh. Take away the commercial support of Falcon Heavy, Vulcan, Starship or HLS, and people don't walk on the moon period. Take away SLS/Orion and we can still make something work by Earth Orbit Rendezvous, probably for a good deal less money.