sevenperforce

And now throttle-down on the core. Good calls.

All four RS-25 engines remain at max thrust.

Me included.

GAWDAMMIT WE'RE OFF Hot DARMMMM that sucker LEFT the pad fast. BOOSTER JETTISON YESSSSSS

COME ON LIGHT THIS DAMN CANDLE ALREADY COUNTDOWN AT 10 MINUTES AND COUNTING

"No constraints to launch" okay can you give us a T+ number then??

I'm just saying, I'm sure that was already planned out aggressively. It's a two-hour window. I'm sure there were 7,200 different subroutines all calculated and classified in advance for each possible second of launch.

Unrelated: the TV stream is horrifyingly annoying. Almost because I know why it has to be so droll.

I'm confident that there's a ginormous well-programmed system that specifically plans out every maneuver and burn and correction based on any possible t0.

Volatiles Investigating Polar Exploration Rover, or VIPER. . . . Their acronyms are getting out of hand.

The four engines on SLS weigh six times as much as the two engines on Vulcan. You’re gonna need a gigantic heli. Bigger than the largest heavy-lift Sikorsky helicopter in existence.

You could commission diving teams to go and dredge up the remains of the SRBs from the Atlantic Ocean and dredge up the remains of the core from the Indian Ocean and melt down all the tangled fragments and use a refinery to separate the raw metals and re-forge them into parts of a new rocket, sure. Recovery and reconstruction of the SRBs isn’t THAT hard. They did that with the Space Shuttle program, after all. But you aren’t really reusing the same SRBs. You’re recovering the smouldering metal cylinders and then cutting them apart and cleaning them and filling the rings up with new propellant and putting them back together, usually in a different order. The cost of recovery is higher than the cost of just sourcing new metal. The core is traveling MUCH too fast to recover. It’s technically in orbit. It would need something like SMART reuse with a separate expandable heat shield and mid-air recovery, or something. And the engines on SLS are almost certainly too heavy for mid-air recovery.

Your proposal that gravity could potentially be the result of 4-space acceleration has a chance of being not only useful for understanding, but actually true. However, the comparison with the common analogy of metric expansion as the expansion of a 4D hypersphere is limited, because that is only useful for understanding and is not actually representative of reality as we know it. Your conjecture may be correct. Maybe there really is an acceleration in 4-space causing the spacetime curvature we observe in 3-space. But even if that’s correct, that would be a separate acceleration/expansion/etc. than the metric expansion of the universe caused by dark energy.

I am quite certain that the plan has been once-around without an orbit for quite some time now.

This is pessimistic. He is incorrect, incidentally. SLS has abort-to-orbit capability in the event of premature shutdown at almost every envelope of flight. But pessimism is always the best approach, especially as a public figure. If you're wrong, everyone's happy and no one cares. If you're right, you're a prophet.

It's a crewed landing. Artemis I is tonight (we hope). Uncrewed SLS Block 1 all-up test. Artemis II is the first crewed flight of SLS. Lunar free-return. Artemis III is the first crewed lunar landing of the program. Orion and Starship HLS will meet up free-flying in cislunar space for the transfers. Artemis IV is the first crewed visit to Gateway. This announcement adds a crewed landing to Artemis IV and says it will happen via Starship HLS through the Gateway.

You would have been really confused if I had gone with my first draft, which called them “STS” and “SLS”.

Over/under on tonight's launch attempt?

As requested: Also I updated the last one:

Oh, shoot, Excel stacked min on top of max rather than showing them on the same scale. My bad. That's corrected.

Here's a comparison for 14 and 33 Raptor 2s at minimum thrust and at full thrust.

Yikes. Source? So, two more static fires, removal from the launch mount to make minor repairs and updates, three more static fires, some on-pad work, another static fire, and then orbital launch attempt.

So much sheer kablooey If those 14 engines are at full throttle, that's about 50% more thrust than Falcon Heavy and almost as much thrust (though not quite) as SLS block 1.

It certainly cannot be an expression of expansion within 3-space, which is why the ongoing and observable metric expansion of the universe is not the source of gravity. I could be wrong, but I don't believe they are in fact functionally distinct. They are the same. Special relativity says that it is 100% impossible to tell the difference between acceleration resulting from an external force and acceleration resulting from a gravitational field. Now, a gravitational field will have tidal effects, which may be detected in some other way, but that raises issue of measuring the distances, which themselves are subject to the gravitational field, so special relativity holds. You're correct that if 3-space was uniformly expanding at a certain rate (it's not uniform, even under metric expansion, until you get to intergalactic distances), then you wouldn't experience any acceleration. However, I don't believe that's quite what the OP is suggesting. What OP is suggesting, as I understand it, is that there is a fourth spatial dimension which is undergoing some sort of acceleration, and it is the acceleration in that fourth spatial dimension which causes the stress-energy-momentum tensor to behave the way that Einstein's field equations say it behaves.

Metric expansion can be conceptualized by imagining 1-space expanding around a 2D circle or 2-space expanding around a 3D sphere or 3-space expanding around a 4D hypersphere, but that doesn't mean the 4D hypersphere is the actual shape of the universe. It's just a concept to understand metric expansion without resorting to infinities. I don't see any reason why gravity couldn't be the result of an acceleration in 4-space, but that acceleration, if it exists, is distinct from the metric expansion of the universe.