sevenperforce

If the ships stay aloft on repulsorlifts rather than by being in orbit, all this makes sense. You still have gravity up there. Same with the Battle of Scarif in Rogue One. That shield gate wasn't in orbit; that shield gate was floating on repulsorlifts, and once a Star Destroyer had its own repulsorlift disabled, it crashed into the shield gate, frying its repulsors and shutting down the shield. It seems that the ships have a sort of "gravitational brake" that locks onto a gravitational gradient with only a small amount of power consumption. Ships can move freely using reaction thrusters in the plane normal to that gradient, but moving up or down in the gravitational potential field is a little trickier. On the topic of Star Wars, I wrote this article about watching the final film...let me know what you all think! https://medium.com/@davidstarlingm/the-final-order-watching-star-wars-for-the-first-time-c840eac4db52

How long do you need to maintain altitude to get your observations?

As @Treveli said, the ships in the SW canon are never in orbit. If you recall Revenge of the Sith, Anakin lands the Invisible Hand after it is disabled in space. The moment its artificial gravity goes haywire, it immediately starts dropping out of the sky. Its entry is hot, but not as hot as it would be if the ship was orbital. SW vehicles (even little speeders) have artificial gravity and can interact directly with a gravitational gradient without using propellant. They do require power, though. One can presume that there is some power interaction between shields, engines, and hyperspace drives, such that a network of ships floating around Naboo could lay down an effective field of fire that would impede any ship trying to enter. Once forced to engage, the entering ship is stalled and so the fleet can converge. Often in real naval history, a blockade is not necessarily about the physical limitations of the ships, but about making a statement. Moor a 120-gun ship-of-the-line carrying 900 crew at the entrance to a bay, and any ports in that bay are effectively shut down. Just because it's possible to sneak a longboat into the bay under cover of night doesn't mean you can maintain shipping; the point is deterrence.

We didn't hear officially but I believe Elon said it was well over.

I am sure it is not. My guess is that the spacing decreases as you go up. So the first three decouplers are between each tank, the next few between every second, the next few between every third, and so forth.

I wonder if it would be possible to have a particle beam which would produce a collimated standing-wave magnetic acceleration tube. So you could fire up the particle beam, trained on your target, and use the beam itself to accelerate an antimatter slug. The beam would also have the pleasant effect of punching an initial hole in your target so you avoid a "fizzle" caused by premature detonation of the antimatter slug.

It's not just about lower thrust and gimballing; it's about the distance between the engine bell and the regolith. In a vacuum, the dynamic pressure of the exhaust stream is going to be nearly inverse-squared. On a notional ten-meter-high lander (for reference, the Apollo Lunar Module came in just over 6 meters), side-mounting the ascent-stage engines and using them for the landing burn places the nozzle rim at least five meters above the surface. Compare to the original Apollo Descent Module, which had an engine bell which came to rest just 35 cm above the surface. Of course, the Apollo descent vehicle dropped the last 1.6 meters after engine cut-off, which would put the final plume length at 2 meters and 5.6 meters, respectively. Yet that difference -- having engines mounted five meters high vs nearly flush with the ground -- would mean that the plume from top-mounted engines would have a dynamic pressure at the surface only 13% of the plume from traditional engines. If you can use gimbal to cant them out by 20 degrees or so, the increased distance to the surface means it drops to just 11%. The downside is that you have to make sure the lower stage material doesn't get torched by sidewash from the engine plume, but that is a fairly short pole.

With all of the regolith-kicking concerns, I am growing more and more fond of lander designs which use a large, non-throttleable, high-efficiency engine for descent and use the ascent stage's engines, mounted in parallel (and perhaps gimbaled outward) for final throttled landing.

The verniers would not have stopped firing after breach. Both main engines were to be fixed, without gimbal, so differential throttling on the verniers was necessary for pitch and yaw control.

They're not rivets; they're bolts. Presumably the nut will be welded onto the skin. The bolt-holes will be filled in with plugs.

The structure can handle it with no problem, but there's a high tipover risk.

Solar flares wouldn't hurt anything. My thought, to make it work properly, would be to have the spacecraft land on a rugged platform similar to a car lift. The platform would be mounted on articulated arms that would then pull the spacecraft through the forcefield.

To get to the Jovian or Saturnian moons in a reasonable timeframe, you need to do a fast transfer, which has substantially greater dV requirements. To get the outgoing leg of a Hohmann transfer to Saturn, for example (suitable for a flyby), you need 7.3 km/s and the outgoing leg may take you as long as ten years without gravity assists. A fast transfer that gets you there in around two years will take 10-11 km/s from LEO. That extra 3-4 km/s is nothing to sneeze at. And, of course, if you make your ship massively larger in order to shave off years of travel time, that also means you reach Saturn at dramatically higher speed. You can't aerobrake safely at those kinds of speeds, even in Titan's atmosphere (Saturn and Titan's gravity will add about 8.5 km/s to your interface velocity, which is about the limits of what a heat shield can tolerate even before adding in the relative closing velocity). So the faster your transfer, the more propellant you need to bring with you for the braking burn. The only way to get that kind of propellant is to mine it out of lunar ice. Of course, departing from the moon rather than from LEO adds more dV to the exit burn. You really need lunar ISRU and either a big NTR or Z-pinch fusion if you want to get to Saturn in a reasonable time.

We'd be better off developing tech for using asteroids for solar lithopropulsion. Then you can bring the asteroids to the astronaut, rather than having to take the astronaut to the asteroid.

I'd suggest attempting a robot Venusian airship, just to see if it is feasible for humans someday. But yeah, @tater is right: with current tech, we can't really send humans beyond Mars. Even a Ceres mission would be asking a lot; there's not enough gravity to do anything and you can't aerobrake so the dv requirements for a round trip are massive. Good news is that developing tech to make Mars trips easier would be an enabler for outer solar system missions.

Yeah, this seems like the best solution. Failsafe would be sliding blast doors.

They clearly left timewarp on too long.

Hydrazine undergoes thermal decomposition at 3000 K, so you can dump in oxidizer willy-nilly to pressurize, or loop a small amount into a catalytic decomposition chamber with the same effect. This does not work so well with HTP, which undergoes thermal decomposition at 150 C.

"When you really want your payload to go to space today...even if it then f's up."

Too bad. Shocking that the mission clock is a single failure point.

Rocket planes flying inverted at orbital speeds will eventually run out of props. There's only so many moar boosters you can boost before you run out of boost.

"Crap, my lower stage is just not the right size for this upper stage. Maybe I can just carefully do a tapered fairing around the interstage...."

I don't know. It almost has a kludgey beauty to it.

The only way you'd want to do pulsed antimatter Orion would be if your containment mechanism was limited in how much antimatter it could constrain. For example, if it was impossible to contain more than about a gram of antimatter in a single container, then it wouldn't make sense to trickle-feed constant-flow antimatter engines from a bunch of tiny antimatter tanks. You're better off just chucking the entire containment mechanism out the back when it is spent. Chances are that the cost of making the antimatter will be more than the cost of making the container so you're not really losing much. Even then, I suppose it would be better (if possible) to make each antimatter unit release containment gradually so that you have more collimated thrust. It would still be a pulsed design but you would use pulsed thrust units like the black-powder BIS lunar lander, rather than pure detonations as Orion. To be fair, this is also a problem with thermonuclear Orion. Only difference is that nukes don't fail passively; antimatter containment does.

Your description is closer to a boosted fission weapon. There are really several different classifications which ought to be understood: Pure fission gun weapon. Forms a critical mass by slamming subcritical masses together. Limited to around 15-20 kilotons; uses enriched uranium; cannot be chained or nested or used as a trigger for a larger weapon. Pure fission implosion weapon. Forms a critical mass by collapsing a spherical shell. Limited to around 500 kilotons; uses plutonium. Good for triggering a larger weapon. Boosted fission implosion weapon. The addition of a tritium-deuterium gas mixture, injected into the core of an implosion weapon, induces a small fusion reaction which enhances the fission of the primary. Most of the yield comes from fission. Multistage boosted fission weapon. Alternate layers of fissile and fusile material. Up to 20% of the yield comes from fusion; the rest from fission. Size-limited to about a megaton. Thermonuclear "hydrogen" weapon. A boosted fission implosion primary is used to produce an x-ray flux that collapses a fusion secondary around a fissile sparkplug, causing the fusion fuel to ignite. With an inert tamper, up to 97% of the yield can come from fusion. Multistage thermonuclear weapon. A thermonuclear hydrogen bomb can be placed inside a depleted uranium tamper that will act as a fissile tertiary, approximately doubling the yield of the bomb. You can then use this entire package as the primary for an even larger thermonuclear weapon, if you want.