RCgothic

I went and looked it up. NRHO isn't *that* long a period, at about 6.5 days. So your nominal stay is at least that long, generally multiples thereof. Then the worst case abort is 4 days depending on orbiting element phasing. So the lander needs at least a week's endurance, or more likely 2 weeks. That's a lot more than the Apollo LM. Ref: https://engineering.purdue.edu/people/kathleen.howell.1/Publications/Conferences/2018_AAS_WhiDavBurMcCPowMcGHow.pdf

Inclination is only one part of the equation. With long-period orbits like NRHO correcting the phase angle to achieve a rendezvous without an unreasonable starting DV can then take weeks.

No, because if the distance is fixed at the same for each, then the plane is no longer making up for being more dangerous per trip by going further. As Tomf mentioned earlier, the risks of flying are concentrated around landing and take off. It's not much less risky to cut down the cruise phase, which is statistically the safest bit of the flight. And actually, short-haul aircraft are smaller, more vulnerable to sudden cross-winds and vortex interference, undergo more frequent landing, take-off, temperature and pressure cycling, and are less well maintained on average. Trains easily come out on top over short distances. Edit: Although now that I'm following that logic in the opposite direction, I suppose there might be a distance over which trains become less safe. Every section of track and every set of points crossed is a potential accident. So extending the trip linearly increases the risk of a train journey, whereas a plane is safely in cruise mode.

Trains are safer in terms of fatalities per trip. Planes are safer in fatalities per mile. The difference is that planes traverse vastly larger distances on each trip than the typical train journey. If you could make the same trip by either mode of transport, trains would be the safer option.

Pretty sure there *are* blast shields between each engine. That's what the black cylinders around each engine are.

Booster engine missed ignitions: Flight 7: Engine to the left of bottom dead centre engine in the ring of 10 on the diagram. Flight 8: 2 engines to the right of bottom dead centre engine in the ring of 10 on the diagram. Engine that didn't restart was the one immediately to the right of the bottom engine. I believe the diagrams are arranged "belly" side down. So engines at the bottom of the diagram would be earth-facing for a pitch up manoeuvre, if that's the direction it goes.

No way did an external fire burn a concentrated hole in an engine nozzle. I could see a leak from a damaged nozzle leading to entrained flames that appear like an engine bay fire as it gets worse. Two engine bell failures is surely an external cause

If Blue Origin ends up lapping SpaceX, cool. That'd be showing a bit less graditem and a bit more ferociter, and progress is progress no matter who makes it. I don't think think that's imminent though. They didn't land, let alone catch, their (smaller) booster, and the second stage they left in orbit caused a high orbit debris event shortly thereafter. At least SpaceX is working out their issues before contributing to Kessler. That said, V2's record is now 0/2 and Booster again didn't light engines for Boostback, one of which stayed off this time, so there clearly are problems that need to be worked out. I remain sceptical the problems are localised to the engines, I think it's more likely to be overall system integration and flight dynamics being uncooperative. That RVac could be solely at fault this time, definitely. It just strikes me as a little weird it looks like a bell extension failure. Bell extensions aren't exactly novel and SpaceX have heaps of experience with them. There must have been some sort of impact event. I think the booster engine-outs were on the same side as last time, so those might have been rotation related maybe? Impressive it made it back to a successful catch with multiple missed engine ignitions.

This does look like the clearest candidate yet for an actual engine failure, but it could still not be the engine's fault if there's an external reason for the hole in the bell. Didn't they say the other day something had collided with one of the mate guide cones on the hot staging ring to dislodge it? It'd be pretty stupid if the collision had been with an RVac engine bell and they flew it anyway.

What's the wind limit for Falcon 9? Starship should eventually be able to do better due to increased mass and reduced fineness ratio. Not to say they'll push it during testing.

I'm still not clear how you manage to take shuttle heritage parts and produce a launcher that's 8x more expensive and can fly 1/6th as often. Literally just omitting the wings, cockpit and heatshield from an orbiter would have resulted in more payload to LEO annually than SLS will ever manage by a long, long distance. It wouldn't have been hard to convert that into more mass to LLO with EOR.

An interesting concept. Does it depend on water penetration for effectiveness? Fairly trivial to make IP67 drones. If it's more like making a conduction path for a bolt of lightning, yeah that becomes a case of thermal and electrical shielding, which is difficult to incorporate on a light drone. I imagine you'd also have to be careful about collateral damage to neighbouring properties and rights of way. A lighting bolt presumably has to arc from the device, through the target, then to ground. If the ground is your neighbour's car they're going to be annoyed. I would have thought the range would be fairly limited as well. It takes a lot of power to project water particularly far. And if you've got a water cannon that can shoot a substantial distance then, well, you've got a water cannon. It's difficult for drones to both resist incoming impacts and fly in water. Also, does it work in the rain? Indoor defenses may need to consider alternatives to water for fire suppression as well

I was in the UK too, but I'd just turned 4. I remember it being on the TV and my parents watching. Didn't understand the significance at the time. It's one of my earlier memories though. I remember the first episode of Star Trek TNG airing in the UK as well, and was about to say that was an earlier memory. I had assumed that was in '87, but having checked just now actually it didn't get to the UK on BBC2 until 1990.

If the soviet space budget hadn't collapsed, Energia would have had a lot of missions I'm sure. The problem(s) with SLS is it's too expensive for any commercial interest, and would shake to bits any scientific payload. ICPS severely limits it's LEO payload due to low TWR. EUS is never coming now. Is crew really its only possible payload? Genuinely struggling to think of an effective use for the built hardware. Is it bulk to fame (notoriety?) / accomplishments ratio even worthwhile for museums to display? No idea how a design process produces a rocket that's only use is to send crew capsules not quite far enough BLEO for far far too many dollars a pop.

Propellant feed lines modified. And as I recall V2 starship had different propellant lines to V1. It also sounds like it took concerted effort to recreate the conditions on the ground - i.e. they needed to know what to look for in order to be able to recreate it. They could have tested indefinitely on the ground and not found this fault mode without experiencing the fault in flight first.