Kryten

They also did initial testing of the LM itself completely uncrewed (Apollo 5), including propulsive tests roughly equivalent to landing and return.

They've done some preliminary observations, but the proper science campaign won't start until next month, so yeah, this is probably just analysis of previous data.

They've rigged together a system to use light pressure to keep it in a stable configuration; the target areas available are limited, and they have to reposition every few months to avoid pointing directly at the sun, but it's a lot better than nothing.

Why would you have to stop it? Yes, it would do major damage, but the idea that one could outright wipe out human civilisation-especially a human civilisation with the kind of technology necessary for off-world colonisation-is ridiculous. Then it's a good thing we're not in the asteroid belt, isn't it? The largest asteroid that actually crosses earth orbit (i.e. could be relevant to this discussion) is about 30km across at it's longest axis, and there's very little chance of any similar asteroids not having already been found and catalogued.

What effect would a plausibly-sized asteroid be expected to actually have that would be any harder to deal with than Veusian or Martian conditions? People being unable to cope with, say, impact winter but being able to survive just fine in permanent gloom dozens of kilometresabove any surface in a toxic atmosphere (as in your own Venus proposal) simply isn't a credible scenario.

This doesn't make a lot of sense. If you can make Mars or (especially) Venus habitable, then you can keep the earth habitable pretty much regardless of what happens to it. There's no plausible scenario short of the sun going red giant that could make earth less hospitable than Venus is now.

True, if you assume that the position of every single atom in the brain needs to be simulated to have a working model of the brain. Given how much change the brain can undergo (chemically and physically) and still remain generally functional, this isn't a very credible assumption.

No crewed flight took place because the L1 system itself never reached the required level of reliability, your supposed 'man-rating' equipment or infrastructure or whatever you think it is would still have to be present. It's far from the only factor, but with modern boosters it is effectively the only factor that matters. Just take a look here if you don't want to believe that. Note that 'Atlas V can accommodate commercial human spaceflight with no changes to the existing vehicles', and that the only changes necessary would be to the pad and range infrastructure. And, of course, you might also want to note that NASA is already paying ULA to make these changes, and the total cost so far has been about $8 million, which is in fact negligible (less than a tenth of the cost of an actual Atlas launch). You mean like they are? See above.

His own money in SpaceX ran out sometime around the last couple of Falcon 1 flights. He's getting by on NASA funding, and commercial launch contracts being made in advance.

Two issues; a) You're wrong, Proton was built from the ground up as a crewed launcher for the L1 program. You're wrong, the cost of 'man-rating' is going to be irrelevant, given a rocket of this size is going to require very high reliability, crewed or not, because of the immense financial risk involved with the gigantic institutional payloads. Anyway, you missed the entire point of my post, which was comparing amortised and non-amortised costs. An individual Saturn V, including launch, was about $1 billion in modern money, compared to about $100 million for Proton-Proton still wins in terms of $/kg, but not by a huge margin, and it's easy to see how improvements to Saturn could have beaten it. However, if you include the total program costs, that Saturn-V jumps to a ridiculous $4 billion, whereas Proton stays almost exactly the same. Why? Because Proton has flown almost thirty times as much.

It wouldn't be cheaper, thanks to your massive booster having no way to amortise costs; look at the $/kg to LEO of Saturn V compared to Proton.

That wouldn't really work, as a very large proportion of the casualties I'm talking about didn't involve flights at all. For example, one incident involved a Titan II missile exploding in it's silo during maintenance work. The accident is clearly attributable to the propulsion system (a leak of fuel ignited), but if it hadn't happened the rocket would have just sat in the silo until it was scrapped.

Sabre also requires liquid hydrogen, which isn't exactly practical for use in storable munitions, whereas many ramjets don't even use liquid fuel.

Could you please go and yammer on about your Orion obsession elsewhere? We don't need yet another thread derailed, particularly one in which it's completely irrelevant.

This, especially given just how close Skylab came to being a complete failure. It shows a major issue with the idea of building large boosters for space exploration; there's no other reasonable payload except stuff like monolithic space stations, so any failure is going to destroy something extremely expensive, and there's much less opportunity for reduction of both cost and risk.

Why not? There's no real reason to believe solids are, done properly, are any less safe than liquid stages. Far more people have been killed by incidents with liquid stages than solid ones.

The program's intended to demonstrate ALHAT guidance, but after what happened to the Alpha vehicle they're making sure the rest of the systems work properly first. They've completed basic vehicle tests and now have the ALHAT system integrated, but it's not planned to be used to actually guide the vehicle with until the flight after the next.

How are those any different? How is something supposed to be 'sent back in the same general direction' without changing direction?

Not even that, apogee about 40km.

Where do you get this stuff? It didn't even have a functioning upperstage, or indeed any other part intended to be in the actual Ares-1; it was a shuttle SRB, Atlas-V avionics, and lots of sheet metal.

'Maybe that means they'll start something they can actually afford to finish.'

Is impossible. You can optimise for one or the other, not both. Those words mean the same thing.

That's petrochemical smog; it's made up of small solid particles, it's not relevant to discussion of distribution of gases.

Yeah, I'm sure they all really appreciated that. Just look how far the Tasmanians have come theses days.

Note the phrase 'rocket of a larger size'- I meant in terms of increased capability, rather than simply new rocket models. For example, both Saturn models both resulted in significant increases in lift capability, whereas the EELVs didn't (except Delta-IVH, but that was designed around launching KH-11 derivatives).