Winter Man

Yeah, remembered that after I said it. Didn't think it worth mentioning as the gist was there.

True, it is far simpler. A hybrid fusion/fission reactor might be best for this application then. Non-breakeven fusion reactor to produce a ton of neutrons (a Farnsworth or Polywell, why not) surrounded with a sub critical thorium (assuming it's all converted to U-233) shell so it can be controlled with the flick of a switch. Or turn of a dial, as it may be.

Then why not just pass xenon over a hot radioisotope? A mass issue perhaps? There's nothing wrong with launching RTGs (which are a fair deal more dangerous than NERVAs, but hippies getting in the way, etc.) so why not this?

Is it even worth developing though? With the Falcon 9-R promising to cut costs down to a fraction whilst keeping a decent safety rate, what's the point?

Was the NERVA capable of using 235 though? I thought it was just hot plutonium like an RTG.

Well, I wouldn't say 'terrorists' would be able to detect a launch, but any spacefaring nation would definitely have satellites up there spying on a weapon like that immediately.

Cartridges are airtight, and no one uses black powder any more except reenactors. From around the 1890's rifles used cordite, which was nitroglycerine, oxidiser (nitrocellulose) and stabiliser. Even that's been replaced a couple of times now too. If you didn't have oxidiser in the cartridge you get deflagration instead of detonation, leading to an incomplete burn of your propellant - the bullet gets in the way of more oxidiser coming in in the form of air down the barrel (likely leaving the bullet stuck halfway down).

Not that virtually any of the CryEngine survived through to Far Cry 2, let alone 3.

Who says there'll be a KSP2? Not everything needs a sequel.

I wouldn't be so sure. See that puff when they hit the ground? I reckon they're more like teflon bonded ceramic.

Well, Ceres accounts for a third of the asteroid belt's entire mass. So it would have been a slightly bigger dwarf planet (one still two or three orders of magnitude less massive than Pluto). Sublimation of surface ice, I'd imagine. Still, worth a look. edit: thought you meant the small amount given off by the surface at all times. The plumes are pretty cool and definitely worth a look.

Higher variance in plant and animal life, resistance to mass extinction events, that sort of thing.

While I'm all for airships, I'd say it'd be far far cheaper to just use a string of fixed ground stations with tethered balloons.

Problem is the distortion isn't actually real, just a convenient way of looking at things. Like how when we're young we're told electrons orbit an atom. The analogy completely breaks down. The two sensor readings on your ship are acceleration and distance, they combine to give you mass. The only use for such a system is identifying an unknown object, be it ship, asteroid, etc. in which case your ship will be crewed. Could make a good plot point in a sci fi, having them all have to stay completely still and silent while they were scanning, kind of like on a submarine (albeit reversed).

It might also be worth pointing out that spacetime doesn't 'displace' like a fluid. It distorts, but you can't really measure how deep a gravity well is without knowing the distance to an object as well as your 'gradient' on the curve. So it's kind of pointless to even bother describing it in such a roundabout way.

Because a planet will distort spacetime noticeably, but we're talking something 18 orders or magnitude larger than a very large spaceship (6E24 vs. around 1E6). If we had accelerometers accurate enough to detect the gravity of a spaceship even within a few kilometres, they'd be thrown off awfully by your own crew moving around your ship.

Thing is, for every ship it'd have a value of 'negligible'.

Probably not. I was using E=1/2m.v^2 and sqrt(E/0.5m)=v, assuming 4 grams at 1200m/s and a 70kg person. E=2880J, sqrt(2880/35) ~= 9m/s. Of course, that's energy not momentum isn't it. Yours is more likely right.

Buy AMD. What the above chart doesn't compare is price. You'll pay 3 times as much for an Intel processor which performs marginally better in tests.

You'd gain about 9m/s every shot fired if I did the calcs right. edit: although saying that, if they were shouldering the rifle correctly they'd be sent into a hilarious spin. Also Army isn't an acronym. /pedantry

No, not yet. Our first Martian colony will probably be built on one of its moons and continue to function in a support role after a surface base is established. That speculation being based purely on the idea that mining and refining the fuel for interplanetary transfers is best in low orbit, which the Martian moons already are.

Because we, the product of said half a billion years of evolution, improved them ourselves. Consider this: Send a robot, it can break and you've wasted an awful lot of money. Send a human and he can fix it. Sure, the human can break, but send enough humans and you've got yourself a self-repairing population that can build more of your precious probes in a lower gravity well. High initial cost, low running cost once established. Same as any high-risk startup. That would be my argument, at least.

The example I gave was more about discovery of different crystalline forms of iron which can be reproduced on Earth. just through different methods. That's generally how industrial discovery works, take a known process, change an unusual variable and see what happens. In this case that variable is gravity, something you can't decrease on Earth. New allotropes can be made in space, studied, then a process for their creation can be devised back on Earth.

I think you're underselling microgravity experiments a little. There's a lot of good come out of research in its effects on metallurgy and crystal growth, not just the human element. Spaceflight isn't just about people, remember, and that's the view a lot of governments take on it. There's far more short term economic value in your space program finding a more efficient way of say, smelting iron, than there is discovering that people get sick in conditions never to be found on Earth. edit: My point being that we'll probably have to rely on private funding for this sort of thing. Private funding by people who just think space is cool.

The Nautilus as far as I remember is primarily a Bigelow project (in terms of who it'll get contracted out to), so it'll probably get launched regardless of NASA funding - someone else'll see the potential.