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Comment Re:Sad but... (Score 1) 130

Unless they're really big (Chelyabinsk, Tunguska, Barringer Crater, etc) meteorites don't explode, they're slowed down to whatever their terminal velocity is by the atmosphere (and burned up to some degree in the process).

Assume this thing was the size of a large brick (give or take), it'd hit with about the same force as if it were tossed out of an aeroplane. It's still going to kill you, but you won't explode.

Every film or TV depiction of a meteorite impact I've ever seen (Deep Impact, Smallville, etc) gets it wrong.

Comment Skynet (Score 4, Funny) 513

When Skynet goes sentient and the machines rise against us, it will be because of idiots putting in programming like this.

It's a machine. If it doesn't do what I tell it (within its design parameters), it's broken.

Now, people who want to "sexually harass" a machine have their own set of issues, but as long as they keep it off the streets and don't scare the horses, that's their problem.

Comment Re:Mars Colonial Transporter (Score 2) 101

Meh. CH4, H2 and RP1 are all clean, cheap fuels - the levels of pollution and fuel costs are practically non-issues here. ISP, thrust and density are what matter. Methane simply lies on the curve between RP-1 and H2 in terms of thrust, density and ISP.

Mostly right. Two out of three for clean: RP-1 has a tendency to coke up and can foul injectors or lead to hot-spots in the cooling tubes if you're re-using the engines. (Merlin's pintle injectors are probably not as prone to coke fouling, and all of this is going to depend on dozens of specific design decisions in the engine.) (The cleanliness of the exhaust is, as you also implied, irrelevant. Expecially compared to storable and/or hypergolic fuels.)

Isp is what matters above a certain altitude, below that what matters it thrust. All the Isp in the world won't help you get off the ground if your thrust to weight ratio is less than one. We've tested nuclear rockets with Isps in the 900s (three times better than LOX-H2) but they were too heavy to get off the ground. (Ion engines have the same problem in spades, but we're not talking about those.) Methane (and RP-1) will give you higher thrust than a comparable LH2 engine. Again, there are tradeoffs -- you could run LH2/LO2 engines O2-rich for higher thrust during part of the launch (although superheated O2 isn't the most benign environment for your pad, or the engine nozzles.)

Glad you brought up density. Many people forget about how this affects rocket performance. For any given mass of fuel (or oxidizer), the denser it is the smaller you can make the fuel tanks. The smaller the tanks, the less dead-weight you're lifting. I believe the latest Falcon-9 super-cools the LOX (making it denser) to take advantage of this. Methane also allows for considerably smaller tanks than LH2, making up some of the Isp disadvantage (the reduced insulation needs and simplified handling also help). (Some of Gary Hudson's old Phoenix SSTO proposals considered using densified (slush) hydrogen to get tankage weight down, but we still have hardly any experience with that stuff, and it's still barely 1/5 density of LCH4).

Comment Altitude only first (Score 4, Informative) 132

The "first" here is that New Shepard made it to the altitude arbitrarily defined as "space". The first launch and landing of a VTOL rocket that had previously flown was back in September of 1993 with DC-X's second flight (first was 8/18/93). Sure, it only went up a few hundred feet ... then stopped dead, hovered, translated sideways another couple of hundred feet, then landed. (I was present for that one. Frickin' awesome!) It flew yet again less than three weeks later.

On June 7 and 8 of 1996, it flew twice within 26 hours. That second flight reached an altitude of 10,300 feet (its record). Nowhere near space, but the DC-X program was more about the control software and reusability than going for altitude (it was a one-third scale prototype of the proposed Delta Clipper). And they were doing it with what is now over twenty year old technology. (Actually older, the thrusters were modified RL-10s from the 60s, much of the flight control avionics was off-the-shelf units that McDonnell-Douglas used in its jet aircraft.)

So, kudos to Blue Origin for reaching the edge of space with a previously-used rocket (something nobody else has done with the arguable exception of Shuttle, which was really never the same twice). But let's put the "first" emphasis where it belongs. (And it is significant -- it doesn't really matter how many times you can re-use a rocket if it won't get you to space in the first place.)

Comment Re:Time Warp (Score 1) 91

Yeah, Sherline, for one, has been making desktop CNC mills and lathes for years, and they even sell them together with a computer. Prices in the $2k to $3k range.

I have no idea of the quality, since I don't (yet) own one, but they look pretty good from my research over the last couple of years.

This is a wild guess on my part, but I think the popularity of 3D printers helped bring down the prices on reasonably sized stepper motors, as well as the cost of the electronics and software.

Comment Re:Not used much anymore (Score 2) 132

You're supposed to use your E6-B before you get in the cockpit, so GPS and VOR won't be much help.

Remember "plan your flight, fly your plan?"

I did a long cross-country flight (Waterloo-Denver and back, with fuel and customs stops each way) solo, in a Cessna 172-RG, with almost nothing but E6-B and paper maps (pre GPS). I did have dual VORs and RDF, but for fun I mostly tracked straightline (rather than VOR to VOR) using the angles to two different VORs to get my position. (Well, that and looking out the windows.)

Neither a VOR nor a GPS will figure your crab angle for you, you have to know the wind speed and direction.

Comment Re:So?! (Score 1) 344

Well said, however, I disagree regarding cold fusion in particular. It should be shunned because it flies in the face of physical laws.

Proved these physical laws beyond a shadow of a doubt, have you? Then why is there still so much of phsysics, cosmology, etc still unexplained? Why bother with the LHC or anything else, let's just shut it all down. Ramze apparently knows all the physical laws already.

They said the same about radiation back when the Curies first demonstrated that radium was generating excess heat just sitting there apparently, by known physical laws, doing nothing.

You're assuming a mechanism and poo-pooing the observations because your mechanism wouldn't allow them. Fine, the excess heat produced by "cold fusion" is not produced by nuclear reactions as high-energy physicists understand them. So, where is it coming from?

Throwing deutrons at each other at high speed to overcome the Coulomb barrier is one approach. Having them sit quietly next to each other within a cell of, say, a palladium crystal lattice so that, eventually, they'll quantum tunnel is another. (I have no idea if that's the actual mechanism, but it fits many of the observations.)

It may well turn out that "cold fusion" isn't a particularly useful method of generating energy (just like, so far, hot fusion). Muon-catalyzed fusion is a recognized form of cold fusion, it's just that the muons don't last long enough to make it worth while. But the effect (if real) may turn out to have other uses.

Comment Re: All about sequels (Score 1) 105

Tom Baker was Dr Who just a few months back. Well, all right, they never came out and said he was the Doctor, just strongly implied it.

But it wouldn't surprise me if the BBC were early adopters of the technology. Loved the scene where Clara Oswald directs the first doctor (William Hartnell) to choose the other Tardis, with the busted chameleon circuit.

A good actor can play another actor playing a role. Dr. Who has done this a few times. In the early scenes of The Man From UNCLE movie, Henry Cavill did a great job of channelling Robert Vaughn playing Napoleon Solo. But I'm glad they didn't put Vaughn's face on him, or try to hew too closely to the original actors' characters.

Comment Re:This'll be lost on new people. (Score 1) 169

They will think it is a spinoff of Lost. In space.

Oh man, that would (well could) be awesome!

A commercial spaceliner crashes somewhere. There's a radio broadcasting a mysterious repeating sequence of numbers, and a hatch leading to a Cold War era lunar base. And what the hell is a polar bear doing on the Moon?

Hmm, on second thoughts, maybe not.

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