Forgot your password?
typodupeerror

Comment: Re: Nuclear Power has Dangers (Score 1) 445

by jd (#48428343) Attached to: What Would Have Happened If Philae Were Nuclear Powered?

They're probably no different from regular battery terminals. Minor metallic taste, nothing special. The taste when wire-cutting with your front teeth is more interesting as you get the plastic overtones. Sniffing molten leaded solder (produces a thick smoke) is also fun. Reminds me a bit of slightly burned cinnamon toast.

I'm not normal, am I?

Comment: Americium is preferred to Plutonium (Score 1) 445

by jd (#48428235) Attached to: What Would Have Happened If Philae Were Nuclear Powered?

It's cheaper, the shielding is lighter, gives about the same results, and the press doesn't hate it so much.

However, it doesn't much matter which you'd use, you'd get superior results. Provided things didn't break in the bounce. That was a particularly nasty prang. The yellow flags are out for sure. I wonder if Murray Walker had predicted it would go smoothly.

The way I would have done it would be to have a radioisotope battery that could run the computers and heaters (if any) but not the instruments or radio. Those should be on a separate power system, running off the battery, although I see no reason why the computer couldn't have an idle mode which consumed minimal power specifically to top off the battery.

The reason? The instruments take a lot of power over a relatively short timeframe. Same with the transmitter. That's a very different characteristic from the computers, which probably have a very flat profile. No significant change in power at different times. The computers can also be digesting data between science runs.

Well, that's one reason. The other is you don't want single points of failure. If one power system barfs, say due to a kilometre-long vault and crunch, the other has to be sufficiently useful to get work done. The problem is weight constraints. It's hard to build gas jets that can steer a fridge-freezer through space, but much harder if there's a kitchen sink bolted on. That means less-than-ideal for both power sources, which means if both function properly, you want to match power draw profiles to power deliverable. That reduces sensitivity to demand, which means you can remove a lot of protection needed for mismatched systems.

What we really need is a collaboration with ESA and NASA to produce an "educational game" where you design a probe and lander (ignoring the initial rocket stage) by plugging components into a frame, then dropping the lander on a comet or asteroid with typical (ie: high) component failure rates. Then instead of abstract discussions, we can get an approximation to "build it and see", which is the correct way to engineer.

Comment: Re: Moat? Electric fence? (Score 1) 206

by jd (#48426769) Attached to: Congress Suggests Moat, Eletronic Fence To Protect White House

That's the problem. One or two civilized actions and people will start expecting it. Before long, the country will be peaceful and almost murder free. It is absolutely essential, to maintain current levels of paranoia, schizophrenia and xenophobia, to eliminate all vestiges of ethics and morality.

Comment: Seems obvious to me. (Score 1) 206

by jd (#48426675) Attached to: Congress Suggests Moat, Eletronic Fence To Protect White House

The Knights Hospitalers (I think, could have been Templars) had a fortress that was never conquered. Attackers would be bottlenecked, relative to defenders, were forever being harassed on the flanks and faced numerous blind corners.

Simply build a reproduction of this fortress around the White House. They can build a moat around it, if they like. Ringed by an electric fence. Oh, the moat needs sharks with lasers. Any suggestion for shark species?

The great thing about this is that the White House can remain a tourist attraction. Everyone loves castles, and taking blindfolded and handcuffed tourists through the maze of twisty little passages (all alike) would surely be a massive draw. BDSM is big business these days.

Comment: Re:Opinion On Basic Income (Score 1) 108

by ranton (#48425687) Attached to: Interviews: Ask Malcolm Gladwell a Question

1) It was also the result of the government funding a massive push to educate the workforce in the post-secondary education system. If you look at 1910, which was an era where big business was running things, 2.7% of the population was college educated. By 1990 it was almost double that.

The notion that industrious people created the middle class is laughable. It was clearly a partnership between the public sector which educated the workforce and the private sector that took this new workforce and created a booming economy.

2) You seem to have some belief that the ruling class is different than the industrious people you keep mentioning. Politicians and business owners make up the ruling class.

3) Yes, government regulations clearly have their costs. There is no such thing as a system with no drawbacks. But any system without regulations is going to turn into an oligarchy in short order.

4) No, we trade liberty for comfort all the time, and it is a good thing. Absolute statements are almost always ridiculous. We trade some liberties to create functioning societies because those societies give us more benefits than the few liberties we gave up.

5) If you think work is not a burden you must never have done back breaking labor. Some work is most definitely a burden.

Comment: Re:Eh arent they trying? (Score 2) 56

by ranton (#48425451) Attached to: US Intelligence Unit Launches $50k Speech Recognition Competition

All the speech recognition software I've used has relied on a controlled environment (e.g. yelling directly into your phone with almost no reverberation, no competing conversations, very little background noise).

...

Modelling all the other kinds of background noise is much, much harder.

I agree, but the issue is this problem is harder than those that industry leaders are putting billions of dollars of R&D money into. What is $50k really going to accomplish? There are Kaggle competitions that pay out more than that for far more trivial problems (like a marginal increase in CTR prediction).

Comment: Re:I'm quite surprised it wasn't (Score 1) 445

by Rei (#48425447) Attached to: What Would Have Happened If Philae Were Nuclear Powered?

And a lot better than Huygens, who they weren't even trying to keep alive at all and whose mission wasn't even designed suchly that Cassini could stay in touch with it until its batteries died.

The results of this mission have been invaluable in learning more about the challenges of landing on a low-gravity body. I look forward to whatever mission turns out to be the next followup that learns from all of the lessons of this mission. :) Maybe some sort of "hopper" probe that can sample all over an asteroid or comet by deliberately bouncing around?

Though to be honest, what I look forward to more than anything is the next dedicated Titan mission.. whether it's a hydrogen blimp, hot air balloon, helicopter, fixed-wing aircraft, tilt-wing aircraft, or whatnot, it's going to be bloody amazing. My favorite approach is that of a tilt-wing aircraft, which gains the high-speed / long range capability of an airplane, but can easily land and do surfacescience while its batteries are RTG-charged for the next flight. Even a sample return stage is a possibility, although difficult... an aerial vehicle can get extremely high in the atmosphere and the gravity's not very intense, so the escape stage requirements should be manageable, and then the escape capsule can use reverse gravitational slingshots and aerocapture to get samples back to earth with minimal additional delta-V. Can you imagine that - samples of the shoreline of an organic sea or cryovolcano from Titan, back on earth? Regardless of what sort of mission profile it has, though, the next Titan mission will have to be nuclear powered.

Comment: Re:I'm quite surprised it wasn't (Score 5, Informative) 445

by Rei (#48424593) Attached to: What Would Have Happened If Philae Were Nuclear Powered?

The entire system is designed to operate in peak loads much of the time with long idle periods between, you can't downsize the battery that much.

And RTGs are heavy compared to their output in the inner solar system. A SNAP-19 fits the generation bill (30 watts at beginning of life) but that's 12 kilograms, which is almost certainly heavier than the solar panels.

But the real reasion is, what others have mentioned, cost. And no, it's not a case of "the cost part itself is largely due to politics", it's that plutonium-238 is simply expensive, period. You're talking a product only produced in a few parts of the world from a raw material (neptunium-237) that's only extracted in a few parts of the world in very small quantities from a raw material (nuclear fuel rods) that's already very expensive and difficult to transport. The neptunium takes years to accumulate in its reactor and must be handled with extreme safety protocols during the extraction, and properly secured against misuse. It then must be irradiated for long periods of time, converting it one atomic collision at a time to plutonium 238 using a tremendous amount of energy. Only then can the plutonium be extracted - and once again, you're talking the need for extreme safety protocols during the process, and proper security. None of that is "politics", it's simply the way it is plus very rational handling procedures.

Power

What Would Have Happened If Philae Were Nuclear Powered? 445

Posted by samzenpus
from the still-going dept.
StartsWithABang writes After successfully landing on a comet with all 10 instruments intact, but failing to deploy its thrusters and harpoons to anchor onto the surface, Philae bounced, coming to rest in an area with woefully insufficient sunlight to keep it alive. After exhausting its primary battery, it went into hibernation, most likely never to wake again. We'll always be left to wonder what might have been if it had functioned optimally, and given us years of data rather than just 60 hours worth. The thing is, it wouldn't have needed to function optimally to give us years of data, if only it were better designed in one particular aspect: powered by Plutonium-238 instead of by solar panels.

Somebody ought to cross ball point pens with coat hangers so that the pens will multiply instead of disappear.

Working...