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What Would Have Happened If Philae Were Nuclear Powered?

robbak With a RTG, it couldn't have got to the comet. (519 comments)

It's a question of weight. No matter how you build them, nuclear Radioisotope Thermal Generators are heavy. This mission was heavily mass-constrained. What they wanted it to do was at the limit of what the rockets were capable of.

Add a several-hundred-kilogram RTG to to mix, and the 'rocket equation' kills you. You just cannot get the probe to the comet. Solar panels were the only option.

about a week ago
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New GCHQ Chief Says Social Media Aids Terrorists

robbak Of course it is. (228 comments)

The largest means of support for terrorist groups is the U.S. Dollar. Perhaps we should get rid of that, too.

about three weeks ago
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Ask Slashdot: Can You Say Something Nice About Systemd?

robbak On a related matter: (928 comments)

With more people jumping to FreeBSD, we might get better hardware support over here.

about a month ago
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To Really Cut Emissions, We Need Electric Buses, Not Just Electric Cars

robbak Re:What makes you think it was environmentalists? (491 comments)

What, coal money bankrolled the 'green' message that demonised nuclear? Well, today's bankrolling of the anti-green message preventing action against climate change certainly backs up your point, I'll give you that.

Of course, the worst thing to ever happen for nuclear *power* happened over Nagasaki and Hiroshima.

about 3 months ago
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To Really Cut Emissions, We Need Electric Buses, Not Just Electric Cars

robbak Well, we really should be at that stage by now. (491 comments)

We should have been working hard at improving nuclear power, and solving its problems, to the point that this would, by now, be a no-brainer. So those polluting diesels are another thing we can blame on the environmentalists that shut down nuclear power research in the '70s.

about 3 months ago
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Dirty Diapers Used To Grow Mushrooms

robbak Re:Might want to rewrite that summary (97 comments)

Well, the sentence parses nice and cleanly. It states that "the average baby will (...) end up in landfill..."

The sentence is plain wrong - what its author wrote differs from what he intended.

about 3 months ago
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Anomaly Triggers Self-Destruct For SpaceX Falcon 9 Test Flight

robbak That's sort of what I thought, too... (113 comments)

But he may have been just making a joke, so I gave him the benefit of the doubt.

about 3 months ago
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Anomaly Triggers Self-Destruct For SpaceX Falcon 9 Test Flight

robbak Re:what does auto-termination mean? (113 comments)

That's pretty much it. The on-board computers detected that the rockets attitude or location was out of limits, so it triggered some explosive detcord fixed against the fuel and lox tanks, tearing them open, so that the rocket safely disintegrates.

I notice from the video that the destruction is done in a way that doesn't mix the LOX and fuel together - you can see the Cold Lox falling away and the ignited cloud of burning RP1 floating higher. Really nice bit of design I hadn't thought of.

about 3 months ago
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Can We Call Pluto and Charon a 'Binary Planet' Yet?

robbak Re:Questions like this really reveal the definitio (115 comments)

Again, I would have to be convinced that a group containing more than two objects with sizes within an order of magnitude of each other would be stable. Myself, I can't see it. Two large moons would push each other into chaotic orbits which would, sooner rather than later, lead to either a collision or an ejection.

The only way I can see a system with two large moons is with a planet that is completely dominant, such as Saturn or Jupiter and it's moons. (I'd argue, for instance, that Earth could not have held on to two moons.)

But these questions can really only be answered when we have more binary-planet candidates to categorize.

about 4 months ago
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Can We Call Pluto and Charon a 'Binary Planet' Yet?

robbak Questions like this really reveal the definitions. (115 comments)

The answer is simple - that Lagrange point is not stable, so the moon would not remain there. Each moon would be pulled from that point by the other's gravity, until they either collide or one or both items are thrown from their orbits.

So as a planet cannot have two moons that orbit opposite each other, the concept of a binary planet with a definition based on the location of its barycenter is valid. But we'd first want to see one - Pluto/Charon is a poor example, as Pluto is considerably larger and heavier than Charon, so 'Planet/moon system' defines it better. If we start to find real binary planet systems outside of our solar system and stat characterizing them, then we will be able to know what sorts of systems happen and how they form, and maybe then we will find that Pluto/Charon belongs as an outlier there. But that's for a future time.

about 4 months ago
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Bose Sues New Apple Acquisition Beats Over Patent Violations

robbak Patent is for use without music? (162 comments)

The thing that commenters over at Ars haven't picked up on - this patent is only infringed if the customer wears the headphones without playing music. Noise cancellation with added music - OK, there's prior art for that. Turn the music off - it becomes patentable technology.

The claim states that Bose is on the hook because their documentation states that you can use the headphones without music for noise cancellation only, which induces their customers to infringe Bose's patents.

How is that legit? How can not adding music create a patentable technology?

about 3 months ago
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Cable Companies: We're Afraid Netflix Will Demand Payment From ISPs

robbak Re:Hmm, an immediate hostile reaction, you say? (200 comments)

Not at all!

But as it currently stands, Comcast's customers are paying Comcast to delver the data from Netflix at up to the speed the customer is paying for. For Comcast to help fund Netflix' expansion so that they could better support Comcast's customers' demands might, just "might," be reasonable. For Comcast to hold Netflix to ransom is certainly not.

about 4 months ago
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Cable Companies: We're Afraid Netflix Will Demand Payment From ISPs

robbak Hmm, an immediate hostile reaction, you say? (200 comments)

"If a broadband provider were to {snip} block or degrade access to its site if it refused to pay a significant fee, such a strategy almost certainly would be self-defeating, in light of the immediately hostile reaction of consumers to such conduct."

You mean the hostile reaction you are getting right now as you do exactly that? Like how every one of your customers that has any other option dumps you in a heartbeat?

Yes, if anyone should be paying anyone, it is Verizon/Comcast that should be paying Netflix, as Netflix is providing the content that Veriz/cast sell to their subscribers.

about 4 months ago
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Aereo Embraces Ruling, Tries To Re-Classify Itself As Cable Company

robbak So, how does this go? (147 comments)

Companies: Hey Courts, Aero is a cable company!
Aero: We really aren't.
Courts: I agree with the Companies. Aero is a cable company.
Aero: Sigh, I guess we'll have to become a cable company then.
Companies: I Object! Aero isn't a cable company!

about 4 months ago
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The View From Inside A Fireworks Show

robbak I can see how you could think it dangerous. (200 comments)

But I can also apply physics and see how the danger is very small.

The biggest point is that the sky is big and both the shells and the drone are small. The chance of the two coming into contact is negligible. The risk of anything bad happening if that happens is also very small - the only thing I can see happening is if a rotor happens to cut the shell's fuse. The shell is too heavy for a fragile drone to have much effect on it.

about 5 months ago
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The View From Inside A Fireworks Show

robbak What he wants versus what is the reality. (200 comments)

The drone genie is out of the bottle. This is the world we not live in - where the possibility of a cheap RC craft being in a particular airspace has to be taken into account.

about 5 months ago
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The View From Inside A Fireworks Show

robbak Heavy solid shell, light fragile drone. (200 comments)

The shell smashes the drone into tiny bits of confetti, and continues on it's merry way. Or, more likely the shell snaps off a rotor arm without noticing.

They will not bounce off each other like billiard balls. That's what happens when you have a collision between equal mass objects in which kinetic energy is conserved. This would be a collision between different mass objects where energy is lost to work - destroying the drone. The one with the most momentum wins.

about 5 months ago
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The View From Inside A Fireworks Show

robbak Re:Illegal and Dangerous? (200 comments)

Professional fireworks are mortar-fired shells, not rockets that can go off-course if nudged. So if a shell hit the drone on the way up, it would smash straight through it and keep on going. There is not enough mass in a drone, and a drone is not solid enough, to deflect the solid mass of a firework shell travelling at speed. It might not quite reach the same height by a few meters, or might end up a couple of feet off target, but neither of these things would matter.

And if the drone is up at altitude where the shells explode, then there is even less speed involved. The shell has reached it's height - so what if it taps a drone before detonating.

There is also whole lot of sky, and both shells and drones are small. The chance of the two coming together is practically nil.

Amazing pictures captured with zero risk. Images from a drone up there amongst it all should be a permanent feature of firework presentations.

about 5 months ago
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The View From Inside A Fireworks Show

robbak What with all the other debris? (200 comments)

The area under a fireworks show already gets peppered with the remains of all the exploded shells. A little added debris from a drone struck by part of the fireworks would make no difference. They always make sure that the fallout zone is in a safe area.

Add to that that the shells are mortar-fired, not rockets, and the risk of this is practically nil. Way less than the risks of just using and handling all that explosive.

Every professional fireworks show - at least, all those that are televised - should include shots from a drone up there amongst it all. The spectacular pictures are well worth the tiny risk.

about 5 months ago

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