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Comment: Re:No need to read TFA ... (Score 1) 346

Yeah, to have local governments build and maintain networks that serve all comers, commercial and private, while recovering all costs from usage-based user fees would be, dare I say it, socialism! Next thing you know, the socialists will even propose to have local governments build and maintain roads for the public good!

Comment: Re:How do they get around the altitude limit? (Score 2) 48

by Phil Karn (#48089469) Attached to: Send Your Own Radiosonde 90,000 Feet Into the Sky (Video)
The problem is ITAR - International Traffic in Arms Regulations. The idea was to keep cheap civilian receivers from being used in ICBMs. For that reason, there's an altitude and velocity limit, but the language was ambiguous. Some manufacturers interpreted it as an altitude AND a velocity, others interpreted it as an OR. The latter create the problem.

Comment: Re:Ion Thruster (Score 1) 48

by Phil Karn (#48089455) Attached to: Send Your Own Radiosonde 90,000 Feet Into the Sky (Video)
Your explanation is pretty much correct. But getting higher with a balloon is literally exponentially more difficult because that's exactly how the density of the atmosphere decreases with height. Your balloon has to expand exponentially as it climbs, and exponentials are not functions to be trifled with. The vertical distance over which the atmospheric density decreases to 1/e of its starting value is the "scale height", and for the earth it is an average of 7.6 km (it varies with temperature). But you can see that just getting to 30 km (100,000') is already about 4 scale heights, with your balloon expanding by a factor of e^4. Even that much is harder than it looks because the balloon expands as rises, and the gas inside cools adiabatically, causing its density to increase. Even in thermal equilibrium with the air outside, that air is awfully cold, which doesn't help decrease the lifting gas density. I think 100 km is completely out of the question. That's the Karman line, and it was chosen as roughly the altitude where an airplane could not generate enough lift to hold itself up even if it was going at orbital velocity. That's not a lot of air.

Comment: Re:10,000 MPH to get into orbit (Score 1) 48

by Phil Karn (#48089425) Attached to: Send Your Own Radiosonde 90,000 Feet Into the Sky (Video)
Not quite. Assuming "100k" means "100 km", conventionally chosen as the edge of space, getting there going straight up from 30 km (an easy weather balloon altitude) requires an upward force greater than the weight of the payload. Anything less and you'll just fall back to earth. If you do this with a rocket (what else would you use?) you will find that doing it slowly is *very* expensive in propellant. In rocketry this is called "gravity loss", and it's one of the reasons rockets don't just go straight up to space even when the intent is to escape the earth. They fly an arched path known as a 'gravity turn': just enough altitude is gained to reduce air drag to an acceptable level while you try to build up horizontal velocity as fast as you can. The less time you spend with your rocket anything but horizontal, the lower your gravity losses will be and the more hard-earned rocket impulse you can devote to getting orbital velocity and *staying* in space.

Comment: Re:Jamming unlinced spectrum is illegal? (Score 1) 278

by Phil Karn (#48060289) Attached to: Marriott Fined $600,000 For Jamming Guest Hotspots
Sorry, but the rules make no distinction between licensed and unlicensed spectrum. If you deliberately interfere with someone else's radio communications, you are breaking the rules.

Marriott's reply is laughable. It might work on unsophisticated readers but not anyone who knows anything about WiFi. They said they wanted to "protect" their guests against "rogue" access points. Well, if those "rogue" access points were spoofing Marriott's own SSID, they might have a point. But I certainly don't set my own portable hotspot SSID to that of any hotel. It's set to something quite unique, and it's encrypted. Nobody is going to mistake it for a hotel's network, much less actually associate with it.

Comment: Re:If the Grand Ayatollah's against it.... (Score 1) 542

by Phil Karn (#47801121) Attached to: Grand Ayatollah Says High Speed Internet Is "Against Moral Standards"
The Christian fundies' fear of Sharia Law is one of the most ironically amusing things to come out of them in recent years. If they didn't spend so much time railing against our consitutitional separation of church and state, maybe, just maybe they might realize that it's exactly what protects them from such an (unlikely) threat.

Comment: Re:Civil Unrest (Score 1) 191

by Phil Karn (#47771569) Attached to: New NRC Rule Supports Indefinite Storage of Nuclear Waste
And civil unrest becomes vastly more likely in a future with runaway global warming and the climatic changes, floods, draughts, food shortages, rising sea levels, mass extinctions, habitat destruction, economic upheavals and the like it will bring. Nuclear power, wind, solar, hydro and geothermal are ALL essential to combat it.

CO2's atmospheric lifetime is something like 1,000 years. How come those who fret about the longevity of nuclear waste never seem to talk about this? With fast reactors that burn the actinides (including plutonium) as fuel, the remaining fission products decay to the level of the original uranium ore (while being considerably more compact) in only a few hundred years, much less than the atmospheric lifetime of CO2.

The hype about "carbon capture" is just that -- hype. But it serves one useful purpose: its utter impracticality shows just how minor the nuclear waste "problem" is by comparison.

Comment: Re:Ridiculous (Score 4, Insightful) 191

by Phil Karn (#47771537) Attached to: New NRC Rule Supports Indefinite Storage of Nuclear Waste
Not far from Yucca Mountain you will find hundreds if not thousands of craters under which are buried the fission and activation products of decades of US nuclear testing. They're not reprocessed and contained in silica glass, they were simply mixed (quite violently) with the soil and rock. And yet they don't seem to go anywhere. There is no need for Yucca Mountain to contain reactor waste for even a hundred years because it will surely be removed and burned as fuel in fast reactors. Once people wake up to the fact that global warming is a vastly greater threat than nuclear power, and that nuclear power is just as essential as wind, solar, geothermal and hydro in combating it, people will realize that "spent" fuel from light water reactors is far too valuable to just throw away.

Comment: Re:central storage or n^x security guard costs / s (Score 2) 191

by Phil Karn (#47771485) Attached to: New NRC Rule Supports Indefinite Storage of Nuclear Waste
Even with cheap solar and wind we will still need nuclear, at least until somebody perfects a cheap, reliable and long-lived utility scale battery. Otherwise we'll never be able to retire all the CO2-belching fossil-fuel plants to match the varying supply with the varying demand.

Comment: Ridiculous (Score 2, Insightful) 191

by Phil Karn (#47770427) Attached to: New NRC Rule Supports Indefinite Storage of Nuclear Waste
I agree that waste in casks at nuclear power plants is reasonably safe but it would still be better to move it to Yucca Mountain. If nothing else, security would be a lot cheaper. It's utterly ridiculous that all that money was spent on a waste repository that, thanks to NIMBYism on the part of Nevada politicians, doesn't look like it'll be used any time soon. At least nuclear waste is the one form of toxic waste that will eventually go away on its own. Arsenic, mercury, lead, thallium and other chemical poisons remain toxic forever.

Comment: Let's privatize the roads too! (Score 1) 338

by Phil Karn (#47733125) Attached to: FCC Warned Not To Take Actions a Republican-Led FCC Would Dislike
Yeah, and we should also ban municipalities from building roads because they discourage private investment in toll roads. All the roads, including the street in front of your house, ought to be sold to UPS. You'd have to get their permission to drive your car on their roads. Since they'd be private property, they'd be within their rights to make any arbitrary rules they wanted. They could ban certain makes or kinds or colors of cars. They could allow you to drive only to certain pre-approved destinations. And don't even think about trying to create a package delivery service to compete with them.

Comment: Re:Applause (Score 1) 771

by Phil Karn (#44517953) Attached to: Encrypted Email Provider Lavabit Shuts Down, Blames US Gov't
Are you sure about this? Would it in fact be possible to gain access to all past stored emails by logging a future user session? Or was it only possible to gain access to future emails by recording a copy of the incoming plaintext before encrypting them with the user's public key? This is an honest question; I hadn't even heard of Lavabit until today (I would have been a customer if I had) so I only know what I've read. Even before today, the past several months have proved what we've all long suspected: a security model that requires the users to trust a commercial service provider is simply not workable. Even (especially) in the United States. Ideally, a security model shouldn't require you to trust anyone in the middle at all. If that's not possible (and for many services, it's not) it should rely on a large volunteer group, at least some of whom are honest. Something like TOR, though it has its own problems.

Comment: Re:Applause (Score 1) 771

by Phil Karn (#44517905) Attached to: Encrypted Email Provider Lavabit Shuts Down, Blames US Gov't
I think you have it basically right. As I understand Lavabit, they encrypted incoming email with a public key for which only the user had the private key. They could not provide plaintext of existing email to a government demand. So the government probably ordered them to keep plaintext copies of all future email, which would be technically possible. The only way to avoid it was to shut down the service altogether. There'd be no reason to shut down the service if the demand was only for existing data as that would not relieve them of the requirement to fork it over. At the moment their MX server is not accepting incoming SMTP connections, which lends weight to my theory. The government could still seize the domain name and set up their own inbound SMTP server, but hopefully the publicity has warned everyone away. Right now there are two MX records for lavabit.com: mx.lavabit.com and lavabit.com, both of which resolve to IPv4 address 72.249.41.52. imap.lavabit.com also resolves to the same IPv4 address. Let's see if those records change...

Comment: Control EV charging, yes; selling EV batteries, no (Score 1) 247

by Phil Karn (#37536328) Attached to: Returning Power From Electric Cars To the Grid
The idea of selling EV battery energy back to the grid is silly given the high depreciation costs of current EV batteries, but a closely related idea makes a lot of sense: allowing the grid operators to control the power level of EV chargers in exchange for lower rates. Even during the day there's almost always unused generation that's much cheaper than the depreciation cost of EV batteries. Problem is, it takes time to fire up in response to an unexpected load increase. Usually the extra load is temporarily met with quickly dispatched (but more costly) spinning reserves until the more economical generators are online. Temporarily reducing EV charging powers could be an alternative to those expensive reserves, and it only needs to last until the extra generation is online. The temporary power reductions could be rotated among different EV drivers so no one user has his cranked down too often or for long.

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