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Comment: A thousand dollars? What the hell. (Score 1) 48

by caffeinated_bunsen (#48087751) Attached to: Send Your Own Radiosonde 90,000 Feet Into the Sky (Video)
If you blow a grand on flying just a camera and tracker, you're doing something amazingly wrong. I worked on a university project that didn't cost that much, and we flew two expensive radios, a SPOT tracker, APRS tracker, Arduino Due flight computer, HD video camera, two GPS receivers, an active thermal control system, and a Kerbal, and we went into it not really knowing what the hell we were doing.

With one flight's worth of experience under my belt, I could put together a decent tracked payload with sensors and a camera for under $200, using off-the-shelf components. Less if I want to spend time making a circuit board. I'm not sure what helium costs these days, but that and a small envelope sure as hell aren't going to add $800 to the bill.

Comment: Re:An EMP from a super solar flare... (Score 1) 151

by caffeinated_bunsen (#47884555) Attached to: To prepare for a coronal mass ejection, I ...

Are you saying that writer doesn't know what he's talking about?

That is exactly the case. There is an infinitesimal kernel of truth at the center of that pearl of idiocy; a high-altitude nuclear detonation does produce geomagnetic field disturbances similar to, but much more violent than, a CME impact. But the effects one normally thinks of as coming from a nuclear EMP -- small electronics being suddenly destroyed by radio-frequency electromagnetic fields -- are absolutely absent from a CME-induced geomagnetic storm.

Comment: Re:Backup My Data (Score 2) 151

by caffeinated_bunsen (#47884321) Attached to: To prepare for a coronal mass ejection, I ...
Or, y'know, be underneath a nice, thick atmosphere. You're absurdly exaggerating the penetrating capability of solar protons. The ones in the CME that will hit on Friday aren't even very energetic, and the MeV scale protons are already here and starting to fade out after a thoroughly unremarkable S1 radiation storm.

Comment: Re:"float down on Europa's atmosphere" (Score 1) 79

There's another possibility that occurred to me: That the actual mission concept does incorporate measures to address those problems, including propulsion on the chipsats, but was so magnificently mangled by the press office and reporters as to create the appearance of complete crackheadedness. This would require a slightly greater-than-usual commitment to misrepresentation and intellectual laziness on the part of the journalism majors, but is within the realm of plausibility.

Comment: Re:"float down on Europa's atmosphere" (Score 1) 79

Trust me, no scientist at Draper spent months on this. It would make some damn sense if they had. It reads like a summer intern's wide-eyed ramblings after they just read about things other cubesats have done, but before they considered any of the actual engineering issues.

And sometimes, you end up with a random /.er who, though the satellite he's working on is only going to low Earth orbit, sees the potential of applying the cubesat fast/cheap/high-risk philosophy to interplanetary missions, had already quantified the problems with power generation at Jovian distances from the sun and the resources required to communicate with a miniscule power budget, and even went and read about the possibility of common materials surviving unshielded reentry a few years ago when the chipsat idea started making headlines.

There's real potential for using cubesats beyond Earth orbit. Lots and lots of people have noticed this, and they've generally also noticed the same set of problems -- power, cold, communication, and radiation. There are possible solutions to each of those, but they come with major costs and the probe described and drawn in the article incorporates none of them.

The aerodynamic entry idea is utter nonsense on that moon, though -- what passes for an atmosphere on Europa would qualify as "ultra-high vacuum" in a laboratory. It's about the same density as what the ISS is orbiting through right now. There is no structure in existence that could decelerate enough in that atmosphere to land gently. The terminal velocity of a flake of monolayer graphene is comparable to rifle muzzle velocities, and functional circuitry is a few orders of magnitude heavier than that.

Comment: "float down on Europa's atmosphere" (Score 2) 79

Um, are we talking about the same Europa here? The one with the atmosphere that barely musters a nanotorr at the surface? The one where the terminal velocity of a scrap of mylar film is on the order of tens of kilometers per second? I think that "float down" plan may have been selected a bit hastily.

At least the chipsats turning into teeny little craters in the ice will reduce the data burden for the cubesat's transmitter, which based on those solar panels has a power budget of about a tenth of a watt to make a link at a range close to a billion kilometers. You can maybe squeeze a few hundred bits per second out of that while you're tying up a DSN dish, otherwise forget it.

Maybe they're thinking of making it an accessory to a full-size probe, but forgot to mention the need to send a few hundred kilograms of other stuff out there too. Or maybe somebody was behind on their press release quota, and this half-baked crap was the best thing they had lying around.

+ - AT&T, Verizon Attempting to Get Government Approval to Cut Off Competitors.->

Submitted by Anonymous Coward
An anonymous reader writes "In Michigan, Senate Bill 636 will remove any remaining requirements of AT&T and Verizon to lease lines to other providers, effectively killing all competing phone and internet providers, including wireless providers, which rely on leasing any connectivity from AT&T or Verizon. Readers should not be fooled by the title of the bill into thinking it only applies to a hard-wired phone line coming into their home or office. What the consumer calls a landline differs greatly from what the law calls a landline."
Link to Original Source

Comment: Re:Uhmm....I sense a problem with scale. (Score 5, Informative) 303

by caffeinated_bunsen (#40511305) Attached to: Making Saltwater Drinkable With Graphene
That's not as big a problem as you'd think. In solution, you don't have molecules of NaCl; you have dissociated ions of Na+ and Cl-, each of which is surrounded by a cluster of rather tightly-bound water molecules. Those clusters are much larger than bare ions or single water molecules, so there's a fair range of pore sizes that will separate the ions from the water.

Comment: Re:Um, no. (Score 3, Informative) 303

by caffeinated_bunsen (#40511095) Attached to: Making Saltwater Drinkable With Graphene
I think they're abusing the terminology a bit, using "RO" to refer to reverse osmosis conducted with existing membrane technologies. The point at issue is that thermodynamics demands that a certain amount of energy be expended in order to reduce the entropy of a homogeneous salt solution by separating it into pure (or at least low-salinity) water and high-salinity leftovers. This is totally independent of the means by which the molecules are separated. In reverse osmosis, that manifests as a minimum pressure necessary to force salt water through any selectively permeable membrane.

Practical RO systems operate with a pressure drop (and therefore energy consumption per unit volume) that's double or triple the osmotic pressure, in order to achieve useful flow rates across thick membranes with relatively low pore densities. A better filter would allow that excess pressure to be reduced, but can't do anything about the cost of reducing the entropy.

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