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Comment: Re:An EMP from a super solar flare... (Score 1) 139

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) 139

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.

Comment: Um, no. (Score 1) 303

by caffeinated_bunsen (#40510837) Attached to: Making Saltwater Drinkable With Graphene
Thank you, anonymous reader, for a confused summary of an idiotic blog post about a moderately dumbed-down article about an interesting article.

What they're talking about is reverse osmosis, and there's no way to make it two or three orders of magnitude more efficient. Commercial systems already hit 30% to 60% of the thermodynamic limit for energy efficiency; all graphene offers in this case is a way to increase the speed, decrease the filter size, or reduce the unnecessarily wasted energy. There's still no getting around that darned osmotic pressure.

Comment: Well there's yer problem. (Score 4, Funny) 132

by caffeinated_bunsen (#39838383) Attached to: The Greatest Machine Never Built
John Graham-Cumming is the leading light behind a project...

Leading lights generally work better in front of things. I think your metaphorator might be a bit misaligned...

Yep. Looks like you've got some sinusoidal co-pleneration between the literal input shafts. Gonna have to replace your main spurving bearing, maybe the secondary too. A couple of the marzel vanes on your imagery agitator are looking a pretty worn, might want to get those replaced while you're at it.

Comment: Re:Restricted (Score 1) 82

by caffeinated_bunsen (#39728869) Attached to: Happy World Amateur Radio Day

There was a forum discussion which someone complained, "so what if I want to talk like a CBer on ham radio? As long as I'm licensed and mention my callsign every 10 min, end of transmission, bla-bla, I can talk in whatever style I want!" However, someone gave example: "That's a big ten-four good buddy and I sure do appreciate that there smokey report on the five oh niner. Well, I'll catch you on the flipper flopper!" Bzzzzztttt. FCC Part 97 prohibits codes and ciphers used to obscure communications.

Which is thoroughly irrelevant to the issue of talking like a CBer. Nothing in your example message is a code or cipher; that's simply slang. All of it is publicly known. The reason hams discourage talking like a CBer is that it makes you sound like one of the drooling shit-flingers who infest CB.

Comment: Re:From the comments below the article... (Score 5, Informative) 171

by caffeinated_bunsen (#33700046) Attached to: Don't Cross the LHC Stream! (Maybe)
I think this is the comment you're referring to:
12. Bethany Says:
September 21st, 2010 at 8:20 am

Alright, here's what I calculated:
The protons are high energy with lorentz factor of gamma=7500, kinetic energy is about K=7×10^6 eV. The paper cited below says that the stopping power of a proton going 10^6 eV is about 2.5×10^8 eV cm^2 g^-1. Using the density of muscular tissue rho=1g cm^3 and the thickness of my hand of 1 cm, the energy deposited is 2.5×10^8 eV. In other units its 1.07×10^-11 calories, 4.49×10^-11 Joules, and 1×10^-14 grams of TNT. If there are hundred billion protons per bunch in the beam (as the video said) then for every bunch you get 4.49 Joules or 0.001 grams of TNT of energy.
(emphasis mine)

There are two beams, each of which contains 2808 bunches. Don't worry about the effect of multiple passes, though, since there won't be any tissue left in the beam's path by the time the first pass is over.

A more informative comment showed up later:
31. Xerxes Says:
September 21st, 2010 at 10:45 am

I think the hand-beam question is best answered by this document:

Granted, a carbon block isn't an exact model of the human hand, but it's probably close enough. The key points are:

1) "this energy deposit over 85 s is long enough to change the density of the target material. The density decreases at the inner part of the beam heated region because of the outgoing shock waves in the transverse direction. As an example, after the impact of 200 bunches with a size of = 0.2 mm, a maximum temperature of 7000K and a density decrease by a factor of 4 is expected." The results of heating your hand to 7000K and increasing its volume by a factor of 4 are probably best not imagined. Since a full beam is 2808 bunches instead of 200, you might want to scale that by a factor of 10 too.

2) But on the other hand (hehe): "The beam tunnels through the target and deposits the energy with a penetration depth of 10 m to 15 m" Since your hand is not 10m thick, you won't pick up the full effect. This paper goes into some detail of the spatial distribution of the energy dump: So at hand-thickness of 2ish cm, you'd only get maybe an eighth of the effects of #1, so your hand will only reach the more modest temperature of 1000K (times 10 for a full 2808 bunches?). The shockwave from the blast will extend several cm in the transverse direction; translation, the rest of your hand will be blown off by the middle of your hand exploding. Probably the part of the accelerator apparatus downstream of your hand picks up the rest of the energy. The rest of you probably wouldn't want to be standing next to it when it blows.

Cool pictures of the effects of a low-energy (450-GeV) beam on copper plates are in

(I spent so much time looking up references, several other people made the same points. Oh well.)

Note particularly the fact that if one beam hit the solid graphite beam dump without being swept around during the pass, the surface would be at 7000 C, and would be well in the process of exploding, by the time the first 200 bunches had hit. Your hand, having a lower boiling point than graphite, would begin to remove itself from the path of the beam somewhat sooner, and would therefore probably absorb rather less energy. That may be small consolation, though, since it pretty much means that the splattered remnants of your hand wouldn't be as intensely radioactive as the carbon in the beam dump would be.

To avoid criticism, do nothing, say nothing, be nothing. -- Elbert Hubbard