I worked on a Navy jet upgrade about 10 years ago. It was a project to replace an antiquated (read that as "wire-wrap technology") autopilot computer with a brand-new, spiffy, fully digital autopilot computer. Of course, just like the B-2, it had to be a form/fit replacement.
I was shocked when, at the first design review, the contractor said they would be using an 80286 as the CPU. Remember, this is 1995. The 80286 was introduced in 1984. By 1995, the Pentium was the standard. So of course I asked "Why use such an older processor, when a newer one would be much much faster?"
Their answer was essentially one word.
HEAT.
The 286 had perfectly adequate processing power to run the fairly simple algorithms needed for autopilot and related functions, including all the error detection and fault logging, as well as the required 2x of government-mandated growth allowance (you MUST use less than 50% of clock times in your design). Using anything more high-powered would generate more heat (which must be dissipated somewhere in the closed environment), and use more current. On a 1960's era airplane, with Kapton wiring and its risk of insulation fires, and its limited power generation ability, you don't toss in higher heat and power requirements without VERY good reasons.
The result turned out to be perfectly adequate, and a vast improvement over the original design.
Let me toss out another interesting statistic. From what I remember from a recent brief, Boeing is right now delivering upgrades to its commercial airline fleet autopilot/navigation computers with 32Mb of data storage installed for the navigation database. Just 32Mb. That's what you're sitting behind in every Southwest or United or American flight you enjoy. With memory so cheap, why not put more in? Same logic, same ideas: for commericial and military programs, you don't overbuild a device just because you can. You'd better have a REALLY good reason to make a change.
We geeks tend to forget that overclocking and water-cooling and 8Gb RAM and 2-TB hard drives are thousands of times overkill for very many purposes.
They are. That's why they want a process which preserves every little bit of audio goodness possible under the already less-than-CD-quality, marginal-bitrate-file circumstances. They'd rather NOT use a process which takes the files and transcodes them TWICE, thus compromising the audio quality even further.
They may not be audiophiles, but they DO prefer to save what little quality they started with.
>Assuming that the satelite was hiding in the shadow of some larger >vessel and not exposed to sunlight heating it up to a few hundred degrees.
Okay, I'll concede the point that it won't be -273C... but it also won't be a few hundred degrees HOT, either.
Thermal management in a satellite is a BIG issue, probably the single most critical element of external satellite design. I read that unprotected vehicle temperatures range from -120 to +180 deg (I'm not sure if this is C versus F, but it's probably deg C).
Most satellites are constructed with highly-reflective films over everything NOT covered by a solar panel, specifically to AVOID excessive warming in any one spot, while also covered with thermal blankets to retain internal heat, so as to minimize the amount of valuable electrical power which must be diverted to heating units.
The sunward side may be warmed despite the reflective films, but the OPPOSITE side of the satellite sees vacuum and absolute zero, thus radiating away heat very quickly. Furthermore, the satellite is dead, thus uncontrolled and spinning at least slowly, so any given side will be radiating away the solar heat every time it faces away from the sun.
And most orbits, it's spending about 45 minutes in total blackness, thus radiating away any external heat buildup.
The propellant tanks are usually fairly well insulated, preventing rapid heat transfer, and they're typically surrounded in structure to help both retain a working temperature and avoid excessive thermal cycling leading to tank overpressure and explosion. In fact, one document I found describes a satellite design that deliberately uses solar energy to keep the tank thawed - but this is a design that requires pointing the satellite in a precise angle to function, and still includes features to keep it cool enough. So a tumbling satellite with this design would have a far colder tank than required for normal operation.
So on balance, I believe it's safe to assume that the propellant would be quite well frozen, thus leading to a 3 foot wide ball of very hazardous "ice" wrapped in steel making its way thru the atmosphere to a largely intact landing.
>Still wanna try to claim that tank would survive reentry?
Absolutely I would claim that.
Hydrazine is a solid below about 1 deg C. This was a dead satellite. No heat, no power supplies. In other words, you have an insulated pressure vessel (fairly well-built) containing 1,000 lb of hydrazine ice at roughly -273 deg C. That's a LOT of thermal mass; the ice inside the tank would absorb a lot of the reentry heat, preventing the metal from melting for quite some time. Did you ever do that science experiment where you try to burn a paper cup containing water? Doesn't work until you boil off all the water. Same thing here, but we're talking about metal which is even more thermally conductive than paper.
Furthermore, a lot of the surrounding structure must ablate or melt away before the tank can be directly affected by the reentry.
Also, in case you want to compare a thousand-pound meteorite to this satellite: a satellite does not orbit as fast as your typical meteor reentry speed, so you cannot compare the reentry energy to a typical meteorite ablation rate.
If you need proof, consider that hydrazine tanks from the Space Shuttle Columbia accident DID impact in some Florida woods. They were NOT cold-soaked at absolute zero for two years - they were prepped for flight, heated, etc., and wrapped in far more spacecraft structure than this satellite. And they were not full, like these tanks were. That should demonstrate the reality of this risk.
>So if it costs $10,000 per pound to put something into space, why don't we gather >these dying satellites and dock them to the ISS for spare parts rather than >blowing them up? They could also be sent to the moon for parts in future missions. >Perhaps this is technically infesible or the cost of doing so would be more than >the parts are worth in space?
Lots of reasons it's both infeasible and impractical.
You cannot simply "gather" a dying satellite. It takes enormous amounts of energy to change the orbit of a big chunk of metal. Either the satellite must do it (which it can't because it's either dead or low on fuel), or you must carry up enough fuel to go reach the satellite, then maneuver back to wherever you want it to go. At $10K/lb, you would spend far more on carrying that fuel to orbit than the cost of the satellite and its parts.
Bear in mind that satellites orbit in a spherical shell between roughly 90 and 23,000 miles above the surface. Lots of empty space must be transversed to reach a given satellite. It's not like they are just parked next to each other, waiting to be collected. And orbits are in all different directions, requiring even more fuel to match orbits.
And no, the technology wouldn't be useful. It's not like a giant Lego collection; parts are highly customized to the exact application. Also, over time, metal in space tends to weld itself together; it's often very difficult to disassemble parts that have been exposed to vacuum for years (ask the Shuttle astronauts who have helped service the Hubble). Furthermore, any kind of disassembly must take place in weightless vacuum - a real hassle itself - and deal with residual toxic propellants, power supplies, even small radioactive power supplies.
Nope, a satellite is essentially expendable, and always will be (at least until we figure out zero point energy, or some other equally miraculous "free" energy solution).
Ummmm... nope. These types of systems are currently being used by US military aircraft currently operating in Iraq and Afghanistan. They regularly save the lives of our servicemen. They are quite well proven. For example:
... but I do write music. Sorry, I have a real problem with Congress taking away my own rights to my own music after just five years. That's a flash in the pan, in terms of my life; for crying out loud, I don't even get some of my own music finished in that short a time. I don't sell my music (or at least, nobody's bothered to buy it yet), but I have a problem with someone saying they can appropriate my own creative works that quickly.
There are other solutions than this that have NOT been tried yet, because the lobby is too big for Congress to act. And this would suffer the same fate.
Actually the helicopter was at 500 feet ALTITUDE. If it was directly over the laser, nobody would have seen the beam. So in reality, the helo was probably at least a half mile (slant range) from the laser. Given this, the beam was probably five or six feet wide - easy to get both aircrew at once.
For all the "oops, it was an accident" types, consider that anyone using a laser beam outside at night is doing it TO LOOK AT THINGS - you will NOT miss an airplane with its flashing beacons and strobe lights. This kind of thing is NOT an accident.
Also, it's very unlikely that the brief flash caused by crossing a stationary or wandering beam would have been a real problem, compared to several seconds of targeted exposure, during which the natural tendency is unfortunately to look AT the beam (and thus increase the risk). So it makes perfect sense to me to prosecute in this case.
> Then he tosses the laptop, reports it, and then he has a perfectly legal excuse > as to why he's holding kiddie porn on his computer.
Really now... think about that for a minute... If he DOES report it, don't you think the authorities will take a pretty careful look at his equipment, too? Do you seriously think any addict would go anywhere near this process? Not a chance.
Call BS if you must, but not on that point.
It seems to me that the BIGGER risk here is the chance of being unfairly nailed yourself for legitimately reporting the material. This law says you must submit not only the report but also the offensive material. Doesn't that make you potentially liable for both possession and interstate transmission of the very offending material itself? Sure, you could argue (correctly) that you were following the law, but how can you prove it? It would be a snowy day in August before I'd want to be part of THAT reporting process, thank you very much.
This whole law smacks of danger on all sides, even if you believe that there can be reasonable limits on freedom.
I'm seeing a lot of comments here focusing on the overly intelligent criminal.
Problem is, MOST of the car chases you see on TV are: 1) Drunks or druggies, not in their right minds 2) Car thieves (not riding their own wheels anyway) 3) Suicide-by-cop idiots, who WANT to be killed, not stopped safely
Okay, fine, the really intelligent criminals might be able to prevent themselves from being stopped this way. Granted. But the really intelligent criminal is NOT going to find himself involved in a car chase anyway, because he's too smart to let that happen.
Frankly, I've wondered for years why they didn't do something like this. Or mount a piton system in the front of your average police cruiser, that could pneumatically or explosively shoot out a grappling hook that stabbed thru the trunk of the fleeing vehicle and drag it to a stop. Most police chases involve very close pursuit at reasonably slow speeds - so why not nail the guy's trunk and drag him to a halt, instead of trying to PITT him and risking all kinds of damage to both vehicles?
So I'm happy to finally see this kind of technology under real development.
And for those of you who are worried about innocent bystanders, remember that EMF falls off as the square of distance. Whatever power kills a car 45 feet away (100 joules) probably won't even blip an engine 450 feet away (1 joule). There will be plenty of chances in most car chases to SAFELY utilize these things. https://answers.google.com/answers/threadview?id=409268
Think rationally for a minute. What benefit can a supposed micro-UAV provide in this kind of gathering? Why on earth would the US Government "out" itself in a situation like this? Any halfway intelligent spy agency (as I believe ours ARE, regardless of any opinions about their oversight) would hold technology like this for really really really important, and otherwise impossible to penetrate, situations, and especially situations where the technology would not be seen (like nighttime).
Think about it. Big gathering. Public place. Plenty of surrounding buildings. No limits on attendance. Hundreds of people waving around cell phone cameras. Recording devices allowed in the area. If you want pictures of who's there, just pretend you're a protester really happy about the size of the crowd, and wander around like an idiot with your (looks like a) $50 CVS disposable video camera, blatantly taking pictures of everything and everyone in sight. You'll get much closer, more stable, clearer pictures, and nobody is the wiser. Why try to hide?
This doesn't pass the basic sniff test. Not many conspiracy theories do, when you really think about them rationally.
I'm a geocacher, and I like to hunt "urban micro" caches - tiny containers hidden in highly-trafficked areas. Hunting for them is not unlike being a spy, I think, and I've found that trying to sneak is very ineffective. If you look like everyone else, and act like everyone else, you can hide your actions a LOT better than if you LOOK like you're trying to hide. Same thing here: it makes a lot more sense to blend in, than try some super-fancy new technology which WILL be noticed.
Incidentally, I am NOT denying these things might exist. But I am pretty certain that if they are being used, it's in much more carefully and wisely chosen scenarios.
In related news... strange lack of "First Posts"
on
Help Find Steve Fossett
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· Score: -1, Offtopic
In related news, no Slashdotters posted a "First Post" response for a matter of several hours. This never-before seen phenomenon was tentatively attributed to the entire Slashdot community immediately joining the virtual search.
I also purchased the full version of MMJB a few versions ago - I think it was version 8 - because I really liked it, much better than WinAmp or other (at the time) available alternatives. I even recommended it to family, and on my music-related website.
Version 9 had some nice new features, together with some added annoyances and nags. I was still sort of happy.
But then version 10 came out... and within weeks I'd uninstalled it and gone back to version 9 (I'm glad I keep copies of my downloaded install programs). Way too many bugs, much slower, many new added nags even in a paid version. And many of the real obvious bugs in version 9 were still present in version 10. Geez, guys, fix the product FIRST, and THEN add features!
But even dealing with version 9 was no longer quite so painless - I now knew that the problems in version 9 would never be fixed. And when we bought an iPod, and had to install iTunes, we never looked back... pretty soon both of our PCs were running iTunes, sharing music with our Roku SoundBridge and syncing our three iPods...
It was a real shame to watch such a decent product decay into such a sorry state.
Hmmm. I wonder if this inflates the apparent popularity of Firefox (not that I consider that a bad thing, mind you).
After all,
1) it's geeks who tend to both use FF *and* block cookies 2) the FF extension architecture makes it easy to use selective cookie blocking tools 3) FF settings allow automatic cookie deletion each time it exits, unlike IE (=IE6, at least)
All in all, I suspect that (*IF* the subject article is accurate) FF users probably account for a disproportionately large chunk of those "re-visits".
I cannot find a good web link, but I clearly recall reading about experiments conducted over 25 years ago (I think I read about it in Science magazine as a teen) where scientists severed the optic nerves of rats, near the location where the two nerve bundles cross just before entering the opposite sides of the brain. They then reconnected the nerves to the wrong eyes. After initially healing from the surgery, the rats were confused for a while, then fairly quickly adapted and within a short period of time (days to weeks) were acting as if nothing were wrong. A similar experiment was conducted on cats by actually inverting one of their eyeballs: http://www.springerlink.com/content/w4t82x8u734014 26/
Why not just get PHProxy (http://whitefyre.com/poxy/ or http://sourceforge.net/projects/poxy/) and run your own proxy server on your own site? Password protect the directory, and nobody else gets to use it (unless you give them the login). Only you see the logs. All traffic looks like it's coming to/from your site. Not completely anonymous (as others here have noted, traffic is still cleartext and can be traced) but it is a surefire way around most corporate firewalls, as long as you don't mind a few frustrations (like incomplete support for flash, etc.). I've been very happy with it, and it's saved me quite a bit of frustration. I'm sure there are other similar products that would work just as well, but I like the open source nature of this one.
I may be in the minority here, but I do have kids. When my 9-year old discovers whatever passes for MySpace at the time we begin to give him access to the web, he's not going to be using it independently of the direct oversight of my wife and myself. He won't be freely using any other web site, for that matter. His right to absolute privacy begins only when he moves out of my house, 9 years from now. If he insists that he is not going to tell me his password, I expect we'll start taking away privileges such as his internet access; if he insists on abusing our trust by using such sites outside our home, other privileges will begin disappearing accordingly.
This is no different than our current approach to discipline (which by the way is apparently working well): his rights currently extend only to being fed and clothed and healthy. His privileges (including toys, visits with friends, computer games, television, etc.) are given in direct proportion to his responsibility. As he acts responsibly, they expand. As he abuses our trust, they contract until he rebuilds our trust.
You may ask, how will you monitor his activities away from home? Naturally we're still figuring that out, but we already have a good start when he visits friends' houses, where he already knows that we expect him to follow our home's rules. For example, he knows (and obeys) our restrictions on what television he may watch, or video games he may play; we verify his obedience with parents. I expect our monitoring will include frequent vanity-Googling-by-proxy - searching for his name, and seeing what pops up. I also expect it will include a healthy dose of two-way trust. He already knows that he can trust us, and that we have his best interests in mind, and we will work together with him to build an appropriate presence online, as part of his responsible upbringing. As attentive parents, I also fully expect that we'll have a very good idea of his avatar choices and will be able to find them on any popular sites. Furthermore, since his rights to privacy don't yet exist, we will not hesitate to install keylogging and screenshot software on his computer, which will continue to live only in the common family room, will continue to be locked to system changes, and let him know that we monitor everything he does - just like we already often listen to his phone calls with less-responsible friends, and we make sure both parties know that we're listening. This is all part of parenting. I would never turn him loose in a city by himself, and letting him loose online is no different.
I'm quite certain that this post will generate some "are you nuts" or "what kind of fanatic are you" replies. Yes, I am a fanatic, in that I'm absolutely convinced of my beliefs (including trusting that God will change my mind if I'm wrong). I am raising my children according to my own beliefs, and teaching them everything I believe, because honestly, if I didn't believe it enough to pass it on to my most dearly valued family, that would show that I didn't really believe it.
>It's "a******* with access to microphones" that sell. "Political Radio Shows"
>these days are to "intelligent discourse" as "Professional Wrestling" is to
>"Combative Sports". Rush Limbaugh was not popular because of his knowledge of
>political matters (which he may well have had), he was popular because he made
>controversial and obviously inflammatory statements on the air. Apparantly, he
>was better at it than Al Franken.
I have been listening to Rush for about 10 years. I can tell you with a great deal of experience that people listen primarily BECAUSE they don't get his viewpoint on the mainstream media (MSM) that existed before he came around. Frankly, 3 to 20 million daily listeners (depending on who you believe) wouldn't stick around one person that long just for the hijinks. And it's those listeners who will be lobbying their congresscritters to kill this legislation.
Contrary to your assertion, everyone that I know who ACTUALLY listens to Rush (and I personally know dozens) thinks that he makes high quality arguments that speak truth, and that the average MSM folks are blathering idiots who desparately need to be countered. Sure, we enjoy his hyperbole, and frankly it's refreshing to hear SOMEBODY tease the liberals mercilessly, but that's secondary to wanting to hear what we believe to be the truth.
And before you go ranting about me and my friends being a bunch of hicks, let me point out that I live in a strongly blue state, with a middle to high income, flight test community of military pilots and scientists and engineers who uniformly have one or more college degrees, plus a fair mix of Walmart-shopping wage earners with high school diplomas. In short, it's not exactly average red state stuff.
So get off your high horse about Rush. We conservatives (some of whom DO read/. despite appearances to the contrary on THIS thread) realize you think Rush is a flaming looney, and Fox News is a bunch of conservative nutjobs, and all creationists are idiots. But that's not any more a realistic assertion than the same assertions about liberals. Both sides are rational, thoughtful individuals with a different view of the same data. Get over it and stop insulting each other. Find a way to discuss the issues, not the flames.
I see a lot of angst in this discussion without a lot of careful thought. (Hey, this IS/. after all... I shouldn't be surprised.)
The performance of these bulbs does vary ***greatly*** with the orientation of their installation.
As a personal example, I bought some CFLs for my parents' house and installed them base-up in overhead recessed fixtures. They were very understandably unhappy with the startup time - almost a minute of dim light in a kitchen is very unacceptable. But those same bulbs, base-down, were fine in other places in the same house. If I'd thought about it ahead of time, we could have purchased CFL "instant-on" bulbs and gotten much improved performance in the recessed cans.
CFLs use various types of gas mixtures, and some use drops of liquid mercury like other big fluorescents. If it's a liquid mercury bulb, it takes a short time to evaporate all the mercury when it's first powered on. In this situation, a base-down bulb will probably brighten faster than a base-up bulb, because the drop of mercury will initially be condensed near the emitter coils. The so-called "instant on" CFLs use a different, non-condensing gas mixture.
Also, the brightness profile may have some effect on bulb lifespan: instant-on bulbs may last a shorter time for various reasons. If you're willing to tolerate a slower warmup, you may pay less over the long run for bulb replacement.
Moral of the story: there are reasons for these differences, and you can use those differences to your advantage, IF you're willing to think thru the data and specs a bit. Don't toss the baby out with the bathwater just because the "Duh, CFLs are good, heh heh heh" line isn't the whole answer.
This isn't a big step for the Navy or Marine Corps.
The NMCI system already requires all users (laptop AND desktop) to log in via a smart card which carries several encryption certificates (among many other things, including personnel data, med history, etc.).
Also, the drives are NTFS formatted, and each user's Docs and Settings directory is locked - you cannot view anyone else's directory without admin privs. Not encrypted, but at least prevented from casual view.
So it's not going to require any extra steps, I imagine, for NMCI users - just a yet-slower computer as it deals with encryption.
Of course the card itself isn't enough to log in - you still need to enter a memorized password. Interestingly, however, the code is purely numeric - a PIN - and unlike the passwords used prior to the smart card, they (so far) have not been required to be changed regularly. Hmmm. A security hole? So it is at least three-factor security: access to the machine, a valid smart card, and a matching PIN. And there is hack-prevention: if you get the PIN wrong three times, the card is locked pending a visit to the card reset office where you must have a separate photo ID to get it unlocked.
This month, the NMCI folks locked down Outlook to prevent use of all non-text email (at least, by regulation; you can still work around it but it's a security violation), to limit the impact of trojan HTML content. Guess we're back to Pine.
No, in Ender's Game, Ender and his fellow soldiers were sending commands via the ansible to other men actually piloting ships. I don't believe the story ever discusses sending drones. As a matter of fact, one of the reasons Ender is so affected by what has happened is that he didn't realize that all those "games" were killing real humans with each of his commands. It wasn't until a bit later that he was affected by the thought of having committed genocide.
>The platters have (per platter) a much smaller edge, so they're going to get less friction from the air.
Not failed physics... this is a flawed analysis.
There are a few different types of drag (I am an aerospace engineer). The relevant one in this case is caused by the surface of the platter, not the edge. Remember, the edge is really acting as if it were stationary - it's not moving the disc laterally thru the air, so the edge is irrelevant. Instead, the disk surface moving past the air drags some of the air with it - this is sometimes referred to as surface drag, or skin friction. No matter how smooth the surface is, moving it thru a "fluid" (such as air) causes shear in the fluid - the fluid closest to the surface is motionless, and the speed builds up as you move out away from the skin. This is called a "boundary layer". This layer can be smooth-flowing ("laminar flow") or rough (turbulent). Smoother skin means laminar flow. But there's STILL drag, no matter how smooth the surface.
So making thinner disks and using more of them means MORE drag, not less.
Actually in this case, however, the motor can be sized DOWN, despite higher operating drag, because the largest power usage comes from spinning up the disc package - and a set of lighter disks will require less power to spin up. Very little power is actually used to keep it spinning, despite the drag.
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I worked on a Navy jet upgrade about 10 years ago. It was a project to replace an antiquated (read that as "wire-wrap technology") autopilot computer with a brand-new, spiffy, fully digital autopilot computer. Of course, just like the B-2, it had to be a form/fit replacement.
I was shocked when, at the first design review, the contractor said they would be using an 80286 as the CPU. Remember, this is 1995. The 80286 was introduced in 1984. By 1995, the Pentium was the standard. So of course I asked "Why use such an older processor, when a newer one would be much much faster?"
Their answer was essentially one word.
HEAT.
The 286 had perfectly adequate processing power to run the fairly simple algorithms needed for autopilot and related functions, including all the error detection and fault logging, as well as the required 2x of government-mandated growth allowance (you MUST use less than 50% of clock times in your design). Using anything more high-powered would generate more heat (which must be dissipated somewhere in the closed environment), and use more current. On a 1960's era airplane, with Kapton wiring and its risk of insulation fires, and its limited power generation ability, you don't toss in higher heat and power requirements without VERY good reasons.
The result turned out to be perfectly adequate, and a vast improvement over the original design.
Let me toss out another interesting statistic. From what I remember from a recent brief, Boeing is right now delivering upgrades to its commercial airline fleet autopilot/navigation computers with 32Mb of data storage installed for the navigation database. Just 32Mb. That's what you're sitting behind in every Southwest or United or American flight you enjoy. With memory so cheap, why not put more in? Same logic, same ideas: for commericial and military programs, you don't overbuild a device just because you can. You'd better have a REALLY good reason to make a change.
We geeks tend to forget that overclocking and water-cooling and 8Gb RAM and 2-TB hard drives are thousands of times overkill for very many purposes.
>I thought /. kids were smarter than this.
They are. That's why they want a process which preserves every little bit of audio goodness possible under the already less-than-CD-quality, marginal-bitrate-file circumstances. They'd rather NOT use a process which takes the files and transcodes them TWICE, thus compromising the audio quality even further.
They may not be audiophiles, but they DO prefer to save what little quality they started with.
>Assuming that the satelite was hiding in the shadow of some larger
>vessel and not exposed to sunlight heating it up to a few hundred degrees.
Okay, I'll concede the point that it won't be -273C... but it also won't be a few hundred degrees HOT, either.
Thermal management in a satellite is a BIG issue, probably the single most critical element of external satellite design. I read that unprotected vehicle temperatures range from -120 to +180 deg (I'm not sure if this is C versus F, but it's probably deg C).
http://books.google.com/books?id=bzD4_hxupI4C
Most satellites are constructed with highly-reflective films over everything NOT covered by a solar panel, specifically to AVOID excessive warming in any one spot, while also covered with thermal blankets to retain internal heat, so as to minimize the amount of valuable electrical power which must be diverted to heating units.
The sunward side may be warmed despite the reflective films, but the OPPOSITE side of the satellite sees vacuum and absolute zero, thus radiating away heat very quickly. Furthermore, the satellite is dead, thus uncontrolled and spinning at least slowly, so any given side will be radiating away the solar heat every time it faces away from the sun.
And most orbits, it's spending about 45 minutes in total blackness, thus radiating away any external heat buildup.
The propellant tanks are usually fairly well insulated, preventing rapid heat transfer, and they're typically surrounded in structure to help both retain a working temperature and avoid excessive thermal cycling leading to tank overpressure and explosion. In fact, one document I found describes a satellite design that deliberately uses solar energy to keep the tank thawed - but this is a design that requires pointing the satellite in a precise angle to function, and still includes features to keep it cool enough. So a tumbling satellite with this design would have a far colder tank than required for normal operation.
So on balance, I believe it's safe to assume that the propellant would be quite well frozen, thus leading to a 3 foot wide ball of very hazardous "ice" wrapped in steel making its way thru the atmosphere to a largely intact landing.
>Still wanna try to claim that tank would survive reentry?
Absolutely I would claim that.
Hydrazine is a solid below about 1 deg C. This was a dead satellite. No heat, no power supplies. In other words, you have an insulated pressure vessel (fairly well-built) containing 1,000 lb of hydrazine ice at roughly -273 deg C. That's a LOT of thermal mass; the ice inside the tank would absorb a lot of the reentry heat, preventing the metal from melting for quite some time. Did you ever do that science experiment where you try to burn a paper cup containing water? Doesn't work until you boil off all the water. Same thing here, but we're talking about metal which is even more thermally conductive than paper.
Furthermore, a lot of the surrounding structure must ablate or melt away before the tank can be directly affected by the reentry.
Also, in case you want to compare a thousand-pound meteorite to this satellite: a satellite does not orbit as fast as your typical meteor reentry speed, so you cannot compare the reentry energy to a typical meteorite ablation rate.
If you need proof, consider that hydrazine tanks from the Space Shuttle Columbia accident DID impact in some Florida woods. They were NOT cold-soaked at absolute zero for two years - they were prepped for flight, heated, etc., and wrapped in far more spacecraft structure than this satellite. And they were not full, like these tanks were. That should demonstrate the reality of this risk.
Want to see a photo of a far smaller hydrazine tank, and some other unidentified tanks, AFTER they landed in Florida? http://www.io.com/~o_m/clfaq/s3.htm
http://www.io.com/~o_m/clfaq/images/debris_shots/tank1.jpg
http://www.io.com/~o_m/clfaq/images/debris_shots/tank2.jpg
http://www.io.com/~o_m/clfaq/images/debris_shots/tank3.jpg
Most interestingly, these bits of spacecraft look completely uncharred, unmelted, almost new except for a lack of paint.
>So if it costs $10,000 per pound to put something into space, why don't we gather
>these dying satellites and dock them to the ISS for spare parts rather than
>blowing them up? They could also be sent to the moon for parts in future missions.
>Perhaps this is technically infesible or the cost of doing so would be more than
>the parts are worth in space?
Lots of reasons it's both infeasible and impractical.
You cannot simply "gather" a dying satellite. It takes enormous amounts of energy to change the orbit of a big chunk of metal. Either the satellite must do it (which it can't because it's either dead or low on fuel), or you must carry up enough fuel to go reach the satellite, then maneuver back to wherever you want it to go. At $10K/lb, you would spend far more on carrying that fuel to orbit than the cost of the satellite and its parts.
Bear in mind that satellites orbit in a spherical shell between roughly 90 and 23,000 miles above the surface. Lots of empty space must be transversed to reach a given satellite. It's not like they are just parked next to each other, waiting to be collected. And orbits are in all different directions, requiring even more fuel to match orbits.
And no, the technology wouldn't be useful. It's not like a giant Lego collection; parts are highly customized to the exact application. Also, over time, metal in space tends to weld itself together; it's often very difficult to disassemble parts that have been exposed to vacuum for years (ask the Shuttle astronauts who have helped service the Hubble). Furthermore, any kind of disassembly must take place in weightless vacuum - a real hassle itself - and deal with residual toxic propellants, power supplies, even small radioactive power supplies.
Nope, a satellite is essentially expendable, and always will be (at least until we figure out zero point energy, or some other equally miraculous "free" energy solution).
>Long and short of it: it is unproven.
... and many many more links... just Google "laser missile jammer". Yes, many of the links describe in-process contracts, but others of these systems are currently fielded on many aircraft. Two aircraft in particular are Air Force One and Marine One. It's about time for these technologies to filter down to the civilian world.
Ummmm... nope. These types of systems are currently being used by US military aircraft currently operating in Iraq and Afghanistan. They regularly save the lives of our servicemen. They are quite well proven. For example:
http://popuplace.com/index.php?ind=media&op=file_view&iden=2391
http://www.topix.com/business/aerospace-defense/2007/06/laser-missile-jammer-to-protect-marine-corps-helicopters
http://209.157.64.200/focus/f-news/1844532/posts
... but I do write music. Sorry, I have a real problem with Congress taking away my own rights to my own music after just five years. That's a flash in the pan, in terms of my life; for crying out loud, I don't even get some of my own music finished in that short a time. I don't sell my music (or at least, nobody's bothered to buy it yet), but I have a problem with someone saying they can appropriate my own creative works that quickly.
There are other solutions than this that have NOT been tried yet, because the lobby is too big for Congress to act. And this would suffer the same fate.
Actually the helicopter was at 500 feet ALTITUDE. If it was directly over the laser, nobody would have seen the beam. So in reality, the helo was probably at least a half mile (slant range) from the laser. Given this, the beam was probably five or six feet wide - easy to get both aircrew at once.
For all the "oops, it was an accident" types, consider that anyone using a laser beam outside at night is doing it TO LOOK AT THINGS - you will NOT miss an airplane with its flashing beacons and strobe lights. This kind of thing is NOT an accident.
Also, it's very unlikely that the brief flash caused by crossing a stationary or wandering beam would have been a real problem, compared to several seconds of targeted exposure, during which the natural tendency is unfortunately to look AT the beam (and thus increase the risk). So it makes perfect sense to me to prosecute in this case.
> Then he tosses the laptop, reports it, and then he has a perfectly legal excuse
> as to why he's holding kiddie porn on his computer.
Really now... think about that for a minute... If he DOES report it, don't you think the authorities will take a pretty careful look at his equipment, too? Do you seriously think any addict would go anywhere near this process? Not a chance.
Call BS if you must, but not on that point.
It seems to me that the BIGGER risk here is the chance of being unfairly nailed yourself for legitimately reporting the material. This law says you must submit not only the report but also the offensive material. Doesn't that make you potentially liable for both possession and interstate transmission of the very offending material itself? Sure, you could argue (correctly) that you were following the law, but how can you prove it? It would be a snowy day in August before I'd want to be part of THAT reporting process, thank you very much.
This whole law smacks of danger on all sides, even if you believe that there can be reasonable limits on freedom.
I'm seeing a lot of comments here focusing on the overly intelligent criminal.
Problem is, MOST of the car chases you see on TV are:
1) Drunks or druggies, not in their right minds
2) Car thieves (not riding their own wheels anyway)
3) Suicide-by-cop idiots, who WANT to be killed, not stopped safely
Okay, fine, the really intelligent criminals might be able to prevent themselves from being stopped this way. Granted. But the really intelligent criminal is NOT going to find himself involved in a car chase anyway, because he's too smart to let that happen.
Frankly, I've wondered for years why they didn't do something like this. Or mount a piton system in the front of your average police cruiser, that could pneumatically or explosively shoot out a grappling hook that stabbed thru the trunk of the fleeing vehicle and drag it to a stop. Most police chases involve very close pursuit at reasonably slow speeds - so why not nail the guy's trunk and drag him to a halt, instead of trying to PITT him and risking all kinds of damage to both vehicles?
So I'm happy to finally see this kind of technology under real development.
And for those of you who are worried about innocent bystanders, remember that EMF falls off as the square of distance. Whatever power kills a car 45 feet away (100 joules) probably won't even blip an engine 450 feet away (1 joule). There will be plenty of chances in most car chases to SAFELY utilize these things.
https://answers.google.com/answers/threadview?id=409268
Oh, please, people.
Think rationally for a minute. What benefit can a supposed micro-UAV provide in this kind of gathering? Why on earth would the US Government "out" itself in a situation like this? Any halfway intelligent spy agency (as I believe ours ARE, regardless of any opinions about their oversight) would hold technology like this for really really really important, and otherwise impossible to penetrate, situations, and especially situations where the technology would not be seen (like nighttime).
Think about it. Big gathering. Public place. Plenty of surrounding buildings. No limits on attendance. Hundreds of people waving around cell phone cameras. Recording devices allowed in the area. If you want pictures of who's there, just pretend you're a protester really happy about the size of the crowd, and wander around like an idiot with your (looks like a) $50 CVS disposable video camera, blatantly taking pictures of everything and everyone in sight. You'll get much closer, more stable, clearer pictures, and nobody is the wiser. Why try to hide?
This doesn't pass the basic sniff test. Not many conspiracy theories do, when you really think about them rationally.
I'm a geocacher, and I like to hunt "urban micro" caches - tiny containers hidden in highly-trafficked areas. Hunting for them is not unlike being a spy, I think, and I've found that trying to sneak is very ineffective. If you look like everyone else, and act like everyone else, you can hide your actions a LOT better than if you LOOK like you're trying to hide. Same thing here: it makes a lot more sense to blend in, than try some super-fancy new technology which WILL be noticed.
Incidentally, I am NOT denying these things might exist. But I am pretty certain that if they are being used, it's in much more carefully and wisely chosen scenarios.
In related news, no Slashdotters posted a "First Post" response for a matter of several hours. This never-before seen phenomenon was tentatively attributed to the entire Slashdot community immediately joining the virtual search.
*grin*
I also purchased the full version of MMJB a few versions ago - I think it was version 8 - because I really liked it, much better than WinAmp or other (at the time) available alternatives. I even recommended it to family, and on my music-related website.
Version 9 had some nice new features, together with some added annoyances and nags. I was still sort of happy.
But then version 10 came out... and within weeks I'd uninstalled it and gone back to version 9 (I'm glad I keep copies of my downloaded install programs). Way too many bugs, much slower, many new added nags even in a paid version. And many of the real obvious bugs in version 9 were still present in version 10. Geez, guys, fix the product FIRST, and THEN add features!
But even dealing with version 9 was no longer quite so painless - I now knew that the problems in version 9 would never be fixed. And when we bought an iPod, and had to install iTunes, we never looked back... pretty soon both of our PCs were running iTunes, sharing music with our Roku SoundBridge and syncing our three iPods...
It was a real shame to watch such a decent product decay into such a sorry state.
Hmmm. I wonder if this inflates the apparent popularity of Firefox (not that I consider that a bad thing, mind you).
After all,
1) it's geeks who tend to both use FF *and* block cookies
2) the FF extension architecture makes it easy to use selective cookie blocking tools
3) FF settings allow automatic cookie deletion each time it exits, unlike IE (=IE6, at least)
All in all, I suspect that (*IF* the subject article is accurate) FF users probably account for a disproportionately large chunk of those "re-visits".
I bet M$FT hates that.
Heh.
When the earth's magnetic field polarity finally swaps, these folks are going to be SO annoyed.
http://www.newscientist.com/article.ns?id=dn4985
For the rest of us, it's a good thing that our GPS receiver belts will still point north.
*grin*
I cannot find a good web link, but I clearly recall reading about experiments conducted over 25 years ago (I think I read about it in Science magazine as a teen) where scientists severed the optic nerves of rats, near the location where the two nerve bundles cross just before entering the opposite sides of the brain. They then reconnected the nerves to the wrong eyes. After initially healing from the surgery, the rats were confused for a while, then fairly quickly adapted and within a short period of time (days to weeks) were acting as if nothing were wrong. A similar experiment was conducted on cats by actually inverting one of their eyeballs:4 26/
c c6/) 4%3A1%3C6%3AMLOCIH%3E2.0.CO%3B2-Y
http://www.springerlink.com/content/w4t82x8u73401
A scientist named George Stratton, as the parent post (and I now see another post below) mentioned, conducted similar experiments on humans with inverting prism glasses, and had similar results. Here is another link to a description:
http://www.springerlink.com/content/w9n3wk699uu5v
And an experiment with lateral offsets to vision, in children (probably related to how eyeglasses affect our brains and our hand-eye coordination):
http://links.jstor.org/sici?sici=0009-3920(193303
The brain is remarkable.
"Ethanol would be stored in its own tank or compartment and would be introduced by a separate direct-injection system."
This does tend to give new meaning to the term "fuel siphoning". Imagine the fun...
*grin*
Why not just get PHProxy (http://whitefyre.com/poxy/ or http://sourceforge.net/projects/poxy/) and run your own proxy server on your own site? Password protect the directory, and nobody else gets to use it (unless you give them the login). Only you see the logs. All traffic looks like it's coming to/from your site. Not completely anonymous (as others here have noted, traffic is still cleartext and can be traced) but it is a surefire way around most corporate firewalls, as long as you don't mind a few frustrations (like incomplete support for flash, etc.). I've been very happy with it, and it's saved me quite a bit of frustration. I'm sure there are other similar products that would work just as well, but I like the open source nature of this one.
I may be in the minority here, but I do have kids. When my 9-year old discovers whatever passes for MySpace at the time we begin to give him access to the web, he's not going to be using it independently of the direct oversight of my wife and myself. He won't be freely using any other web site, for that matter. His right to absolute privacy begins only when he moves out of my house, 9 years from now. If he insists that he is not going to tell me his password, I expect we'll start taking away privileges such as his internet access; if he insists on abusing our trust by using such sites outside our home, other privileges will begin disappearing accordingly.
This is no different than our current approach to discipline (which by the way is apparently working well): his rights currently extend only to being fed and clothed and healthy. His privileges (including toys, visits with friends, computer games, television, etc.) are given in direct proportion to his responsibility. As he acts responsibly, they expand. As he abuses our trust, they contract until he rebuilds our trust.
You may ask, how will you monitor his activities away from home? Naturally we're still figuring that out, but we already have a good start when he visits friends' houses, where he already knows that we expect him to follow our home's rules. For example, he knows (and obeys) our restrictions on what television he may watch, or video games he may play; we verify his obedience with parents. I expect our monitoring will include frequent vanity-Googling-by-proxy - searching for his name, and seeing what pops up. I also expect it will include a healthy dose of two-way trust. He already knows that he can trust us, and that we have his best interests in mind, and we will work together with him to build an appropriate presence online, as part of his responsible upbringing. As attentive parents, I also fully expect that we'll have a very good idea of his avatar choices and will be able to find them on any popular sites. Furthermore, since his rights to privacy don't yet exist, we will not hesitate to install keylogging and screenshot software on his computer, which will continue to live only in the common family room, will continue to be locked to system changes, and let him know that we monitor everything he does - just like we already often listen to his phone calls with less-responsible friends, and we make sure both parties know that we're listening. This is all part of parenting. I would never turn him loose in a city by himself, and letting him loose online is no different.
I'm quite certain that this post will generate some "are you nuts" or "what kind of fanatic are you" replies. Yes, I am a fanatic, in that I'm absolutely convinced of my beliefs (including trusting that God will change my mind if I'm wrong). I am raising my children according to my own beliefs, and teaching them everything I believe, because honestly, if I didn't believe it enough to pass it on to my most dearly valued family, that would show that I didn't really believe it.
>It's "a******* with access to microphones" that sell. "Political Radio Shows"
/. despite appearances to the contrary on THIS thread) realize you think Rush is a flaming looney, and Fox News is a bunch of conservative nutjobs, and all creationists are idiots. But that's not any more a realistic assertion than the same assertions about liberals. Both sides are rational, thoughtful individuals with a different view of the same data. Get over it and stop insulting each other. Find a way to discuss the issues, not the flames.
>these days are to "intelligent discourse" as "Professional Wrestling" is to
>"Combative Sports". Rush Limbaugh was not popular because of his knowledge of
>political matters (which he may well have had), he was popular because he made
>controversial and obviously inflammatory statements on the air. Apparantly, he
>was better at it than Al Franken.
I have been listening to Rush for about 10 years. I can tell you with a great deal of experience that people listen primarily BECAUSE they don't get his viewpoint on the mainstream media (MSM) that existed before he came around. Frankly, 3 to 20 million daily listeners (depending on who you believe) wouldn't stick around one person that long just for the hijinks. And it's those listeners who will be lobbying their congresscritters to kill this legislation.
Contrary to your assertion, everyone that I know who ACTUALLY listens to Rush (and I personally know dozens) thinks that he makes high quality arguments that speak truth, and that the average MSM folks are blathering idiots who desparately need to be countered. Sure, we enjoy his hyperbole, and frankly it's refreshing to hear SOMEBODY tease the liberals mercilessly, but that's secondary to wanting to hear what we believe to be the truth.
And before you go ranting about me and my friends being a bunch of hicks, let me point out that I live in a strongly blue state, with a middle to high income, flight test community of military pilots and scientists and engineers who uniformly have one or more college degrees, plus a fair mix of Walmart-shopping wage earners with high school diplomas. In short, it's not exactly average red state stuff.
So get off your high horse about Rush. We conservatives (some of whom DO read
I see a lot of angst in this discussion without a lot of careful thought. (Hey, this IS /. after all... I shouldn't be surprised.)
p ?t=104314
The performance of these bulbs does vary ***greatly*** with the orientation of their installation.
As a personal example, I bought some CFLs for my parents' house and installed them base-up in overhead recessed fixtures. They were very understandably unhappy with the startup time - almost a minute of dim light in a kitchen is very unacceptable. But those same bulbs, base-down, were fine in other places in the same house. If I'd thought about it ahead of time, we could have purchased CFL "instant-on" bulbs and gotten much improved performance in the recessed cans.
CFLs use various types of gas mixtures, and some use drops of liquid mercury like other big fluorescents. If it's a liquid mercury bulb, it takes a short time to evaporate all the mercury when it's first powered on. In this situation, a base-down bulb will probably brighten faster than a base-up bulb, because the drop of mercury will initially be condensed near the emitter coils. The so-called "instant on" CFLs use a different, non-condensing gas mixture.
Also, the brightness profile may have some effect on bulb lifespan: instant-on bulbs may last a shorter time for various reasons. If you're willing to tolerate a slower warmup, you may pay less over the long run for bulb replacement.
See the discussion on this link, or google for "cfl base-up brightness":
http://www.candlepowerforums.com/vb/showthread.ph
Moral of the story: there are reasons for these differences, and you can use those differences to your advantage, IF you're willing to think thru the data and specs a bit. Don't toss the baby out with the bathwater just because the "Duh, CFLs are good, heh heh heh" line isn't the whole answer.
This isn't a big step for the Navy or Marine Corps.
The NMCI system already requires all users (laptop AND desktop) to log in via a smart card which carries several encryption certificates (among many other things, including personnel data, med history, etc.).
Also, the drives are NTFS formatted, and each user's Docs and Settings directory is locked - you cannot view anyone else's directory without admin privs. Not encrypted, but at least prevented from casual view.
So it's not going to require any extra steps, I imagine, for NMCI users - just a yet-slower computer as it deals with encryption.
Of course the card itself isn't enough to log in - you still need to enter a memorized password. Interestingly, however, the code is purely numeric - a PIN - and unlike the passwords used prior to the smart card, they (so far) have not been required to be changed regularly. Hmmm. A security hole? So it is at least three-factor security: access to the machine, a valid smart card, and a matching PIN. And there is hack-prevention: if you get the PIN wrong three times, the card is locked pending a visit to the card reset office where you must have a separate photo ID to get it unlocked.
This month, the NMCI folks locked down Outlook to prevent use of all non-text email (at least, by regulation; you can still work around it but it's a security violation), to limit the impact of trojan HTML content. Guess we're back to Pine.
No, in Ender's Game, Ender and his fellow soldiers were sending commands via the ansible to other men actually piloting ships. I don't believe the story ever discusses sending drones. As a matter of fact, one of the reasons Ender is so affected by what has happened is that he didn't realize that all those "games" were killing real humans with each of his commands. It wasn't until a bit later that he was affected by the thought of having committed genocide.
>It would look *stunning* in purple.
y lon_5#Drazi)
No, I think green would be better.
(It's an insider's joke, people.... http://en.wikipedia.org/wiki/Civilizations_in_Bab
>The platters have (per platter) a much smaller edge, so they're going to get less friction from the air.
i f
Not failed physics... this is a flawed analysis.
There are a few different types of drag (I am an aerospace engineer). The relevant one in this case is caused by the surface of the platter, not the edge. Remember, the edge is really acting as if it were stationary - it's not moving the disc laterally thru the air, so the edge is irrelevant. Instead, the disk surface moving past the air drags some of the air with it - this is sometimes referred to as surface drag, or skin friction. No matter how smooth the surface is, moving it thru a "fluid" (such as air) causes shear in the fluid - the fluid closest to the surface is motionless, and the speed builds up as you move out away from the skin. This is called a "boundary layer". This layer can be smooth-flowing ("laminar flow") or rough (turbulent). Smoother skin means laminar flow. But there's STILL drag, no matter how smooth the surface.
Here's a good illustration: http://wright.nasa.gov/airplane/Images/boundlay.g
So making thinner disks and using more of them means MORE drag, not less.
Actually in this case, however, the motor can be sized DOWN, despite higher operating drag, because the largest power usage comes from spinning up the disc package - and a set of lighter disks will require less power to spin up. Very little power is actually used to keep it spinning, despite the drag.