Do you mean "a couple square meters because it's so small" or "a couple square meters because it runs with a hot frame on reentry and only needs to shield the leading edges?
Because it's so small.
Building a complete multistage rocket and expending the energy to leave the atmosphere just to launch a small single-person capsule would be a huge economic waste.
A six-person capsule would be more reasonable. For transfer purposes, you could probably use a capsule smaller than Apollo. Here
is an example of what I'm assuming. This would require a tiny fraction of the heat shield of the shuttle.
There basically are three major cases of nuclear-power on spacecraft: nuclear-powered liftoff stages, nuclear reactor powered deep space drives, and radioisotope thermal generators (RTGs) for electrical power. I'm not sure which incident you're referring to, but it's probably an RTG (which are very common, and which is not a nuclear fission reactor). The Soviet Union put a few dozen actual fission reactors in orbit. (A couple of these accidently reentered, and the are still in orbits that will decay within a few hundred years). The US has only put up one or two test fission reactors.
RTGs are potentially worrisome, but the fuel can be heavily protected as you mention. However, they are most often used as electrical power generators, not propulsion systems. RTG fuel is nasty stuff even before the RTG is put in use.
Fission reactors (not RTGs) that are not activated until orbit really aren't that much of a big deal on launch because they can be fueled with fresh U-235 which really isn't very radioactive or dangerous until you switch the reactor on and start generating fission products. The only issue is if they don't make it out of earth orbit and eventually the orbit decays. Powering an ion drive with one of these to do missions to the outer planets might make a lot of sense.
The scariest nuclear propulsion case a the high-thrust rocket used for the first or second stage liftoff. These have been successfully tested on the ground but never flown. They basically pack all of the power of a large commercial nuclear plant into a package only a few feet in diameter. They run full blast with little or no shielding. There is no way to heavily shield or isolate the fuel without impeding the huge heat transfer rate that is necessary to propel the massive amounts of propellant gas out the rocket.
These high-thrust rockets operate at the very fringes of material strength capabilities and probably have a high probability of disintegrating, spewing partially spent fuel and waste into the atmosphere. That's one reason that they've never been actually used.
Expensive compared to the job they do? nope. they are miuch cheaper than an ablative heat shield.
Then again, a reasonable human launch system would only need a couple of square meters of heat shield in the first place, so the relative cost per square meter would be insignificant.
Given a choice, I'd pick a nice monolithic low-tech ablative shield over a glued-on patchwork of finicky tiles with thousands of individual potential points of failure.
Now, anywhere else on the web, you'd expect that the link in there would point to further information on that specific criticism of Wikipedia. But, instead it points to a page defining the term "critic"! How useless is that?
If that bothers you, why don't you go ahead and change the link?
Money spent on sports, cars, stereos, TVs, wine, restaurant meals, movies, snacks, games and vacations could also be better spent elsewhere. Am I correct to assume that you have completely forsaken all of these frivolities in favor of helping your fellow man?
Its main effect is to take out all the small/medium players and polarize the market into FOSS and the commercial giants
Ummm... just about every market consolidates into giants as it matures. I doubt that it has much to do with FOSS software. Did it take the Free-and-Open-Source-Car movement drive all of the small automobile manufacturers out of the market? Nope, it happened all on its own.
By the same token, Intel probably wouldn't be here in their current form if it weren't for AMD and the other X86 clone manufacturers. The PC industry would be reluctant to stick with a CPU architecture that is only available from a single source. (In fact, Intel originally licensed AMD to produce 8086s because IBM insisted on having a second source as a condition for choosing the CPU for its new PCs.)
I think it works with VoIP, but it's so small and light I don't know where the computer is. There's a DSL wire so it must not be wireless. Maybe it's VoIP over DSL? Yes, that's probably it.
A while back I read an article about some jackasses with too much time on their hands. It seems they built a circuit board to transport *TCP/IP* over one of these Phone boxes by actually modulating the packets onto the analog audio signal! They must have got the idea from one of those April fools day RFCs or something.
If Apple hadn't stolen/borrowed the GUI from Xerox, it might never have seen the light of day.
That's right... nobody else would ever have independently come up with the GUI concept. We'd still all be sitting around thinking "Gee... this terminal-based interface sucks. There hasn't been any new UI designed in over 30 years. There must be a better way, but nobody seems to be able to think of one! Oh well."
so, you're telling me that dumping 500 billions tons of land mass into the ocean wouldn't cause water levels to rise???
Of course it will rise. Do the math: 500e9 tons of rock ~= 100e9 m^3; ocean area ~= 3.6e14 m^2 -> water level rises about 0.27 millimeters. A measurable amount, but well less than 1/1000 of what they're speculating that melting glaciers might cause.
Why would anyone want to use an Intel chip or an AMD chip is beyond me. All that backwards-compatible legacy circuitry eating up real-estate on the die.
The legacy circuitry allows the chip to use an old-school compact instruction format, thus saving die real-estate in the instruction cache. The caches on modern chips are much bigger than the logic core, with or without legacy circuits.
Intel's IA64/VLIW architecture is much more technologically impressive than AMD64's.
It might look impressive on paper, but in the real world, other than providing a good brain teaser for compiler writers, it hasn't been very impressive at all.
People will need news papers for some time to come.
The funny thing is that you can buy blank newsprint to pack your dishes for moving without staining them with ink. At the couple of places I've seen it, it cost many times as much per sheet as printed newspapers.
Clearly the newspaper industry is providing a major value to the general public by providing a low-cost alternative to unprinted newspaper stock. I think that they'll do just fine.
Radar loses out on the resolution to optical before you even get to the moon's orbit.
However, active radar might give you the exact distance to the object. This could supplement the optical data, which just gives you the direction to the rock at each point in time.
Maybe the software industry would have creaked along with heavy patents, but I think that the average software product would have needed far more resources put into licensing negotiations, license accounting and pointless evasive coding techniques than into actual productive development. The bottom line is that people would have paid more for fewer features.
I disagree that forcing everyone to be different from any previous products is inherently good. If everybody has to invent a new blue-sky user experience for every single product, user training costs would go through the roof, and compatibility between products would be minimal or nonexistent.
Virtually all your examples were overcome by companies licensing said patents, something likely possible in any patent system.
Assuming the patent holder deigns to license the patents rather than using them simply to protect their market position while they sit on their laurels.
The US Patent system, had it worked correctly, would have saved a number of budding software companies from Microsoft.
Yes, if software patents had been widespread from the start, there would be no Microsoft as we know it. In fact, we would just be entering a golden age of computing right now:
The Visicalc spreadsheet patents would have just expired a few years ago, allowing Lotus-123 to get started.
The Xerox GUI patents would have recently expired, so Apple could have introduced the Mac at the turn of the millennium.
The id first-person-shooter patents would be expiring in a few short years from now. The whole gaming industry would be abuzz with anticipation of 3D games from more than one vendor!
We would have only about 8 more years of paying royalties to CERN for browsing the web. In a few years, software vendors would be starting to plan features for a long-awaited successor to the Mosaic browser.
Linux would just now be able to host the kinds of server tasks that were common in the mid 80s, and more capabilities would become legal each year!
Driven by the demands created by the burgeoning patent-protected software market, Intel would be introducing the Pentium I just about now.
Wrong. x86 is an aging, bulky CISC architecture. ppc is a leaner RISC-based architecture.
You do realize that all modern X86s use a RISC-like core, and the PPC architecture has so many bells and whistles that it barely qualifies as RISC at all? The X86 instruction code translation layer adds overhead, but this overhead has remained constant as overall CPU gate count has increased exponentially. It is no longer a major factor.
Power levels are largely determined by silicon process details, cache size and marketing-driven architecture decisions such as cranking GHz at the expense of IPC (which are all orthogonal to which particular instruction set is presented to the programmer).
Slashdot Mirror
Because it's so small.
Building a complete multistage rocket and expending the energy to leave the atmosphere just to launch a small single-person capsule would be a huge economic waste.
A six-person capsule would be more reasonable. For transfer purposes, you could probably use a capsule smaller than Apollo. Here is an example of what I'm assuming. This would require a tiny fraction of the heat shield of the shuttle.
RTGs are potentially worrisome, but the fuel can be heavily protected as you mention. However, they are most often used as electrical power generators, not propulsion systems. RTG fuel is nasty stuff even before the RTG is put in use.
Fission reactors (not RTGs) that are not activated until orbit really aren't that much of a big deal on launch because they can be fueled with fresh U-235 which really isn't very radioactive or dangerous until you switch the reactor on and start generating fission products. The only issue is if they don't make it out of earth orbit and eventually the orbit decays. Powering an ion drive with one of these to do missions to the outer planets might make a lot of sense.
The scariest nuclear propulsion case a the high-thrust rocket used for the first or second stage liftoff. These have been successfully tested on the ground but never flown. They basically pack all of the power of a large commercial nuclear plant into a package only a few feet in diameter. They run full blast with little or no shielding. There is no way to heavily shield or isolate the fuel without impeding the huge heat transfer rate that is necessary to propel the massive amounts of propellant gas out the rocket.
These high-thrust rockets operate at the very fringes of material strength capabilities and probably have a high probability of disintegrating, spewing partially spent fuel and waste into the atmosphere. That's one reason that they've never been actually used.
Then again, a reasonable human launch system would only need a couple of square meters of heat shield in the first place, so the relative cost per square meter would be insignificant.
Given a choice, I'd pick a nice monolithic low-tech ablative shield over a glued-on patchwork of finicky tiles with thousands of individual potential points of failure.
They can be effective. We've just seen that they can also mislead you into starting an expensive war by mistake.
If that bothers you, why don't you go ahead and change the link?
Money spent on sports, cars, stereos, TVs, wine, restaurant meals, movies, snacks, games and vacations could also be better spent elsewhere. Am I correct to assume that you have completely forsaken all of these frivolities in favor of helping your fellow man?
Ummm... just about every market consolidates into giants as it matures. I doubt that it has much to do with FOSS software. Did it take the Free-and-Open-Source-Car movement drive all of the small automobile manufacturers out of the market? Nope, it happened all on its own.
These rovers are traditionalists who choose to keep the customs of their homeland, so they still celebrate the earth holidays.
By the same token, Intel probably wouldn't be here in their current form if it weren't for AMD and the other X86 clone manufacturers. The PC industry would be reluctant to stick with a CPU architecture that is only available from a single source. (In fact, Intel originally licensed AMD to produce 8086s because IBM insisted on having a second source as a condition for choosing the CPU for its new PCs.)
A while back I read an article about some jackasses with too much time on their hands. It seems they built a circuit board to transport *TCP/IP* over one of these Phone boxes by actually modulating the packets onto the analog audio signal! They must have got the idea from one of those April fools day RFCs or something.
"5" is mine, free and clear. All mine!
5
That's right... nobody else would ever have independently come up with the GUI concept. We'd still all be sitting around thinking "Gee... this terminal-based interface sucks. There hasn't been any new UI designed in over 30 years. There must be a better way, but nobody seems to be able to think of one! Oh well."
Of course it will rise. Do the math: 500e9 tons of rock ~= 100e9 m^3; ocean area ~= 3.6e14 m^2 -> water level rises about 0.27 millimeters. A measurable amount, but well less than 1/1000 of what they're speculating that melting glaciers might cause.
The legacy circuitry allows the chip to use an old-school compact instruction format, thus saving die real-estate in the instruction cache. The caches on modern chips are much bigger than the logic core, with or without legacy circuits.
If you slapped 6MB of cache on a Z-80, it would get high specmarks too.
It might look impressive on paper, but in the real world, other than providing a good brain teaser for compiler writers, it hasn't been very impressive at all.
The funny thing is that you can buy blank newsprint to pack your dishes for moving without staining them with ink. At the couple of places I've seen it, it cost many times as much per sheet as printed newspapers.
Clearly the newspaper industry is providing a major value to the general public by providing a low-cost alternative to unprinted newspaper stock. I think that they'll do just fine.
However, active radar might give you the exact distance to the object. This could supplement the optical data, which just gives you the direction to the rock at each point in time.
I disagree that forcing everyone to be different from any previous products is inherently good. If everybody has to invent a new blue-sky user experience for every single product, user training costs would go through the roof, and compatibility between products would be minimal or nonexistent.
Assuming the patent holder deigns to license the patents rather than using them simply to protect their market position while they sit on their laurels.
Yes, if software patents had been widespread from the start, there would be no Microsoft as we know it. In fact, we would just be entering a golden age of computing right now:
The Visicalc spreadsheet patents would have just expired a few years ago, allowing Lotus-123 to get started.
The Xerox GUI patents would have recently expired, so Apple could have introduced the Mac at the turn of the millennium.
The id first-person-shooter patents would be expiring in a few short years from now. The whole gaming industry would be abuzz with anticipation of 3D games from more than one vendor!
We would have only about 8 more years of paying royalties to CERN for browsing the web. In a few years, software vendors would be starting to plan features for a long-awaited successor to the Mosaic browser.
Linux would just now be able to host the kinds of server tasks that were common in the mid 80s, and more capabilities would become legal each year!
Driven by the demands created by the burgeoning patent-protected software market, Intel would be introducing the Pentium I just about now.
You do realize that all modern X86s use a RISC-like core, and the PPC architecture has so many bells and whistles that it barely qualifies as RISC at all? The X86 instruction code translation layer adds overhead, but this overhead has remained constant as overall CPU gate count has increased exponentially. It is no longer a major factor.
Power levels are largely determined by silicon process details, cache size and marketing-driven architecture decisions such as cranking GHz at the expense of IPC (which are all orthogonal to which particular instruction set is presented to the programmer).
It's possible that the extra fuel weighs less than heat-shielded wings and a tail plus wheeled landing gear.
You wanted them to launch health, environment, education and alternative fuels into space on an unproven rocket?