I would like to see the money we are spending on the international space station go to creating an international moon-base. If we create two compartments, one for humans and one for other animals (like Biosphere), we would be able to study how the radiation of space affects living things, what can adapt, and what can't, etc.
The ISS is still a pretty necessary first step. It gives us a place nearby where we can test most of our habitat technology without being out of rescue range, and we can study radiation effects just as easily there as on the moon. It also lets us further study the effects of microgravity, which we'll need to have a very good handle on before attempting a Mars mission (for most craft designs I've heard about, at least).
The ISS is also an excellent launch platform and docking station for lunar-orbit craft. This would let you use ion- or plasma-drive craft that wouldn't be able to land to move easily between earth- and lunar-orbit and back, establish a permanent space station around the _moon_, and in general make the logistics of earth/moon travel and lunar exploration/colonization much easier.
Keeping the ground-to-orbit steps of lunar missions (on both ends) separate from the orbit-to-orbit step makes it a *lot* easier to plan lunar surface missions, gives them a greater chance of success, and makes it easier to recover from catastrophes at most stages.
My favorite theory is that the other two planets were actually much more suited to whatever form of life originally seeded them, the Earth being just a little different in sunlight penetration and a few chemical balancing acts. The other two planets therefore flourished quickly, the simple lifeforms used up the resources that were available quickly, and this caused, slowly at first, a change in climate. But once that change was set in motion it never ceased until we end up with the two completely unlivable (by our standards) planets and the completely habitable (again by our standards) Earth.
I don't think we need to invoke magical "life using up resources" scenarios to explain climate changes on Mars and Venus. Their own structure and location does this well enough.
For Mars: Mars is large enough to hold a thick atmosphere for a while, but small enough that it won't hold it over geological time. It started with composition similar to most of the inner solar system, and lost its volatiles (including water and most of its atmosphere) over succeeding eons. Bacterial life may or may not have had time to evolve or be seeded before this, but atmosphere loss made it moot (for the planet's surface, at the very least).
For Venus: I personally have doubts about this planet ever being a nicer place than it currently is. The article doesn't claim that it is; it only presents a method to test for a more water-rich past. At any rate, the presence or absence of water on Venus doesn't change much. It's close to the sun, and doesn't have a big moon to strip away most of its atmosphere like Earth did. As soon as it had an appreciable atmosphere (probably always; it would have formed with the planet), runaway greenhouse effects took over. Water would actually have helped this happen.
Bacteria might exist on Venus. We don't know yet.
In both cases, the presence or absence of bacteria doesn't do much to affect the planetary climate.
Now, for the special case, Earth. Earth is the only planet that we know of where bacteria *did* play a big role in shaping the composition of the atmosphere. They didn't make earth more hospitable by doing it - on the contrary, they could only do it because Earth was so hospitable in the first place (thus leaving them billions of years to work in). Earth owes its wonderful climate to good positioning (just the right amount of sunlight), large mass (enough to keep an atmosphere over geological time), and and a large moon (to strip away most of the atmosphere early in Earth's history, preventing another "Venus").
Even the case for Earth's oxygen atmosphere being the result of the work of bacteria is an open question. Earth's gravity well is deep enough to hold on to heavy molecules like nitrogen and oxygen, but if free hydrogen ever forms, it can escape (albeit slowly). Photoionization of water and ammonia and methane in Earth's early reducing atmosphere would have liberated enough hydrogen to gradually change the composition of Earth's atmosphere to be dominated by other elements.
Today, in Earth's later years, life has an important role regulating the transport of carbon from rocks to the atmosphere and back, but the lion's share of the work was done without life's help.
I know it's FAA regulation - but what is a laptop or a discman really going to do?
Exactly what the root post of this thread said they will do - louse up the navigation equipment.
While you're in the air, 30k feet above anything that might hit you, this isn't an issue. But when the plane is landing, it's following interference fringes of a couple of radio beacons by the runway. You do *NOT* want anything that even *might* be transmitting RF to be active during takeoff or landing. Airports have enough problems with noise from the local radio stations.
The recon satellietes that the Air Force and CIA operate allow us to observe our friends and enemies from afar, day or night. These 'birds' are impervious to any weapon currently deployed.
Um, no.
A hobbyist's rocket with a box of nails on the top, and you can kiss any LEO satellite goodbye. The spy satellites are all in LEO - you can't get decent image resolution from any higher.
The magic here is that you don't need to achieve orbit to wreck a satellite - you just need to get something up to orbital _altitude_, and let the satellite smack into the shrapnel it spreads around before the shrapnel falls back to earth. It takes 30 MJ/kg to get into a stable orbit. It only takes about 3 to raise a rocket to orbital height. This is very, very easy.
A friend of mine once had fun with the Canadian postal service (actually, with the recipients).
Item one: A shred of cardboard with a stamp and an address on it.
It made it through.
Item two: A processed cheese slice, wrapped in paper, and addressed to a friend.
The friend took one look at it, wrote "return to sender" on it and stuck on another stamp. The sending friend was convulsed with laughter for several minutes upon receiving this.
Item three: Pig intestines, wrapped (I hope!).
We'd just done a dissection lab in high school biology... I don't remember who she sent them to, but it was at least two people. Didn't hear how that one turned out...
Basically there has to be a better way of escaping the Earths atmosphere surely. A lot of people think that the only reason that NASA persists with shuttles and rockets is because it is good for the american aerospace industry and the american airforce.
What about giant elevator like you see in sci-fi films. Let's face it, anything that doesn't involve sitting on top of several tons of rocket fuel would do.
The problem is that chemical rockets are the only practical option we have for getting into space at all, for the next several decades at the *very* least.
The reason: Thrust. We have other drives in production, finally, but none of them are *anywhere* close to being able to produce thrust above one gravity, and they aren't going to any time soon - they're high efficiency drives designed for long-haul propulsion of craft that are already in space.
What other options do we have? The NERVA drive? Only if we want to spray radioactive exhaust everywhere. Fusion? Not for another few decades, and almost certainly not at one gravity (plasma pressure won't be high enough in any magnetic field we can produce, and inertial schemes aren't very practical as thrusters). Ion drives and so forth are low-thrust drives - completely useless for ground-to-orbit, however useful they may be out in space.
Laser launching? You can only use the atmosphere as reaction mass for the first few tens of kilometres. This gives accelerations that are far too high for human passengers, even if the craft and ground-station could handle the required laser intensity. Carry your own reaction mass? You can't heat it much hotter than conventional rocket fuel without destroying your rocket nozzles, which means your cargo to ship weight ratio will be similar to that of chemical rockets.
As a cargo lifter, this *might* be practical.
A railgun? Again, unless it's a cargo lifter, it'll have to be hundreds or thousands of kilometres long, and the projectile will vapourize on contact with the atmosphere (rockets don't get up to orbital velocity until they're out of most of the atmosphere).
A space elevator? Maybe in a few decades when we have the required materials, but certainly not any time soon. Nothing we're even close to producing in quantity will cut it, though we have glimmers of interesting materials in the lab.
In short, chemical rockets persist because they're simply the best tool we have for the job.
As far as bringing water to mars is concerned, it would cost *far* less to transport it from the asteroid belt. Earth's gravity well is *very* deep, and we have to use inefficient high-thrust rockets to get out of it. Ocean level problems can be solved by paying more attention to the composition of our atmosphere (tailoring greenhouse effect and cloud-forming to suit our needs).
First, just to make sure we all know this: The primary purpose of this mission is to determine the interior composition of the comet. Any ballistics experiments are just useful side effects.
For the environmentalists - remember that this comet is going to boil away into nothingness in a few million years anyways.
Secondly, this is important to The Rest Of Us because we hope to be *mining* objects like this some day. Small objects in the solar system tend to fall into one of only a handful of composition categories, and this probe will let us get good prospecting data on one such category.
For a commercial vendor, try American Superconductor. Their web page is at http://www.amsuper.com . They sell many devices based on superconductors, and some raw materials as well (under "Products & Solutions", "Electric Power Applications").
While the problem of small groups with moderate resources engineering viruses is indeed a serious one, I'm skeptical of claims that any virus or even set of viruses would be able to wipe out humanity.
Mainly this comes from circumstantial evidence: As far as we can tell, nothing like this has ever happened, despite random genetic crossovers happening fairly frequently with bacteria and viruses.
Not an iron-clad argument, and a super-virus would still be very bad, but I'm skeptical of most "doomsday" hype.
Actually, we have seen it. It's called "AMD". They take the CISC instructions and translate them into RISC instructions that can be more highly optimized
All Intel processors from the Pentium Pro onwards have done this, too. You'll be hard-pressed to find an x86 clone that *doesn't* do this, as it makes a lot of the hardware design much easier.
Storage and mail server meltdown may be issues, but the time spent downloading spam isn't. The banner ad at the top of the screen here was 10k. That's the equivalent of five moderately lengthy spam emails. A typical web mage has many images (adverts and non-adverts), and Joe User will surf through many pages in a day. Someone who never touches a web browser might see their charges rise due to spam, but anyone who browses even a little bit has a much, much bigger drain on their phone bill than spam would ever produce.
The ISP, too, is processing image and other binary data as the bulk of its traffic. Spam does load down the mail server quite a bit, but not the pipe.
I don't *like* spam, and I don't think I should be *sent* spam, but the "time to download" argument doesn't hold water.
Several generations from now, will our children look back and wonder how we could have recklessly polluted space like that?
Um, if we took the entire mass of our *planet* and spread it around the inner solar system as a dust cloud, it wouldn't have any environmental effect on other planets in the vicinity.
How's the exhaust from a probe supposed to do anything?
I'm overlooking the fact that cosmic rays already send more hard radiation through the inner solar system than we could ever hope to put there.
The only legitimate concern is dumping radioactive waste just above the Earth's atmosphere. The simple solution: shield the ship until you're far away from Earth!
My question is, what ARE the byproducts of this process, and are they radioactive? Would a drive based on this process wind up spitting out a radioactive plume?
That depends on which isomer of Am242 they're referring to ("m" denotes an isomer, a metastable energetic state of Am242 with its own decay properties). According to the handy description of Am242 at http://environmentalchemistry.com/yogi/periodic/Am -pg2.html , most of the decay chains involve alpha and beta emissions, which will (hopefully) leave the Americium atoms in the film on the engine. A few low-probability reactions (or one high-probability reaction for the most energetic isomer of Am242) result in spontaneous fission, which will indeed send a likely-radioactive fragment out into space.
They key words here are "into space". This drive will never produce enough thrust to be useful for lifting off of a planet; the exhaust throughput is far too low. Out in space, a few traces of radioactive atoms are a non-issue (we already have plenty streaming down in the form of cosmic rays).
Umm. No. No, it's not. It's beside the point anyway, because the heat of the reactor is contained by a magnetic field. You see, it has to be that way - people don't react well to temperatures found on the surface of the Sun.
Actually, you do get a heat pollution problem with any power source that isn't recycled solar (i.e. solar, wind, biomass). This is due to the fact that whenever power is _used_, the energy usually winds up as heat at the end of the road. Already, this causes local problems (cities heat up their local environment and any adjacent body of water), and when/if humanity consumes an amount of power comparable to that received by the earth from the sun, it will become a global problem.
That having been said, by the time this is a concern, we'll have the industrial capacity to get rid of it. It's straightforward to dump this heat into space; just set up a few square kilometres of piping and mirrors next to each city, and put it on the "hot" end of a heat exchanger. Compared to the cost of the city, it's cheap, and it solves any heat pollution problems associated with the city.
A random project that could use good documentation is the Linux Media Labs video capture project, at http://www.linuxmedialabs.com . They're building a card around the Zoran 36060 chipset (MPEG encoder/decoder). The card's been working for quite a while now, and the driver's been in ok shape for almost as long, but they have *NO* decent documentation on writing programs that use the device (just installation docs and chipset docs).
I wrote reverse-engineered documentation for version 1.0.9 of the driver, which they thanked me for and then promptly ignored (they've belatedly added a link to my now-defunct web page; I was hoping they'd take over maintaining/hosting the document). My own version has since dropped off the face of the web (I graduated, and that web account went *poof*).
If you decide to reverse-engineer the current version of their driver and write docs for it, I guarantee that many people who *use* the card will be grateful. I still get occasional requests for help, even though my own document is now hideously out of date. The LML team itself will be vaguely supportive and maybe answer questions for you now and then when they feel like it. To get a copy of my document, hunt down my email address in the LML33 message boards.
Trying to pull that much power from a headphone jack would probably blow the buffer or amplifier that's on the other end. The headphone jack on your typical sound card, for example, is only specced to about 4 watts. Your computer consumes much more power than that, and the power consumption for charging will be comparable to this or greater than this (unless you want to spend far more time charging than using).
OTOH, if they wired the headphones the cheap and crappy way (in parallel), you can pull a fair bit more power without damaging anything... as long as nobody else is trying the same stunt. YMMV. I wouldn't risk it.
An outlet that's specifically designed for charging other devices might be more practical, but bear in mind that something like an airphone probably has lower power consumption than your computer, and the charger will thus be specced for lower power on charging (no reason to charge it faster than, say, 4x usage power consumption [random figure]).
Lastly, if you have a power converter in your charger (as is likely), you'll probably be producing a lot of RF noise during charging (as most compact power supplies/power converters are switched at high frequency to let you make inductive components smaller).
My advice: Shell out for an extra battery.
This experiment ignores the big problems.
on
Green Mars
·
· Score: 3
While interesting for a sound-bite, this experiment doesn't prove a whole lot about growing plants on Mars.
Soil is pretty much inert. It's there to keep the plant from falling over. If you're lucky, you'll get soil with good water retention/drainage capabilities. However, this isn't exactly hard to come by or hard to produce yourself. While at any given time, soil will have nutrients and so forth in it, these cycle through fairly quickly - you have to keep adding them back, by using natural or artificial fertilizer.
The main problems with growing plants on Mars are, in order:
Lack of water.
No water, no plants. Water provides hydrogen for hydrocarbon synthesis. We simply don't know whether there's much water present on Mars. There are trace amounts in the atmosphere and ice caps, but we'll need more than trace amounts for agriculture. There may or may not be ice deposits beneath the planet's surface.
Air Pressure.
Anything growing on Mars would have to be in a pressurized greenhouse. The air is far too thin to support life otherwise (low throughput by weight and very low boiling point of water at Martian densities (if liquid water can exist at all)).
Mostly-CO2 atmosphere
Most plants do not grow in an atmosphere of pure CO2. You'd have to fiddle with the atmosphere composition inside your pressurized greenhouse, which will take a fair bit of startup effort (it may be self-sustaining once plants are growing).
Lack of nitrogen, phosphorus, and potassium.
These are the primary nutrients supplied by fertilizer. You're going to have to make sure that there are minerals bearing all of these within easy reach of any large-scale agriculture, and you're going to have to have the industry to process them into fertilizer. Appropriate minerals may or may not show up on orbital surveys (depends on the geology). I have no idea how common these minerals are. Common or not, industry is expensive.
Lack of sunlight.
Mars is (very roughly) twice as far from the sun as the Earth. It gets one quarter as much sunlight. While some plants will grow under these conditions, they won't grow as well as they would on Earth.
Unshielded sunlight.
Our atmosphere screens out a lot of the UV and other nastiness produced by the sun. The martian atmosphere won't (it's far too thin). Ionizing radiation (UV and other) will damage the plants' health more rapidly than on Earth.
While these issues are all tractable, none of them are addressed by the article. Thus, I have trouble taking the article seriously.
Don't discard the possibility of building something neat yourself.
Back in my younger days, I got so sick of taking my 286 down from its inaccessible shelf to poke at cards that I took the thing down, gutted the case, and nailed the innards to the wall. It worked fine for several years, and got more than a few odd looks.
As another example, one of the disk arrays at the University is inside a home-made plexiglass box. It looks cool, it works well, and you can build something like that with a sheet of plexiglass, a saw, and a tube of epoxy. I'm still considering my fishtank-in-computer-in-fishtank idea.
Take an old machine, take a few carpentry tools, and let your imagination run wild. You may be pleasantly surprised at the results.
Yeah.. I can see how it's easily portable with graphics, doing chapters, PAGE BREAKS, headers and footers on pages (which may or may not be common) and have you ever pulled in HTML to edit on any of the above?
Ok, I'll bite.
Firstly, you seem to be missing the main point of the question. This isn't about finding a generic format for page layout - it's about how to best transfer specification documents so that they can be written anywhere and read anywhere. HTML works wonderfully for this.
Secondly, _yes_, you can do all of the above, when it makes _sense_ to do so.
Page breaks? Easy. Have a set of linked documents instead of one big page. This is useful under some circumstances (like dividing a large document into sections).
Chapters? Um, you _have_ the tools to emphasize chapter headings, and you _have_ page breaks if you really feel you have to use them. Where's the problem?
Graphics? If I need a figure, that's what the image tag is for. If I want to have anything fancier than an image in a box... then I should have someone else write the standards document. Again, we aren't making magazine articles here - the goal is to find a format suitable for a *technical description*. Visual gingerbread is _counterproductive_; it distracts the reader.
Headers/footers? Frames work fine for that, if you have a real reason to use them. I personally can't think of any, for this application. For my own documents, if I'm writing something that must be pretty, I use a script to prettify things consistently.
I vote for HTML. Yes, it isn't great for fine layout control, but you don't *NEED* perfect layout control. We're writing standards specs here, not doing graphic design.
The advantages: HTML is readable on any platform under the sun (and quite a few in caves), and most word processors can export using it.
If the documents have figures, they can be saved as one of.gif/.png/.jpg, and read by most browsers.
This is the only way I've found to get MS Word-users to give me readable documents, among other things.
This seems like an expensive and inefficient solution for the problem you describe. PCs are actually pretty bad at doing signal processing; there's a whole class of chips (DSPs) that are optimized for it. There are almost certainly DSP-based hardware boards/widgets that will handle a lot of these effects for you, and it wouldn't surprise me to learn that there was a general-purpose programmable DSP card on the market too. Researching this before you spend money on a cluster would be a Good Idea.
Assuming that the software's there, dedicated DSP hardware should by far be the cheapest and easiest solution.
OTOH, good luck finding the software.
Addendum: Actually, I think that the effects generators on most modern sound cards are just DSPs, RAM, and some firmware. You might be able to find (or write or contract) hacked drivers that would let you arbitrarily reprogram this for your own purposes.
We're not going to lose the moon. All that'll happen is the moon's orbit around the earth will be synchronized with the earth's rotation.
Actually he's right; what's happening is that angular momentum is being transferred from the Earth (Earth's spin) to the moon (moon's tangential velocity). This is called "tidal drag". It may end with the moon gaining enough tangential velocity to escape, or it may end with the Earth's rotation synchronizing to the moon's orbit; which case occurs depends on whether the kinetic energy bound up in the earth's rotation is greater than the orbital binding energy of the moon at its present distance.
When the moon formed, it was much closer to Earth than it now is. Tidal drag moved it to its present distance.
Seriously, logistically, oil-based fuels are just about the worst you can imagine. Yes, it costs money to retool, but probably less than the medical costs related to burning gasoline alone. And the retooling creates job and economic opportunities anyway.
My objection was that hydrogen was one of the worse alternatives we could be using. Its only advantage is that the fuel cells that process it are simple and cheap compared to cells that process methane or methanol.
Heck, even methane would be better than hydrogen, because you don't have the diffusion problem.
Ethanol, the subject of a previous slashdot story, would work fine in conventional engines and can be stored as a liquid, but is hard to build a fuel cell for.
Methanol can be produced as easily as ethanol, and is simple enough to be processed electrochemically with some efficiency. Most importantly, because it can be stored as a liquid, you get most of your infrastructure for free and don't pay an energy density penalty.
You'd also have to overhaul all gas stations to handle a gas instead of a liquid as their main product. Yes, they handle propane already, but you'd have to tear up and replace the gas pumps and main storage tank.
Isn't that a little tautological? We can't do X because X contradicts what we do?
It is a bit tautological, but it would still be a major investment to overhaul all gas stations, on top of the other costs for switching fuel types. This makes liquid fuels more financially attractive, and thus more likely to be implemented when fossil fuels finally become expensive enough to warrant it.
As a result of that accident hydrogen has gotten a really bad rap when it's not all that dangerous and has a lot of benefits. Clean cars being one example.
Hydrogen isn't a viable replacement for gasoline in cars. It can only be stored as a compressed gas, which has a far lower energy density than liquid gasoline. Further, because hydrogen molecules are so small, they have a tendency to diffuse through many metals and other materials, so containers/hoses/seals/etc. are annoying to build.
You'd also have to overhaul all gas stations to handle a gas instead of a liquid as their main product. Yes, they handle propane already, but you'd have to tear up and replace the gas pumps and main storage tank.
IMO, something like methanol is a better solution. You can burn it cleanly in conventional engines, or you can burn it in specially built fuel cells. It can be stored as a liquid with a not-too-bad energy density, and it can be produced easily.
Slashdot Mirror
I would like to see the money we are spending on the international space station go to creating an international moon-base. If we create two compartments, one for humans and one for other animals (like Biosphere), we would be able to study how the radiation of space affects living things, what can adapt, and what can't, etc.
The ISS is still a pretty necessary first step. It gives us a place nearby where we can test most of our habitat technology without being out of rescue range, and we can study radiation effects just as easily there as on the moon. It also lets us further study the effects of microgravity, which we'll need to have a very good handle on before attempting a Mars mission (for most craft designs I've heard about, at least).
The ISS is also an excellent launch platform and docking station for lunar-orbit craft. This would let you use ion- or plasma-drive craft that wouldn't be able to land to move easily between earth- and lunar-orbit and back, establish a permanent space station around the _moon_, and in general make the logistics of earth/moon travel and lunar exploration/colonization much easier.
Keeping the ground-to-orbit steps of lunar missions (on both ends) separate from the orbit-to-orbit step makes it a *lot* easier to plan lunar surface missions, gives them a greater chance of success, and makes it easier to recover from catastrophes at most stages.
My favorite theory is that the other two planets were actually much more suited to whatever form of life originally seeded them, the Earth being just a little different in sunlight penetration and a few chemical balancing acts. The other two planets therefore flourished quickly, the simple lifeforms used up the resources that were available quickly, and this caused, slowly at first, a change in climate. But once that change was set in motion it never ceased until we end up with the two completely unlivable (by our standards) planets and the completely habitable (again by our standards) Earth.
I don't think we need to invoke magical "life using up resources" scenarios to explain climate changes on Mars and Venus. Their own structure and location does this well enough.
For Mars: Mars is large enough to hold a thick atmosphere for a while, but small enough that it won't hold it over geological time. It started with composition similar to most of the inner solar system, and lost its volatiles (including water and most of its atmosphere) over succeeding eons. Bacterial life may or may not have had time to evolve or be seeded before this, but atmosphere loss made it moot (for the planet's surface, at the very least).
For Venus: I personally have doubts about this planet ever being a nicer place than it currently is. The article doesn't claim that it is; it only presents a method to test for a more water-rich past. At any rate, the presence or absence of water on Venus doesn't change much. It's close to the sun, and doesn't have a big moon to strip away most of its atmosphere like Earth did. As soon as it had an appreciable atmosphere (probably always; it would have formed with the planet), runaway greenhouse effects took over. Water would actually have helped this happen.
Bacteria might exist on Venus. We don't know yet.
In both cases, the presence or absence of bacteria doesn't do much to affect the planetary climate.
Now, for the special case, Earth. Earth is the only planet that we know of where bacteria *did* play a big role in shaping the composition of the atmosphere. They didn't make earth more hospitable by doing it - on the contrary, they could only do it because Earth was so hospitable in the first place (thus leaving them billions of years to work in). Earth owes its wonderful climate to good positioning (just the right amount of sunlight), large mass (enough to keep an atmosphere over geological time), and and a large moon (to strip away most of the atmosphere early in Earth's history, preventing another "Venus").
Even the case for Earth's oxygen atmosphere being the result of the work of bacteria is an open question. Earth's gravity well is deep enough to hold on to heavy molecules like nitrogen and oxygen, but if free hydrogen ever forms, it can escape (albeit slowly). Photoionization of water and ammonia and methane in Earth's early reducing atmosphere would have liberated enough hydrogen to gradually change the composition of Earth's atmosphere to be dominated by other elements.
Today, in Earth's later years, life has an important role regulating the transport of carbon from rocks to the atmosphere and back, but the lion's share of the work was done without life's help.
I know it's FAA regulation - but what is a laptop or a discman really going to do?
Exactly what the root post of this thread said they will do - louse up the navigation equipment.
While you're in the air, 30k feet above anything that might hit you, this isn't an issue. But when the plane is landing, it's following interference fringes of a couple of radio beacons by the runway. You do *NOT* want anything that even *might* be transmitting RF to be active during takeoff or landing. Airports have enough problems with noise from the local radio stations.
The recon satellietes that the Air Force and CIA operate allow us to observe our friends and enemies from afar, day or night. These 'birds' are impervious to any weapon currently deployed.
Um, no.
A hobbyist's rocket with a box of nails on the top, and you can kiss any LEO satellite goodbye. The spy satellites are all in LEO - you can't get decent image resolution from any higher.
The magic here is that you don't need to achieve orbit to wreck a satellite - you just need to get something up to orbital _altitude_, and let the satellite smack into the shrapnel it spreads around before the shrapnel falls back to earth. It takes 30 MJ/kg to get into a stable orbit. It only takes about 3 to raise a rocket to orbital height. This is very, very easy.
It made it through.
The friend took one look at it, wrote "return to sender" on it and stuck on another stamp. The sending friend was convulsed with laughter for several minutes upon receiving this.
We'd just done a dissection lab in high school biology... I don't remember who she sent them to, but it was at least two people. Didn't hear how that one turned out...
Ah, the fun we had when we were kids
Basically there has to be a better way of escaping the Earths atmosphere surely. A lot of people think that the only reason that NASA persists with shuttles and rockets is because it is good for the american aerospace industry and the american airforce.
What about giant elevator like you see in sci-fi films. Let's face it, anything that doesn't involve sitting on top of several tons of rocket fuel would do.
The problem is that chemical rockets are the only practical option we have for getting into space at all, for the next several decades at the *very* least.
The reason: Thrust. We have other drives in production, finally, but none of them are *anywhere* close to being able to produce thrust above one gravity, and they aren't going to any time soon - they're high efficiency drives designed for long-haul propulsion of craft that are already in space.
What other options do we have? The NERVA drive? Only if we want to spray radioactive exhaust everywhere. Fusion? Not for another few decades, and almost certainly not at one gravity (plasma pressure won't be high enough in any magnetic field we can produce, and inertial schemes aren't very practical as thrusters). Ion drives and so forth are low-thrust drives - completely useless for ground-to-orbit, however useful they may be out in space.
Laser launching? You can only use the atmosphere as reaction mass for the first few tens of kilometres. This gives accelerations that are far too high for human passengers, even if the craft and ground-station could handle the required laser intensity. Carry your own reaction mass? You can't heat it much hotter than conventional rocket fuel without destroying your rocket nozzles, which means your cargo to ship weight ratio will be similar to that of chemical rockets.
As a cargo lifter, this *might* be practical.
A railgun? Again, unless it's a cargo lifter, it'll have to be hundreds or thousands of kilometres long, and the projectile will vapourize on contact with the atmosphere (rockets don't get up to orbital velocity until they're out of most of the atmosphere).
A space elevator? Maybe in a few decades when we have the required materials, but certainly not any time soon. Nothing we're even close to producing in quantity will cut it, though we have glimmers of interesting materials in the lab.
In short, chemical rockets persist because they're simply the best tool we have for the job.
As far as bringing water to mars is concerned, it would cost *far* less to transport it from the asteroid belt. Earth's gravity well is *very* deep, and we have to use inefficient high-thrust rockets to get out of it. Ocean level problems can be solved by paying more attention to the composition of our atmosphere (tailoring greenhouse effect and cloud-forming to suit our needs).
First, just to make sure we all know this: The primary purpose of this mission is to determine the interior composition of the comet. Any ballistics experiments are just useful side effects.
For the environmentalists - remember that this comet is going to boil away into nothingness in a few million years anyways.
Secondly, this is important to The Rest Of Us because we hope to be *mining* objects like this some day. Small objects in the solar system tend to fall into one of only a handful of composition categories, and this probe will let us get good prospecting data on one such category.
For a commercial vendor, try American Superconductor. Their web page is at http://www.amsuper.com . They sell many devices based on superconductors, and some raw materials as well (under "Products & Solutions", "Electric Power Applications").
While the problem of small groups with moderate resources engineering viruses is indeed a serious one, I'm skeptical of claims that any virus or even set of viruses would be able to wipe out humanity.
Mainly this comes from circumstantial evidence: As far as we can tell, nothing like this has ever happened, despite random genetic crossovers happening fairly frequently with bacteria and viruses.
Not an iron-clad argument, and a super-virus would still be very bad, but I'm skeptical of most "doomsday" hype.
Actually, we have seen it. It's called "AMD". They take the CISC instructions and translate them into RISC instructions that can be more highly optimized
All Intel processors from the Pentium Pro onwards have done this, too. You'll be hard-pressed to find an x86 clone that *doesn't* do this, as it makes a lot of the hardware design much easier.
Storage and mail server meltdown may be issues, but the time spent downloading spam isn't. The banner ad at the top of the screen here was 10k. That's the equivalent of five moderately lengthy spam emails. A typical web mage has many images (adverts and non-adverts), and Joe User will surf through many pages in a day. Someone who never touches a web browser might see their charges rise due to spam, but anyone who browses even a little bit has a much, much bigger drain on their phone bill than spam would ever produce.
The ISP, too, is processing image and other binary data as the bulk of its traffic. Spam does load down the mail server quite a bit, but not the pipe.
I don't *like* spam, and I don't think I should be *sent* spam, but the "time to download" argument doesn't hold water.
Several generations from now, will our children look back and wonder how we could have recklessly polluted space like that?
Um, if we took the entire mass of our *planet* and spread it around the inner solar system as a dust cloud, it wouldn't have any environmental effect on other planets in the vicinity.
How's the exhaust from a probe supposed to do anything?
I'm overlooking the fact that cosmic rays already send more hard radiation through the inner solar system than we could ever hope to put there.
The only legitimate concern is dumping radioactive waste just above the Earth's atmosphere. The simple solution: shield the ship until you're far away from Earth!
Pollution in deep space is a non-issue.
My question is, what ARE the byproducts of this process, and are they radioactive? Would a drive based on this process wind up spitting out a radioactive plume?
m -pg2.html , most of the decay chains involve alpha and beta emissions, which will (hopefully) leave the Americium atoms in the film on the engine. A few low-probability reactions (or one high-probability reaction for the most energetic isomer of Am242) result in spontaneous fission, which will indeed send a likely-radioactive fragment out into space.
That depends on which isomer of Am242 they're referring to ("m" denotes an isomer, a metastable energetic state of Am242 with its own decay properties). According to the handy description of Am242 at http://environmentalchemistry.com/yogi/periodic/A
They key words here are "into space". This drive will never produce enough thrust to be useful for lifting off of a planet; the exhaust throughput is far too low. Out in space, a few traces of radioactive atoms are a non-issue (we already have plenty streaming down in the form of cosmic rays).
Umm. No. No, it's not. It's beside the point anyway, because the heat of the reactor is contained by a magnetic field. You see, it has to be that way - people don't react well to temperatures found on the surface of the Sun.
Actually, you do get a heat pollution problem with any power source that isn't recycled solar (i.e. solar, wind, biomass). This is due to the fact that whenever power is _used_, the energy usually winds up as heat at the end of the road. Already, this causes local problems (cities heat up their local environment and any adjacent body of water), and when/if humanity consumes an amount of power comparable to that received by the earth from the sun, it will become a global problem.
That having been said, by the time this is a concern, we'll have the industrial capacity to get rid of it. It's straightforward to dump this heat into space; just set up a few square kilometres of piping and mirrors next to each city, and put it on the "hot" end of a heat exchanger. Compared to the cost of the city, it's cheap, and it solves any heat pollution problems associated with the city.
A random project that could use good documentation is the Linux Media Labs video capture project, at http://www.linuxmedialabs.com . They're building a card around the Zoran 36060 chipset (MPEG encoder/decoder). The card's been working for quite a while now, and the driver's been in ok shape for almost as long, but they have *NO* decent documentation on writing programs that use the device (just installation docs and chipset docs).
I wrote reverse-engineered documentation for version 1.0.9 of the driver, which they thanked me for and then promptly ignored (they've belatedly added a link to my now-defunct web page; I was hoping they'd take over maintaining/hosting the document). My own version has since dropped off the face of the web (I graduated, and that web account went *poof*).
If you decide to reverse-engineer the current version of their driver and write docs for it, I guarantee that many people who *use* the card will be grateful. I still get occasional requests for help, even though my own document is now hideously out of date. The LML team itself will be vaguely supportive and maybe answer questions for you now and then when they feel like it. To get a copy of my document, hunt down my email address in the LML33 message boards.
Trying to pull that much power from a headphone jack would probably blow the buffer or amplifier that's on the other end. The headphone jack on your typical sound card, for example, is only specced to about 4 watts. Your computer consumes much more power than that, and the power consumption for charging will be comparable to this or greater than this (unless you want to spend far more time charging than using).
OTOH, if they wired the headphones the cheap and crappy way (in parallel), you can pull a fair bit more power without damaging anything... as long as nobody else is trying the same stunt. YMMV. I wouldn't risk it.
An outlet that's specifically designed for charging other devices might be more practical, but bear in mind that something like an airphone probably has lower power consumption than your computer, and the charger will thus be specced for lower power on charging (no reason to charge it faster than, say, 4x usage power consumption [random figure]).
Lastly, if you have a power converter in your charger (as is likely), you'll probably be producing a lot of RF noise during charging (as most compact power supplies/power converters are switched at high frequency to let you make inductive components smaller).
My advice: Shell out for an extra battery.
Soil is pretty much inert. It's there to keep the plant from falling over. If you're lucky, you'll get soil with good water retention/drainage capabilities. However, this isn't exactly hard to come by or hard to produce yourself. While at any given time, soil will have nutrients and so forth in it, these cycle through fairly quickly - you have to keep adding them back, by using natural or artificial fertilizer.
The main problems with growing plants on Mars are, in order:
No water, no plants. Water provides hydrogen for hydrocarbon synthesis. We simply don't know whether there's much water present on Mars. There are trace amounts in the atmosphere and ice caps, but we'll need more than trace amounts for agriculture. There may or may not be ice deposits beneath the planet's surface.
Anything growing on Mars would have to be in a pressurized greenhouse. The air is far too thin to support life otherwise (low throughput by weight and very low boiling point of water at Martian densities (if liquid water can exist at all)).
Most plants do not grow in an atmosphere of pure CO2. You'd have to fiddle with the atmosphere composition inside your pressurized greenhouse, which will take a fair bit of startup effort (it may be self-sustaining once plants are growing).
These are the primary nutrients supplied by fertilizer. You're going to have to make sure that there are minerals bearing all of these within easy reach of any large-scale agriculture, and you're going to have to have the industry to process them into fertilizer. Appropriate minerals may or may not show up on orbital surveys (depends on the geology). I have no idea how common these minerals are. Common or not, industry is expensive.
Mars is (very roughly) twice as far from the sun as the Earth. It gets one quarter as much sunlight. While some plants will grow under these conditions, they won't grow as well as they would on Earth.
Our atmosphere screens out a lot of the UV and other nastiness produced by the sun. The martian atmosphere won't (it's far too thin). Ionizing radiation (UV and other) will damage the plants' health more rapidly than on Earth.
While these issues are all tractable, none of them are addressed by the article. Thus, I have trouble taking the article seriously.
Don't discard the possibility of building something neat yourself.
Back in my younger days, I got so sick of taking my 286 down from its inaccessible shelf to poke at cards that I took the thing down, gutted the case, and nailed the innards to the wall. It worked fine for several years, and got more than a few odd looks.
As another example, one of the disk arrays at the University is inside a home-made plexiglass box. It looks cool, it works well, and you can build something like that with a sheet of plexiglass, a saw, and a tube of epoxy. I'm still considering my fishtank-in-computer-in-fishtank idea.
Take an old machine, take a few carpentry tools, and let your imagination run wild. You may be pleasantly surprised at the results.
Yeah.. I can see how it's easily portable with graphics, doing chapters, PAGE BREAKS, headers and footers on pages (which may or may not be common) and have you ever pulled in HTML to edit on any of the above?
Ok, I'll bite.
Firstly, you seem to be missing the main point of the question. This isn't about finding a generic format for page layout - it's about how to best transfer specification documents so that they can be written anywhere and read anywhere. HTML works wonderfully for this.
Secondly, _yes_, you can do all of the above, when it makes _sense_ to do so.
Page breaks? Easy. Have a set of linked documents instead of one big page. This is useful under some circumstances (like dividing a large document into sections).
Chapters? Um, you _have_ the tools to emphasize chapter headings, and you _have_ page breaks if you really feel you have to use them. Where's the problem?
Graphics? If I need a figure, that's what the image tag is for. If I want to have anything fancier than an image in a box... then I should have someone else write the standards document. Again, we aren't making magazine articles here - the goal is to find a format suitable for a *technical description*. Visual gingerbread is _counterproductive_; it distracts the reader.
Headers/footers? Frames work fine for that, if you have a real reason to use them. I personally can't think of any, for this application. For my own documents, if I'm writing something that must be pretty, I use a script to prettify things consistently.
I vote for HTML. Yes, it isn't great for fine layout control, but you don't *NEED* perfect layout control. We're writing standards specs here, not doing graphic design.
.gif/.png/.jpg, and read by most browsers.
The advantages: HTML is readable on any platform under the sun (and quite a few in caves), and most word processors can export using it.
If the documents have figures, they can be saved as one of
This is the only way I've found to get MS Word-users to give me readable documents, among other things.
This seems like an expensive and inefficient solution for the problem you describe. PCs are actually pretty bad at doing signal processing; there's a whole class of chips (DSPs) that are optimized for it. There are almost certainly DSP-based hardware boards/widgets that will handle a lot of these effects for you, and it wouldn't surprise me to learn that there was a general-purpose programmable DSP card on the market too. Researching this before you spend money on a cluster would be a Good Idea.
Assuming that the software's there, dedicated DSP hardware should by far be the cheapest and easiest solution.
OTOH, good luck finding the software.
Addendum: Actually, I think that the effects generators on most modern sound cards are just DSPs, RAM, and some firmware. You might be able to find (or write or contract) hacked drivers that would let you arbitrarily reprogram this for your own purposes.
Just a few thoughts.
We're not going to lose the moon. All that'll happen is the moon's orbit around the earth will be synchronized with the earth's rotation.
Actually he's right; what's happening is that angular momentum is being transferred from the Earth (Earth's spin) to the moon (moon's tangential velocity). This is called "tidal drag". It may end with the moon gaining enough tangential velocity to escape, or it may end with the Earth's rotation synchronizing to the moon's orbit; which case occurs depends on whether the kinetic energy bound up in the earth's rotation is greater than the orbital binding energy of the moon at its present distance.
When the moon formed, it was much closer to Earth than it now is. Tidal drag moved it to its present distance.
Seriously, logistically, oil-based fuels are just about the worst you can imagine. Yes, it costs money to retool, but probably less than the medical costs related to burning gasoline alone. And the retooling creates job and economic opportunities anyway.
My objection was that hydrogen was one of the worse alternatives we could be using. Its only advantage is that the fuel cells that process it are simple and cheap compared to cells that process methane or methanol.
Heck, even methane would be better than hydrogen, because you don't have the diffusion problem.
Ethanol, the subject of a previous slashdot story, would work fine in conventional engines and can be stored as a liquid, but is hard to build a fuel cell for.
Methanol can be produced as easily as ethanol, and is simple enough to be processed electrochemically with some efficiency. Most importantly, because it can be stored as a liquid, you get most of your infrastructure for free and don't pay an energy density penalty.
You'd also have to overhaul all gas stations to handle a gas instead of a liquid as their main product. Yes, they handle propane already, but you'd have to tear up and replace the gas pumps and main storage tank.
Isn't that a little tautological? We can't do X because X contradicts what we do?
It is a bit tautological, but it would still be a major investment to overhaul all gas stations, on top of the other costs for switching fuel types. This makes liquid fuels more financially attractive, and thus more likely to be implemented when fossil fuels finally become expensive enough to warrant it.
As a result of that accident hydrogen has gotten a really bad rap when it's not all that dangerous and has a lot of benefits. Clean cars being one example.
Hydrogen isn't a viable replacement for gasoline in cars. It can only be stored as a compressed gas, which has a far lower energy density than liquid gasoline. Further, because hydrogen molecules are so small, they have a tendency to diffuse through many metals and other materials, so containers/hoses/seals/etc. are annoying to build.
You'd also have to overhaul all gas stations to handle a gas instead of a liquid as their main product. Yes, they handle propane already, but you'd have to tear up and replace the gas pumps and main storage tank.
IMO, something like methanol is a better solution. You can burn it cleanly in conventional engines, or you can burn it in specially built fuel cells. It can be stored as a liquid with a not-too-bad energy density, and it can be produced easily.