Yeah, other sources are similar, and Zener diodes are probably the easiest devices to produce noisier versions of (and still maintain high noie quality). I mention resistors mainly because the physics behind them is the easiest to understand.
Resistor thermal noise is also inherently quantum in origin, and much easier to measure. All it takes is a resistor, a good analog amplifier, and an A/D converter -- which could all fit on a single piece of silicon if you wanted.
Just because it's not a troll doesn't mean it's a good patent. It may be that the solution is obvious to one "skilled in the art" even though no one seriously considered the problem before. Just because the university thought of it first doesn't mean it's a good patent.
Of course, I haven't looked at the details of the patent or the case. It may well be a blatant attempt by Intel to rip off a clever idea from the university. My guess is that reality is somewhere in between...
Another contradiction of capitalism that is an observation in Marxist theory is the desire of an individual firm to pay its employees as little as possible, but that depends on well-paid consumers having enough money to buy their products.
All that is is negative feedback. If you want to create a system capable of optimizing itself to changing conditions without a very complicated model and detailed control system (with attendant long, involved tuning process), be it an economy or a simple industrial process, you'll probably find it best to put multiple forces in place that oppose each other in such a way that they balance at an equilibrium point that's near the optimum. There is nothing "contradictory" about market forces being in opposition. One can argue about how well it works (imho, it clearly does a near-perfect job in some cases and an awful job in others), but as part of a design of an economic framework it's not at all clear it's a bad route to take.
Seriously, try creating a *good* control scheme for a simple system that doesn't involve a negative feedback loop. Then consider how amazingly not simple an economy is.
Some would say that there is no right to privacy in the constitution, but I say there it is, staring you in the face, as the underlying presumption that created the first phrase in the fourth amendment.
It doesn't need to be in the Constitution. It is a basic right. The Constitution was written on the principle that it does not grant rights. It prevents the government from taking away rights you *already possess*. It is abundantly clear, both from the text itself and the discussions that led to it, that the Constitution enumerates a subset of our rights. The fact that it is not mentioned in the Constitution does not mean you don't have it -- quite the opposite. If it isn't mentioned, that means the government has no right to touch it.
Both are true, actually. The CFCs cause it, but the chemistry mostly happens on the surfaces of ice crystals. Normally those are exceedingly rare that high up, since the water vapor mostly freezes out and falls before then. So adding more water vapor to the upper atmosphere probably is a bad idea, actually.
Hydrogen is normally produced via steam reforming and related processes (water gas shift reaction, coal gassification, etc), not electrolysis. That is, the hydrogen and the energy to produce it both come from fossil fuels (mostly natural gas, but oil and coal can both be used -- though in the case of coal all the hydrogen is coming from the water).
And actually, there is currently a *huge* hydrogen production industry. It's just mostly used on site at large plants rather than shipped to consumers as energy storage. Ammonium nitrate fertilizer is a *gigantic* market, and it's made by combining atmospheric nitrogen and hydrogen into ammonia, and then converting some of that ammonia into nitric acid before combining the two to form AN.
The availability of hydrogen is actually only a minor detail in this design. The price and the awkwardness of handling the ultra light weight ultra cold liquid are much more relevant.
They're claiming a price point comparable to current business class fares. There are enough business class fares sold currently to support a small fleet of such airplanes flying a few flights on the relevant long-haul routes. Anyone willing to pay for business class is certainly willing to pay a similar amount (or probably at least a moderate premium) to cut their flight time from 12+ hours to 2-4.
I can't speak to the details of this specific airplane, mostly because those details don't exist yet, but there has been significant work lately in reducing sonic booms through careful airframe shaping. They can probably fly supersonic overland as long as they're at altitude and not near population centers -- but I certainly can't guarantee that, and it's certainly subject to regulatory issues. Of course, the market *might* be big enough even with only the transoceanic flights -- LA to Sydney, Tokyo, Beijing, NYC to Western Europe, and possibly a few others.
Like you, I think the issues are more regulatory than technical. However, I think they have a lot more to do with development schedules and costs than they do with the existence of a sufficiently large market. If they can get the money and build it on the budget they say they can, the market will be there. Of course, that's a really, really big if.
Price will come down if fuel economy is reasonable and there are enough airplanes and flights to amortize development costs over. My impression (I've been following them for a while, and talked to people who should know) is that they're technically competent, and if they say they can get the price down, they can -- but that they're being overly optimistic about the market. Of course, if the government is paying for a low of the development, that helps a lot.
Noise is actually quite amenable to a technical solution. The first problem (noise near the airport) is a result of high-power, high exhaust velocity engines, combined with a need to get up to supersonic speeds quickly. If, as they claim, the airplane is efficient in the subsonic regime as well, then there is less pressure to accelerate rapidly. Efficient low-speed operation also inherently implies a lower exhaust speed (which they discuss briefly: variable high-bypass flow), which implies less noise -- for a given engine, noise power scales roughly (very roughly) linearly with exhaust velocity.
Noise from sonic booms is remarkably controllable, with sufficient work on the precise shape of the airframe. The technology to do that, high performance CFD, simply didn't exist when the Concorde was designed. They don't discuss it, but it's far too early in the design cycle for that to mean anything. Right now they're basically just trying to build the engine and convince people that a market exists at a price point they can reach. That requires design studies and concept art, but it's not yet time to be fine tuning the aerodynamics.
I'd say the technical problems, including noise, are amenable to solution if they manage to get the funding they need without too much interference. The market ones, less so. I'm sure one day we'll see supersonic airliners, but there are some *major* non-technical hurdles in the way of building anything the size of an A380.
Of course, it's wicked cool and I'd love to see it happen. Especially since the basic engine technology is also behind their Skylon SSTO spaceplane concept...
If I go to space, it won't be through NASA -- my odds on that are no better than average. I won't go into details except to reiterate that my odds aren't good even so, and it will be a while if I do. There exists a set of not-implausible optimistic assumptions that has me getting a ride to space, which is more than most people can say. I'm young and patient; I'll take what I can get, for now.
Of *course* there are better ways to draw broad maps of a planet than to have a person walk it. You are aware that the MER *rovers* aren't doing that either, right? They're doing basic geology.
So, let's craft an interesting set of mission parameters for a moon of Jupiter; it doesn't really matter which one. In fact, I'll make the goals broadly applicable enough that they'd be reasonable on the Moon or Mars too. I'm not a geologist or a planetary scientist or any other such directly relevant profession, so these are mostly a big stab in the dark at things that might be interesting.
It starts with sample return. No instruments you bring with you can match those on Earth, so you should bring samples back. 100kg seems rather minimal; 500kg would be nice. There should be a variety of types of rock, from a variety of locations. I'd like core samples from at least a meter below the surface. A dozen locations and 2-3 samples each ought to suffice. I'd like pictures of rocks and their insides after cleaving them open with a hammer. A few hundred rocks will enough, but it should include all obviously distinct varieties to be found. Oh, and the sample return and cleaved rocks should both include anything that looks especially interesting, for whatever reason.
I'd like to see a battery of tests for signs of microbial activity -- starting with the Viking method, but with variation and repetition. I'd like to see GCMS results for organics on a host of samples. I'd like rough scans for interesting microscopic features that might indicate fossil records or anything else of interest on at least a few hundred rocks, with detailed examination of anything out of the ordinary. Oh, and more samples collected from the region / type of rock that produced it.
Seriously, that's just scratching the surface on both the geology and biology fronts -- and it doesn't even touch things like weather, or ISRU tests, or looking for water. And it's all things that would be reasonable to expect from a relatively small, short dedicated science mission. And any robot would have trouble doing that on Earth, let alone in space -- even before you count the *huge* added value of on-site decision making. Of course, this would be accompanied by a fully robotic orbiting survey craft as well, but that's beside the point.
You're welcome to point out that I've stacked the deck in favor of humans, here, because I have. But not through any underhanded tricks; all I've done is set the mission requirements high. Which is exactly the point I've been trying to make -- as soon as you ask for significant science returns, humans are better, faster, and cheaper. Sure, that won't always be the case, but it will be for the near future. If you settle for a few photos and scratching a couple millimeters off a few rocks, robots do well -- but your science return per dollar spent is a lot higher on the manned mission that costs more and returns a *lot* more data.
These are large ships, with large anchors. Imagine how big an anchor, and how strong an anchor chain, you'd need for a ship with displacement measured in tens of kilotons.
I don't think House and CSI are really the same thing, but I figure I've made my point in that regard.
The cost per pound to launch things has come down, but only slightly. The reason is most emphatically not that we need technological breakthroughs. The energy required is large, as you say, but that's only a very small fraction of the cost (for most launchers, the propellant costs are comparable to the accounting errors). What's needed is simple: someone has to decide that they want to build a launcher that is cheap, reliable, and most importantly flies often (without that you'll never get the first two). We need to stop chasing performance numbers and instead focus on cost. Who cares if the fully fuelled stage weighs more on the pad for the same delivered payload, if by doing so you can have higher margins and therefore less expensive production. You don't need every last second of Isp if sacrificing a couple percent means the engine gets enough cheaper to lower your overall costs. The breakthroughs required are not in the technology, but how the design and development is done. If someone had decided that cost per pound actually mattered enough to be worth chasing, then launch costs would already be down by that factor of ten.
Effectiveness per pound has gone up dramatically in some ways, and very little in others. The most relevant being that a person and the equipment to keep them alive has not gotten substantially lighter. Even so, and with increased competition from robots, people on site remain the most effective option anywhere it's viable -- provided you're actually willing to ask for an agressive set of mission goals. If you keep scaling back missions to make them cheaper, you get robots that do the mission, but the science return per dollar spent drops precipitously. (Of course, there are plenty of missions that can't be done by people yet -- Messenger and New Horizons come to mind as obvious examples.)
At the start of the 1970s, space *was* booming; that ended with the Apollo program. There have been ups and downs since; fortunately, we seem to be on an upswing right now, but that's as much or more due to private sector things as it is to pure science and exploration missions. And, even though private sector stuff is how I'm personally involved, I think the pure science missions are by far the most interesting right now.
Perhaps one day robots will surpass people for general purpose work; but that day is neither today nor in the immediate future.
Astronauts, even if they are only highly skilled technicians, can do the basic science work. They might not be the principle investigator, but there are many qualities that make them superior to robots. They're general purpose and good at using a multitude of tools. They can be given complex and somewhat vague instructions and perform them well -- and those instructions are trivially easy to update in the middle of a mission. And, perhaps most importantly, they can go "that's interesting..." and take creative action that hadn't been previously discussed.
It's also worth noting that the reasons undersea robots work so well don't apply in space. In deep ocean, humans are actually far more limited in capability than they are in even fairly old space suits. And perhaps more importantly, there's a human only a few hours away who can perform general repairs and diagnosis. If you could haul your Mars robot back to Earth, spend a few hours working on it, and send it back in 12-24 hours, at lower cost than just sending a person, then the motivation for sending people would be much less clear. But you can't -- in space, if you want a person within a few hours range, they have to be on site.
People wish for a cure for cancer, but it is not the fuel of imaginations. There is no Star Trek about a cure for cancer. That's not to say it's not important or worth working towards; quite the opposite. It just isn't something that inspires wonder and awe and sparks the imagination the way space exploration once did and hopefully will again.
Space is most emphatically not prohibitively expensive -- not if the goal is for humanity to have a presence in space, and to explore and learn. Sure it is if the goal is for every person to take vacations on the moon, but that's not the point. The fact that a few private sector hobbyists can do what they are should be a clue that space is amazingly accessible to humanity, not that's it inaccessible to individuals.
And lastly, it's nothing at all like asking for computers in every home 50 years ago. It would be more like asking why computer technology grew at an explosive pace until the 1970s and then slowed to a trickle -- because that's basically what happened with space exploration. The probes we send out have gotten a bit more sophisticated, but the goals for the missions have become more modest as we send robots instead of people. The cost of access has stayed about the same, when it should have come down by a factor of ten. Hopefully SpaceX and evetually other companies will change that, but it is shameful that it took so long.
The question isn't "why do you care more about robots." There are a million things that can take center stage for any person. The question is, Why no sense of wonder and curiosity about the universe? Why would you look at the night sky and be so uninterested as to settle for a few photographs, when we can do so much more? There are multitudes of technological fields I'd love to see progress in, and think that research effort is worth spending. Once there was a sense of wonder among the general populace, a desire to learn about and explore the universe. Now? It's gone, as best I can tell. Even among the geeks, it's fading. What happened?
I think you're wrong in several ways. People are intested in genetics, semiconductors, and nanotechnology -- but there is no sense of awe, no sense of wonder, at least among the general public. Sure, people care, but they don't *dream*. There's no exploration involved (except in a metaphorical sense).
Furthermore, space isn't *that* expensive. We could be doing a lot more on not much increase in budget if the willpower was there. And it wouldn't take much willpower and effort to bring the cost down dramatically -- it's happening slowly thanks to the private sector, but it could have been much faster if people wanted it. The biggest limitations are in our imaginations and desires, not technical capability or budgets.
We should not simply sit back and passively wait for abstract technological forces to make space more accessible without our intervention. We should ask why it hasn't happened already, and push for it to happen *now*. The universe awaits us -- all we have to do is decide we want it.
Firstly, I believe my odds of going are significantly better than the average person's, due to my career choice. Still not good, but way better than average.
Secondly, sending a robot isn't as good as sending a person, even if only for purely sentimental reasons -- which are not without value. And if you say they are, then I ask very simply -- what is wrong with you? Have you no sense of wonder? No drive to see humanity explore?
And thirdly, robots are *not* substitutes for humans when it comes to doing basic science. The MER robots do in a day what a trained geologist could do in a couple minutes. The problem is that we're too modest in what we ask for from our missions. If we started by asking what a trained scientist could do given a week or two, and wrote that up as the mission objectives, you'd rapidly discover that no robot we could imagine building in the near future could complete the mission.
What kind of geek are you? How can you not look at the sky and want to *go* there? If you truly tihnk robots can do anything you want done up there, then I believe you have misplaced your imagination.
You check the amp requirements of the fridge, and the rated amperage of the cord. If the former is higher than the latter, don't use that combination. 20 gauge is probably rated around 4 amps (the exact number will depend on insulation etc) -- barely enough for lamp cord, which is usually 18 gauge.
Yeah, if you just stay away from it and don't hang out downwind, you should be ok. Collecting a souvenir that might have hydrazine on it would spectacularly unwise, though.
Hydrazine is more flammable than gasoline, by a wide margin. Flammability limits in air are approximately 2% to 100% -- It's a monopropellant, so it doesn't actually need oxygen to burn (it's a fuel, though, so it will burn faster and hotter with oxygen). That makes it more flammable than even hydrogen. Fortunately it has a lower vapor pressure, so the flash point is somewhat elevated. As a fire hazard, I'd call gasoline worse, but hydrazine is plenty bad enough.
Hydrazine is explosive by itself, without any additions of components. However, it's relatively insensitive, so this is really only a concern to industrial handlers, not to someone who finds a satellite crashed in their yard.
Hydrazine is toxic well beyond the level of bleach. LD50 for skin contact is somewhere around a teaspoon -- a fairly minor spill. At levels well below that, it will cause *permanent* damage to your liver, kidneys, and probably others. There's nothing in your house where a small splash on your skin warrants a trip to the ER (and if there is, you must have some neat hobbies!).
Hydrazine isn't as caustic as some household cleaners; this is mostly relevant when engineering with it, not for hazards of encountering it. It does mean it will eat away many sorts of gloves you might wear -- which makes the previous point and the next three relevant.
It's not just that hydrazine is carcinogenic. Lots of things are carcinogenic in large quantities; a few are in any quantity. Hydrazine is one of the latter (obviously risk level depends on exposure). Some chemicals your body can safely metabolize small amounts of without any increased risk; hydrazine is not one of these. What makes hydrazine so nasty is that, combined with the degree of potency. Monomethyl hydrazine (I don't have data handy for straight hydrazine, which is less nasty; the satellite could well be using straight hydrazine as a monopropellant or MMH or UDMH as a fuel in a bipropellant; all three are commonly used) is one of the most potent carcinogens known. One study showed that a carefully sized single drop of MMH on the skin of lab rats caused cancer in 90%. They had to be careful to keep the drop size down so that it didn't kill the rats by being toxic, though.
Mutagenic and teratogenic are nasty at similar levels; the effects are just slightly different than being carcinogenic. Planning on having kids you want to be healthy? Don't handle hydrazine derivatives.
Now, all that said, with sufficient budget and in the right setting it can be handled mostly safely. "Some thing landed in my backyard; I think I'll get a souvenir" is not that setting. And, depending on the design of the satellite, it's entirely possible a mostly undamaged propellant tank could survive reentry -- similar components have done so previously on other satellite reentries, and on Columbia.
You're surrounded by low level background risks, and things that you shouldn't drink. Hydrazine goes well beyond that -- you'd do better to think of it as a chemical weapon that happens to be to slow to be useful as such. It's only mildly less potent than some of them.
Personally, I wouldn't want to keep anything that's flammable, explosive, toxic, corrosive, carcinogenic, mutagenic, and teratogenic. At least it's not radioactive...
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Yeah, other sources are similar, and Zener diodes are probably the easiest devices to produce noisier versions of (and still maintain high noie quality). I mention resistors mainly because the physics behind them is the easiest to understand.
Resistor thermal noise is also inherently quantum in origin, and much easier to measure. All it takes is a resistor, a good analog amplifier, and an A/D converter -- which could all fit on a single piece of silicon if you wanted.
Just because it's not a troll doesn't mean it's a good patent. It may be that the solution is obvious to one "skilled in the art" even though no one seriously considered the problem before. Just because the university thought of it first doesn't mean it's a good patent.
Of course, I haven't looked at the details of the patent or the case. It may well be a blatant attempt by Intel to rip off a clever idea from the university. My guess is that reality is somewhere in between...
Another contradiction of capitalism that is an observation in Marxist theory is the desire of an individual firm to pay its employees as little as possible, but that depends on well-paid consumers having enough money to buy their products.
All that is is negative feedback. If you want to create a system capable of optimizing itself to changing conditions without a very complicated model and detailed control system (with attendant long, involved tuning process), be it an economy or a simple industrial process, you'll probably find it best to put multiple forces in place that oppose each other in such a way that they balance at an equilibrium point that's near the optimum. There is nothing "contradictory" about market forces being in opposition. One can argue about how well it works (imho, it clearly does a near-perfect job in some cases and an awful job in others), but as part of a design of an economic framework it's not at all clear it's a bad route to take.
Seriously, try creating a *good* control scheme for a simple system that doesn't involve a negative feedback loop. Then consider how amazingly not simple an economy is.
Some would say that there is no right to privacy in the constitution, but I say there it is, staring you in the face, as the underlying presumption that created the first phrase in the fourth amendment.
It doesn't need to be in the Constitution. It is a basic right. The Constitution was written on the principle that it does not grant rights. It prevents the government from taking away rights you *already possess*. It is abundantly clear, both from the text itself and the discussions that led to it, that the Constitution enumerates a subset of our rights. The fact that it is not mentioned in the Constitution does not mean you don't have it -- quite the opposite. If it isn't mentioned, that means the government has no right to touch it.
But then, no one actually reads it any more.
It might not fund the Iraq war for all that long, but when you focus it on a single project $1,200,000,000 is realy an awfully big number...
Both are true, actually. The CFCs cause it, but the chemistry mostly happens on the surfaces of ice crystals. Normally those are exceedingly rare that high up, since the water vapor mostly freezes out and falls before then. So adding more water vapor to the upper atmosphere probably is a bad idea, actually.
Hydrogen is normally produced via steam reforming and related processes (water gas shift reaction, coal gassification, etc), not electrolysis. That is, the hydrogen and the energy to produce it both come from fossil fuels (mostly natural gas, but oil and coal can both be used -- though in the case of coal all the hydrogen is coming from the water).
And actually, there is currently a *huge* hydrogen production industry. It's just mostly used on site at large plants rather than shipped to consumers as energy storage. Ammonium nitrate fertilizer is a *gigantic* market, and it's made by combining atmospheric nitrogen and hydrogen into ammonia, and then converting some of that ammonia into nitric acid before combining the two to form AN.
The availability of hydrogen is actually only a minor detail in this design. The price and the awkwardness of handling the ultra light weight ultra cold liquid are much more relevant.
They're claiming a price point comparable to current business class fares. There are enough business class fares sold currently to support a small fleet of such airplanes flying a few flights on the relevant long-haul routes. Anyone willing to pay for business class is certainly willing to pay a similar amount (or probably at least a moderate premium) to cut their flight time from 12+ hours to 2-4.
I can't speak to the details of this specific airplane, mostly because those details don't exist yet, but there has been significant work lately in reducing sonic booms through careful airframe shaping. They can probably fly supersonic overland as long as they're at altitude and not near population centers -- but I certainly can't guarantee that, and it's certainly subject to regulatory issues. Of course, the market *might* be big enough even with only the transoceanic flights -- LA to Sydney, Tokyo, Beijing, NYC to Western Europe, and possibly a few others.
Like you, I think the issues are more regulatory than technical. However, I think they have a lot more to do with development schedules and costs than they do with the existence of a sufficiently large market. If they can get the money and build it on the budget they say they can, the market will be there. Of course, that's a really, really big if.
Price will come down if fuel economy is reasonable and there are enough airplanes and flights to amortize development costs over. My impression (I've been following them for a while, and talked to people who should know) is that they're technically competent, and if they say they can get the price down, they can -- but that they're being overly optimistic about the market. Of course, if the government is paying for a low of the development, that helps a lot.
Noise is actually quite amenable to a technical solution. The first problem (noise near the airport) is a result of high-power, high exhaust velocity engines, combined with a need to get up to supersonic speeds quickly. If, as they claim, the airplane is efficient in the subsonic regime as well, then there is less pressure to accelerate rapidly. Efficient low-speed operation also inherently implies a lower exhaust speed (which they discuss briefly: variable high-bypass flow), which implies less noise -- for a given engine, noise power scales roughly (very roughly) linearly with exhaust velocity.
Noise from sonic booms is remarkably controllable, with sufficient work on the precise shape of the airframe. The technology to do that, high performance CFD, simply didn't exist when the Concorde was designed. They don't discuss it, but it's far too early in the design cycle for that to mean anything. Right now they're basically just trying to build the engine and convince people that a market exists at a price point they can reach. That requires design studies and concept art, but it's not yet time to be fine tuning the aerodynamics.
I'd say the technical problems, including noise, are amenable to solution if they manage to get the funding they need without too much interference. The market ones, less so. I'm sure one day we'll see supersonic airliners, but there are some *major* non-technical hurdles in the way of building anything the size of an A380.
Of course, it's wicked cool and I'd love to see it happen. Especially since the basic engine technology is also behind their Skylon SSTO spaceplane concept...
If I go to space, it won't be through NASA -- my odds on that are no better than average. I won't go into details except to reiterate that my odds aren't good even so, and it will be a while if I do. There exists a set of not-implausible optimistic assumptions that has me getting a ride to space, which is more than most people can say. I'm young and patient; I'll take what I can get, for now.
Of *course* there are better ways to draw broad maps of a planet than to have a person walk it. You are aware that the MER *rovers* aren't doing that either, right? They're doing basic geology.
So, let's craft an interesting set of mission parameters for a moon of Jupiter; it doesn't really matter which one. In fact, I'll make the goals broadly applicable enough that they'd be reasonable on the Moon or Mars too. I'm not a geologist or a planetary scientist or any other such directly relevant profession, so these are mostly a big stab in the dark at things that might be interesting.
It starts with sample return. No instruments you bring with you can match those on Earth, so you should bring samples back. 100kg seems rather minimal; 500kg would be nice. There should be a variety of types of rock, from a variety of locations. I'd like core samples from at least a meter below the surface. A dozen locations and 2-3 samples each ought to suffice. I'd like pictures of rocks and their insides after cleaving them open with a hammer. A few hundred rocks will enough, but it should include all obviously distinct varieties to be found. Oh, and the sample return and cleaved rocks should both include anything that looks especially interesting, for whatever reason.
I'd like to see a battery of tests for signs of microbial activity -- starting with the Viking method, but with variation and repetition. I'd like to see GCMS results for organics on a host of samples. I'd like rough scans for interesting microscopic features that might indicate fossil records or anything else of interest on at least a few hundred rocks, with detailed examination of anything out of the ordinary. Oh, and more samples collected from the region / type of rock that produced it.
Seriously, that's just scratching the surface on both the geology and biology fronts -- and it doesn't even touch things like weather, or ISRU tests, or looking for water. And it's all things that would be reasonable to expect from a relatively small, short dedicated science mission. And any robot would have trouble doing that on Earth, let alone in space -- even before you count the *huge* added value of on-site decision making. Of course, this would be accompanied by a fully robotic orbiting survey craft as well, but that's beside the point.
You're welcome to point out that I've stacked the deck in favor of humans, here, because I have. But not through any underhanded tricks; all I've done is set the mission requirements high. Which is exactly the point I've been trying to make -- as soon as you ask for significant science returns, humans are better, faster, and cheaper. Sure, that won't always be the case, but it will be for the near future. If you settle for a few photos and scratching a couple millimeters off a few rocks, robots do well -- but your science return per dollar spent is a lot higher on the manned mission that costs more and returns a *lot* more data.
These are large ships, with large anchors. Imagine how big an anchor, and how strong an anchor chain, you'd need for a ship with displacement measured in tens of kilotons.
I don't think House and CSI are really the same thing, but I figure I've made my point in that regard.
The cost per pound to launch things has come down, but only slightly. The reason is most emphatically not that we need technological breakthroughs. The energy required is large, as you say, but that's only a very small fraction of the cost (for most launchers, the propellant costs are comparable to the accounting errors). What's needed is simple: someone has to decide that they want to build a launcher that is cheap, reliable, and most importantly flies often (without that you'll never get the first two). We need to stop chasing performance numbers and instead focus on cost. Who cares if the fully fuelled stage weighs more on the pad for the same delivered payload, if by doing so you can have higher margins and therefore less expensive production. You don't need every last second of Isp if sacrificing a couple percent means the engine gets enough cheaper to lower your overall costs. The breakthroughs required are not in the technology, but how the design and development is done. If someone had decided that cost per pound actually mattered enough to be worth chasing, then launch costs would already be down by that factor of ten.
Effectiveness per pound has gone up dramatically in some ways, and very little in others. The most relevant being that a person and the equipment to keep them alive has not gotten substantially lighter. Even so, and with increased competition from robots, people on site remain the most effective option anywhere it's viable -- provided you're actually willing to ask for an agressive set of mission goals. If you keep scaling back missions to make them cheaper, you get robots that do the mission, but the science return per dollar spent drops precipitously. (Of course, there are plenty of missions that can't be done by people yet -- Messenger and New Horizons come to mind as obvious examples.)
At the start of the 1970s, space *was* booming; that ended with the Apollo program. There have been ups and downs since; fortunately, we seem to be on an upswing right now, but that's as much or more due to private sector things as it is to pure science and exploration missions. And, even though private sector stuff is how I'm personally involved, I think the pure science missions are by far the most interesting right now.
Perhaps one day robots will surpass people for general purpose work; but that day is neither today nor in the immediate future.
Astronauts, even if they are only highly skilled technicians, can do the basic science work. They might not be the principle investigator, but there are many qualities that make them superior to robots. They're general purpose and good at using a multitude of tools. They can be given complex and somewhat vague instructions and perform them well -- and those instructions are trivially easy to update in the middle of a mission. And, perhaps most importantly, they can go "that's interesting..." and take creative action that hadn't been previously discussed.
It's also worth noting that the reasons undersea robots work so well don't apply in space. In deep ocean, humans are actually far more limited in capability than they are in even fairly old space suits. And perhaps more importantly, there's a human only a few hours away who can perform general repairs and diagnosis. If you could haul your Mars robot back to Earth, spend a few hours working on it, and send it back in 12-24 hours, at lower cost than just sending a person, then the motivation for sending people would be much less clear. But you can't -- in space, if you want a person within a few hours range, they have to be on site.
People wish for a cure for cancer, but it is not the fuel of imaginations. There is no Star Trek about a cure for cancer. That's not to say it's not important or worth working towards; quite the opposite. It just isn't something that inspires wonder and awe and sparks the imagination the way space exploration once did and hopefully will again.
Space is most emphatically not prohibitively expensive -- not if the goal is for humanity to have a presence in space, and to explore and learn. Sure it is if the goal is for every person to take vacations on the moon, but that's not the point. The fact that a few private sector hobbyists can do what they are should be a clue that space is amazingly accessible to humanity, not that's it inaccessible to individuals.
And lastly, it's nothing at all like asking for computers in every home 50 years ago. It would be more like asking why computer technology grew at an explosive pace until the 1970s and then slowed to a trickle -- because that's basically what happened with space exploration. The probes we send out have gotten a bit more sophisticated, but the goals for the missions have become more modest as we send robots instead of people. The cost of access has stayed about the same, when it should have come down by a factor of ten. Hopefully SpaceX and evetually other companies will change that, but it is shameful that it took so long.
The question isn't "why do you care more about robots." There are a million things that can take center stage for any person. The question is, Why no sense of wonder and curiosity about the universe? Why would you look at the night sky and be so uninterested as to settle for a few photographs, when we can do so much more? There are multitudes of technological fields I'd love to see progress in, and think that research effort is worth spending. Once there was a sense of wonder among the general populace, a desire to learn about and explore the universe. Now? It's gone, as best I can tell. Even among the geeks, it's fading. What happened?
I think you're wrong in several ways. People are intested in genetics, semiconductors, and nanotechnology -- but there is no sense of awe, no sense of wonder, at least among the general public. Sure, people care, but they don't *dream*. There's no exploration involved (except in a metaphorical sense).
Furthermore, space isn't *that* expensive. We could be doing a lot more on not much increase in budget if the willpower was there. And it wouldn't take much willpower and effort to bring the cost down dramatically -- it's happening slowly thanks to the private sector, but it could have been much faster if people wanted it. The biggest limitations are in our imaginations and desires, not technical capability or budgets.
We should not simply sit back and passively wait for abstract technological forces to make space more accessible without our intervention. We should ask why it hasn't happened already, and push for it to happen *now*. The universe awaits us -- all we have to do is decide we want it.
I beg to disagree on all counts.
Firstly, I believe my odds of going are significantly better than the average person's, due to my career choice. Still not good, but way better than average.
Secondly, sending a robot isn't as good as sending a person, even if only for purely sentimental reasons -- which are not without value. And if you say they are, then I ask very simply -- what is wrong with you? Have you no sense of wonder? No drive to see humanity explore?
And thirdly, robots are *not* substitutes for humans when it comes to doing basic science. The MER robots do in a day what a trained geologist could do in a couple minutes. The problem is that we're too modest in what we ask for from our missions. If we started by asking what a trained scientist could do given a week or two, and wrote that up as the mission objectives, you'd rapidly discover that no robot we could imagine building in the near future could complete the mission.
What kind of geek are you? How can you not look at the sky and want to *go* there? If you truly tihnk robots can do anything you want done up there, then I believe you have misplaced your imagination.
Indeed. The date of the last footprints on the Moon.
How is it that Americans have lost their sense of wonder?
December 14, 1972 is the anniversary I pay the most attention to. I sincerely hope we go back.
You check the amp requirements of the fridge, and the rated amperage of the cord. If the former is higher than the latter, don't use that combination. 20 gauge is probably rated around 4 amps (the exact number will depend on insulation etc) -- barely enough for lamp cord, which is usually 18 gauge.
Yeah, if you just stay away from it and don't hang out downwind, you should be ok. Collecting a souvenir that might have hydrazine on it would spectacularly unwise, though.
I suppose I wasn't clear on the details.
Hydrazine is more flammable than gasoline, by a wide margin. Flammability limits in air are approximately 2% to 100% -- It's a monopropellant, so it doesn't actually need oxygen to burn (it's a fuel, though, so it will burn faster and hotter with oxygen). That makes it more flammable than even hydrogen. Fortunately it has a lower vapor pressure, so the flash point is somewhat elevated. As a fire hazard, I'd call gasoline worse, but hydrazine is plenty bad enough.
Hydrazine is explosive by itself, without any additions of components. However, it's relatively insensitive, so this is really only a concern to industrial handlers, not to someone who finds a satellite crashed in their yard.
Hydrazine is toxic well beyond the level of bleach. LD50 for skin contact is somewhere around a teaspoon -- a fairly minor spill. At levels well below that, it will cause *permanent* damage to your liver, kidneys, and probably others. There's nothing in your house where a small splash on your skin warrants a trip to the ER (and if there is, you must have some neat hobbies!).
Hydrazine isn't as caustic as some household cleaners; this is mostly relevant when engineering with it, not for hazards of encountering it. It does mean it will eat away many sorts of gloves you might wear -- which makes the previous point and the next three relevant.
It's not just that hydrazine is carcinogenic. Lots of things are carcinogenic in large quantities; a few are in any quantity. Hydrazine is one of the latter (obviously risk level depends on exposure). Some chemicals your body can safely metabolize small amounts of without any increased risk; hydrazine is not one of these. What makes hydrazine so nasty is that, combined with the degree of potency. Monomethyl hydrazine (I don't have data handy for straight hydrazine, which is less nasty; the satellite could well be using straight hydrazine as a monopropellant or MMH or UDMH as a fuel in a bipropellant; all three are commonly used) is one of the most potent carcinogens known. One study showed that a carefully sized single drop of MMH on the skin of lab rats caused cancer in 90%. They had to be careful to keep the drop size down so that it didn't kill the rats by being toxic, though.
Mutagenic and teratogenic are nasty at similar levels; the effects are just slightly different than being carcinogenic. Planning on having kids you want to be healthy? Don't handle hydrazine derivatives.
Now, all that said, with sufficient budget and in the right setting it can be handled mostly safely. "Some thing landed in my backyard; I think I'll get a souvenir" is not that setting. And, depending on the design of the satellite, it's entirely possible a mostly undamaged propellant tank could survive reentry -- similar components have done so previously on other satellite reentries, and on Columbia.
You're surrounded by low level background risks, and things that you shouldn't drink. Hydrazine goes well beyond that -- you'd do better to think of it as a chemical weapon that happens to be to slow to be useful as such. It's only mildly less potent than some of them.
Yeah, have fun with the hydrazine.
Personally, I wouldn't want to keep anything that's flammable, explosive, toxic, corrosive, carcinogenic, mutagenic, and teratogenic. At least it's not radioactive...