Windmills are the wrong analogy, and profplump did not break the laws of thermodynamics with his suggestion. Windmills operate at the temperature of the exhaust reservoir - the atmosphere. If the exhaust from a turbine is 1000 K, though, and the atmospheric temperature is 300 K, then additional turbines can be used to recover a maximum of 70% of the available thermal energy. There are many power plant and jet engine designs that have multiple turbines in a single flowpath. The number of turbines is limited by considerations relative to added profitability and performance for each additional turbine stage.
You are correct that thermal energy in its lowest state cannot be used to do work, but if it is already in that state, then it must be at the same temperature as the surroundings and would thus not contribute additional heat as pollution. The question is, is it worth it financially to convert "extra" radiated heat to electricity using sterling engines or other methods.
Adding 20% to the length of the SRB means the entire internal grain has to be redesigned - all of it. For a motor of that size, that is equivalent to designing a new rocket. ATK is getting paid between two and three billion dollars just to develop it.
Certainly, you can put a person on top of an RS-68. NASA was going to do that with the Orbital Space Plane on a Delta IV, a program which got canceled when the new administration took over. Manrating isn't so much a matter of redesign as it is a process of ensuring that a certain level of reliability is met, which can also be done through testing. As Mike Griffin has said, we launch multi-billion dollar satellites on those engines, so we take a similar level of precaution to protect those extremely expensive satellites as we would to protect people. It is when the engine doesn't meet the specified level of reliability that redesigning has to take place.
The J-2X is almost totally new. The major similarities are 1) they both use a gas generator cycle (so does the RS-68, and so did the kerosene fueled F-1) and 2) they both have a name that includes "J-2". Otherwise, they are very different. Different materials, different pumps, the J-2X even uses an ablative (passively cooled) nozzle, whereas the J-2 used hundreds of tubes welded together for cooling.
One difference is that Ares V doesn't use a shuttle external tank, or anything like it. It uses a much thicker and longer tank that has the same orange foam on the outside. Another difference is that Ares V doesn't use shuttle solid rocket boosters. It uses new longer boosters that (might) use the same sized steel (maybe, still up for debate) casing.
The Ares isn't simpler because that booster (5 segment SRB)on the bottom doesn't exist yet. Nor do the propellant tanks (18 ft diameter) or the engine for the upper stage (J-2X). All of those corollary elements (4 segment SRB, 28 ft diameter shuttle ET, RS-68 engine) already exist for the Jupiter-120.
The initial architecture of Constellation was based on the congressional requirement that NASA actually use Shuttle derived rockets. The moment the original architecture was rolled out, though, (space shuttle main engines, four segment solid rocket boosters, 28 ft diameter tank), NASA ditched both the SSMEs and the 4 seg SRBs. They couldn't air start the SSME, so they had to develop a new engine. (The J-2X sounds like the Apollo J-2, but they have very few components in common, and the J-2X is 30% more powerful.) Then, they dumped the SSMEs for the Ares V core vehicle, and replaced them with RS-68s from the Delta IV. That was a smart move because the cost is way lower. But, since the performance is lower, they had to enlarge the tank (read develop a brand new one.) Now, it's 33 ft in diameter, and requires all new tooling and massive modifications to the manufacturing, preparation and launch facilities. That costs a lot, too. All this after developing another much smaller but equally expensive Crew Launch Vehicle. So, while the Ares now has nothing in common with the Shuttle, it costs many times more to develop, and twice as much to operate. DIRECT does have the side effect of maintaining more jobs than Ares does in the near term, but in the long run, Ares would require more employees, and that is a large part of where the cost increase comes from. The extra money saved would be used to speed up the moon missions by two years, close NASA's manned spaceflight gap by three or four years, and perform more science missions.
It's the management that actually chose the configuration. Most of the engineers are busting their brains trying to make the concept work, wondering why their managers didn't pick a more workable and affordable concept.
The space shuttle also didn't have an escape system. The Orion capsule will. It is safer to use liquid fueled engines that can be shut down, but if the space shuttle had been designed in such a way that the astronauts could separate their vehicle from the rocket, the Challenger crew might still have survived, even with the solid boosters on the side.
The Ares I-X has no commonality with the actual Ares I. It will still use a four segment solid rocket motor from the space shuttle, instead of the five segment one (a $2 billion dollar development project) that the real Ares I will use, and will have a dummy fifth segment and dummy upperstage. The actual Ares I-Y (a closer test vehicle that uses the proper solid rocket motor) won't fly until 2013, and the real Ares I won't fly until 2015 at the earliest and can't fly earlier because the upper stage engine won't be ready until around that time. The flight next year is more of a political stunt by NASA to give the appearance of progress. It's like driving out a Ferrari, but the body is plastic, and there's a Ford engine and a one gear forward only transmission under the hood.
Throw a solar panel on the roof. You can move at 10-15 mph to get to a charging location. If it's nighttime, rather than tow the vehicle, have the tow company bring out a trailer with a fast charger on it and you can be fully charged and on your way in 15 minutes.
I live in southern Mississippi. We don't even have a bus to ride. If we did, I'd probably use it a lot, unless it cost as much to ride as it does in Salt Lake or was as crowded as the buses in Tirana. By the way, the Seattle bus sytem is very nice. The difference, I think, is a combination of culture and available infrastructure. When I lived in Seattle, my coworkers would bike 12 miles to work, and then run another 5 miles in the afternoon. I walked ten times more than I do now. We were more health minded. We could do this, though, because there are nice wide walking/biking trails that go from the U District to who knows where (SeaTac airport maybe). Where I live now, the roads (aside from the highways) are 15 feet wide and have no sidewalks. It isn't even safe to walk because the cars are all going at 55 mph in 30 mph zones. Wider roads with side walks, walking trails, and/or slower (and thus less gas guzzling) driving, would make it much easier to live a conservational lifestyle here.
A series of books that I enjoyed reading as a fifth grader was "Jack Anderson's Presents The Young Astronauts" by Rick North. It only had six books as I recall, and I was disappointed that it ended there. Basically, it was about an international program to launch a flotilla of three large spaceships full of teenagers mostly. The ships go on a one way trip to Mars to establish a permanent colony. It has some drama, an interesting international cast of characters, and a poor side attempt at romantic conflict, but on the whole I found it to be an enjoyable piece of semi-realistic sci-fi.
[quote]My Core 2 Duo Mac mini + ViewSonic VP171s are both listed at 30-35W average.
Hearing about videocards requiring power connectors AND wasting 300W of power just seems insane to me.[/quote]
Right, so you get 15-18 watts per core. I'm not going to defend this concept for a graphics card, but for a 32 core mini-supercomputer, 9 watts per core isn't bad at all. I would just hope the chips include the floating point operations fix that went out with the replacement chips.
Anything in the future is speculative, so don't sweat it too heavily.
I said "cryogenic" (i.e. hydrogen) rocket fuel, which RP-1 is most definitely not. Even at a dollar a pound, though, it is still miniscule in comparison to the current price to launch a rocket, which was my point in that argument.
I am well aware of the fact that oxidizer is needed because I test liquid fueled rockets for a living, thank you.
It's true that solar sails cannot move huge amounts of ore or the like, but many of them might be able to move a useful amount of already processed metals at a greatly reduced cost. It's probably not the best way to do it, though. I was making the point that there are other ways to move around in space that are not as expensive as our basic chemical rockets. Still, rocket fuel could be mined from comets and some asteroids in the form of water which can be electrolyzed into hydrogen and oxygen (inefficient propulsion, probably). Run the hydrogen through a nuclear reactor and one could get much better performance. Solar thermal or electric rocketry isn't out either. Who knows what technology would be used for sure. The point is that without Earth's huge gravity well, it becomes much easier to get around.
One wouldn't need to take a re-entry vehicle up to space from Earth, either, because, remember, the raw materials for such vehicles are already in space; it's what you're mining. The re-entry vehicles can also be part of the product, since they're mostly metal just with some ablative carbon lining (most asteroids contain large amounts of carbon) and a parachute. That's just a possible example. I'm not trying to predict the future, just consider some possibilities.
Exploration does cost a lot. But when you have ore with 90% iron/nickel (some asteroids) and maybe.1% rare metals, it doesn't take any exploration to find it beyond looking through a telescope and analyzing the light with a spectroscope - much cheaper than drilling underground.
Finally, I don't pretend that any of this will happen at any point in the near future. But, according to the likes of Gerard O'Neil and John C. Lewis, this solar system has the energy and resources to support more than a quadrillion people. The demand for in space mining wouldn't really come until the people who need it already live in space. It would just be a big benefit to those already living here on Earth.
Because the demand for cheap spaceflight would be present industry with a large enough market to encourage investment in the technology. Cryogenic rocket fuel is fairly cheap stuff - like $.50 a pound, same as gasoline - so the cost is in the vehicle and the operations. Boeing spent seven billion dollars developing the 777, and has sold hundreds of them for $120 million a pop. (Granted, due to fuel prices, a lot of them are on the ground). It would require a comparable investment to develop a reusable rocket with good maintainability and high reusability. Besides, once your actually in space, you can use things like solar sails or magnetic sails. Even plain old rockets aren't so bad then because they no longer have to get off of the surface of the Earth, so they can operate at a lower thrust level (lower engine mass) and require less fuel (low delta-V).
So, really, the issue is low demand. If more people had a good valuable reason to go into space, the market would provide them with a way. So far, the only way to make money is with telecommunications, and at the low rate of launch, it is more profitable for companies to build a smaller number of expendable launch vehicles that have a higher per unit cost.
Carbon nanotubes might also be carcinogenic - very small and can easily be lodged in lung tissue. I'm not dumping on the idea of using them for electronics, I just think more research needs to be done before nanotubes are declared as the best solution for the electronics industry.
Yes, but think about all of the heavy metals and toxic chemicals that have been dumped into those landfills, and think about how much it will cost to comply with OSHA standards to get to the recyclable materials. It may not be as economically viable as it sounds.
That same majority of the American population is not given access to said nuclear weapons, so your conclusion is flawed.
Please do not equate my intelligence with a morning television entertainer.
I'm not trying to perpetuate a religious argument or anything, but I would just like to point out two or three things in response.
First, map 34 in Figure 4 shows the Colombian people having some origin in the regions around Eastern Iran and Western India, not China. The Jewish nation was taken captive into Persia (modern Iran) circa 722 B.C. A couple of other contemporary invasions also sent descendants of Israel all over the old world. That is early enough to match Mormon scripture, though the migratory pattern doesn't match the scenario described in the book.
Second, the Book of Mormon states the people described therein were of the tribe of Manasseh, not Judah. "Jew" only referred to their nationality, not their ethnicity.
Third, most Jews in Israel today are descendants of the European Jews of the Diaspora rather than those present in the land of Palestine during the later Biblical periods.
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Maybe woment don't go into CS as much because the men in CS don't have as much earning potential as they used to.
Windmills are the wrong analogy, and profplump did not break the laws of thermodynamics with his suggestion. Windmills operate at the temperature of the exhaust reservoir - the atmosphere. If the exhaust from a turbine is 1000 K, though, and the atmospheric temperature is 300 K, then additional turbines can be used to recover a maximum of 70% of the available thermal energy. There are many power plant and jet engine designs that have multiple turbines in a single flowpath. The number of turbines is limited by considerations relative to added profitability and performance for each additional turbine stage. You are correct that thermal energy in its lowest state cannot be used to do work, but if it is already in that state, then it must be at the same temperature as the surroundings and would thus not contribute additional heat as pollution. The question is, is it worth it financially to convert "extra" radiated heat to electricity using sterling engines or other methods.
Since you know at best .01% of all science, I must question your conclusions.
...or any of the Democrat US presidents for that matter?
Adding 20% to the length of the SRB means the entire internal grain has to be redesigned - all of it. For a motor of that size, that is equivalent to designing a new rocket. ATK is getting paid between two and three billion dollars just to develop it. Certainly, you can put a person on top of an RS-68. NASA was going to do that with the Orbital Space Plane on a Delta IV, a program which got canceled when the new administration took over. Manrating isn't so much a matter of redesign as it is a process of ensuring that a certain level of reliability is met, which can also be done through testing. As Mike Griffin has said, we launch multi-billion dollar satellites on those engines, so we take a similar level of precaution to protect those extremely expensive satellites as we would to protect people. It is when the engine doesn't meet the specified level of reliability that redesigning has to take place. The J-2X is almost totally new. The major similarities are 1) they both use a gas generator cycle (so does the RS-68, and so did the kerosene fueled F-1) and 2) they both have a name that includes "J-2". Otherwise, they are very different. Different materials, different pumps, the J-2X even uses an ablative (passively cooled) nozzle, whereas the J-2 used hundreds of tubes welded together for cooling.
One difference is that Ares V doesn't use a shuttle external tank, or anything like it. It uses a much thicker and longer tank that has the same orange foam on the outside. Another difference is that Ares V doesn't use shuttle solid rocket boosters. It uses new longer boosters that (might) use the same sized steel (maybe, still up for debate) casing.
The Ares isn't simpler because that booster (5 segment SRB)on the bottom doesn't exist yet. Nor do the propellant tanks (18 ft diameter) or the engine for the upper stage (J-2X). All of those corollary elements (4 segment SRB, 28 ft diameter shuttle ET, RS-68 engine) already exist for the Jupiter-120.
The initial architecture of Constellation was based on the congressional requirement that NASA actually use Shuttle derived rockets. The moment the original architecture was rolled out, though, (space shuttle main engines, four segment solid rocket boosters, 28 ft diameter tank), NASA ditched both the SSMEs and the 4 seg SRBs. They couldn't air start the SSME, so they had to develop a new engine. (The J-2X sounds like the Apollo J-2, but they have very few components in common, and the J-2X is 30% more powerful.) Then, they dumped the SSMEs for the Ares V core vehicle, and replaced them with RS-68s from the Delta IV. That was a smart move because the cost is way lower. But, since the performance is lower, they had to enlarge the tank (read develop a brand new one.) Now, it's 33 ft in diameter, and requires all new tooling and massive modifications to the manufacturing, preparation and launch facilities. That costs a lot, too. All this after developing another much smaller but equally expensive Crew Launch Vehicle. So, while the Ares now has nothing in common with the Shuttle, it costs many times more to develop, and twice as much to operate. DIRECT does have the side effect of maintaining more jobs than Ares does in the near term, but in the long run, Ares would require more employees, and that is a large part of where the cost increase comes from. The extra money saved would be used to speed up the moon missions by two years, close NASA's manned spaceflight gap by three or four years, and perform more science missions.
It's the management that actually chose the configuration. Most of the engineers are busting their brains trying to make the concept work, wondering why their managers didn't pick a more workable and affordable concept.
The per launch cost of the DIRECT launcher would be lower than that of the Ares I, so in comparison, it would be free payload.
The space shuttle also didn't have an escape system. The Orion capsule will. It is safer to use liquid fueled engines that can be shut down, but if the space shuttle had been designed in such a way that the astronauts could separate their vehicle from the rocket, the Challenger crew might still have survived, even with the solid boosters on the side.
The Ares I-X has no commonality with the actual Ares I. It will still use a four segment solid rocket motor from the space shuttle, instead of the five segment one (a $2 billion dollar development project) that the real Ares I will use, and will have a dummy fifth segment and dummy upperstage. The actual Ares I-Y (a closer test vehicle that uses the proper solid rocket motor) won't fly until 2013, and the real Ares I won't fly until 2015 at the earliest and can't fly earlier because the upper stage engine won't be ready until around that time. The flight next year is more of a political stunt by NASA to give the appearance of progress. It's like driving out a Ferrari, but the body is plastic, and there's a Ford engine and a one gear forward only transmission under the hood.
Throw a solar panel on the roof. You can move at 10-15 mph to get to a charging location. If it's nighttime, rather than tow the vehicle, have the tow company bring out a trailer with a fast charger on it and you can be fully charged and on your way in 15 minutes.
I live in southern Mississippi. We don't even have a bus to ride. If we did, I'd probably use it a lot, unless it cost as much to ride as it does in Salt Lake or was as crowded as the buses in Tirana. By the way, the Seattle bus sytem is very nice. The difference, I think, is a combination of culture and available infrastructure. When I lived in Seattle, my coworkers would bike 12 miles to work, and then run another 5 miles in the afternoon. I walked ten times more than I do now. We were more health minded. We could do this, though, because there are nice wide walking/biking trails that go from the U District to who knows where (SeaTac airport maybe). Where I live now, the roads (aside from the highways) are 15 feet wide and have no sidewalks. It isn't even safe to walk because the cars are all going at 55 mph in 30 mph zones. Wider roads with side walks, walking trails, and/or slower (and thus less gas guzzling) driving, would make it much easier to live a conservational lifestyle here.
A series of books that I enjoyed reading as a fifth grader was "Jack Anderson's Presents The Young Astronauts" by Rick North. It only had six books as I recall, and I was disappointed that it ended there. Basically, it was about an international program to launch a flotilla of three large spaceships full of teenagers mostly. The ships go on a one way trip to Mars to establish a permanent colony. It has some drama, an interesting international cast of characters, and a poor side attempt at romantic conflict, but on the whole I found it to be an enjoyable piece of semi-realistic sci-fi.
[quote]My Core 2 Duo Mac mini + ViewSonic VP171s are both listed at 30-35W average. Hearing about videocards requiring power connectors AND wasting 300W of power just seems insane to me.[/quote] Right, so you get 15-18 watts per core. I'm not going to defend this concept for a graphics card, but for a 32 core mini-supercomputer, 9 watts per core isn't bad at all. I would just hope the chips include the floating point operations fix that went out with the replacement chips.
Anything in the future is speculative, so don't sweat it too heavily. I said "cryogenic" (i.e. hydrogen) rocket fuel, which RP-1 is most definitely not. Even at a dollar a pound, though, it is still miniscule in comparison to the current price to launch a rocket, which was my point in that argument. I am well aware of the fact that oxidizer is needed because I test liquid fueled rockets for a living, thank you. It's true that solar sails cannot move huge amounts of ore or the like, but many of them might be able to move a useful amount of already processed metals at a greatly reduced cost. It's probably not the best way to do it, though. I was making the point that there are other ways to move around in space that are not as expensive as our basic chemical rockets. Still, rocket fuel could be mined from comets and some asteroids in the form of water which can be electrolyzed into hydrogen and oxygen (inefficient propulsion, probably). Run the hydrogen through a nuclear reactor and one could get much better performance. Solar thermal or electric rocketry isn't out either. Who knows what technology would be used for sure. The point is that without Earth's huge gravity well, it becomes much easier to get around. One wouldn't need to take a re-entry vehicle up to space from Earth, either, because, remember, the raw materials for such vehicles are already in space; it's what you're mining. The re-entry vehicles can also be part of the product, since they're mostly metal just with some ablative carbon lining (most asteroids contain large amounts of carbon) and a parachute. That's just a possible example. I'm not trying to predict the future, just consider some possibilities. Exploration does cost a lot. But when you have ore with 90% iron/nickel (some asteroids) and maybe .1% rare metals, it doesn't take any exploration to find it beyond looking through a telescope and analyzing the light with a spectroscope - much cheaper than drilling underground.
Finally, I don't pretend that any of this will happen at any point in the near future. But, according to the likes of Gerard O'Neil and John C. Lewis, this solar system has the energy and resources to support more than a quadrillion people. The demand for in space mining wouldn't really come until the people who need it already live in space. It would just be a big benefit to those already living here on Earth.
Because the demand for cheap spaceflight would be present industry with a large enough market to encourage investment in the technology. Cryogenic rocket fuel is fairly cheap stuff - like $.50 a pound, same as gasoline - so the cost is in the vehicle and the operations. Boeing spent seven billion dollars developing the 777, and has sold hundreds of them for $120 million a pop. (Granted, due to fuel prices, a lot of them are on the ground). It would require a comparable investment to develop a reusable rocket with good maintainability and high reusability. Besides, once your actually in space, you can use things like solar sails or magnetic sails. Even plain old rockets aren't so bad then because they no longer have to get off of the surface of the Earth, so they can operate at a lower thrust level (lower engine mass) and require less fuel (low delta-V). So, really, the issue is low demand. If more people had a good valuable reason to go into space, the market would provide them with a way. So far, the only way to make money is with telecommunications, and at the low rate of launch, it is more profitable for companies to build a smaller number of expendable launch vehicles that have a higher per unit cost.
Carbon nanotubes might also be carcinogenic - very small and can easily be lodged in lung tissue. I'm not dumping on the idea of using them for electronics, I just think more research needs to be done before nanotubes are declared as the best solution for the electronics industry.
Yes, but think about all of the heavy metals and toxic chemicals that have been dumped into those landfills, and think about how much it will cost to comply with OSHA standards to get to the recyclable materials. It may not be as economically viable as it sounds.
That same majority of the American population is not given access to said nuclear weapons, so your conclusion is flawed. Please do not equate my intelligence with a morning television entertainer.
Right, so what you're saying is that Bush doesn't support and hasn't tried sanctions against Iran? I think you need to read some news.
Duh! I stand corrected. The map shows people emanating from Colombia, going towards Persia.
I'm not trying to perpetuate a religious argument or anything, but I would just like to point out two or three things in response. First, map 34 in Figure 4 shows the Colombian people having some origin in the regions around Eastern Iran and Western India, not China. The Jewish nation was taken captive into Persia (modern Iran) circa 722 B.C. A couple of other contemporary invasions also sent descendants of Israel all over the old world. That is early enough to match Mormon scripture, though the migratory pattern doesn't match the scenario described in the book. Second, the Book of Mormon states the people described therein were of the tribe of Manasseh, not Judah. "Jew" only referred to their nationality, not their ethnicity. Third, most Jews in Israel today are descendants of the European Jews of the Diaspora rather than those present in the land of Palestine during the later Biblical periods.