The hydrogen is used to carry the momentum but the energy needs to come from some electrical power source. solar works near the sun but in deep space some type of nuclear is the only practical option. At the power levels required for nuclear powered rockeets (like plasma drives ) a nuclear reactor (not an isotope source) is probably the only practical solution.
I'm more worried about a different problem: If people mostly use autonomous cars their driving skills will deteriorate. We are already seeing this with airline pilots (air france 447 or the recent SFO crash) where the pilots become dependent on automation, and don't have the proper skills when it is not available. These are professional pilots with required recurrent training. What about an average driver who lets his car do 99% of the driving for him - how will he do when he needs to drive but the automation is no longer available.
That said, I think self driving cars are a really nice technology, but we need to take care with how we implement them.
It isn't just that the 3rd party doesn't have a realistic chance. The problem is that voting for a 3rd party acts as a spoiler for the major party you most agree with. Casting a vote for a liberal 3rd party candidate is in reality casting 1/2 vote for the conservative main candidate - probably the person you LEAST want to win. Remember Bush vs Gore (+ Nader). Do you think the Nader voters got the result they wanted?
Yes, its a prisoner's dilemma, if everyone suddenly decided that 3rd party candidates were viable it might work, but that isn't going to happen.
Also, as another poster mentioned, many of the 3rd party candidates are completely nuts.
So, what is your plan? Maybe use the internet to organize an effective resistance against the government? That might work except for the problem that the government is aware of everything you do on the internet and has the power to stop your plan before it gets going. You can organize protests - and those will be allowed to continue as long as the don't pose a threat to the power structure.
You can personally try to use violence to stop the government, but you will lose. If enough people did this or took other illegal actions the situation would just become more oppressive.
If one of the major parties took a stand against this it would get my vote, but neither party does so. I could make a protest vote for a 3rd party, but that won't change the outcome of the elections. It would be very interesting to see if a large ground-swell of votes for a third party could happen.
I think the only hope of improving things is through the legal system. Maybe donating money to the ACLU and similar organizations is the most effective strategy.
OTOH being part of an evil empire sounds sort of appealing. If we get to build lost of cool stuff, I'm in.
I think that American users have more to fear from US government spying than foreign users do. Frankly I don't care if the Chinese government has access to all of my personal data - they have very little ability to or interest in interfering with my life. The US government on the other hand is much more likely to act against me in response to my (hypothetical) online mis-behavior. In the same way Chinese citizens have little to fear from the US government but a lot to fear from their own.
The very important exception to this is when you are dealing with industry trade secrets it is quite possible that foreign governments with links to industry represent a larger threat than your own. Of course while the NSA as an organization almost certainly does not sell trade secrets that they have obtained, it is possible that individuals working for the NSA might do so. Snowdon stole a bunch of information and turned it public, another man in the same situation might well have sold it.
The problem is that they waste YOUR time. You could spend hours in detention. Miss your flight connection and need to buy very expensive last minute one-way tickets.
Then when they arrest you for possession of child-porn, what is the next part of your plan. Or are you sure that a government that is willing to apply this sort of underhanded trick is not willing to falsify data to arrest someone who is "obviously" a bad person.
I was considering a SSTO to include return, since as you say it doesn't do much good to get the entire rocket into orbit, but then need to throw it away.
I don't think it is completely impossible, but so far it hasn't been practical. People have worked VERY hard on materials for spacecraft, and they do adjust the H2, LOX mixture to include tank weight (and engine temperatures). One indication of how well launch vehicles are optimized is how little the technology has changed in 40 years. The LEO payload to launch weight ration of a saturn V was 24:1 to 30:1 (sources vary). Its 37:1 for an Ariane 5 and 32:1 for a Falcon 9.
The concept of a combined air-breathing engine / rocket is reasonable - and has be around since the 60s. One very serious technical difficulty is the need to slow the input air to sub-sonic speeds without creating too much drag. Their design airbreathign speed of about mach 5 is probably limited by this.
Then the question is whether carrying all of the extra weight of the more complex engine into orbit loses more energy than you gain from using air-breathing to get to mach 5.
It might be a better fit as an engine for a first stage of a 2-stage reusable. If you are only accelerating the heavier engine to say mach 10, then staging it might be a win. Maybe not.
A single stage to orbit vehicle is very difficult. The amount of fuel a rocket needs to carry increases exponentially with the ratio of the required velocity change to the exhaust velocity. The options are very limited.
Solid propellants have much too low exhaust velocity for this to be workable.
Kerosene / Oxygen is a typical rocket propellant, but the exhaust velocity is low enough that a single stage to orbit would require an unreasonable ratio of fuel to rocket mass. I don't remember any design concepts for kerosene / O2 rockets for single stage to orbit.
Hydrogen / Oxygen has higher exhaust velocity but liquid hydrogen is very low density so the fuel tanks become enormous, and heavy. There have been design studies for Hydrogen / oxygen single stage to orbit, but it doesn't look very practical - you basically have an enormous flying fuel tank.
The more exotic chemical fuel mixes don't improve things a lot and are too toxic and expensive for atmospheric use. Fluorine / Beryllium / Hydrogen tri-propellant has good specific impulse but is insanely deadly in multiple ways.
Nuclear thermal (like NERVA) could probably do it, but people are understandably unwilling to put 100GW class nuclear reactors in rockets and launch them.
Airbreathing rockets (like ram-jets / scram jets) don't need to carry their own oxidizer and in principal do much better. The problem is that hypersonic ram-jets are very difficult to build and wind up heavy and inefficient. (Mach ~8, only 1/3 of orbital speed, 1/10 orbital energy) is the highest speed ramjet that I am aware of. For various fundamental reasons you expect the performance of ramjets to drop with velocity. Since ramjets also don't work at low speeds, you wind up needing a 3 stage rocket: conventional, scram-jet, conventional, and it ends up not having any advantage over just conventional rockets.
The basic technology for getting things into orbit hasn't changed in over 50 years, and really isn't likely to change - just no clear path. The best approach is probably what Space-X is doing, optimizing the design, and working to make each of the stages recoverable to reduce costs.
The "tourist" sub-orbital rockets don't seem to me to be developing technologies that are applicable to orbital flights. They may attract a few people who are willing to spend $100K for a few minutes of zero-G, but I suspect that most wealthy thrill-seekers will quickly find that a ride in a MIG-29 is a lot more fun and less expensive.
If they develop better technology sooner then..... THEY WIN. This is a good argument that if we don't want to LOSE we should put more effort into developing new technology.
In the 1800's China made the mistake of falling off the technology curve. As a result they were beaten and humiliated by the advanced technology of the western powers. Revenge would be poetic and well deserved, but personally I'd like to not be on the receiving end.
The older generation grew up along with technology, younger people grew up with complex technology already developed. The older generation can remember whn you could count the transistors in a computer and I think has a stronger tendency to think of complex technology as a system of simpler components. I think that younger people have a more "functional" view, less interest in understanding the detailed underpinnings.
Put positively, the younger generation as an approach to technology that is more like abstract mathematics - once you know how something behaves you no longer need to understand why it behaves that way. Rather than getting bogged down in trying to figure out how data is sent between phones, they are happy to write an app that takes advantage of that data. This sort of view allows you to write code that takes advantage of the vast array of existing complex systems that are already available.
Put negatively technology is more "magic" to the younger generation - cell phones just work, they are less likely to wonder how the hell someone can "find" your phone to call you when you are in a country that you have never visited before. This can lead to trusting "magic" technology but not understanding its limits. This sort of view can result in writing horrifically inefficient code that is layered on top of other code that you don't understand at all.
Not easy to find a party that that I agree with. Also it often possible for a 3rd party candidate to act as a "spoiler", decreasing the chances of the main party candidate with the most similar agenda and helping the candidate with the views with which you most strongly disagree.
As an american citizen it is not easy to figure out how to deal with this. Neither party is running on the "stop being evil" platform. Minor protests don't have much effect in this country and a revolution is clearly worse than what we have now.
Did he have reason to believe that the people he was helping were criminals? Even then its a bit tricky - how clear does the evidence need to be for a person to be guilty of aiding a criminal? Should I refuse to provide services to someone dressed like a gangster because I think that they may have committed a crime?
If it is illegal to teach people to avoid a polygraph, what about teaching other skills that can evade police detection. Is teaching encryption illegal? Is discussing mobile phone tracking illegal? Costuming and disguise?
I think that it only makes sense to criminalize aiding a SPECIFIC crime, not providing tools that could be used to commit a crime
There is also the "life, liberty and pursuit of happiness" clause in the declaration of independence. For many people long distance travel is required for their jobs, which provide income that allows a "pursuit of happiness". For others the travel itself is part of the pursuit of happiness.
Since air travel is in may instances the only practical way to do long distance travel, preventing someone from traveling by air reduces their right to travel and thereby their right to pursue happiness.
People may wish to claim that travel is a "privilege", but that sort of argument would allow the government to take pretty much anything except food, shelter, and those rights that are explicitly granted, and such an interpretation seems at odds with the intent of the constitution.
Trying to out-spend the NSA on setting up nodes is not likely to work.
I think the only safe assumption is that the NSA or other government organizations has access to any data transmitted through a commonly-used system. A real expert in security and encryption might be able to determine that a particular system is safe, but as a random user you can't necessarily trust any statements made by "experts" because those experts could be NSA plants.
I don't think you can use technology to stop government spying, you need to change the LAWS.
Without some level of technology (here I'm including neolithic), the desert and the arctic are deadly - just a bit more slowly than space.
Of course we don't need to go to space any more than we needed to leave the trees. Hopefully likely the species who do explore space will find us adorable and give their children little stuffed human toys when they visit the zoo.
The saddest part is that he doesn't feel the need to mention the moon colonies except to discuss improved communication with them. Humanities future in space was so obvious that it didn't even need to be stated.
When you have a constant inflow and outflow, if there is any calibration error on the flow meters that error will integrate over time to look like a gain or loss in level. You could imagine having flow and level sensors everywhere, but you still have issues with temperature variations (the thermal expansion of water isn't all that small). Still you could do it with arrays of temperature sensors in each tank, level sensors and calibrated flow-meters. Starts to get pretty complex.
There are lots of commercial solutions out there for level monitoring with distributed data systems but when you are trying to find leaks that represent a small fraction of the total volume it gets difficult.
It is still possible that a simple level monitoring system would help - but if so, they might as well use a commercial system .
Just because there are people opposed to President Obama for racist reasons doesn't mean that there aren't rational reasons to oppose his policies.
One of the big problems with the partisan divide in the US is that each side can point to a subset of crazies on the other side and claim that the crazy's views invalidate all the opinions on the other side.
Any idea of the relative kinetic energy of the comet and the mass ejection? Solar impacting objects are moving quite fast, and the corona is rather diffuse, still I would expect the CME to represent a lot more energy, with no clear mechanism for triggering by the comet impact.
There is enough time for electromagnetic signals to transmit the information across the sun. The comet presumably looks like a clump of fast moving plasma by the time it hits.
Maybe it should include a "dispersal charge" that activates if the engine fails above 100' AGL to insure that no large pieces of machine or pilot reach the ground.....
Yes, but regulations aside, learning to fly either a helicopter or jet-pack before using one yourself is probably a lifespan extending activity.
I wonder how you learn to fly the jetpack. There are lots of 2-person helicopters to learn in. The jetpack seems to offer a lot of wile-e-coyote possibilities if you don't know exactly what you are doing.
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The hydrogen is used to carry the momentum but the energy needs to come from some electrical power source. solar works near the sun but in deep space some type of nuclear is the only practical option. At the power levels required for nuclear powered rockeets (like plasma drives ) a nuclear reactor (not an isotope source) is probably the only practical solution.
I'm more worried about a different problem: If people mostly use autonomous cars their driving skills will deteriorate. We are already seeing this with airline pilots (air france 447 or the recent SFO crash) where the pilots become dependent on automation, and don't have the proper skills when it is not available. These are professional pilots with required recurrent training. What about an average driver who lets his car do 99% of the driving for him - how will he do when he needs to drive but the automation is no longer available.
That said, I think self driving cars are a really nice technology, but we need to take care with how we implement them.
It isn't just that the 3rd party doesn't have a realistic chance. The problem is that voting for a 3rd party acts as a spoiler for the major party you most agree with. Casting a vote for a liberal 3rd party candidate is in reality casting 1/2 vote for the conservative main candidate - probably the person you LEAST want to win. Remember Bush vs Gore (+ Nader). Do you think the Nader voters got the result they wanted?
Yes, its a prisoner's dilemma, if everyone suddenly decided that 3rd party candidates were viable it might work, but that isn't going to happen.
Also, as another poster mentioned, many of the 3rd party candidates are completely nuts.
So, what is your plan? Maybe use the internet to organize an effective resistance against the government? That might work except for the problem that the government is aware of everything you do on the internet and has the power to stop your plan before it gets going. You can organize protests - and those will be allowed to continue as long as the don't pose a threat to the power structure.
You can personally try to use violence to stop the government, but you will lose. If enough people did this or took other illegal actions the situation would just become more oppressive.
If one of the major parties took a stand against this it would get my vote, but neither party does so. I could make a protest vote for a 3rd party, but that won't change the outcome of the elections. It would be very interesting to see if a large ground-swell of votes for a third party could happen.
I think the only hope of improving things is through the legal system. Maybe donating money to the ACLU and similar organizations is the most effective strategy.
OTOH being part of an evil empire sounds sort of appealing. If we get to build lost of cool stuff, I'm in.
I think that American users have more to fear from US government spying than foreign users do. Frankly I don't care if the Chinese government has access to all of my personal data - they have very little ability to or interest in interfering with my life. The US government on the other hand is much more likely to act against me in response to my (hypothetical) online mis-behavior. In the same way Chinese citizens have little to fear from the US government but a lot to fear from their own.
The very important exception to this is when you are dealing with industry trade secrets it is quite possible that foreign governments with links to industry represent a larger threat than your own. Of course while the NSA as an organization almost certainly does not sell trade secrets that they have obtained, it is possible that individuals working for the NSA might do so. Snowdon stole a bunch of information and turned it public, another man in the same situation might well have sold it.
The problem is that they waste YOUR time. You could spend hours in detention. Miss your flight connection and need to buy very expensive last minute one-way tickets.
Then when they arrest you for possession of child-porn, what is the next part of your plan. Or are you sure that a government that is willing to apply this sort of underhanded trick is not willing to falsify data to arrest someone who is "obviously" a bad person.
I was considering a SSTO to include return, since as you say it doesn't do much good to get the entire rocket into orbit, but then need to throw it away.
I don't think it is completely impossible, but so far it hasn't been practical. People have worked VERY hard on materials for spacecraft, and they do adjust the H2, LOX mixture to include tank weight (and engine temperatures). One indication of how well launch vehicles are optimized is how little the technology has changed in 40 years. The LEO payload to launch weight ration of a saturn V was 24:1 to 30:1 (sources vary). Its 37:1 for an Ariane 5 and 32:1 for a Falcon 9.
The concept of a combined air-breathing engine / rocket is reasonable - and has be around since the 60s. One very serious technical difficulty is the need to slow the input air to sub-sonic speeds without creating too much drag. Their design airbreathign speed of about mach 5 is probably limited by this.
Then the question is whether carrying all of the extra weight of the more complex engine into orbit loses more energy than you gain from using air-breathing to get to mach 5.
It might be a better fit as an engine for a first stage of a 2-stage reusable. If you are only accelerating the heavier engine to say mach 10, then staging it might be a win. Maybe not.
A single stage to orbit vehicle is very difficult. The amount of fuel a rocket needs to carry increases exponentially with the ratio of the required velocity change to the exhaust velocity. The options are very limited.
Solid propellants have much too low exhaust velocity for this to be workable.
Kerosene / Oxygen is a typical rocket propellant, but the exhaust velocity is low enough that a single stage to orbit would require an unreasonable ratio of fuel to rocket mass. I don't remember any design concepts for kerosene / O2 rockets for single stage to orbit.
Hydrogen / Oxygen has higher exhaust velocity but liquid hydrogen is very low density so the fuel tanks become enormous, and heavy. There have been design studies for Hydrogen / oxygen single stage to orbit, but it doesn't look very practical - you basically have an enormous flying fuel tank.
The more exotic chemical fuel mixes don't improve things a lot and are too toxic and expensive for atmospheric use. Fluorine / Beryllium / Hydrogen tri-propellant has good specific impulse but is insanely deadly in multiple ways.
Nuclear thermal (like NERVA) could probably do it, but people are understandably unwilling to put 100GW class nuclear reactors in rockets and launch them.
Airbreathing rockets (like ram-jets / scram jets) don't need to carry their own oxidizer and in principal do much better. The problem is that hypersonic ram-jets are very difficult to build and wind up heavy and inefficient. (Mach ~8, only 1/3 of orbital speed, 1/10 orbital energy) is the highest speed ramjet that I am aware of. For various fundamental reasons you expect the performance of ramjets to drop with velocity. Since ramjets also don't work at low speeds, you wind up needing a 3 stage rocket: conventional, scram-jet, conventional, and it ends up not having any advantage over just conventional rockets.
The basic technology for getting things into orbit hasn't changed in over 50 years, and really isn't likely to change - just no clear path. The best approach is probably what Space-X is doing, optimizing the design, and working to make each of the stages recoverable to reduce costs.
The "tourist" sub-orbital rockets don't seem to me to be developing technologies that are applicable to orbital flights. They may attract a few people who are willing to spend $100K for a few minutes of zero-G, but I suspect that most wealthy thrill-seekers will quickly find that a ride in a MIG-29 is a lot more fun and less expensive.
If they develop better technology sooner then..... THEY WIN. This is a good argument that if we don't want to LOSE we should put more effort into developing new technology.
In the 1800's China made the mistake of falling off the technology curve. As a result they were beaten and humiliated by the advanced technology of the western powers. Revenge would be poetic and well deserved, but personally I'd like to not be on the receiving end.
The older generation grew up along with technology, younger people grew up with complex technology already developed. The older generation can remember whn you could count the transistors in a computer and I think has a stronger tendency to think of complex technology as a system of simpler components. I think that younger people have a more "functional" view, less interest in understanding the detailed underpinnings.
Put positively, the younger generation as an approach to technology that is more like abstract mathematics - once you know how something behaves you no longer need to understand why it behaves that way. Rather than getting bogged down in trying to figure out how data is sent between phones, they are happy to write an app that takes advantage of that data. This sort of view allows you to write code that takes advantage of the vast array of existing complex systems that are already available.
Put negatively technology is more "magic" to the younger generation - cell phones just work, they are less likely to wonder how the hell someone can "find" your phone to call you when you are in a country that you have never visited before. This can lead to trusting "magic" technology but not understanding its limits. This sort of view can result in writing horrifically inefficient code that is layered on top of other code that you don't understand at all.
Not easy to find a party that that I agree with. Also it often possible for a 3rd party candidate to act as a "spoiler", decreasing the chances of the main party candidate with the most similar agenda and helping the candidate with the views with which you most strongly disagree.
As an american citizen it is not easy to figure out how to deal with this. Neither party is running on the "stop being evil" platform. Minor protests don't have much effect in this country and a revolution is clearly worse than what we have now.
Did he have reason to believe that the people he was helping were criminals? Even then its a bit tricky - how clear does the evidence need to be for a person to be guilty of aiding a criminal? Should I refuse to provide services to someone dressed like a gangster because I think that they may have committed a crime?
If it is illegal to teach people to avoid a polygraph, what about teaching other skills that can evade police detection. Is teaching encryption illegal? Is discussing mobile phone tracking illegal? Costuming and disguise?
I think that it only makes sense to criminalize aiding a SPECIFIC crime, not providing tools that could be used to commit a crime
There is also the "life, liberty and pursuit of happiness" clause in the declaration of independence. For many people long distance travel is required for their jobs, which provide income that allows a "pursuit of happiness". For others the travel itself is part of the pursuit of happiness.
Since air travel is in may instances the only practical way to do long distance travel, preventing someone from traveling by air reduces their right to travel and thereby their right to pursue happiness.
People may wish to claim that travel is a "privilege", but that sort of argument would allow the government to take pretty much anything except food, shelter, and those rights that are explicitly granted, and such an interpretation seems at odds with the intent of the constitution.
Trying to out-spend the NSA on setting up nodes is not likely to work.
I think the only safe assumption is that the NSA or other government organizations has access to any data transmitted through a commonly-used system. A real expert in security and encryption might be able to determine that a particular system is safe, but as a random user you can't necessarily trust any statements made by "experts" because those experts could be NSA plants.
I don't think you can use technology to stop government spying, you need to change the LAWS.
Without some level of technology (here I'm including neolithic), the desert and the arctic are deadly - just a bit more slowly than space.
Of course we don't need to go to space any more than we needed to leave the trees. Hopefully likely the species who do explore space will find us adorable and give their children little stuffed human toys when they visit the zoo.
The saddest part is that he doesn't feel the need to mention the moon colonies except to discuss improved communication with them. Humanities future in space was so obvious that it didn't even need to be stated.
When you have a constant inflow and outflow, if there is any calibration error on the flow meters that error will integrate over time to look like a gain or loss in level. You could imagine having flow and level sensors everywhere, but you still have issues with temperature variations (the thermal expansion of water isn't all that small). Still you could do it with arrays of temperature sensors in each tank, level sensors and calibrated flow-meters. Starts to get pretty complex.
There are lots of commercial solutions out there for level monitoring with distributed data systems but when you are trying to find leaks that represent a small fraction of the total volume it gets difficult.
It is still possible that a simple level monitoring system would help - but if so, they might as well use a commercial system .
Just because there are people opposed to President Obama for racist reasons doesn't mean that there aren't rational reasons to oppose his policies.
One of the big problems with the partisan divide in the US is that each side can point to a subset of crazies on the other side and claim that the crazy's views invalidate all the opinions on the other side.
True, but it is probably easier to imagine mechanisms that don't need a lot of energy gain.
Any idea of the relative kinetic energy of the comet and the mass ejection? Solar impacting objects are moving quite fast, and the corona is rather diffuse, still I would expect the CME to represent a lot more energy, with no clear mechanism for triggering by the comet impact.
There is enough time for electromagnetic signals to transmit the information across the sun. The comet presumably looks like a clump of fast moving plasma by the time it hits.
Maybe it should include a "dispersal charge" that activates if the engine fails above 100' AGL to insure that no large pieces of machine or pilot reach the ground.....
Yes, but regulations aside, learning to fly either a helicopter or jet-pack before using one yourself is probably a lifespan extending activity.
I wonder how you learn to fly the jetpack. There are lots of 2-person helicopters to learn in. The jetpack seems to offer a lot of wile-e-coyote possibilities if you don't know exactly what you are doing.