Have you looked into the Werner Von Braun Mars mission? He planned it during the 40's and 50's. It's pretty interesting. It's also much bigger than Zubrin's and uses nuclear propulsion and such. After all Von Braun designed the Saturn V, so you can imagine the scale of the things. Granted, it would be more expensive but it has a lower risk associated with it, I think, because there are several ships going together.
Re:existing, profitable LEO satellite constellatio
on
A Eulogy for Iridium
·
· Score: 1
What is an "embedded monitoring system"? I get the general idea, but do you have some examples?
For 30000 you can buy a much better helicopter. It LOOKS like a helicopter too. I don't remember its name though but I've seen it in a lot of movies and they also use it for some kind of medical rescue missions. It's a single person helicopter, similar in shape to say Bell helos. I remember checking on the web and it cost a bit less than $30000, but I guess its maintenance costs are higher. They can also be armed with small missiles or machine guns.
Satellites suffer from the same problem, but they still manage to keep their antennas pointing to Earth at all times by precessing or by using star sensors and earth sensors that give you the pointing direction with respect to what you need in order to keep you direction. So I guess they can use some fixed object like a building to use as an attitude reference. There might also be problems with ground roughness but this cannot be detected even by human balance, but only by the feeling in your feet.
You keep stuff balanced with gyros. Modern gyros are nanomachines that when started point to the same point in the universe for like a 1000 years. Fighter planes have them and satellites have a bunch of these. The newest ones levitate on a magnetic field and are damn accurate. Should we even say better than human balance control?
My thought is that in a philosophy class you can say whatever and get A-. Also, perfect AI is not necessariliy a "mirror of human thought and behavior". The point is that a human can process only so much information at only a fraction of the speed a computer would. So if an AI is controlling a real time system for example, it would do much better than a human because it would be able to take more information into account. The goal in AI is not to create some intelligent system that is as smart as a human, but to have a system that will do BETTER than a human in the area of its expertise and also will give the solution FASTER, preferably in realtime. Why bother? Well why do airplanes have autopilot? Modern autopilots can take off, cruise and land without human assistance -- why do you think landings are so smooth?. Space probes have an AI pilot -- sending a human pilot with each probe is not exactly feasible. To sum up, we are not aiming for a perfect AI, we just need AI that does better and faster than human in its area of expertise. We don't need Daneel Olivaw.
For FFT you have an input array, and output array, so it's not that memory consuming. I'd never heard of the Kallman filter before, but FFT can be used to multiply polynomials in nlogn time which is useful when you are using a Taylor series to represent a function.
Sometimes I am truly astounded that we got to the moon and back. Not because we couldn't build the rockets, but because the guidance and control is so complex. Actually for going to the Moon you don't need to be that exact. The thing is that they always have extra fuel to tweak the orbits and you don't need complicated instruments for that. Granted, it is a 3-body problem which has to be solved (i.e. no closed form solution), but you can get a pretty good approximation for the amount of delta v needed (=>amount of fuel you need) using spheres of influence in the calculation. I am sure they threw in a significant amount of extra fuel just to make sure the craft doesn't escape Earth's sphere of influence, because the transfer velocity for going to the Moon is very close to the escape velocity from earth (~11 km/s). Also, there is a human pilot on board so that helps - no need for electronic thruster control. And probably the most important thing, that greatly helped in the orbit calculation -- the FFT algorithm. Yep. It's not called "Fast" for nothing you know. It's probably not an exaggeration to say that FFT got man to the moon.
Actually Ivy CS departments rank pretty high (in the top 10 usually) and Princeton and Cornell have pretty good engineering programs. Of course I'm biased as you can see from my user info.
Actually the Heisenberg Uncertainty principle says that: deltaX * deltaP > hbar which mean that the uncertainty in position times the uncertainty in momentum for a particle is always bigger than the planck constant divided by 2*PI (this number is called hbar). So you cannot determine the position AND the momentum of a particle exactly at the same time along one axis. Every particle has 3 equations like this one for each direction in 3d space. Thus you could determine the exact x-position AND y-momentum for example, but not x-position and x-momentum and the same time.
signal latency depends on the relative position of the planets in their orbits and for Earth and Mars it varies a lot. I think the max distance between the two is about 360 million kilometers, which would be about 19 light minutes, so 20 minute latency is about right -- planetary transfers are usually done so that your craft arrives to the destination when the start and end points are farthest (this is a simplistic way of explaining a Hohmann transfer).
Yeah, I thought that NASA had some contribution to SETI, even if it is a small one, and NASA being nonprivate... Anyway, I am contributing to SETI too by running that screensaver but it's like looking for a needle in a haystack. Besides we know that any message would have been sent many years ago.
On the equator the rotational speed 500m/s if you launch due east. So on a mission that has a total deltaV of say 8000-9000 m/s it is significant, but not overwhelming. We were talking about nuclear rockets which apparently give you twice higher specific impulse, but pollute, so the rotational factor would not be that significant. Another problem would be that you can only launch in polar orbit in this case so you need to do a large plane change in orbit. The deltaV for this will be very high, so it all depends on the comparative efficiency of nuclear vs. chemical. By the way they launch from Florida not just because of the assist due to spinning earth, but because it gives you more choice for what inclination you want for the orbit, From Florida you can do anything from 28.5 to 90 degrees without doing a costly plane change in orbit. From Maine obviously you can do from about 45 to 90 degrees which is less choice.
I was talking about manned launches because I was replying to the guy who was talking about Mars. Also, the one about the bystanders was figuratively speaking. I know that people watch from miles away. Also, for unmanned launches (satellites) they usually use smaller rockets which spin, don't they? For manned launches, it would mean that thay would have to install the ejection seats or escape pod or whatever in case the engine fails.
Radioactive dust is not radioactive forever. There is a certain period of time after which most of the radiation is gone. Theoretically, if they see the ice caps starting to withdraw, they would stop launching so that the radioactive dust decays. You know that the Bikini atol that was a testground for the US is now pretty much radiation free and there are fish again in the waters there. The point is, it doesn't take too much time for radioactive dust to become harmless.
From what I've heard, the Russians tested nuclear propulsion rockets way back then in the 1950/60s. Nuclear performed slightly better than chemical propulsion, but they probably didn't push the technology too much. Myself, I have nothing against nuclear propulsion, I mean they could make a big launchpad in Antarctica or somewhere and launch from there. Many radioactive particles would get caught in the magnetosphere which is strong around the poles. Gamma rays would kill humans in long range, but there are not too many humans in Antarctica. There would be not much radiactive dust because most of it would remain frozen there. Of course I know the above idea will never happen, because most people wince when they hear "nuclear" anything.
Actually the article was not specific at all. There was no technical info apart from them saying that in the future they will build the largest rocket engine ever. The size of the rocket engine is not the only factor in determining the maximum payload the rocket could take into orbit. Also, usually several smaller engines is better, because this way you can stabilize using rotation along the main axis. For example the Russian N-1, that was really the biggest *booster* ever built had 31 engines I believe, some of which were small and on the periphery to provide spin stability. The space shuttle has relatively small thrust vectoring engines to maintain stability, because it can't spin-stabilize (astronauts will start puking). Also, on the space shuttle, during launch if one (or even two) engine fails, they can still land safely -- provided it is after the short risky period immediately after launch. Imagine if you had one huge engine instead and it failed. Basically your booster will just fall on the ground and explode. This will not be safe for astronauts or bystanders. Another factor is the design of the booster (the big cylindrical thing we usually call a rocket) itself. The payload capability depends more on that than the size of the engine(s). IIRC the overall acceleration depends more on the engines. I think this article is misleading, or at least naive.
I think many people on Slashdot would argue about Gates/Allen being some of the best programmers. You may be right that *in the past* many good programmers did not finish college. But also, mind you that back then (~25 years ago) most universities did not have a computer science major. Gates was a math major. Also, back then computer graphics was practically non-existant. I don't think that Gates/Wozniak would know any of the amazing hacks that are done in computer games to make them run fast (like not having specular light reflections in Quake). And I don't think that you can learn those by just coding from age 13. Things have become much more complicated in the last 20 years and not going to college will probably not help you. I know, Einstein flunked math even though he was Einstein but not everyone is Einstein.
First let me make it clear that I don't support this guy's argument about cost. BUT... You say that we have no right to destroy "their stuff". I believe we do, just like we think we have the right to kill (execute) other humans. That is, if we benefit from destroying something, we would destroy it. That is why we are human. Learn to live with it. I am pretty sure you are human too, so you have the concept of destruction deeply embedded in your genetical makeup. Deal with it.
The USSR probably had Crays imported from Switzerland. You know they may look like a western country (no export restrictions against them) but are actually neutral so they wouldn't mind selling to the USSR. I assume that the US itself could have directly traded with the Russions, it would not be too surprising...
Slashdot Mirror
Have you looked into the Werner Von Braun Mars mission? He planned it during the 40's and 50's. It's pretty interesting. It's also much bigger than Zubrin's and uses nuclear propulsion and such. After all Von Braun designed the Saturn V, so you can imagine the scale of the things. Granted, it would be more expensive but it has a lower risk associated with it, I think, because there are several ships going together.
What is an "embedded monitoring system"? I get the general idea, but do you have some examples?
Lower tech got us to the moon. I have yet to see high tech do that.
Here is a link to a description of the helicopter I described.
For 30000 you can buy a much better helicopter. It LOOKS like a helicopter too. I don't remember its name though but I've seen it in a lot of movies and they also use it for some kind of medical rescue missions. It's a single person helicopter, similar in shape to say Bell helos. I remember checking on the web and it cost a bit less than $30000, but I guess its maintenance costs are higher. They can also be armed with small missiles or machine guns.
Satellites suffer from the same problem, but they still manage to keep their antennas pointing to Earth at all times by precessing or by using star sensors and earth sensors that give you the pointing direction with respect to what you need in order to keep you direction. So I guess they can use some fixed object like a building to use as an attitude reference. There might also be problems with ground roughness but this cannot be detected even by human balance, but only by the feeling in your feet.
Well yeah, but which ISP can afford to spend hundreds of millions of dollars per year to maintain the satellites?
You keep stuff balanced with gyros. Modern gyros are nanomachines that when started point to the same point in the universe for like a 1000 years. Fighter planes have them and satellites have a bunch of these. The newest ones levitate on a magnetic field and are damn accurate. Should we even say better than human balance control?
My thought is that in a philosophy class you can say whatever and get A-. Also, perfect AI is not necessariliy a "mirror of human thought and behavior". The point is that a human can process only so much information at only a fraction of the speed a computer would. So if an AI is controlling a real time system for example, it would do much better than a human because it would be able to take more information into account. The goal in AI is not to create some intelligent system that is as smart as a human, but to have a system that will do BETTER than a human in the area of its expertise and also will give the solution FASTER, preferably in realtime. Why bother? Well why do airplanes have autopilot? Modern autopilots can take off, cruise and land without human assistance -- why do you think landings are so smooth?. Space probes have an AI pilot -- sending a human pilot with each probe is not exactly feasible. To sum up, we are not aiming for a perfect AI, we just need AI that does better and faster than human in its area of expertise. We don't need Daneel Olivaw.
For FFT you have an input array, and output array, so it's not that memory consuming. I'd never heard of the Kallman filter before, but FFT can be used to multiply polynomials in nlogn time which is useful when you are using a Taylor series to represent a function.
Sometimes I am truly astounded that we got to the moon and back. Not because we couldn't build the rockets, but because the guidance and control is so complex.
Actually for going to the Moon you don't need to be that exact. The thing is that they always have extra fuel to tweak the orbits and you don't need complicated instruments for that. Granted, it is a 3-body problem which has to be solved (i.e. no closed form solution), but you can get a pretty good approximation for the amount of delta v needed (=>amount of fuel you need) using spheres of influence in the calculation. I am sure they threw in a significant amount of extra fuel just to make sure the craft doesn't escape Earth's sphere of influence, because the transfer velocity for going to the Moon is very close to the escape velocity from earth (~11 km/s). Also, there is a human pilot on board so that helps - no need for electronic thruster control.
And probably the most important thing, that greatly helped in the orbit calculation -- the FFT algorithm. Yep. It's not called "Fast" for nothing you know. It's probably not an exaggeration to say that FFT got man to the moon.
Actually Ivy CS departments rank pretty high (in the top 10 usually) and Princeton and Cornell have pretty good engineering programs.
Of course I'm biased as you can see from my user info.
Actually the Heisenberg Uncertainty principle says that :
deltaX * deltaP > hbar
which mean that the uncertainty in position times the uncertainty in momentum for a particle is always bigger than the planck constant divided by 2*PI (this number is called hbar).
So you cannot determine the position AND the momentum of a particle exactly at the same time along one axis. Every particle has 3 equations like this one for each direction in 3d space. Thus you could determine the exact x-position AND y-momentum for example, but not x-position and x-momentum and the same time.
You can distill water no problem. It's just more expensive to do it.
signal latency depends on the relative position of the planets in their orbits and for Earth and Mars it varies a lot. I think the max distance between the two is about 360 million kilometers, which would be about 19 light minutes, so 20 minute latency is about right -- planetary transfers are usually done so that your craft arrives to the destination when the start and end points are farthest (this is a simplistic way of explaining a Hohmann transfer).
Yeah, I thought that NASA had some contribution to SETI, even if it is a small one, and NASA being nonprivate... Anyway, I am contributing to SETI too by running that screensaver but it's like looking for a needle in a haystack. Besides we know that any message would have been sent many years ago.
Nice troll, but for your information SETI is mostly funded privately, so it's not your tax dollars that are wasted.
On the equator the rotational speed 500m/s if you launch due east. So on a mission that has a total deltaV of say 8000-9000 m/s it is significant, but not overwhelming. We were talking about nuclear rockets which apparently give you twice higher specific impulse, but pollute, so the rotational factor would not be that significant. Another problem would be that you can only launch in polar orbit in this case so you need to do a large plane change in orbit. The deltaV for this will be very high, so it all depends on the comparative efficiency of nuclear vs. chemical.
By the way they launch from Florida not just because of the assist due to spinning earth, but because it gives you more choice for what inclination you want for the orbit, From Florida you can do anything from 28.5 to 90 degrees without doing a costly plane change in orbit. From Maine obviously you can do from about 45 to 90 degrees which is less choice.
I was talking about manned launches because I was replying to the guy who was talking about Mars. Also, the one about the bystanders was figuratively speaking. I know that people watch from miles away. Also, for unmanned launches (satellites) they usually use smaller rockets which spin, don't they? For manned launches, it would mean that thay would have to install the ejection seats or escape pod or whatever in case the engine fails.
Radioactive dust is not radioactive forever. There is a certain period of time after which most of the radiation is gone. Theoretically, if they see the ice caps starting to withdraw, they would stop launching so that the radioactive dust decays. You know that the Bikini atol that was a testground for the US is now pretty much radiation free and there are fish again in the waters there. The point is, it doesn't take too much time for radioactive dust to become harmless.
From what I've heard, the Russians tested nuclear propulsion rockets way back then in the 1950/60s. Nuclear performed slightly better than chemical propulsion, but they probably didn't push the technology too much.
Myself, I have nothing against nuclear propulsion, I mean they could make a big launchpad in Antarctica or somewhere and launch from there. Many radioactive particles would get caught in the magnetosphere which is strong around the poles. Gamma rays would kill humans in long range, but there are not too many humans in Antarctica. There would be not much radiactive dust because most of it would remain frozen there.
Of course I know the above idea will never happen, because most people wince when they hear "nuclear" anything.
Actually the article was not specific at all. There was no technical info apart from them saying that in the future they will build the largest rocket engine ever. The size of the rocket engine is not the only factor in determining the maximum payload the rocket could take into orbit. Also, usually several smaller engines is better, because this way you can stabilize using rotation along the main axis. For example the Russian N-1, that was really the biggest *booster* ever built had 31 engines I believe, some of which were small and on the periphery to provide spin stability. The space shuttle has relatively small thrust vectoring engines to maintain stability, because it can't spin-stabilize (astronauts will start puking). Also, on the space shuttle, during launch if one (or even two) engine fails, they can still land safely -- provided it is after the short risky period immediately after launch. Imagine if you had one huge engine instead and it failed. Basically your booster will just fall on the ground and explode. This will not be safe for astronauts or bystanders.
Another factor is the design of the booster (the big cylindrical thing we usually call a rocket) itself. The payload capability depends more on that than the size of the engine(s). IIRC the overall acceleration depends more on the engines.
I think this article is misleading, or at least naive.
I think many people on Slashdot would argue about Gates/Allen being some of the best programmers. You may be right that *in the past* many good programmers did not finish college. But also, mind you that back then (~25 years ago) most universities did not have a computer science major. Gates was a math major. Also, back then computer graphics was practically non-existant. I don't think that Gates/Wozniak would know any of the amazing hacks that are done in computer games to make them run fast (like not having specular light reflections in Quake). And I don't think that you can learn those by just coding from age 13. Things have become much more complicated in the last 20 years and not going to college will probably not help you. I know, Einstein flunked math even though he was Einstein but not everyone is Einstein.
First let me make it clear that I don't support this guy's argument about cost. BUT... You say that we have no right to destroy "their stuff". I believe we do, just like we think we have the right to kill (execute) other humans. That is, if we benefit from destroying something, we would destroy it. That is why we are human. Learn to live with it. I am pretty sure you are human too, so you have the concept of destruction deeply embedded in your genetical makeup. Deal with it.
The USSR probably had Crays imported from Switzerland. You know they may look like a western country (no export restrictions against them) but are actually neutral so they wouldn't mind selling to the USSR. I assume that the US itself could have directly traded with the Russions, it would not be too surprising...