I think that a lot of U.S. nuke missile arsenal predateds GPS -- maybe they upgraded avionics to take advantage of it, I don't know. If there was to be any sort of a nuclear showdown, then the GPS would either go down or the clear data would be turned off, only encrypted one remaining. I think that if you're after long range weapons, you really need INS, and for that accurate geoid is a must. I would presume that any sort of a ballistic or cruise missle guidance system would have targeting accuracy specified without GPS augmentation (inertial only), with augmentation providing a "free" improvement if available.
Apart from GPS and GLONASS, there is no "other" sat-based navigation available yet. Getting any sort of a satnav receiver through its paces of military QA, you can't really add support for other systems on a whim. I think that all satnav receivers installed in U.S. weapons support GPS, and won't support anything else in the next decade or two.
You don't use the geoid to plan any sort of a trajectory. You use it for inertial navigation -- for converting outputs of your inertial reference sensors (gyros and accelerometers) into a position fix. To do this accurately, you need accurate, low-drift and low-noise sensors. Once your sensors get good enough, improving their accuracy doesn't improve the accuracy of your fix! To get any further improvement, you need to improve the accuracy and resolution of your geoid data. By my back-of-the-envelope calculations, GOCE's geoid is supposedly (based on published details) good enough to match the best inertial reference sensors out there, and would allow you to obtain the best inertial fix that's possible with current technology.
Wait a minute, didn't accurate geoid use to be highly classified information? As in "used for missle inertial navigation" kind of classified? I wouldn't be surprised if the German data could be imported into the U.S., but couldn't be re-exported, for example... Does anyone know more about this?
For starters: ignore eyewitnesses. Hard evidence only: high resolution photographs, no SD quality crap, or 10th generation VCR, or -- worse yet -- stuff filmed from TV. There was a Discovery piece long time ago (5+ years) where they wasted half an episode on a guy who was showing something weird. Well, it was taped from the TV using a camera. The red "lights" they were wasting time on? Clearly rear lights of a car outside the window, reflected on the TV screen, aberration and all. It boggles the mind how gullible the "reporter" and the interviewee were: you'd typically associate that with advancedly-senior population... Those were "young" guys (40s). Of course it's but an anecdote, but so far every piece of "evidence" I've seen on line was silly like that. Mostly low resolution, many generations old copies where you could almost make anything look like it. Now I've read a while ago that there were suppsedly some U.S. military reports about UFOs. I don't know about U.S. military, but I spoke to an air force colonel in Europe who was similarly gullible. It was hard not to laugh.
GPS is not too slow for anything here, nor too inaccurate. GPS is combined with inertial reference to provide a realtime 6 DOF position/orientation in space. The problem is you need airspeed, not ground track speed! GPS only gives you the latter.
Without any way to know the current speed, the plane lost altitude and crashed
As far as I know, on that particular type you can continue level flight safely without airspeed data. There are tables and you pretty much look up the throttle setting given air density, the latter can be approximated from GPS/INS in case your static system is dead, too. You just need to be aware that the Pitots have iced over. If you are unaware, shit goes wrong, and my bet is that it's a human factor at play, just like with China Airlines 006 where the underlying wetware problem was similar: a disconnect between pilot's situational model and real situation.
Last time courts had "consensus" to influence science, people were burned, stoned or banished. Your "level of proof" has been shown time and time again to be inadequate to uniformly administer basic justice, I hate to think how quickly all scientific progress would stall if juries were to judge academic papers...
If you're an engineer, you should humbly presuppose that you simply don't know enough what it is, and that most likely whatever observations you made are subject to biases typical of eyewitnesses. If you truly think that it's "interesting" that you don't know what something is (it's unidentified, ha), then you must suffer from horrible obsession of identifying stuff. A lot of the stuff we see is pretty much unidentified, people just don't realize it much. Our brains replace the visual reality with a best fit representation, based on previous experiences. When not actively looking for something odd, our brain will interrupt us only when something is "just too weird"; otherwise it keeps feeding us the best-fit. Go somewhere where it's "visually busy". A park, maybe. A place that you walk through often. Look around. You'll be surprised.
No shit, Sherlock. So what would it be if it wasn't a hoax? It would be nothing more than an unidentified flying object. The fact that something is a UFO is a rather mundane statement of fact: no, we don't know what it is yet. Tough shit.
People have this crazy expectation that if you keep randomly shooting pictures, everything on them will be identifiable. Well, guess what, sometimes it's too hard to tell. Yes, really. UFOs will appear on photos and movies by definition. The bad aspect is that everyone associates UFOs with paranormal or extraterrestrial activity -- now that's what I call batshit crazy.
Nothing here, move along, people are stupid like always, keep the line moving,...
I don't think that his residual tax rate (local, state and federal), after all the credits and deductions, is above 10%. Not with a non-working wife and 6 kids. The current rule of thumb is that a family with 2 kids earning 80k pays about 2% combined federal, state and local. Go ahead, you can try it out on turbotax online for free -- you only pay if you actually want to submit the return, but you can put all the numbers in for free and get the tax due amount.
The legend of tall proportions is IMHO the overblown chemical toxicity of plutonium. Plutonium is minimally chemically toxic. In fact, the whole linked document only ever mentions radio-"toxicity", not chemical toxicity!
Toxicity of plutonium derives from the biological effects of radiation emitted during the radiological decay of plutonium isotopes.
Chemically it's a nasty metal for sure, but nothing out of the ordinary. AFAIK you can handle solid plutonium with minimal protection (chemical gloves, particulate respirator). Plutonium oxides and hydrides form when exposed to moisture (with and without oxygen present), and those can spontaneously ignite. In a dry atmosphere, handled in gloves so that you won't get it moist from handling with bare skin, it's OK.
It was useless for its intended purpose. You don't launch land imaging satellites for the entertainment value of their output. It's a conundrum: the taxpayers would fume if you tried to get funding for a satellite designed only to snap nice pictures that had no other uses. Yet when the same taxpayer looks at the pictures, he likes and appreciates the ones that have no scientific value over those that are indeed valuable (but boring). I think that the confusion may be planted in early education, where kids are routinely told to accept and regurgitate senseless things... over time, entertainment is the only common ground in understanding, everything else having been artificially made unfashionable ("nerdy").
Ah-ha, thank you! I learned something new. So, the delta-v, as you correctly stated, is only 12km/s. That underscores my point that going towards the Sun is even worse than departing the Solar System.
Is there anything similarly simple that relates to swingbys? Are there any theoretical limits to what can be achieved with swingbys, if one ignores atmospheric drag and mission lifetime?
If it weren't for the log records and the apparent ineptitude of the plagiarist lady, I'd say that this was a lot of ado about nothing. Checking WHOIS records and JFIF image data is basic web reasearch, done by thousands every day I'm sure. I'd chalk it up to coincidence. With the logs and publication record of the plagiarist lady (not much there, in fact), I'd tend to think it was in fact plagiarism.
doesn't that mean it's all in one blob with no moderation by control rods (as in gone critical)
-- control rods don't moderate, water does!! You need moderator to keep the neutron capture high by the fissile material. Control rods are neutron absorbers, not moderators. Without water mixed in, the "blob" can of course maintain the chain reaction, but at a much lower heat output than if there was water moderator present between the chunks of fuel. I was looking around and could only figure ballpark of 10% of normal operating thermal output. Perhaps a nuclear engineer could pitch in with an actual figure.
To escape the solar system from Earth, you need dv=42km/s, whereas the Earth's orbital velocity is 30km/s. Unless you can get dv from flybys, you're looking at pretty much same ballpark in terms of delta-v to go into the Sun as to leave the solar system starting from Earth.
Eventually, I'm sure, some enthusiast group will work on setting up simulators for the avionics, and they'll get flight software running for others to play with. Just like it happened with Apollo's software (what was left of it, that is). Hopefully NASA will preserve shuttle's mission software better than MIT did Apollo's.
So you say that strap-on solid boosters that would blow up the first stage would be OK if only the shuttle was on top of the 2nd stage? Can I have what you had? Solid and liquid propellants don't mix...
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I think that a lot of U.S. nuke missile arsenal predateds GPS -- maybe they upgraded avionics to take advantage of it, I don't know. If there was to be any sort of a nuclear showdown, then the GPS would either go down or the clear data would be turned off, only encrypted one remaining. I think that if you're after long range weapons, you really need INS, and for that accurate geoid is a must. I would presume that any sort of a ballistic or cruise missle guidance system would have targeting accuracy specified without GPS augmentation (inertial only), with augmentation providing a "free" improvement if available.
Apart from GPS and GLONASS, there is no "other" sat-based navigation available yet. Getting any sort of a satnav receiver through its paces of military QA, you can't really add support for other systems on a whim. I think that all satnav receivers installed in U.S. weapons support GPS, and won't support anything else in the next decade or two.
You don't use the geoid to plan any sort of a trajectory. You use it for inertial navigation -- for converting outputs of your inertial reference sensors (gyros and accelerometers) into a position fix. To do this accurately, you need accurate, low-drift and low-noise sensors. Once your sensors get good enough, improving their accuracy doesn't improve the accuracy of your fix! To get any further improvement, you need to improve the accuracy and resolution of your geoid data. By my back-of-the-envelope calculations, GOCE's geoid is supposedly (based on published details) good enough to match the best inertial reference sensors out there, and would allow you to obtain the best inertial fix that's possible with current technology.
Wait a minute, didn't accurate geoid use to be highly classified information? As in "used for missle inertial navigation" kind of classified? I wouldn't be surprised if the German data could be imported into the U.S., but couldn't be re-exported, for example... Does anyone know more about this?
For starters: ignore eyewitnesses. Hard evidence only: high resolution photographs, no SD quality crap, or 10th generation VCR, or -- worse yet -- stuff filmed from TV. There was a Discovery piece long time ago (5+ years) where they wasted half an episode on a guy who was showing something weird. Well, it was taped from the TV using a camera. The red "lights" they were wasting time on? Clearly rear lights of a car outside the window, reflected on the TV screen, aberration and all. It boggles the mind how gullible the "reporter" and the interviewee were: you'd typically associate that with advancedly-senior population... Those were "young" guys (40s). Of course it's but an anecdote, but so far every piece of "evidence" I've seen on line was silly like that. Mostly low resolution, many generations old copies where you could almost make anything look like it. Now I've read a while ago that there were suppsedly some U.S. military reports about UFOs. I don't know about U.S. military, but I spoke to an air force colonel in Europe who was similarly gullible. It was hard not to laugh.
GPS is not too slow for anything here, nor too inaccurate. GPS is combined with inertial reference to provide a realtime 6 DOF position/orientation in space. The problem is you need airspeed, not ground track speed! GPS only gives you the latter.
Without any way to know the current speed, the plane lost altitude and crashed
As far as I know, on that particular type you can continue level flight safely without airspeed data. There are tables and you pretty much look up the throttle setting given air density, the latter can be approximated from GPS/INS in case your static system is dead, too. You just need to be aware that the Pitots have iced over. If you are unaware, shit goes wrong, and my bet is that it's a human factor at play, just like with China Airlines 006 where the underlying wetware problem was similar: a disconnect between pilot's situational model and real situation.
Last time courts had "consensus" to influence science, people were burned, stoned or banished. Your "level of proof" has been shown time and time again to be inadequate to uniformly administer basic justice, I hate to think how quickly all scientific progress would stall if juries were to judge academic papers...
Well said.
If you're an engineer, you should humbly presuppose that you simply don't know enough what it is, and that most likely whatever observations you made are subject to biases typical of eyewitnesses. If you truly think that it's "interesting" that you don't know what something is (it's unidentified, ha), then you must suffer from horrible obsession of identifying stuff. A lot of the stuff we see is pretty much unidentified, people just don't realize it much. Our brains replace the visual reality with a best fit representation, based on previous experiences. When not actively looking for something odd, our brain will interrupt us only when something is "just too weird"; otherwise it keeps feeding us the best-fit. Go somewhere where it's "visually busy". A park, maybe. A place that you walk through often. Look around. You'll be surprised.
even MUFON has concluded it was a hoax
No shit, Sherlock. So what would it be if it wasn't a hoax? It would be nothing more than an unidentified flying object. The fact that something is a UFO is a rather mundane statement of fact: no, we don't know what it is yet. Tough shit.
People have this crazy expectation that if you keep randomly shooting pictures, everything on them will be identifiable. Well, guess what, sometimes it's too hard to tell. Yes, really. UFOs will appear on photos and movies by definition. The bad aspect is that everyone associates UFOs with paranormal or extraterrestrial activity -- now that's what I call batshit crazy.
Nothing here, move along, people are stupid like always, keep the line moving,...
I don't think that his residual tax rate (local, state and federal), after all the credits and deductions, is above 10%. Not with a non-working wife and 6 kids. The current rule of thumb is that a family with 2 kids earning 80k pays about 2% combined federal, state and local. Go ahead, you can try it out on turbotax online for free -- you only pay if you actually want to submit the return, but you can put all the numbers in for free and get the tax due amount.
Hey, you did the work from scratch and that's what counts.
The legend of tall proportions is IMHO the overblown chemical toxicity of plutonium. Plutonium is minimally chemically toxic. In fact, the whole linked document only ever mentions radio-"toxicity", not chemical toxicity!
Toxicity of plutonium derives from the biological effects of radiation emitted during the radiological decay of plutonium isotopes.
Chemically it's a nasty metal for sure, but nothing out of the ordinary. AFAIK you can handle solid plutonium with minimal protection (chemical gloves, particulate respirator). Plutonium oxides and hydrides form when exposed to moisture (with and without oxygen present), and those can spontaneously ignite. In a dry atmosphere, handled in gloves so that you won't get it moist from handling with bare skin, it's OK.
It was useless for its intended purpose. You don't launch land imaging satellites for the entertainment value of their output. It's a conundrum: the taxpayers would fume if you tried to get funding for a satellite designed only to snap nice pictures that had no other uses. Yet when the same taxpayer looks at the pictures, he likes and appreciates the ones that have no scientific value over those that are indeed valuable (but boring). I think that the confusion may be planted in early education, where kids are routinely told to accept and regurgitate senseless things... over time, entertainment is the only common ground in understanding, everything else having been artificially made unfashionable ("nerdy").
Ah-ha, thank you! I learned something new. So, the delta-v, as you correctly stated, is only 12km/s. That underscores my point that going towards the Sun is even worse than departing the Solar System.
Is there anything similarly simple that relates to swingbys? Are there any theoretical limits to what can be achieved with swingbys, if one ignores atmospheric drag and mission lifetime?
If it weren't for the log records and the apparent ineptitude of the plagiarist lady, I'd say that this was a lot of ado about nothing. Checking WHOIS records and JFIF image data is basic web reasearch, done by thousands every day I'm sure. I'd chalk it up to coincidence. With the logs and publication record of the plagiarist lady (not much there, in fact), I'd tend to think it was in fact plagiarism.
I think that the 42km/s figure already factors in Earth's orbital velocity. I'd have to double-check that, though.
Thank you, this was very informative!
doesn't that mean it's all in one blob with no moderation by control rods (as in gone critical)
-- control rods don't moderate, water does!! You need moderator to keep the neutron capture high by the fissile material. Control rods are neutron absorbers, not moderators. Without water mixed in, the "blob" can of course maintain the chain reaction, but at a much lower heat output than if there was water moderator present between the chunks of fuel. I was looking around and could only figure ballpark of 10% of normal operating thermal output. Perhaps a nuclear engineer could pitch in with an actual figure.
To escape the solar system from Earth, you need dv=42km/s, whereas the Earth's orbital velocity is 30km/s. Unless you can get dv from flybys, you're looking at pretty much same ballpark in terms of delta-v to go into the Sun as to leave the solar system starting from Earth.
I'd say that 1.2% of current debt is a hell of a lot of money ;)
Eventually, I'm sure, some enthusiast group will work on setting up simulators for the avionics, and they'll get flight software running for others to play with. Just like it happened with Apollo's software (what was left of it, that is). Hopefully NASA will preserve shuttle's mission software better than MIT did Apollo's.
So you say that strap-on solid boosters that would blow up the first stage would be OK if only the shuttle was on top of the 2nd stage? Can I have what you had? Solid and liquid propellants don't mix...
Guess what. SST was a contributor to the budget hole. Good riddance. Go SpaceX (no, I'm not affiliated with them).
They are careful because that RCS section is quite toxic. MMH can kill very easily if you're not careful.
Agreed. Pease and Feynman have a similar approach to things. To me, that's the quintessence of genius.