ARS Posted March 6, 2018 Share Posted March 6, 2018 Some nuclear weapons does require 2 keys to activate, however, unlike what movies commonly depicted, the 2-keyed lock isn't that close. In real life, they are usually placed far enough so that one person cannot turn both keys by themselves to gain access to nuclear weapons, requiring 2 person and turning keys at the same time to gain access. On the other hand, some Soviet nuclear silo has 3 blast doors covering it, each requiring 3 keys from 3 owners turned at the same time to open it, totalling 9 person to fully unlock the silo's door Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted March 6, 2018 Share Posted March 6, 2018 (edited) Spoiler 1 hour ago, ARS said: In real life, they are usually placed far enough so that one person cannot turn both keys by themselves to gain access to nuclear weapons, requiring 2 person and turning keys at the same time to gain access. S. smiles at them. Spoiler 1 hour ago, ARS said: totalling 9 person to fully unlock the silo's door It is heavy to push. 4 hours ago, p1t1o said: The US have since admitted that for several years, many of the codes actually at the weapon interface (ie: not in the authorisation process) were set to "00000", partly due to the fear that the code could be inputted incorrectly and partly due to bureaucracy. I've read about this several times before, but isn't it an urban legend. Aren't the journalists confusing "Launch code should be always 00000000" and "Dials should be always set into 00000000 position". The latter case would look very reasonable, just because they would not be thinking in which direction should they turn the dials to set "33985234" from the original random "97843558" (with shaking hands and mad faces). Edited March 6, 2018 by kerbiloid Quote Link to comment Share on other sites More sharing options...
p1t1o Posted March 6, 2018 Share Posted March 6, 2018 (edited) 29 minutes ago, kerbiloid said: I've read about this several times before, but isn't it an urban legend. Obviously there is the classification barrier when talking about almost anything along this subject, and even publicly declassified things can be heavily redacted or less than totally accurate, along with nobody wanting to officially admit anything embarrassing. But it does appear in several seperate sources (not counting websites, never count websites), significantly including Eric Schlosser's "Command and Control" which is a fairly well respected source. Im sure if I re-read a bunch of stuff in my "library" I could find at least one other equally reliable source but thats neither here nor there. Combined many other scary stories, some of which are very well documented as real - it isnt so hard to believe. At the very least, its either false or real, its almost certainly not a mis-interpretation of the instructions. Edited March 6, 2018 by p1t1o Quote Link to comment Share on other sites More sharing options...
YNM Posted March 8, 2018 Share Posted March 8, 2018 On 06/03/2018 at 8:26 PM, kerbiloid said: I've read about this several times before, but isn't it an urban legend. Reports were from past contractors or something, so there's only so much to know is it true or not. On 06/03/2018 at 8:05 PM, ARS said: Some nuclear weapons does require 2 keys to activate, however, unlike what movies commonly depicted, the 2-keyed lock isn't that close. Here's what it claims to be a preserved system off Titan missiles : Now, what's interesting wrt the "0000" thing, is that the unlock for this particular system is an alphabetic one. Or at least, so it seems - possible confusioning perhaps ? Quote Link to comment Share on other sites More sharing options...
p1t1o Posted March 8, 2018 Share Posted March 8, 2018 10 minutes ago, YNM said: Now, what's interesting wrt the "0000" thing, is that the unlock for this particular system is an alphabetic one. Or at least, so it seems - possible confusioning perhaps ? If it was true, Its likely it was only the case for a certain missile system (minuteman most likely), for a certain period of time, not all missiles in the inventory for the duration of the cold war. @YNM @kerbiloid With a little googling, the source of the idea is a Dr. Bruce G. Blair who was a minuteman launch officer. Here's a link documenting some of what he has said on the matter, its a page from the book "Nuclear Shadowboxing: Cold War Redux" https://books.google.com/books?id=oO6pwt8016QC&pg=SL252-PA93&lpg=SL252-PA93&dq=Our+launch+checklist+in+fact+instructed+us,+the+firing+crew,+to+double-check+the+locking+panel+in+our+underground+launch+bunker+to+ensure+that+no+digits+other+than+zero+had+been+inadvertently+dialed+into+the+panel.&source=bl&ots=Sx9rmecSRu&sig=ob6FqwbRX3EJH4H-ht5q2f12YUw&hl=en&sa=X&ved=0ahUKEwjX1dT51dzZAhUoxVkKHTQxDiEQ6AEINjAB#v=onepage&q=Our launch checklist in fact instructed us%2C the firing crew%2C to double-check the locking panel in our underground launch bunker to ensure that no digits other than zero had been inadvertently dialed into the panel.&f=false And here is an article where Blair responds to the government's denial that a "00000" code was ever used. http://foreignpolicy.com/2014/01/21/air-force-swears-our-nuke-launch-code-was-never-00000000/ In the end, it will be very difficult to confirm this either way. On the one hand, we have an ex-crewmember giving first-hand reports, on the other, official denial, and on a third had arguments about misunderstanding how the systems worked. It is unlikely in the extreme, that an officially-produced documents spelling out the use of a "00000"-style passcode, would ever reach public domain even if it ever did exist. Things like this do not subscribe to the same freedom-of-information laws. It is also the kind of thing that you would expect the authorities to deny, if it were true, but I admit that that is vulnerable to the logical fallacy "they deny it so it must be true!". It may have even been true but never documented. Or it indeed may be an urban myth born out of the ether. But then a lot of things around nuclear history are like this. Its also worth noting, just generally, that in the wake of 9/11, a lot of publicly available information has been removed from various places, not that they've "re-classified" things that were once public domain, but various documentation is now much harder to get to see. What *is* documented and generally accepted though, is that Strategic Air Command at the time, was definitely interested in keeping the launch process as simple as possible specifically to lower the possibility of mistakes and to make the whole process quicker. For me, the weight of evidence "rings true", Id put money on it, and its more interesting to think of it as true, especially since there are other things just as bad that did actually happen - like a live warhead accidentally falling off aircraft or being drawn from stocks, loaded onto an aircraft and flown across the country without any authorisation whatsoever. And my favorite - Remember how there was a concern that the first nuclear weapons might "ignite" the atmosphere and end all life on the planet? It was never a possibility of course, and most of the principle scientists knew this very well, but it was a conversation that had to be had: Quote During the next three months scientists in secret conference discussed the dangers of fusion but without agreement. Again Compton took the lead in the final decision. If, after calculation, he said, it were proved that the chances were more than approximately three in one million that the earth would be vaporized by the atomic explosion, he would not proceed with the project. Calculations proved the figures slightly less - and the project continued. 3 in a million. Would you roll that dice? With the entire human civilisation at stake? People win the lottery every dang DAY at odds worse than that by orders of magnitude... Also note that the calculated probability was *not* zero. I think as science has improved (it WAS early days after all) the possibility has been erased entirely, but still, someone - someone in authority - sat down and said "this is a level of threat we are willing to accept" whilst talking about slagging the entire surface of the Earth. http://large.stanford.edu/courses/2015/ph241/chung1/ Quote Link to comment Share on other sites More sharing options...
ARS Posted March 13, 2018 Share Posted March 13, 2018 Is there an absolute minimum limit of star sizes? Does the "miniature sun" in spider-man movie possible? (the movie is clearly ignoring heat and radiation effect) Quote Link to comment Share on other sites More sharing options...
p1t1o Posted March 13, 2018 Share Posted March 13, 2018 22 minutes ago, ARS said: Is there an absolute minimum limit of star sizes? Yes, definitely. The mass must be sufficient to produce conditions in the core to start fusion. 24 minutes ago, ARS said: Does the "miniature sun" in spider-man movie possible? Nope. Observe - Jupiter is not a star. *** https://www.google.de/search?q=minimum+star+mass&oq=mini&aqs=chrome.1.69i57j69i59l3j0l2.5775j0j7&sourceid=chrome&es_sm=122&ie=UTF-8 Quote Link to comment Share on other sites More sharing options...
wumpus Posted March 13, 2018 Share Posted March 13, 2018 On 3/6/2018 at 8:05 AM, ARS said: Some nuclear weapons does require 2 keys to activate, however, unlike what movies commonly depicted, the 2-keyed lock isn't that close. In real life, they are usually placed far enough so that one person cannot turn both keys by themselves to gain access to nuclear weapons, requiring 2 person and turning keys at the same time to gain access. On the other hand, some Soviet nuclear silo has 3 blast doors covering it, each requiring 3 keys from 3 owners turned at the same time to open it, totalling 9 person to fully unlock the silo's door My understanding was that if one guy opened the missile hatch, pretty much any other submariner could launch the missiles. Not that the warhead would be armed, but it would fire the missile. The idea of a nuclear-armed country (with early submarine warming RADAR) would wait until a full broadside from an Ohio-class boomer explodes to launch a retaliatory strike seems unlikely. - While this story seemed quite true, I have no idea if it was Ohio class or earlier. I doubt they could/would change the issue, and the earlier boomers certainly had plenty of firepower. The old joke was the "third most powerful man in the world was the captain of a US boomer". Quote Link to comment Share on other sites More sharing options...
DAL59 Posted March 13, 2018 Share Posted March 13, 2018 Iron Man should be covered in airbags. Quote Link to comment Share on other sites More sharing options...
Green Baron Posted March 13, 2018 Share Posted March 13, 2018 7 hours ago, ARS said: Is there an absolute minimum limit of star sizes? Yes, these are the brown and/or red dwarves and the minimum size to start an own fusion is ~13 Jupiter masses for deuterium fusion. If this is a full featured star can be discussed. http://iopscience.iop.org/article/10.1088/0004-6256/147/5/94/meta ~0.075 * mass of sun is needed for self sustained hydrogen fusion in a star's core. Example: http://www.eso.org/public/news/eso0503/ and https://sites.uni.edu/morgans/astro/course/Notes/section2/fusion.html Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted March 14, 2018 Share Posted March 14, 2018 (edited) I watched the most recent Designated Survivor last night, which dealt with an issue on the ISS. It wasn't bad science so much as bad facts; the most glaring was referring to the Soyuz "escape pod" and that the station had a crew of four. Of course, most people on this forum would know that the Soyuz only seats three. At another point they referred to the "photovoltaic radiators." Um, those are two separate components. (I stand corrected, there is such a thing) I was also wondering if the resupply rocket they showed, which I think was a Delta-II, could deliver a decent payload to the ISS, but a little googling showed that it could send up to 8000lbs to LEO, so I guess that was legit enough... But then, anyone watching a TV show that deals with their profession generally laughs at how far from reality it is, so I guess it's excusable for the sake of watchability. Like when they showed a ship docking with the ISS, it was coming in way faster than reality. Understandable enough, or it would be painful to watch. But to see it come in "hot" and just stop when it docked, with no apparent transfer of momentum even, just looked so wrong. Edited March 14, 2018 by StrandedonEarth Quote Link to comment Share on other sites More sharing options...
mikegarrison Posted March 14, 2018 Share Posted March 14, 2018 On 3/8/2018 at 4:46 AM, p1t1o said: And my favorite - Remember how there was a concern that the first nuclear weapons might "ignite" the atmosphere and end all life on the planet? It was never a possibility of course, and most of the principle scientists knew this very well, but it was a conversation that had to be had: 3 in a million. Would you roll that dice? With the entire human civilisation at stake? People win the lottery every dang DAY at odds worse than that by orders of magnitude... Also note that the calculated probability was *not* zero. I think as science has improved (it WAS early days after all) the possibility has been erased entirely, but still, someone - someone in authority - sat down and said "this is a level of threat we are willing to accept" whilst talking about slagging the entire surface of the Earth. http://large.stanford.edu/courses/2015/ph241/chung1/ It wasn't that long ago that people were claiming there was a non-zero chance that the Large Hadron Collider would somehow trigger the destruction of the Earth, possibly by making "strangelets" that would trigger a sort of "Ice-nine" event. I remember reading some calculations that the LHC was actually less likely to do that than some of the lower-energy colliders that had already been built. In a way I guess that is comforting, but also in a way not so much. Quote Link to comment Share on other sites More sharing options...
YNM Posted March 14, 2018 Share Posted March 14, 2018 11 hours ago, ARS said: Is there an absolute minimum limit of star sizes? Does the "miniature sun" in spider-man movie possible? (the movie is clearly ignoring heat and radiation effect) Definitely no. Unless that thing is actually a hollow sphere/torus inside. Quote Link to comment Share on other sites More sharing options...
DAL59 Posted March 14, 2018 Share Posted March 14, 2018 1 hour ago, StrandedonEarth said: photovoltaic radiators Would it be possible to combine a radiator with a solar panel? Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted March 14, 2018 Share Posted March 14, 2018 (edited) 16 minutes ago, DAL59 said: Would it be possible to combine a radiator with a solar panel? I suppose. The Gigantors in KSP, before the radiators were added, were suppose to also double as radiators. But that is not how the ISS is built; they are separate components. Whoops, I googled an image for clarification, and found that there are radiators specifically for the solar panels, and they're actually called the.... photovoltaic radiators. Presumably to cool the power management systems/batteries, etc. Next someone will tell me they're sending up a four-seat Soyuz... Edited March 14, 2018 by StrandedonEarth Quote Link to comment Share on other sites More sharing options...
p1t1o Posted March 14, 2018 Share Posted March 14, 2018 7 hours ago, DAL59 said: Would it be possible to combine a radiator with a solar panel? Whilst Im sure its possible, I can think of one issue. Generally you want solar panels to face the sun - expose as much area as possible to the light. With radiators, you want them edge-on to the sun, so that they can shed as much heat as possible. Quote Link to comment Share on other sites More sharing options...
DDE Posted March 14, 2018 Share Posted March 14, 2018 6 hours ago, DAL59 said: Would it be possible to combine a radiator with a solar panel? It wouldn’t be terribly efficient, and I’m not sure how well photocells respond to heating, but it may be possible to design them as passive cooling fins. Not terribly efficient, though. 18 hours ago, ARS said: Is there an absolute minimum limit of star sizes? Does the "miniature sun" in spider-man movie possible? (the movie is clearly ignoring heat and radiation effect) Keep in mind that the movie also doesn’t feature a true stellar fusion but has to involve some McGuffin in the form of dedicated fusion fuel. Of course, the tiny sun working is also internally consistent - BECAUSE IT SOMEHOW HAS A GRAVITY WELL COMPARABLE TO EARTH’S. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted March 14, 2018 Share Posted March 14, 2018 2 hours ago, p1t1o said: Whilst Im sure its possible, I can think of one issue. Generally you want solar panels to face the sun - expose as much area as possible to the light. With radiators, you want them edge-on to the sun, so that they can shed as much heat as possible. You could use the solar panels as shade for the radiators. Solar panels don't like heat so you want to use the back of solar panels to help keep them cold. Still you could have an T style setup with solar panel is the top of T. This would make the design harder to fold and rotate. It might be an relevant design if you build it in space. Quote Link to comment Share on other sites More sharing options...
p1t1o Posted March 14, 2018 Share Posted March 14, 2018 5 minutes ago, magnemoe said: You could use the solar panels as shade for the radiators. Solar panels don't like heat so you want to use the back of solar panels to help keep them cold. Still you could have an T style setup with solar panel is the top of T. This would make the design harder to fold and rotate. It might be an relevant design if you build it in space. Sure, you can use them to compliment each other, but it sure sounds like combining them into a single thing is not optimal. Quote Link to comment Share on other sites More sharing options...
YNM Posted March 14, 2018 Share Posted March 14, 2018 1 hour ago, p1t1o said: but it sure sounds like combining them into a single thing is not optimal. Put them on a cross / perpendicular setup say. The tracking requirement could be lessened. Quote Link to comment Share on other sites More sharing options...
ARS Posted March 14, 2018 Share Posted March 14, 2018 Isn't solar panel performance decreased when being exposed with high temperature (you know, when a radiator is attached behind it since it "radiates" heat, including to the panel itself)? I think this might be possible, but at the cost of heavier solar panel assembly and much more complex mechanism Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted March 14, 2018 Share Posted March 14, 2018 Solar panels on Soyuz are part of antennas. Radiator is another detail. 5 hours ago, magnemoe said: You could use the solar panels as shade for the radiators. and as umbrellas against rain. If a panel shades the radiator, then the radiator radiates into the panel. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted March 14, 2018 Share Posted March 14, 2018 1 hour ago, kerbiloid said: Solar panels on Soyuz are part of antennas. Radiator is another detail. and as umbrellas against rain. If a panel shades the radiator, then the radiator radiates into the panel. It also depend if this is an real problem, on an capsule or an space station you use the radiators to cool life system and electronic so the radiators would just be lukewarm. if you have hot processes you would run them in an separate high temperature radiator. Wonder if the solar panels might radiate heat to the radiator instead. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted March 14, 2018 Share Posted March 14, 2018 51 minutes ago, magnemoe said: Wonder if the solar panels might radiate heat to the radiator instead. Then we call these panels radiators. Quote Link to comment Share on other sites More sharing options...
ARS Posted March 16, 2018 Share Posted March 16, 2018 Is it true that longer barrel makes the bullet more accurate because the grooves inside the barrel allows the bullet to spin further, thereby increasing it's stability and accuracy? How about a shorter barrel with tighter grooves? (Makes the bullet spin inside the barrel with the number of rotation comparable with longer barrel, but at shorter barrel length) Quote Link to comment Share on other sites More sharing options...
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