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Question: say one of these planes is flying above me and someone shoots a surface to air in the general direction of this plane, and in the process of destroyin

by S_A_P 7y ago

Question: say one of these planes is flying above me and someone shoots a surface to air in the general direction of this plane, and in the process of destroying said missile an errant laser beam strikes me as I watch from the ground. What happens to me? Mainly curious as to the power of the beam as a thought experiment.

hurtle_shurtle 7y ago
> Question: We can tell it’s a question, from the question mark at the end.
mr_overalls 7y ago
This scenario has been carefully explored since the mid-1980s. For clarification, are you made of popcorn? https://www.youtube.com/watch?v=rthHSISkM7A&t=16s https://www.youtube.com/watch?v=rthHSISkM7A&t=16s
- S_A_P 7y ago
  That was one of my first thoughts too. I am curious if/how deadly the lasers are, and I have resisted the Dr Evil quote fingers until now.
hguant 7y ago
Off the cuff? Probably nothing fatal. Lets assume the laser works by dumping a lot of thermal energy into the missile. It's safe to assume for two reasons - primarily because I think that the power requirements for anything other than that would be ridiculous, and because they specifically talked about 'destroying' the missiles in question, rather than simply burning out the sensor package. Also...that's pretty much how laser/directed energy weapons work - you dump energy into a point until it catches fire. People are mostly water (citation needed). Missiles are mostly meta (ibid)l. Water takes a lot of energy to heat up, while metal heats up quite easily - we know this because we know that a Calorie {kilo-calorie for those at home} is the amount of energy needed to raise 1 kilogram of water 1 degree C, and is equal to ~4500 joules. To do the same thing to copper and steel, you need something like 350 and 500 joules, respectively (this is a property called specific heat, and is really cool and I wish I wasn't bad at thermo so I could talk about it more accurately). Anyway, it takes a very large amount of energy to hurt a person, and a smaller amount to destroy a missile. There are two ways of getting that energy out of a laser - in one big ass pulse, or in a longer stream. Looking at the mount, and the platform the laser is to be deployed on, I believe this works with a 'stream' of energy. Fighter jets are not power plants (citation needed) and have a lot of high powered electrical equipment on them already (radar(s), communications devices, whatever sensor packages they have, flight avionics, cooling, and the computer(s) that co-ordinate all this). You don't want your displays going dark because you're charging the laser. Additionally, high energy pulses tend to be destructive to their components. Having only one anti missile shot before you have to under go maintenance to replaced a bunch of fused emitters and whatnot doesn't' seem like the best idea. With a lower energy continuous beam, you don't have that destructive flow, and while the total power draw is probably similar to a pulse, you're pulling that over a longer period, which is much easier to plan for. Pulling it all together - the laser's target has different thermal properties than a human does, and probably takes a few seconds 'on target' to work. Depending on how long you stayed in the beam, I'd expect anything from first to second degree burns, probably from the water in your cells turning to steam and bursting, but nothing catastrophically bad unless you were lasered continuously the entire time, and even then I don't think it would kill you, just burn you quite badly. Unless you looked into it. That would probably go poorly for everyone.
iguy 7y ago
Presumably the beam is focused on the target, and then if you're far behind it, the energy will be spread over a much larger area than on the missile.

by S_A_P 7y ago

hurtle_shurtle 7y ago

> Question: We can tell it’s a question, from the question mark at the end.

mr_overalls 7y ago

This scenario has been carefully explored since the mid-1980s. For clarification, are you made of popcorn? https://www.youtube.com/watch?v=rthHSISkM7A&t=16s https://www.youtube.com/watch?v=rthHSISkM7A&t=16s

S_A_P 7y ago
That was one of my first thoughts too. I am curious if/how deadly the lasers are, and I have resisted the Dr Evil quote fingers until now.

hguant 7y ago

Off the cuff? Probably nothing fatal. Lets assume the laser works by dumping a lot of thermal energy into the missile. It's safe to assume for two reasons - primarily because I think that the power requirements for anything other than that would be ridiculous, and because they specifically talked about 'destroying' the missiles in question, rather than simply burning out the sensor package. Also...that's pretty much how laser/directed energy weapons work - you dump energy into a point until it catches fire. People are mostly water (citation needed). Missiles are mostly meta (ibid)l. Water takes a lot of energy to heat up, while metal heats up quite easily - we know this because we know that a Calorie {kilo-calorie for those at home} is the amount of energy needed to raise 1 kilogram of water 1 degree C, and is equal to ~4500 joules. To do the same thing to copper and steel, you need something like 350 and 500 joules, respectively (this is a property called specific heat, and is really cool and I wish I wasn't bad at thermo so I could talk about it more accurately). Anyway, it takes a very large amount of energy to hurt a person, and a smaller amount to destroy a missile. There are two ways of getting that energy out of a laser - in one big ass pulse, or in a longer stream. Looking at the mount, and the platform the laser is to be deployed on, I believe this works with a 'stream' of energy. Fighter jets are not power plants (citation needed) and have a lot of high powered electrical equipment on them already (radar(s), communications devices, whatever sensor packages they have, flight avionics, cooling, and the computer(s) that co-ordinate all this). You don't want your displays going dark because you're charging the laser. Additionally, high energy pulses tend to be destructive to their components. Having only one anti missile shot before you have to under go maintenance to replaced a bunch of fused emitters and whatnot doesn't' seem like the best idea. With a lower energy continuous beam, you don't have that destructive flow, and while the total power draw is probably similar to a pulse, you're pulling that over a longer period, which is much easier to plan for. Pulling it all together - the laser's target has different thermal properties than a human does, and probably takes a few seconds 'on target' to work. Depending on how long you stayed in the beam, I'd expect anything from first to second degree burns, probably from the water in your cells turning to steam and bursting, but nothing catastrophically bad unless you were lasered continuously the entire time, and even then I don't think it would kill you, just burn you quite badly. Unless you looked into it. That would probably go poorly for everyone.

iguy 7y ago

Presumably the beam is focused on the target, and then if you're far behind it, the energy will be spread over a much larger area than on the missile.