Triggerhappy wrote:Ill get back to you all with a 3 rail station
This laser will need to vaporise the whole asteroid unless it's actually powerful enough to move said multi-kilogram-probably asteroid in a short time? And that takes less power than shifting a station in on itself?
Vaporise? Who said vaporise?
Vaporise a few kg of mass on the surface of the rock and give it an "engine" to push it off the collision course.
Comment - this was meant as a short response system, where the asteroid is detected only seconds out .
So... lets assume your weird station.
100 meter arm length ~ 5 meter edge length. Filled with granite. Massing about 14000tons total (13.75e6kg).
You have 10 seconds to move the whole station about fifty meters, because thats the maximum you can shift the cross point without moving the center of mass of the whole construct (less if the crosspoint isnt massless which it cant be because you have the mechanics to throw around 14kilotons around in a few seconds there)
netting a needed top speed of 5m/s.
Which equals 171e6 J.
Or about 40kg of TNT to get out of the way in time.
(with the time you need to accelerate included you need a higher top speed, 10m/s (at 1/5th of a g) quadrupling the energy needed=160kg of TNT)
Plus losses and the center piece i neglected for simplicity.
So you are easily up to 60(240) kilogram of tnt you waste with every avoidance maneuver.
And those costs also go up with the square of the inverse of the time you take to avoid
You are better off just throwing the energy at the rock.
In either laser form (less efficient, but less maintainance) or in form of a hundred gram block of said granite in a mass driver.
Laser emitters need repairs and replacements, often after only a few shots. A rail system can be built to be far more durable over long uses.
My laser pointers last for decades.
Lab lasers also cant be used only once or twice, not even the many kilowatt ones.
As long as you cool them appropriately a laser has basically infinite lifetime.
I also personally have access to dirt cheap 40W continuous mode
semiconductor laser modules now
which have basically unlimited lifetime.
which can be pulsed to a kilowatt or so with enough cool off between usages.
And theres 10kw industrial cutting lasers to buy now.
(continuous mode with potential pulsing to much higher levels again.)
And those things definitely last longer than one or two uses
Extrapolate to a world where space is industrialised and you have an industrial need for a couple hundred kilowatt lasers.
Affordable industrial reliability level laser systems