Yet, this is not what this station is meant to do. It is not meant to shoot at asteroids. Its there to dodge them.
"Its not there to be reasonable or economic"
A lot of mechanical energy. That you recuperate.
So, you want your station to move out the way in 5 seconds.
Using the same, small, 100meter arm length station that requires 20m/s average velocity, amounting to 40m/s peak velocity using a minimum acceleration sheme not to jank the thing to pieces.
Yielding 11.2 gigajoule of kinetic energy at peak for the station. (About three tons of tnt)
To store that much energy you'd need about 300 tons of better-than-state-of-the-art capacitors (EDLC's with 36kj/kg).
Thats three space shuttles worth of capacitors.
Not payload, the whole shuttle.
Plus power systems to handle the 4.5 gigawatt of powerflow, the power flow three times as large as the largest nuclear power plant in the USA is spitting out...
Plus the equipment has to be extra large because its flow direction can be inverted.
So you are probably looking at something in the area of two kilotons of power equipment.
The full space shuttle launch system, orbiter, tank, boosters, fully tanked.
1/7th of the mass you want to hurl around in the first place.
And thats ignoring any additional mass penalties that come from having a station sturdy enough to withstand the forces that come from accelerating many kilotons of rock at 1.6g.
Along with saving on lasers and everything needed to deal with them. (Targeting systems, turret mounts, power lines)
Because your giant nuclear power plant equivalent is cheaper?
and a lot of [lasers] to cover several approach vectors to the station too.
That is not how orbital mechanics work.
Everything comes from ~ the same direction.
And a properly placed laser covers half of the sky.
Sure, a one meter rock. You need to lock onto it and fire a precise shot
That thing is coming straight at you.
Angular velocity =0.
That thing is equivalent to a stationary target.
while losing very little energy on the asteroid itself.
So, look at the numbers i outlined earlier for the energy needed and lets assume very generous 90% efficiency at driving and recuperating. (Probably a lot lower because such ridicolous power density systems lose a lot of efficiency)
81% round trip efficiency.
2.2GJ of waste heat. (500kg of tnt)
"very little energy needed"
Good luck locking onto, and hitting, a rock traveling in a retrograde orbit for example, in, eh, 5 seconds. All that is skilled by twitching the station out of the way in a short time.
Its sure as frak easier than putting the power equipment to supply a fair chunk of the USA into the station
You would not have time to make a lot of short bursts, and then wait to see what effect it had after each hit.
"Lot of small bursts" = a couple of salvos 30microseconds long each
And "wait to see" can be done in fractions of a second by analysing the light coming back from the plasma plume.
Brightness ~ total amount of energy in the ejecta
Doppler shift of the light ~ speed at which the ejecta are travelling
size of the rock ~ mass of the rock
Gives you the total impulse transferred to the asteroid and thus its vector change as soon as a few photons come back from the laser hit.
What kind of detection array do you use that can tell you the rock's exact size and mass? Must be very expensive and fragile...
A radar array.
Or an optical telescope.
You know, the same stuff you need to detect an asteroid in the first place.
And what if the asteroid is spinning, so you shooting it off course just results with the energy being spread out over the surface of the damn thing?
By using a stupid properly pulsed laser that doesnt dwell for 5 seconds but only for a couple of microseconds or a milisecond or two in extreme cases.
Which is enough to have essentially instant point sources on any concievable asteroid.
So, you spot an asteroid 5 seconds out from impact. You want to measure its mass, composition, waste energy testing it with a laser, and then try to precision-burn it out of it's path without shattering it?
"Waste power" *points at loss calculations*
a basic spectroscopic application needs single digit amounts of joule in energy. Thats a measurement error.
You wouldn't know it, because this asteroid defence package sounds very expensive for a storage station.
Go ahead, calculate the costs for a fixed size laser package you can mass produce and sell to everyone and compare it to gigantic multi kiloton mechanical systems needed to jerk the station around.
And then say again its "very expensive"
Time. The issues is time. A station can dodge in 5 seconds. That... process sounds like it could take a while.
Distance 300km, 5 seconds at a retrograde earth orbit.
probing laser takes 1ms to reach the asteroid.
Wait 2ms until theres a good plume to probe.
1ms for the probing light to return from the rock.
5 ms to measure and calculate what you need.
you can do that at 111fps.
Some rock will shatter. Other will melt. Guessing wrong can be fatal.
Again, materials dont vary by that far.
At the point where you shatter (and still push away, conservation of impulse still applies) one rock the other one is definitely off course as well.
Further advantages of crowbar station:
1 - Docking with the station becomes significantly easier - stop somewhere nearby the station, and it will maneuver any container you want right by your ship.
2 - If said containers are fuel tanks, you can transfer fuel between any two containers on the station, simply by shifting around some containers
3 - Rotation without gyros and engines.
4 - Its a station that can dodge. Without using fuel. Precision railguns, impact missiles, and non-pulse lasers are helpless against said station. ( everything else though will kill the flimsy sucker )
1: you mean like a crane? The things that are usually used for such purposes? with much higher precision and much lower infrastructure cost?
2: except if they are on the same arm. Just use a hose.
3: within very very limited parameters and still needing RCS thrusters or gyros to get the precision you need to do anything
4: if you can only spot a meter wide rock at 5 seconds separation you definitely wont spot a railgun round, or its 15 brothers in a spread pattern that makes your evasion pointless.
And 50 meters for a guided
weapon that wants to hit you? What chances do you think you have?
Or against its sibling half a second behind that looks at your evasive maneuver with enough time left to neutralise your jerking.