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Re: Post Your Favorite Sci-Fi Concept Art

#227
Dinosawer wrote:
Triggerhappy wrote: It's damn well near impossible to aim at s small pice of rock traveling at you long enough to vaporizer any part of it.
We can NOW aim well enough to hit a small mirror on the moon with a laser.
Aiming at a rock is easy.
True. Nearly forgot about this one. :mrgreen:
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Re: Post Your Favorite Sci-Fi Concept Art

#228
Triggerhappy wrote: Rocks come in different materials - the same amount of energy fired at it with a laser can do anything from heat it up slightly to shatter it into a lot of small dust that is now coming at you. You won't even know what the mass of the rock is and where to fire to set it off course.
its nice that you can use lasers to find those things out in the first place :P

laser spectroscopy isnt hard to do and takes a fraction of the time the rock could possibly need to reach you.
(in addition that rocks dont have that variable of a composition, theres a couple of general classes of asteroids)

then you know what it is, and you already know how large it is by looking at it with your detecion array.
so you know its mass and composition good enough.

and why wouldnt you know where to hit the rock to get it off course? orbital mechanics arent hard, especially for an asteroid defense package computer which is built to calculate that :P
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Re: Post Your Favorite Sci-Fi Concept Art

#229
Cornflakes_91 wrote: laser spectroscopy isnt hard to do and takes a fraction of the time the rock could possibly need to reach you.
(in addition that rocks dont have that variable of a composition, theres a couple of general classes of asteroids)
I thought about that too! But I thought "Well, you're already trying to move it into another direction. And you don't know how much energy you need. So how would you know how much energy you would need for the laser spectroscopy?" :think:
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Flatfingers wrote: 23.01.2017: "Show me the smoldering corpse of Perfectionist Josh"
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Re: Post Your Favorite Sci-Fi Concept Art

#230
Triggerhappy wrote: a lot of small dust that is now coming at you.
you mean in the same size regime of the dust thats already going to sandblast you all the time anyway?

the smaller the rock the more of them are out there. exponentially.

if a med sized rock is such a common occurence that you have to desing a station to actively avoid them you are going to get many many many grain sized impacts you cant avoid.

you already have to be able to just eat sand coming at you with that speed, so the sanded rock is a definite upgrade.

besides the very very serious overkill and order of magnitude difference (aka bullshit) of you accidentally blasting a rock to pieces in the first place :P

heat of melting/vaporisation varies, yes, but not by orders of magnitude for things that are solid in the same temperature range :P
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Re: Post Your Favorite Sci-Fi Concept Art

#231
Cornflakes_91 wrote:
Triggerhappy wrote: a lot of small dust that is now coming at you.
you mean in the same size regime of the dust thats already going to sandblast you all the time anyway?

the smaller the rock the more of them are out there. exponentially.

if a med sized rock is such a common occurence that you have to desing a station to actively avoid them you are going to get many many many grain sized impacts you cant avoid.

you already have to be able to just eat sand coming at you with that speed, so the sanded rock is a definite upgrade.

besides the very very serious overkill and order of magnitude difference (aka bullshit) of you accidentally blasting a rock to pieces in the first place :P

heat of melting/vaporisation varies, yes, but not by orders of magnitude for things that are solid in the same temperature range :P
He had enough. He's already dead! :lol: :monkey:
Automation engineer, lateral thinker, soldier, addicted to music, books and gaming.
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Flatfingers wrote: 23.01.2017: "Show me the smoldering corpse of Perfectionist Josh"
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Re: Post Your Favorite Sci-Fi Concept Art

#232
JanB1 wrote:He had enough. He's already dead! :lol: :monkey:
Boy, I am never dead.
JanB1 wrote:Well, we TURN the station with the help of gyroscopes and don't NEED to MOVE it, because we move the asteroids instead of the station. That is our point.
Yet, this is not what this station is meant to do. It is not meant to shoot at asteroids. Its there to dodge them. Reasons why shooting them is dumb coming right up.
JanB1 wrote:Yeah, yeah, recuperation factor is nice, and lasers don't recuperate any energy they fired. But how much energy do you need in the first place?
A lot of mechanical energy. That you recuperate. Along with saving on lasers and everything needed to deal with them. (Targeting systems, turret mounts, power lines, and a lot of them to cover several approach vectors to the station too.
JanB1 wrote:Again, we are talking about the far future where we have space stations like this idling somewhere around, and we're talking about MILIseconds. I think it's not THAT hard to aim at a piece of rock for a few milliseconds.

Wait a second...what size of rocks are we even talking about here? I'm assuming >1m?
Sure, a one meter rock. You need to lock onto it and fire a precise shot, unless you want a LOT more power demand firing several shots. Even in the future, it would be difficult, most likely, to target and fire on a rock traveling at you with any speed comparable to what it takes to simply and quickly shift two arms of station out of the way, while losing very little energy on the asteroid itself. 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.
JanB1 wrote:And that's why you use pulse lasers. You fire small burst until the desired effect is reached.
:D
You would not have time to make a lot of short bursts, and then wait to see what effect it had after each hit.
A rock, that you just spotted, traveling at you, FAST.
We can hit a the moon, yes, but after a LOT of precise targeting and adjusting that probably took days to set up. And we know EXACTLY where the mirrors are to do that, too.
Cornflakes_91 wrote:
Triggerhappy wrote: Rocks come in different materials - the same amount of energy fired at it with a laser can do anything from heat it up slightly to shatter it into a lot of small dust that is now coming at you. You won't even know what the mass of the rock is and where to fire to set it off course.
its nice that you can use lasers to find those things out in the first place :P

laser spectroscopy isn't hard to do and takes a fraction of the time the rock could possibly need to reach you.
(in addition that rocks don't have that variable of a composition, there's a couple of general classes of asteroids)

then you know what it is, and you already know how large it is by looking at it with your detector array.
so you know its mass and composition good enough.

and why wouldn't you know where to hit the rock to get it off course? orbital mechanics aren't hard, especially for an asteroid defense package computer which is built to calculate that :P
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...
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?

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?
You wouldn't know it, because this asteroid defence package sounds very expensive for a storage station.
JanB1 wrote:I thought about that too! But I thought "Well, you're already trying to move it into another direction. And you don't know how much energy you need. So how would you know how much energy you would need for the laser spectroscopy?" :think:
Time. The issues is time. A station can dodge in 5 seconds. That... process sounds like it could take a while.
Cornflakes_91 wrote:
Triggerhappy wrote: a lot of small dust that is now coming at you.
you mean in the same size regime of the dust that's already going to sandblast you all the time anyway?

the smaller the rock the more of them are out there. exponentially.

if a med sized rock is such a common occurrence that you have to design a station to actively avoid them you are going to get many many many grain sized impacts you cant avoid.

you already have to be able to just eat sand coming at you with that speed, so the sanded rock is a definite upgrade.

besides the very very serious overkill and order of magnitude difference (aka bullshit) of you accidentally blasting a rock to pieces in the first place :P

heat of melting/vaporisation varies, yes, but not by orders of magnitude for things that are solid in the same temperature range :P
Right, so would you rather shatter the rock in several parts, all traveling at you now? Instead of dust?
Turning a rock to dust is not realistic, I agree. You would a few smaller rocks instead! Still fatal!

Some rock will shatter. Other will melt. Guessing wrong can be fatal.



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 )
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Re: Post Your Favorite Sci-Fi Concept Art

#233
Triggerhappy wrote: Sure, a one meter rock. You need to lock onto it and fire a precise shot, unless you want a LOT more power demand firing several shots. Even in the future, it would be difficult, most likely, to target and fire on a rock traveling at you with any speed comparable to what it takes to simply and quickly shift two arms of station out of the way, while losing very little energy on the asteroid itself. 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.
a. Why the hell would you be so stupid as to put a station in a retrograde orbit when asteroids are around? There is literally no reason ever you'd want to do that that could ever outweigh the sheer stupidity of doing that.
(because guess what, asteroids can easily be too larger for your station to dodge)
b. Did we forget how to build telescopes and radar? 5 seconds is in no way a realistic number. Several hours, days and even weeks more so.
c. Something that is moving toward you is not a moving object, its position does not change (it just becomes a larger target over time) and thus aiming at it is dead easy because you don't even have to factor in sideways motion.
(Yes, orbits are curved, but that's not noticeable at all at the scale we're talking about)
d. In any realistic orbit the speed something moves towards you is gonna be very low (because gravity just works that way), not high.
Warning: do not ask about physics unless you really want to know about physics.
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Re: Post Your Favorite Sci-Fi Concept Art

#234
Dinosawer wrote:
Triggerhappy wrote: Sure, a one meter rock. You need to lock onto it and fire a precise shot, unless you want a LOT more power demand firing several shots. Even in the future, it would be difficult, most likely, to target and fire on a rock traveling at you with any speed comparable to what it takes to simply and quickly shift two arms of station out of the way, while losing very little energy on the asteroid itself. 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.
a. Why the hell would you be so stupid as to put a station in a retrograde orbit when asteroids are around? There is literally no reason ever you'd want to do that that could ever outweigh the sheer stupidity of doing that.
(because guess what, asteroids can easily be too larger for your station to dodge)
b. Did we forget how to build telescopes and radar? 5 seconds is in no way a realistic number. Several hours, days and even weeks more so.
c. Something that is moving toward you is not a moving object, its position does not change (it just becomes a larger target over time) and thus aiming at it is dead easy because you don't even have to factor in sideways motion.
(Yes, orbits are curved, but that's not noticeable at all at the scale we're talking about)
d. In any realistic orbit the speed something moves towards you is gonna be very low (because gravity just works that way), not high.
^this
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Re: Post Your Favorite Sci-Fi Concept Art

#235
Triggerhappy wrote: 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"
Triggerhappy wrote: 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.
Triggerhappy wrote: 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?
Triggerhappy wrote: 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.

Triggerhappy wrote: 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.
Triggerhappy wrote: 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)
"cold" station.
"very little energy needed"

Triggerhappy wrote: 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 :P
Triggerhappy wrote: 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.

Triggerhappy wrote: 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.
Triggerhappy wrote: 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.
Triggerhappy wrote: 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.
Triggerhappy wrote: 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"
Triggerhappy wrote: 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.

=9ms

you can do that at 111fps.

:P

Triggerhappy wrote: 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.

Triggerhappy wrote: 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? :P

2: except if they are on the same arm. Just use a hose.
Works everywhere.

3: within very very limited parameters and still needing RCS thrusters or gyros to get the precision you need to do anything :P

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? :P
Or against its sibling half a second behind that looks at your evasive maneuver with enough time left to neutralise your jerking.
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Re: Post Your Favorite Sci-Fi Concept Art

#240
In a theoretical situation where retrograde orbit would be necessary, this would be a way to do it. Other places this would be of use - debris rich orbit - transport traveling through a relatively asteroid-rick piece of space at extreme speeds ( eg a large percent of light speed )

I am, however, becoming convinced of my underestimation of radars. It seems that 5 second response time is nice but completely useless since you will likely know of it's approach long before it hits.


As pointed out, the station would not need to move quickly to dodge - there would be plenty of time ahead of the impact to shift the arms. A light nudge on each arm in the right direction by the center piece will place it soon enough in the right position. And breaking those arms will return almost all the power used to move them in the first place.

That saves us no capacitors and generators.

Good point on the lasers, I should have thought of that. One laser to cover the only approach vector. Corrected. ONE laser system. Still a laser system, still on a mining station, and still you risk incorrectly offsetting the asteroid, without the ability to evade it and not use up fuel.

Precise shot on the rock itself, if you want to off-set it and not crack or burn though it. 1 meter across target hundreds of kilometers away.

Power density, power demand, and stress lowered by release of time constraints thanks to Dino. Fixes that.

And each salvo will need to be powerful enough to eject plasma.

Both will give you size and reflective properties, not exact volume and mass.

See above - still need to hit a very small location on a 1m across or so rock hundreds of kilometers away.

Yes yes, apologies for lackluster statement there, 5 second warning is unrealistically small.


The station IS the crane! :D

A hose of appropriate size would have trouble connecting between two moving arms. Just pointing out that this would not be an issue since containers can move nearby each other.

RCS thrusters or gyros for precision? Why? A shift of a few centimeters in the right direction and you are slowly rotating just how you want to.


For all who missed the joke of my picture earlier - it was a joke.

Trigger is very tired of reading wikipedia articles and googling things with the words 'space', 'station', 'laser' and 'asteroid' in them. Lets call this party off for now, you can even put in the last two cents.
~Cornstock-shaped-storage-battle-platform and twitching-crowbar-crucifixion-storage-dancer-station shall remain the void of dreams forever, dodging/shooting down space pebbles.~
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