Comic Discussion > QUESTIONABLE CONTENT
WCDT: 2465-2469 (10-14 June, 2013) Weekly Comic Discussion Thread
Akima:
--- Quote from: J on 13 Jun 2013, 15:40 ---i'm pretty sure there are international treaties against the weaponization of space. one thing the us & ussr managed to agree on was that space-based weapons were a bad idea.
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There are treaties prohibited placing "weapons of mass destruction" in space, but there is no restriction on "conventional" weapons, I believe. The "Outer Space Treaty" certainly makes that distinction. With regard to the legal status of orbital habitats, Article VI is relevant, and gives additional point to the USAF personnel on the station.
--- Quote from: Skewbrow on 13 Jun 2013, 23:59 ---To make it fall from the orbit at all, they need to give it a shove in the opposite direction for otherwise the rod would just continue its free fall motion along the station. The bigger the shove the faster it will fall from the orbit. But unless you spend a lot of energy (that they don't have at the station),
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Where do you get the energy-shortage from? Hannerdad has a space-plane that can fly directly from a normal airfield to orbit. I doubt if attaching simple retro-rockets to his rods would pose much of a challenge. He'd just need the equivalent of a torpedo-tube to push the rod away from the station (assuming he has no other launch-platform), and then fire a single-use, jettisonable retro-rocket of the sort that was used to deorbit the Mercury capsules.
Breathe, Sam, breathe!
ZoeB:
--- Quote from: Skewbrow on 13 Jun 2013, 23:59 ---TL; DR; Orbital bombardment doesn't sound very energy efficient. You spend a huge amount of energy to get that mass into orbit only to have atmospheric drag consume most of it when falling.
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Only if in a circular orbit. A high eccentricity "Molniya" type orbit, all you need is a slight nudge at apogee. That way perigee would be inside the Earth ie you get re-entry, at a near-normal angle if you do it right.
See the description under my icon.
Skewbrow:
True. But would that change affect the impact speed significantly? Possibly, as the projectile will not necessarily be entering the atmosphere at a small angle. I realize that the comparison to meteorites in my previous post was off the mark because of this: a smaller angle of entry means that MORE of the kinetic energy will be lost due to atmospheric drag!)
What about response time? You could only launch within a narrow window near apogee, so for this to be part of a weapon system you either need to wait for one of the stations to be at the right place or have many more stations forming a network (for planetwide coverage)? If the main use of these would be penetrate bunkers and such, then you may afford to wait for a couple of hours, so may be this point is moot?
PintsizeForPresident:
--- Quote from: Skewbrow on 13 Jun 2013, 23:59 ---Would anyone have a clue about the speed of the Apollo landing modules after entering the atmosphere, but before they opened the parachutes? A tungsten rod would fall faster than that (weight, shape).
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I think the re-entry speed of ICBM re-entry vehicles would give a better estimate. IIRC these have a pretty high terminal velocity, to minimize response time as much as possible. Apollo, on the other hand, was designed to "gently" (if 9 g is your idea of gently) decelerate the craft, to keep its passengers alive.
Then again, researching this topic on the internet may not be the wisest thing to do... That being said, this wikipedia entry notes that "impact is at a speed of up to 4 km/s".
Skewbrow:
Ahh! Good point about Apollo. I agree that ICBM is the more realistic comparison, so 4km/s (Mach 12) is close to the mark.
This has been a good discussion in the sense that I may have learned a few things. This article was a good read (for me).
--- Quote from: Akima on 14 Jun 2013, 01:05 ---Where do you get the energy-shortage from? Hannerdad has a space-plane that can fly directly from a normal airfield to orbit. I doubt if attaching simple retro-rockets to his rods would pose much of a challenge. He'd just need the equivalent of a torpedo-tube to push the rod away from the station (assuming he has no other launch-platform), and then fire a single-use, jettisonable retro-rocket of the sort that was used to deorbit the Mercury capsules.
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I concede the point that it would be trivial for him to make something like a rod drop from the orbit. But what kind of trajectory would the dropping rod follow? The Mercury capsules were also meant to protect the pilot during re-entry, so the point raised by PFP stands. They were aiming at a small angle of attack. So I don't know how much delta vee they could get, or need, from the retro rocket. I would think that when dropping an object from a low altitude orbit it goes roughly like: more delta vee => steeper descent, larger angle of attack => less time for the atmospheric drag to slow the object down (but also more severe heating) => higher impact speed.
All this while I've been ignoring the need for a manouverable re-entry. I would think that this is a must, if you want to hit something the size of a bunker (or the basement of CoD).
--- Quote from: ZoeB on 14 Jun 2013, 01:44 ---See the description under my icon.
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No need for that. Your drawing and explanation was clear enough. FYI (in case it matters how you choose to communicate) my PhD was in abstract algebra. I studied quite a bit of theoretical physics as an undergrad, but my understanding of theoretical mechanics was never much higher than Spiegel's Schaum series book (to those who don't know: this is an admission of being relatively ignorant), and it has taken quite a few hits in the 30 years that have passed.
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