Hit a target from space, anywhere, in less than an hour.

[MechAg94]

When I saw the X37B launch article, I would thinking about our past discussion on the best way to kill satellites.  Dropping rods is pretty cool also.  Think this is an alternative to the nuclear bunker buster?

Several years ago I remember seeing an article that the Air Force was looking at orbital bombardment options, but the issue was getting the weapons in orbit in the first place.  Maybe they are solving that.

[Waitone]

Great book on rods of god, space fighters. micro satellites, etc.

Space Wars: The First Six Hours of WWIII by William B Scott et al.

The book is a novel treatment of something like 6 war game scenarios conducted over the past few years by the military.  I never realized how dependent upon satellites our society really is.

[AJ Dual]

The other thing this solves is having something in orbit is much better for tactical spaceborne strikes. You launch something on a ballistic ICMB trajectory, Russia and China tend to get antsy. (Like the ideas to put KEW's or conventionals on ICBM's...) Otherwise you have to get on the red-phone, warn them in advance, and hope they don't turn around and call Iran/North Korea etc...

Once it's in orbit, only 100 miles up, warning time is way less, especially if you don't care how fast it "lands". 

What would be REALLY cool is we had a way to strike someone with lightning, say when they're giving a speech outdoors at a big public appearance. It would go over really well in the superstitious Middle East.

Nope. Not us... What did you say happened again? Lightning? Really? Wow... 

[kgbsquirrel]

The other thing this solves is having something in orbit is much better for tactical spaceborne strikes. You launch something on a ballistic ICMB trajectory, Russia and China tend to get antsy. (Like the ideas to put KEW's or conventionals on ICBM's...) Otherwise you have to get on the red-phone, warn them in advance, and hope they don't turn around and call Iran/North Korea etc...

Once it's in orbit, only 100 miles up, warning time is way less, especially if you don't care how fast it "lands". 

What would be REALLY cool is we had a way to strike someone with lightning, say when they're giving a speech outdoors at a big public appearance. It would go over really well in the superstitious Middle East.

Nope. Not us... What did you say happened again? Lightning? Really? Wow... 

100 miles is actually pretty low for satellites. Lots of atmo drag there, Shift up a couple hundred more to get a good stable parking spot. I like the idea of around 800-1000 miles up though. More energy gathered from the decent. Then again you have the potential overspeed problem resulting in either incineration during reentry of the dart or it's instant vaporization on impact rather than the tremendous kinetic energy transfer we're going for.

[Tallpine]

100 miles is actually pretty low for satellites. Lots of atmo drag there, Shift up a couple hundred more to get a good stable parking spot. I like the idea of around 800-1000 miles up though. More energy gathered from the decent. Then again you have the potential overspeed problem resulting in either incineration during reentry of the dart or it's instant vaporization on impact rather than the tremendous kinetic energy transfer we're going for.

Plausible deniability 

Asteroid strikes do happen now and then.

[kgbsquirrel]

Plausible deniability 

Asteroid strikes do happen now and then.

Yeah, of course. And it's not our fault if the total estimated number of asteroid strikes for this geological era all happen in the span of a month, is it? 

[roo_ster]

Jfruser, since you have the math done already.

At least one article talked about darts in the range of 6 meters long, 30 cm diameter, made of tungsten.  Big boom?

I'll see if I can dig that article up.

edit:
Found it, it was a popular science article.

Rods from God

I have no idea where their info came from or what the phrase "up to" means in this context, but it seems likely that given the choice of cheaper , but still effecive weapons, or really cool overkill America goes for the really cool every time.

6m W rod 15cm in diam in LEO at 150KM up:
36.59        KtTNT

I haven't had the time to try out kgbsquirrel's idea of dropping them from WAY up there.  Just don't have time this weekend.  Frankly, SOMEBODY have worked the problem and derived the equation for some orbital mass with an initial velocity.  I do suspect the amount of KE would be megaton range.

I still like the idea of "cluster" KE munitions for area targets. 

Code: [Select]

For 6m Rod Dropped from LEO

Variable / Unit / Whatever                       Symbol         Value              Units         Notes
Start Orbit Height                               Ho                  150000        m             150Km
Start Velocity Minimum                           Vo                    7814        m/s           Low Earth Orbit at 150Km
Rod Radius                                       Rr                    0.15        m             10 cm diameter
Rod Length                                       h                        6        m             Double length of rod
Rod Frontal Area                                 A                  0.07065        m^2                                                                        0
Rod Volume                                       vol                 0.4239        m^3                                                                        0
Rod Mass                                         Mrod              8160.075        Kg/m^3        Tungsten, baby, cause its more dense
densityW (tungsten)                              dW                   19250        Kg/m^3                                                                     0
Rod Coeff Drag                                   Cd                    0.04        none          Streamlined body
Start KE in Orbit                                KEo               2.49E+11        joules        Starting off 2 orders of magnitude greater than KE penetrator
Velocity at Impact                               Vt                      18        mach          mach = 340.3 m/s @ 15degC
Velocity at Impact                               Vt                  6125.4        m/s           Very conservative, given a cones Cd = .5
Kinetic Energy @ Impact W                        KEw               1.53E+11        joules                                                                     0
Kiloton TNT                                      KtTNT             4.18E+09        joules                                                                     0
Kinetic Energy @ Impact W                        KEw                  36.59        KtTNT                                                                      0
Kiloton                                          Kt                2.00E+06        Lbs                                                                        0
Kinetic Energy @ Impact W                        KEw               7.32E+07        LbTNT         


[RevDisk]

6m W rod 15cm in diam in LEO at 150KM up:
36.59        KtTNT

I'd say that's about perfect, for anything other than taking out entire cities.   Personally, I'd say a bit shorter and a bit thicker.  But that's just personal preference.


25-30 Kt yield is about perfect for a surface point target.  Only issue would be if it was really deeply buried bunker.  Kinetic kill isn't great for that.  You want overpressure to do the job for you.

[Snowdog]

I recall reading about these "rods from God" in an article, but I admit I really know little about their effects.

The energy generated such a weapon would be focused downwards of course, correct?   Would this be essentially a bunkerbuster?  The overpressure/thermal energies experienced a few hundred yards away from the impact site wouldn't hold a candle to a tactical nuke, again being the energies are expended downwards, right (and the lack of a fission or fusion reaction)? 

I'll have to read up on this I guess.

[S. Williamson]

Why not use cermet?  Wouldn't it be cheaper to utilize than tungsten, too?

[kgbsquirrel]

Why not use cermet?  Wouldn't it be cheaper to utilize than tungsten, too?

Are there cermets that can equal tungsten's density?

[Perd Hapley]

.

[S. Williamson]

Are there cermets that can equal tungsten's density?

Why not depleted uranium, then?

.

..

[kgbsquirrel]

Why not depleted uranium, then?

It's pyrophoric and has a tendency to leave 0.1 micron sized particles in it's wake and all over the impact zone. Not something you want to be around. At that size gas masks are rather useless and heavy metal poisoning, especially of transuranics, is rather nasty.

I asked about the cermet density because as I understand it those are generally composed of nickel or cobalt and things like alumina.

[S. Williamson]

I see where we're going with this, now.    Mass and high melting/sublimation point.

I was thinking of a hardness factor with the cermet, and mass with the DU.

[RevDisk]

I'm annoying jfruser and physics.  I think I can script a "APS Orbital Kinetic Weapon Yield Calculator"

[MillCreek]

I see where we're going with this, now.    Mass and high melting/sublimation point.

I was thinking of a hardness factor with the cermet, and mass with the DU.

This is the reason that tungsten is the preferred metal for this application.  High melting point, high density and low toxicity.  Although I suppose the toxicity point is moot if you are in the impact zone.  But someone has to come along and bag all the bodies.

[AJ Dual]

This is the reason that tungsten is the preferred metal for this application.  High melting point, high density and low toxicity.  Although I suppose the toxicity point is moot if you are in the impact zone.  But someone has to come along and bag all the bodies.

At 2 dozen + kT, there won't be many bodies, assuming the target is some sort of secure installation in a remote area that does not have a population surrounding it. 

After seeing some of the math, I'm still surprised the MIRV impact wasn't more spectacular. It must have been slowing way down.

[kgbsquirrel]

At 2 dozen + kT, there won't be many bodies, assuming the target is some sort of secure installation in a remote area that does not have a population surrounding it. 

After seeing some of the math, I'm still surprised the MIRV impact wasn't more spectacular. It must have been slowing way down.

I'm not sure the inert test mirvs are designed for use as kinetic weapons. It would mostly be the ablative heat shield shell and the guidance system sans nuclear physics package. As mentioned elsewhere it's quite possible that the test mirv just vaporized on impact with little energy transfer.

[Gowen]

That depends grossly on who the human in question is. If it's OBL or someone like that, it could well be worth it.

You must remember that the US has outlawed political assassination.  While OBL is a legitimate target (I question if obama would designate him as such), Ahmadinejad isn't, until he attacked this country or we decided to attack his.  Though, I don't know if obama would make any political leader a target in war or retaliate if attacked.

[CNYCacher]

I am also wondering how you could compare a ground impact to an air-burst nuke in terms of destructive power above ground.  I would imagine that a significant portion of the energy would be dissipated deep into the earth.  That's not to say that there wouldn't be massive destruction, I'm just not sure how useful the kinetic energy calculations are if you are comparing them to air-burst.

Now, if you could find a way to shatter the dart above the intended target, you could transfer most or all of the energy directly into the air, causing the same effect as an air-burst bomb.  It would take a relatively small explosion to yield huge results.  I don't know what it would take to shatter the rod into small pieces, but it would be pretty small compared to shat you would get out of it.

I'm not sure the inert test mirvs are designed for use as kinetic weapons. It would mostly be the ablative heat shield shell and the guidance system sans nuclear physics package. As mentioned elsewhere it's quite possible that the test mirv just vaporized on impact with little energy transfer.

The energy has to go somewhere.

[MicroBalrog]

You must remember that the US has outlawed political assassination.  While OBL is a legitimate target (I question if obama would designate him as such), Ahmadinejad isn't, until he attacked this country or we decided to attack his.  Though, I don't know if obama would make any political leader a target in war or retaliate if attacked.

No, no, that's not my point.

My point is, that a single human is valuable enough to shoot with this if they're an important personage - an enemy general, a commander, etc. WHat the rules are for engagement, I don't know.

Also, how would this work with something like a docked ship?

[CNYCacher]

Also, how would this work with something like a docked ship?

I think it would sink. 

[roo_ster]

CYNC:

I am not sure about the whole "vaporize on contact" issue.  One reason I would push for a cluster version in addition ot the unitary version.  The energy release when, say, a 1-5Kg tungsten mini-rod goes plasma has got to be harmful to plants, pets,enemy infantry, and material anywhere close.

RevDisk:

I responded to your PM.  Likely not enough to help, just enough to drive you up a wall in frustration.  Thanks (or retaliation) not necessary, as I am here to serve.

[Bigjake]

That's the coolest thing ever. 

Practically screams Heinlein.   

I think Venezuela is do for some unfortunate meteor activity.