Ok here is a website allows one to set up some of the conditions of an object striking the earth from space. It could have some use to some Evil GM's, if they wish to send some runners into an adventure after such an event occurred. Or even more Evil GM's have it happen while the Team is there.

http://www.lpl.arizona.edu/impacteffects/

Be warned you may spend some time, entering in different parameters.

WMS

so now we can generate realistic orbital bovine bombardments? 0.o

Ah, I've spent many a happy hour on that site. It is highly addictive, especially if you're a geology geek (which I am at times).

So, now that you've brought that up, there are three objects that need to be tested:
A Thor shot
An off-course Ares space craft
A cow (I knew that it was going to come up, just getting it out of the way now)

Now as for the Thor shot...

Distance... well, I'll put down 100 km.

As for size and mass, ideal kinetic bombardment projectiles are made of tungsten, as it has the highest heat capacity and least thermal expansion of any metal, and are about the size of a telephone pole, maybe a bit thicker.

20,000 kg per cubic meters
3 meters diameters (it's assuming a spherical projectile, a Thor shot would be elongated to help it pass through the atmosphere)

15 km/s (low Earth orbit velocity is 8 km/s; figure that they'd do a retrorocket fire to slow the Thor shot so its orbit degrades and then have another rocket help push it on it's way down)

90 degree impact (I think this is fairly obvious why)

And, just for giggles, sedimentary rock, because it's about as dense as concrete.

And we get... 4.25 x 10^12 joules at impact... or a little over ten tons of TNT. A little disappointing, but then, considering what it's used for, that seems to be fairly ideal.

hmm, maybe its time to upgrade, to something like a blue whale?

Only if it's one of those surprised-looking ones.

I was just going to ask what the density of a surprised sperm whale is.

Density of said creature, is greater than a box of Twinkies, but not as durable.

Then do some orbital juggernaut bombardments. In SR 3 they were some tough nasty armadillo things. Have them be in a ball and fall down to the earth.

hmm, when one start moving into paracritter territory, all kinds of ammo starts showing up.

lol... so now we need an awakened cow?

what happens if we launch an awakened (dual natured) cow at an astral being? =P

(note: the trickiest part is getting the dual natured critter to survive the trip *up*... down is easy, you just put them in a container that will not burn up before it hits =P )

or atleast provide it with a drop away heat shield for the reentry part of the trip.

Well then not as high up. Airplane drops would suffice for paracritter or bovine for that matter. Unless you are trying to take out tanks with them I see no problem with dropping them from 20,000 feet (~6100 meters.)

I don't think this calculator is very accurate when dealing with velocities near the speed of light in a vacuum.

Hmmm, an awakened species of cow that is not dual natured and has immunity to heat/fire. I suppose being immune to suffocation would help, too, although a small reentry pod would help with that.

Depends, would it's immunity: reentry power still work if it were dead?
Still, I'd be sad if there wasn't a "........mmmmoooooOOOOOOOOOOOSPLAT!"