Congressional candidate: Moon-colonizing companies could destroy cities by dropping rocks

[Cripplecreek]

"Brianna Wu" is an avowed mentally ill nutcase, not just your regular nutter

Its elite nutbaggery.

[geronl]

For reference, a 1000 kg rock traveling at the speed of Apollo 13 (~40,000 kph) has the energy of about 1.5 tons of TNT.  You'd need a mass of 5000 kg to reach 1 kT.

If you dropped Brianna Wu from orbit, he/she/it would likely be able to take out a Wal-Mart

[geronl]

Its elite nutbaggery.

not only is he/she/it an elitist nutbag, but a snobbish, holier-than-thou one.

[Smokin Joe]

For reference, a 1000 kg rock traveling at the speed of Apollo 13 (~40,000 kph) has the energy of about 1.5 tons of TNT.  You'd need a mass of 5000 kg to reach 1 kT.

So 20MT would be 2000 times that, or roughly 1.333 million kilos. Mare Basalts run about 3300 kg/m³, so it would take about 404 m³ to get a 20MT whack, not allowing for ablation.

Very roughly a 10 meter sphere should do the trick.

Highland rock (feldspathic) has a lower density, around 2650 Kg/m³, so it would take a larger sphere, and the impact breccia samples at about 2400 kg/m³ would have to be even larger, but I think would be more likely to fragment during atmospheric entry.

IF (and that's a big if) that 10 meter ball of basalt hit the surface without breaking up, that would be roughly a 7 mile radius with 5 psi of overpressure (roughly the 'kill' radius of the impact, with widespread serious injury and death). Expect total devastation in roughly a three mile diameter area (not adjusting for terrain) with rare survivors only in protected locations, most concrete buildings would collapse in the 20 psi overpressure, if the effects are equivalent to a groundburst nuke.

It would take some whoppers to be planet wreckers, but 30-50 ft. chunks could do some serious damage to populated areas.

Lunar rock density source: http://www.psrd.hawaii.edu/CosmoSparks/July12/PSRD-Lunar-rock-densities.pdf

[Smokin Joe]

not only is he/she/it an elitist nutbag, but a snobbish, holier-than-thou one.

(Everyone should send her a pebble) 

[Elderberry]

For reference, a 1000 kg rock traveling at the speed of Apollo 13 (~40,000 kph) has the energy of about 1.5 tons of TNT.  You'd need a mass of 5000 kg to reach 1 kT.

the 5000kg rock @ 40,000kph would have 7.5tons, not 1 kT

[r9etb]

the 5000kg rock @ 40,000kph would have 7.5tons, not 1 kT

You're quite right.  In my little spreadsheet I forgot to convert from kph to m/sec.

[Suppressed]

Titanium dioxide (Rutile) melts around 1800 degrees C.

Most of the lunar titanium is in ilmenite, which melts at only 1050 degrees C.

[Just_Victor]

You're quite right.  In my little spreadsheet I forgot to convert from kph to m/sec.

I think the Lockheed Mars lander team has an opening for you  :)

[Elderberry]

I think the Lockheed Mars lander team has an opening for you  :)

I used to love the Lunar Lander program. Do you think they'd take me?
And I landed the Shuttle Motion Base Simulator once. And it was survivable.

[Just_Victor]

I used to love the Lunar Lander program. Do you think they'd take me?
And I landed the Shuttle Motion Base Simulator once. And it was survivable.

Survivable.  Maybe with Musk's team....

[Elderberry]

Survivable.  Maybe with Musk's team....

I swear! I didn't even pop a tire. The cross winds were murder.

[Smokin Joe]

the 5000kg rock @ 40,000kph would have 7.5tons, not 1 kT

Well, heck. I think we're going to need a bigger rock!

[Smokin Joe]

Most of the lunar titanium is in ilmenite, which melts at only 1050 degrees C.

Oh. Well, that means more ablation, too...

[EC]

Well, heck. I think we're going to need a bigger rock!

Nah - free MIRV. 

If you do the orbit right, so the rock is coming as near straight down as makes no difference, you aren't going to need worry too much about ablation. 100 miles isn't much resistance to something that moves through the entire depth of air in 15 seconds.

[Smokin Joe]

Nah - free MIRV. 

If you do the orbit right, so the rock is coming as near straight down as makes no difference, you aren't going to need worry too much about ablation. 100 miles isn't much resistance to something that moves through the entire depth of air in 15 seconds.

Use the basalt, it's more dense, and less likely to fragment. 

[bigheadfred]

I swear! I didn't even pop a tire. The cross winds were murder.

It's a long walk home.

[Oceander]

The Moon is a Harsh Mistress.


Actually, she isn't that nuts. This is something that has been explored by the US Military in many different ways. Kinetic Bombardment. If you are already up there, it is far more of an efficient way of attack that shooting rockets from continent to continent.

The nuts part comes from the slander that private companies, rather than governments, would do this.  The only people with an incentive to do something like this would be a socialist/fascist government; in other words, a government run by hard left democrats like social justice warriors. 

[Cripplecreek]

The nuts part comes from the slander that private companies, rather than governments, would do this.  The only people with an incentive to do something like this would be a socialist/fascist government; in other words, a government run by hard left democrats like social justice warriors.

The kind that would say "We'll take their oil"

[Elderberry]

A Simple Targeting Procedure For Lunar Trans-Earth
Injection
Shane Robinson and David Geller†
Utah State University, Logan, Utah, 84322-4130, United States

http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1120&context=spacegrant

[Joe Wooten]

The meteor that crashed into Russia  was estimated to be about 55 feet in diameter, weighing 100,000 tons, at a speed of 46,000 mph, and had an energy of 500 kilotons, about 25 times the energy of “Fat Man” that exploded over Nagasaki.

http://www.dailymail.co.uk/news/article-2280920/Meteor-crashed-Russia-largest-space-rock-hit-earth-century-claim-scientists.html

What would the size and speed of Brianna Wu’s rock be to have the energy of 100’s of nuclear bombs?

I know he (Wu) did not, but has anyone else considered the effort needed to build a mass driver that can fling rocks big enough to do mass damage. It would take years of concentrated effort and HUGE amounts of money to get the supporting infrastructure built on the moon to be able to do that. BY the time something like this could become a problem, I'm sure an easy solution will be available.

[Just_Victor]

I know he (Wu) did not, but has anyone else considered the effort needed to build a mass driver that can fling rocks big enough to do mass damage. It would take years of concentrated effort and HUGE amounts of money to get the supporting infrastructure built on the moon to be able to do that. BY the time something like this could become a problem, I'm sure an easy solution will be available.

But stuff is lighter on the moon, so you can just pick up a boulder at chuck it at earth.  Right?

[Joe Wooten]

But stuff is lighter on the moon, so you can just pick up a boulder at chuck it at earth.  Right?

Right........

[Smokin Joe]

But stuff is lighter on the moon, so you can just pick up a boulder at chuck it at earth.  Right?

Slow and steady wins the race. low constant acceleration, or just give it the right nudge (and trajectory) and let gravity do the rest. The movement of the earth isn't exactly a secret.

[thackney]

But stuff is lighter on the moon, so you can just pick up a boulder at chuck it at earth.  Right?

I was thinking Catapults.

(Actual I first thought Trebuchets, because Trebuchets are cool, but low gravity works against those)