The Near Earth Asteroid 433 Eros is about 6.7 trillion tons. It is the second-largest near-Earth asteroid (NEA) after 1036 Ganymed.
Eros is an S-type asteroid and 17% are of this type.
C-type asteroids are carbonaceous asteroids. They are the most common variety forming around 75% of known asteroids.
Eros has a lot of gold and platinum in it. Perhaps a $100 trillion plus at $1000/ounce. The issue would be how much could be mined in a year and how would it effect market prices. Eros is shaped like a 33 km by 13 km by 13 km banana.
Eros is typical of stony meteorites, then it contains about 3% metal. With the known abundance's of metals in meteorites, even a very cautious estimate suggests 20,000 million tonnes of aluminium along with similar amounts of gold, platinum and other rarer metals.
It takes about 2,000 calories to boil a gram of iron so the equivalent of between 20 to 200 thousand megatons of TNT would be needed to start liberating substantial quantities of iron from the asteroid. But this energy could be obtained from the Sun. One of the main uses for placing a lot of power generation into space using the nuclear cannon is to provide the gigawatts of industrial power needed to process asteroids.
This chart of space velocities corrects some previous information that I had for the nuclear cannon
Near Earth Asteroids
Near Earth Asteroids (NEA) at wikipedia.
As of May 2008, 5,474 NEOs have been discovered: 65 near-Earth comets and 5,409 near-Earth Asteroids. Of those there are 453 Aten asteroids, 2,053 Amor asteroids, and 2,894 Apollo asteroids.
743 NEAs have an absolute magnitude of 17.75 or brighter, which roughly corresponds to at least 1 km in size.
Summary of the Nuclear Cannon Idea
the key points:
* the idea hinges on achieving and the payload/projectile surviving thousands of G's of acceleration
* In George Dyson's book he mentions Johndale Solem designing a 100G asteroid interceptor
* This is only for launching High-G payload, not people
* With salt domes that are 6.5 kilometers, I believe that large diameter, 5 kilometers deep shafts could be made relatively easily.
* A launch tube can also be added be lain on the slope of a mountain like Mt Kenya (20-30 mile slope)
Differences from Solem 100G interceptor - even higher Gs and bigger.
One shot plate does not have to survive one thousand pulses just one and damage is ok so long as payload stays contained.
There is stronger metal now than 40-50 years ago. 250,000-400,000 PSI instead of about 50,000 PSO strength metal.
An intermediate design is maximum G [whatever that level is] unmanned accelerator over the North Pole. Fewer air pulses to get to escape velocity and less fallout because of fewer pulses.
Three other points :
Pascal-A/B "launched a concrete plug at 6 times escape velocity. A proof of concept that an object can be accelerated by a nuclear device to multiples of escape velocity.
The asteroid and meteor FAQ explains how atmospheric resistance is a problem for small objects. If an object (round object like a meteor) is less than 8 tons then it loses all of its momentum and gets mostly destroyed trying to pass through the atmosphere at high speed. On the very large end of the scale, a meteoroid of 1000 tons (9 x 10^5 kg would retain about 70% of its cosmic velocity. A 100,000 ton object passes through the atmosphere like it is not there.
How big can even a mostly metallic projectile be and still take the high-Gs of acceleration without losing the cargo?
Thus the logic of the large objects is that if we can accelerate the big object with a nuke then the atmosphere (a few hundred tons of air in the cylinder of air that is in the way) effects the overall momentum less than for a big object. The nuclear cannon is better than the chemical cannon since it is tougher to scale the chemical cannon to large size and there is more trouble getting the chemical cannon up to escape velocity projectiles. With Nuclear it should be more dialing it back to not destroy the projectile.
If we do it underground, I am pretty sure that a scheme can be devised to trap more if not all fallout and we only have to negotiate the exception to the Threshold Test ban (USSR/Russia is the only other signer to the Threshold test ban). No exception is needed for tests or small scale efforts up to 150 kilotons. 150 kilotons probably enough to launch 500 tons through the atmosphere. The Comprehensive test ban has not been ratified yet by the USA. Suggest ratifying it with an exception for space launches. Leave the partial test ban alone.
There seems to be experimental proof that we can accelerate something to high-Gs with a nuke. If we accelerate bigger with a bigger nuke can we not destroy the projectile ? If we go big (at least 1000 tons, but bigger is better) then we have no atmosphere problem.
Big Acceleration - Yes
Big Object - Yes
Cleaner underground -Yes, and many more tricks possible than with air bursts
Would this be very useful and cheap ? - seems to be yes (big cheap payloads)
Can it be made even cleaner - Many ways - details to be sorted out
Technically should work and be very clean.
Are there missing major technical points ?
Things to be researched
Pusher - projectile details
the underground chamber, shaft and containment
Can it be made good enough so that politicians and public agree to actually do it ? We can only try to make it as good as possible and get support and move it along from technical proof, computer simulated then get Los Alamos, DOE and then others on board.