One billionaire's mission to bring a 500-ton asteroid to Earth by 2025
arstechnica.com
arstechnica.com
But on the other hand, the smelted ore is much more valuable if used for earth-orbit construction, especially high orbit construction. SpaceX charges about 2,000,000 USD per ton to launch a payload into low earth orbit. The cost to put 500 tons of ore into space from earth would thus be 1 billion USD. By comparision, the mass of the International Space Station is about 500 tons.
This rough analysis shows that the most cost-effective mission would be the construction of large space facilities using material smelted from a well-chosen asteroid.
Maybe the investors have in mind something like the Stanford Torus: http://en.wikipedia.org/wiki/Stanford_torus
On the other hand, you're right: it's worth more money in space.
Anyways, I think its good that we're starting with something 500 tons. Big enough to be interesting, not big enough to cause a huge catastrophe if it ends up colliding with Earth. When we're better at it we can go for larger asteroids.
A lunar base would be very expensive in terms of initial construction because it costs so much to climb from the Earth's surface through the Earth's gravity well, and then to descend safely on to the Moon's surface.
An interesting solution that I've followed has been the proposal to send tiny self-replicating robots to the Moon and have them construct everything else from Lunar materials. See for example: http://www.islandone.org/MMSG/aasm/
This good idea was most recently promoted by Newt Gingrich during his US presidential primary campaign. My own opinion is that private investment, not government money, should be used for space-based economic projects.
See: http://upload.wikimedia.org/wikipedia/commons/8/82/Orbitalal...
http://upload.wikimedia.org/wikipedia/commons/c/c9/Deltavs.s...
As you can see, getting from earth to LEO requires 9.3-10 km/s of dv, depending on the type of rocket you are using. All of this must be high-thrust propulsion, otherwise you'll immediately fall back to earth. 9.3-10 km/s of high-thrust propulsion is indeed quite costly to implement.
On the other hand, to go from the lunar surface to LEO is only 5.5 km/s of dv -- and only 1.6 km/s of this (the trip from the lunar surface to lunar orbit) needs to be under high thrust. The rest of the dv can be done with relatively inexpensive low-thrust techniques which require little or even no propellants -- such as ion propulsion, solar sails, and aerocapture.
So to a rough order of magnitude, it's 2-6 times cheaper to get to LEO from the moon than from the earth.
Edit: miscalculated the lunar surface->LEO dv requirement.
A chart http://upload.wikimedia.org/wikipedia/commons/c/c9/Deltavs.s...
Yes, I realize 500 tons is far too small to do that.
I expect some sort of space treaty to regulate the safe operation of such a venture, and in return provide some liability limits on the required insurance. Otherwise the investors have a tiny chance of being wiped out financially if some city gets hit.
I agree with you. I expect that should a city get hit, then international outcry would lead to the confiscation of all of the investor's assets, despite being shielded by a limited liability corporation.
For that reason the investors need insurance - and a very large amount of it considering the damage that a direct hit on a major city might cause. The investors would seek some sort of limit on the liability - say 100 billion dollars, and in return they should eagerly submit to regulatory oversight of their plans, procedures and operations.
In order to insure such an asteroid moving scheme and establish a premium, insurance companies must determine a risk probability distribution, and they must know what the maximum liability would possibly be. Over many decades, there may be observations of close calls or actual damage causing situations that can inform the actuarial calculation, but at the initial point its simply educated estimates.
So the investors chose that asteroid diameter so as to minimize potential damage due to an impact on Earth.
... shouldn't they be?!
This is true for everything moving in space: vehicles, rocks - all potential weapons .. just from (ahem) potential.
We need to be real careful that we don't regulate this activity right out of existence.
Carl Sagan spoke out against research into destroying "rogue" comets or asteroids that might hit Earth. He believed that the potential for military misuse of the technology far outweighed any real collision threat.
According to this calculator, a 500ton roughly spherical rock, assuming a density of 3g/m^3 so a surface area of 3600m^2 would live for 20 years at 500km altitude.
http://www.lizard-tail.com/isana/lab/orbital_decay/
At altitudes higher than 1000km, the thing could live for centuries, although no matter how high, orbits still get perturbed eventually and decay (in the Earth-Moon system).
(Note that at 380km altitude, the ISS is never more than 1-2 years away from burning up in the atmosphere, so it needs periodic boosts to prevent it)
Nuclear fuel resources are essentially inexhaustible -- there is enough Thorium to feed constant growth for at least tens of thousands of years. Which should be enough for development of fusion.
Source?
"Perhaps more significantly, low-energy pathways lead away from L1 and L2, which can be exploited to send spacecraft to Jupiter, Mars, asteroids, for less fuel. They make an excellent staging point," Belbruno said. "Placing spacecraft at these points gives one a high ground, so to speak." Not only would they be interesting places to position a space station, but from there China could perform planetary exploration, both in piloted and automated mode.
from: http://www.space.com/13375-china-moon-probe-deep-space-missi... And also see: http://en.wikipedia.org/wiki/Lagrange_point
(Kinda curious what y'all find objectionable about this idea.)
My remark was a reflection about, but not agreement with, the notion that the resource motivated wars of exploitation a couple of centuries ago are possibly about to begin anew in Space.
It should be entirely possible to craft international treaties to preclude extraterrestrial resource conflict while maximizing the commercial opportunities that will benefit us - either as owners or as customers.
What you meant: "It's deeply unfortunate that we're at the point of venturing to other planets but we still haven't managed to get past all our petty divisions on this one."
How it reads: "I prefer to think of humanity as a unified whole and view national boundaries as pernicious fictions, and it bothers me when other people talk about these fictional boundaries in the context of something as important as space exploration. Please phrase it differently from now on."
The latter reading comes across as kind of pedantic and bossy, not to mention unrealistic.