I’m split as to Gregor’s thoughts on Planetary Resources. On one hand I agree it is rather foolish to parade this as a project that will meaningfully affect resource limitations on Earth, at least for the next 2 or 3 decades or longer. Even for utilizing purely robotic mining & processing of near Earth asteroids, the time it takes to get both the spacecraft to the objects and the extracted materials back to Earth or Earth orbit would be very long (not to mention irregular schedules… these asteroids may be close in a relative distance sense, but their orbits may only allow limited time windows for sending materials elsewhere). This long time delay between investment and return and the irregular deliveries would make for a very challenging, and probably discouraging, business model when shorter-term and less uncertain opportunities exist. And even considering the most potentially profitable and valuable resource, Helium-3 for energy, depends on our research on nuclear fusion making immense strides first in order to be a useful resource.
But on the other hand, while I don’t see this as our resource savior, I do think the project has potential merit if pursued primarily with the intent of creating a space economy for space-based activities and industries. Space-based resources are very likely to be cost prohibitive when compared to even shrinking available resources on Earth, but if they are meant to be used in projects and industries in orbit and beyond they will likely be very competitive compared to hauling materials from Earth. This is stated as one of their primary goals on their site ("Harnessing valuable minerals from a practically infinite source will provide stability on Earth, increase humanity’s prosperity, and help establish and maintain human presence in space"). So I wonder why are they selling this also as a means of alleviating resource issues on Earth in anything but the very, very long term? They HAVE to know the limitations and logistical challenges better than I do (I have had only 5 years experience and much of it only partially applicable to space exploration), and despite the perhaps overwhelming optimism on some of their members’ part, at least on the surface they are doing this largely with their own money which I expect would induce some caution even the most optimistic individual. I have two guesses… the first is as Gregor hints at, that perhaps they do realize that the resource scarcity issue needs a very long term vision and investment, and that maybe they don’t expect to make money or benefit directly from this but perhaps their children and grandchildren will. The second guess is that they primarily care about space exploration and creating a space-based economy and infrastructure out of both personal and financial interest, but realize they need more than that to sell other people on signing on to it. Making allusions to helping solve resource problems on Earth is one of many tempting hooks, and while making such a pitch is potentially shady or dishonest it very well may work in getting them to their goals. I suspect that they know that such a grand project would eventually provide great benefits for mankind, just not in the way they’re suggesting or as immediately as they make it out to be. Kind of like the initial discovery of the New World didn’t yield the kind of result or profit that Columbus and his backers in Spain expected, this project probably won’t benefit us in they way these guys say it will.
I’m just guessing here but those are the only things that make sense to me. I sincerely hope that they are not really betting everything on getting a good ROI for bringing minerals back to Earth, because if they really do I suspect the odds will be high of their project imploding in an epic way.
You seem totally oblivious to loss of heat by infrared radiation. Heat added on earth is lost to space by radiation. You are making yourself look really ignorant. http://en.m.wikipedia.org/wiki/Thermal_radiation
You might want to check your sources. The earth absorbs energy from the sun and reflects some of that energy in the form of long form radiation (infrared) back into space. The numbers are not in balance. The imbalance is what explains climate change and why we aren’t ‘iceball earth.’ http://icp.giss.nasa.gov/education/radforce/page2.html
Doug
As I discuss in Part II, the venture capitalists behind Planetary Resources seem not to have considered that if mining for minerals on asteroids were actually profitable, both in energy and financial terms, then it’s not likely more than a handful of people or institutions could afford such prices, back on earth. Imagine oil at $5000 a barrel, and the Alberta Tar Sands operating exclusively to produce a small amount of oil purchased only by governments, annually. It doesn’t work.
There’s an optimal level of price and consumption for any resource or product. Outside of that band, in either direction, you run into limits. As always, the technology people tend to run into business model problems when they depart the world of Bits and try to get stuff done in the world of Atoms.
Back in the 1970s Princeton physics professor Gerard K. O’Neill proposed his "high frontier" concept for mining Lunar materials and catapulting them to L5 for processing. Models were built and the L5 Society lobbied on behalf of the proposal. Of course this was also the decade when a group of scientists led by MIT professor Dennis Meadows conducted their Limits to Growth research using system dynamics modelling techniques developed by MIT professor Jay W. Forrester. So, let’s see where we are today 40 years later…no mining of the Lunar surface seems to have occurred unless you count the few boxes of Lunar materials returned to Earth by the Apollo astronauts, but the LTG model runs seem to have held up pretty well over that time. Three years ago professor Meadows publicly remarked that the course of events had actually overtaken the model runs to the extent that policy makers only have 20 years left in which to prepare a large human population for a controlled collapse of industrial civilization. He warned that the time leading up to the collapse of industrial civilization would be dangerous and events could spin completely out of control. The problems of material and population growth in a finite world is that they will not be widely recognized until it is too late. It could be that we are pre-disposed to run head first into the wall of ecological and geological scarity at full speed before we are willing to organize our lives on a different basis. Anyway, Enlightenment thinking and economic liberalism fueled by a bonanza of fossil energy has run out of gas…literally, and all we really have to look forward to is the struggle over the last stocks of life-sustaining resources on the planet followed by a massive die-off.
[quote=rhare]Tom Murphy’s stuff is great in that regard and some of his other works pokes pretty large holes in ideas many people accept as probable. I think his "Why not space?" article is great at debunking any of the space based solutions to problems.[/quote]Tom Murphy’s articles do nothing of the sort.
In Stranded Resources Murphy paints the following picture: an asteroid 1 kilometer in diameter, 5 kilometer/second delta V needed and oxygen/methane propellant – this mix has about 3.3 km/x exhaust velocity.
In an actual asteroid retrieval proposal the suggested asteroid size is about 7 meters. Not only because this is doable but also for safety considerations. Delta V for parking many asteroids in high lunar orbit is in the neighborhood of .2 km/sec, much smaller than the 5 km/s Murphy suggests. Exhaust velocity in the KISS Proposal is around 30 kilometers/second.
The propellant mass in these two scenarios vary by nine orders of magnitude.
Anyone who cites Murphy’s "Do The Math" to debunk asteroid mining obviously hasn’t bothered to Do The Math.
For a more detailed critique of Murphy’s "Why Not Space?" and "Stranded Resources" see Murphy’s Mangled Math.
[quote=HopDavid]In an actual asteroid retrieval proposal the suggested asteroid size is about 7 meters. Not only because this is doable but also for safety considerations. Delta V for parking many asteroids in high lunar orbit is in the neighborhood of .2 km/sec, much smaller than the 5 km/s Murphy suggests. Exhaust velocity in the KISS Proposal is around 30 kilometers/second.
[/quote]
Okay time to do a little math…
The proposal estimates costs (I’m sure they are low) to be $2.6B to bring a 7m asteroid to earth. So lets assume you can find a 7m asteroid made of solid gold, then maybe it would be worth it, since the asteroid at $1600/oz would be worth around $178B. However, since asteroids are either rock, or iron you get a whole lot less. For a solid iron asteroid your return is $212K worth of iron at today’s prices.
I don’t believe anything I have read from Murphy says you can’t figure out how to technically get an asteroid, build space based energy, etc. The problem is the costs are enormous, risks very high, and just not worth it on a material basis compared to traditional sources here on earth. My guess is your can mine a landfill far far cheaper than you can haul stuff back from space.
The point Murphy makes in the articles I have read is that space is expensive, risky, extremely inhospitable to humans, and other than for scientific interest/research is not worth doing. It it’s far easier and more economical to concentrate on more terrestrial based solutions. His math shows what Gregor is pointing out in this article, that proponents of space based solutions provide false hope where much more mundane solutions are attainable.
I would also argue that even if we currently had the technology to implement space mining today, the time frame for any meaningful change is too far out to make any difference. We will have to deal with our current crop of issues using only resources found her on earth.
Okay time to do a little math…
The proposal estimates costs (I’m sure they are low) to be $2.6B to bring a 7m asteroid to earth. So lets assume you can find a 7m asteroid made of solid gold,[/quote]
Gold? Please. Do some research.
The first asteroids Planetary Resources hopes for aren’t gold, nor platinum nor diamonds. But water rich asteroids.
In his essays Murphy correctly points out the importance of delta V. Propellant high on the slopes of earth’s gravity well would break the exponent in Tsiolkovsky’s Rocket Equation. And that is exactly what Planetary Resources is hoping to do. This could make space travel much cheaper, a prerequisite for mining asteroidal platinum.
Murphy does look at the idea of refueling in space. There are potential propellant sources nearby in terms of delta V: Near Earth Asteroids or the lunar cold traps. Does he look at these? No, he suggests Jupiter or Titan. Were you to suggest Jupiter as a potential propellant source, the Planetary Resources engineers would correctly dismiss you as utterly clueless.
This isn’t math, rather extremely vague handwaving. I want to look at Murphy’s numbers.
His numbers are drastically inflated. Examples:
For example 5 kilometers per second needed delta V to retrieve an asteroid. There are many asteroids much closer in terms of delta V.
Murphy’s Methane/lox propellant gives has an exhaust velocity of 3.3 km/s. The ion engine Planetary resources is 30 km/s.
There are many bad numbers in Murphy’s arguments. Some of them are from out and out bad math. For example his failure to patch conics correctly.
And he uses false numbers to make this point. Parroting the point Murphy claims to make does not defend his math.