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Space Forum / Space Flight / April 2006retrieving material from asteroids
Most studies of O'Neill type colonies assume that we would get the millions of tons of material from the moon via a catapult. However, there are some Near Earth Asteroids where the return dV to the earth-moon space is astonishingly small. For Nereus, 1982 DB, it is about 60 m/s, or 135 mph. This opens the possibility of bringing back enormous payloads on the order of 100,000 tons at a time relatively cheaply. For example, a small mass driver with a specific impulse of 200 (approx. 2000 m/sec) would need to expend only 3000 tons of material to move it to the earth-moon space. However, I don't know enough orbital mechanics to know if we would need short impulses for part of the return as I believe it uses lunar gravity assist. So does anyone know if the low-g acceleration of a small mass driver would be sufficient, or do we also need higher gee thrust for part of the mission? -- Larry Gales Depending on the details of the trajectory, a modest mass driver would be overkill. The trick is to use weak stability boundary trajectories developed by Dr Ed Belbruno. We are currently exploring the architecture of a system like this at SSI. > Date: Wed, 15 Mar 2006 19:41:59 -0000 > From: lsvalentine@verizon.net [quoted text clipped - 5 lines] > developed by Dr Ed Belbruno. We are currently exploring the > architecture of a system like this at SSI. ============================= I would like to hear more about that -- Larry Lawrence Gales <larryg@u.washington.edu> wrote: >I would like to hear more about that Here's an article on its application for the Genesis mission. http://www.sciencenews.org/articles/20050416/bob9.asp > Most studies of O'Neill type colonies assume that we would get the > millions [quoted text clipped - 3 lines] > This opens the possibility of bringing back enormous payloads > on the order of 100,000 tons at a time relatively cheaply. > For example, a small mass driver with a specific impulse of 200 (approx. > 2000 m/sec) would need to expend only 3000 tons of material to move it > to the earth-moon space. LG raises an interesting topic here... :) I have considered this idea before, though not to a sufficient level of detail as to be able to quantify the precise dynamical parameters. In this article, I was proposing to capture asteroid # 887 Alinda into a HEO via lunar gravity-assist:- http://www.astroscience.org/abdul-ahad/earth-ring.htm Now my thinking is that, in practice, it may be more sensible to shatter the asteroid first in it's own heliocentric orbit into smaller fragments, and then to transport the resulting fragments individually to make the task more easily manageable. Of course that then means one has to re-assemble the fragments into the intended 'shell' to build the space station/orbital colony. AA What is this fixation with going to a big asteroid and then go to the trouble to take a chunk off? Why not just go to a chunk sized asteroid in the first place? You want 1,000 tons? Do you A: Go to a 1 billion ton asteroid, land, and dig out 1000 tons to return to Earth Orbit. B: Go to a 1,000 ton asteroid, which is far more common than the larger variety. > What is this fixation with going to a big asteroid and then go to the > trouble to take a chunk off? [quoted text clipped - 6 lines] > B: Go to a 1,000 ton asteroid, which is far more common than the larger > variety. It all depends on the end goals of what one is seeking to achieve and the availability of asteroids in near Earth space with a favourable mass/orbit geometry mix for capturing such bodies economically. To build a small orbital habitat, you could capture an 'Earth approacher' or an 'Earth grazer' NEO like #4179 Toutatis. To build something more substantial, like the 'Celestial Titanic' or ultimately an interstellar ark of the size and architecture defined in my sci-fi novel, you'd need something much larger. That's where you would look to a body from the asteroid main belt, like #887 Alinda, as shown in my article. AA http://www.publishedauthors.net/aa_spaceagent/ abdul.a...@ntlworld.com wrote: > > What is this fixation with going to a big asteroid and then go to the > > trouble to take a chunk off? [quoted text clipped - 13 lines] > To build a small orbital habitat, you could capture an 'Earth > approacher' or an 'Earth grazer' NEO like #4179 Toutatis. By Toutatis!!! Do you know how big it is? According to Wikipedia (http://en.wikipedia.org/wiki/4179_Toutatis) it's 50 billion tons. That's enough for 50 O'Neill cylinders (less wastage) or 4,000 Stamford Torii. Here's a proposal to get 1m asteroids http://alglobus.net/NASAwork/papers/AsterAnts/paper.html These will require much less delta V to capture than Toutatis. > Depending on the details of the trajectory, a modest mass driver would > be overkill. The trick is to use weak stability boundary trajectories > developed by Dr Ed Belbruno. We are currently exploring the > architecture of a system like this at SSI. I'm focusing on stockpiling, the flow of materials (and processed/finished goods), and the capacity of a multiple of cargo crafts. It's not so much the distance involved as it is the constant flow and profitability. We wouldn't have imports from China if distance really mattered - it just doesn't. And where the heck is the competition and the shorter route to the East in all this? If it makes money, who cares? I would start with a two month window per near asteroid, start building spinning skinny long cigars (containing agri/food production capability as well), then move up from there (spinning wheels, etc). Let's not overly, and unnecessarily, complicate the thing. http://www.cygo.com/ |
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