I am an amateur follower of astronomy, and an enthusiast for space colonization. Recently, I have also become a self-published science fiction author. Thinking about the barriers to successful travel to the asteroids, I have come up with an idea. I don�t know if this is original, or practical, but I would love to find out. I wonder if anyone more expert can help me. Please tweet your reactions or any useful links. Illustration of ideas described below

I make the following assumptions:

  1. A major barrier to travel to the asteroids is the long time needed for a relatively economical orbit. Typical transfer orbits to asteroids take between one and four years, during which solar and cosmic radiation exposure would exceed safe limits, and a huge mass of consumables would be needed for life support.
  2. Numerous small asteroids pass relatively close to the Earth and to Mars every year, say within 4 million km, and with relative speeds in the 5km/s range. Further, most small asteroids contain at least some ice, and their aphelia are often well out into the asteroid belt.
  3. Given a nuclear reactor, it should be practical to make a device that converts ice into rocket propellant, and that ice would also allow replenishment of at least some life support supplies.

If these assumptions are broadly correct, it seems to me that these small asteroids could be used as an intermediate step to get to the asteroid belt safely. A nuclear-powered ship launched at the right time could transfer to one of these small rocks as it passed by, taking a few weeks and a delta-V of about 8 km/s. It need only carry propellant for that one leg, because once at the rock they could refuel, using the ice they find there. By burying itself in the surface of the rock, it could ride out solar storms, using the bulk of the asteroid for radiation protection. Once the natural orbit of the rock carries it out into the belt, it would pass relatively close to several bigger asteroids, and the colonists could transfer to one of these, again using about 8km/s of delta-V.

Using my limited maths and programming skills, I have made a simulation of the movements of many asteroids, which I use to frame the events in my stories. I wonder if anyone can tell me if I am completely off on this? It�s quite possible I have made an error, or some of my starting assumptions are wrong. I assert that it makes a fine background for science fiction, but what if it were true, and practical? Can anyone shed any light? Tweet to the above address, or email me.