I E mailed the professor in the story about habitable zone terrestrial planets and he replied back. Here is what we talked about (his replies are in blue) he quoted my original e mail and answered by inserting his answers in my e mail's text.
Professor Jones;
I enjoyed your article on exosolar terrestrial planets recently carried by space.com but it got me thinking about a question i have had from time to time. I'll be brief; Are there stable orbital tracks in out solar system which are unoccupied?if so can you provide me with data on this question. for example; are the conditions that prevented a planet from forming in the area of the asteroid belt likely to have abated by now? would some sort of gravitational tide tear a planet apart if it was put there?
There are many tracks in the Solar System that offer orbital stability and that are unoccupied. The asteroids are in a zone where the gravitational buffeting by Jupiter prevented the formation of a planet, and still does so. This buffeting also prevented Mars from becoming as large as the Earth. But any planet somehow put there fully formed would not be torn apart.
I have layman level discussions on this from time to time concerning megascale engineering. creating a planet to match as closely as possible all earth like parameters such as temperature range, atmospheric pressure, magnetic field, gravity and so on. I have determined enough material is probably left in the solar system at various places like the asteroid belt, kuiper belt and oort cloud and the earth crossing near sun objects to equal earth's mass density and therefore gravity. I have worked out ways of controlling the spin.
The total mass today in the asteroids is insufficient to make a planet of any size. The Edgeworth-Kuiper belt and the Oort cloud could beef this up to a planet, but to be habitable all this material would have to be assembled in the habitable zone, which doesn't extend far beyond Mars. The stunted growth of Mars has led to loss of much of its atmosphere, so its surface is not habitable today.
I would appreciate your ideas on this subject. particularly since your article mentioned computer modeling to determine stable orbits around another sun it should be easy to run that model on our own system here. Thanks in advance.
You can assume (to a first approximation) that anywhere closer to the Sun than the middle of the asteroid belt is likely to offer stable orbits, with narrow zones of exception, such as near Mars, the Earth, Venus, and Mercury. The habitable zone extends today from just beyond the orbit of Venus to just beyond the orbit of Mars.