Colonization of the outer Solar System elsewhere in the Solar System, perhaps via the proposed Interplanetary Transport Network, may be feasible in the not-so-distant future. This could make colonization of the Moon, Mercury and main-belt asteroids more practical. Robert Zubrin identified Saturn, Uranus and Neptune as "the Persian Gulf of the Solar System", as the largest sources of deuterium and helium-3 to drive a fusion economy, with Saturn the most important and most valuable of the three, because of its relative proximity, low radiation, and excellent system of moons. Zubrin identified Titan as possessing an abundance of all the elements necessary to support life, making Titan
History of Solar System formation and evolution hypotheses stars and clusters and the star-clouds of the Milky Way", which proposed that the planets formed in the outer Solar System and were captured by the Sun; the moons were formed in thus manner and were captured by the planets. This caused a feud with Forest Moulton, who co-developed the planetesimal hypothesis. A preview was presented in 1909 at a meeting of the ASP (Astronomical Society of the Pacific) at the Chabot Observatory in Oakland, Cal., and newspaper headlines blared "Prof. See's Paper Causes Sensation" (San Francisco Call) and "Scientists in Furore Over Nebulae" (San Francisco Examiner). Our current knowledge