http://www.helium.com/knowledge/19115-factors-to-consider-in-mans-desire-to-explore-outer-space.xml Helium.com > Astronomy > Factors to consider in man's desire to explore outer space en-us Copyright Helium.com Mon, 05 May 2008 19:39:55 GMT Mon, 05 May 2008 19:39:55 GMT