The Cosmic Ancestry hypothesis - about which this site has a large amount of information - treats all of evolution, not just the origin of life on Earth, as due to interaction with cosmic microorganisms. www.panspermia.org
Short scientific article by John R. Gribbin. "Spreading of life-bearing spores across the Galaxy (panspermia) may be easier than is usually acknowledged." arxiv.org/abs/astro-ph/9909013