The son of John Simpson Lewis, a YMCA professional, and Elsie Dinsmore Vandenbergh, a school teacher.
He received his Ph.D in geochemistry and cosmochemistry from University of California, San Diego in 1968, where he studied under Harold Urey.
Prior to joining the University of Arizona, Lewis taught space sciences and cosmochemistry at the Massachusetts Institute of Technology.
Lewis is a frequent commentator on the Chinese network CCTV when China broadcasts its major missions live.
He was a member of the Board of Directors of American Rocket Company and is currently Chief Scientist at Deep Space Industries.