Physics professor Ralph Gellert has made the  “Top 45 Over 45″  list, produced annually by Zoomer Magazine to celebrate Canadians who are making a difference. It’s the cover story for the magazine’s October issue.

Gellert is recognized for his work on the Alpha Particle X-Ray Spectrometer, (APXS), which is  mounted on the arm of Curiosity, NASA’s minivan-sized rover that touched down on Mars in August. Gellert also helped engineer the APXS systems used on twin rovers launched in 2003.

He is currently working at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. Once back in Guelph, Gellert and a team will run day-to-day APXS operations and analysis from a specially equipped room in the MacNaughton Building.

Others on the Top 45 list include Lt.-Gov. David Onley, Alberta Premier Alison Redford, NDP leader Thomas Mulcair, Equestrian show jumper Ian Millar, Actor Christopher Plummer, and Olympian Lesley Thomson-Willie.