Steven Weldon Squyres (born January 9, 1956) is the James A. Weeks Professor of Physical Sciences at Cornell University in Ithaca, New York. His research area is in planetary sciences, with a focus on large solid bodies in the Solar System such as the terrestrial planets and the moons of the Jovian planets. Squyres was the principal investigator of the Mars Exploration Rover Mission (MER). He is the recipient of the 2004 Carl Sagan Memorial Award and the 2009 Carl Sagan Medal for Excellence in Communication in Planetary Science. Squyres also received the 2010 Mines Medal for his achievements as a researcher and professor. He is the brother of Academy Award-nominated film editor Tim Squyres.