Five hundred years ago, Copernicus advanced the theory that the Earth was not the center of the Solar System. That theory revolutionized our understanding of the Universe. It was initially met with great opposition because of what it meant about our own significance. Today there is a second Copernican revolution underway that will once again alter our significance. Advances in technologies and techniques are enabling the detection, observation and study of Earth-like planets around other stars. And several deep-space missions are currently exploring potentially-habitable worlds within our Solar System as possible abodes for life beyond the Earth. As one such mission, the two intrepid robotic explorers, Spirit and Opportunity, have been exploring the surface of Mars for evidence of past habitable environments that could have supported life. The rovers have traversed great plains, climbed mountains, descended into deep craters and survived rover-killing dust storms and frigid winters. Both rovers have found clues that Mars was once Earth-like with a potential for life. Soon they will be joined by another larger, more capable rover on the surface. Within the next few years, we may be poised to answering that central question, "Are we alone in the Universe?"
John L. Callas, of NASA's Jet Propulsion Laboratory, Pasadena, Calif., has been project manager of NASA's Mars Exploration Rover project since March 2006. Previously, as science manager and then deputy project manager, he had helped lead the rover project since 2000. Callas grew up near Boston, Mass. He received his Bachelor's degree in Engineering from Tufts University, Medford, Mass., in 1981 and his Masters and Ph.D. in Physics from Brown University, Providence, R.I., in 1983 and 1987, respectively. He joined JPL to work on advanced spacecraft propulsion, which included such futuristic concepts as electric, nuclear and antimatter propulsion. In 1989 he began work supporting the exploration of Mars with the Mars Observer mission and has since worked on seven Mars missions. In addition to his Mars work, Callas is involved in the development of instrumentation for astrophysics and planetary science, and teaches mathematics at Pasadena City College as an adjunct faculty member.
The Second Copernican Revolution: Our Changing View of Our Place in the Universe