EVENTS For information on JPL tours and the speakers bureau, visit our PUBLIC SERVICES site. The Solar System Ambassador Program sponsors events in communities around the country. Find out how to become a volunteer Solar System Ambassador.		Topic - Mars Global Surveyor Across the Centuries Mars Global Surveyor Across the Centuries presented by Dr. Terry Martin JPL Research Scientist, Earth and Planetary Atmospheres If you wish to view a tape of this show please contact Sherri Rowe-Lopez at (818) 354-6170.   Thursday, April 17 The von Kármán Auditorium at JPL 4800 Oak Grove Drive Pasadena, CA Friday, April 18 The Vosloh Forum at Pasadena City College 1570 East Colorado Blvd. Pasadena, CA Both lectures begin at 7 p.m. Admission is free. Seating is limited. For more information, call (818) 354-0112. The Mars Global Surveyor (MGS) spacecraft has now circled the Red Planet during two successive centuries, 1997 to 2003 and has redefined our knowledge of Mars' surface, atmosphere, interior, and history. MGS has returned more data about the red planet than all other Mars missions combined and has produced the most accurate global topographic map of any planet in the solar system. Some of the spacecraft's key findings include the revelation of gullies and debris-flow features that suggest current sources of liquid water, similar to an aquifer, at or near the surface of the planet. The spacecraft has also significantly improved the understanding of atmospheric dynamics. As the next Mars rover mission is prepared for launch, the accomplishments of the Mars Global Surveyor Spacecraft and its science teams give us perspective on where we are going.