PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

Contact: Guy Webster, (818) 354-6278

INTERNET ADVISORY February 9, 2001

       During a live webcast on Tuesday, Feb. 13, an experienced mission planner for interplanetary spacecraft will explain how to choose the best routes for getting to destinations such as Mercury, Mars and Saturn.

       Charley Kohlhase, who has led trip-planning efforts for NASA missions to most of the planets in the solar system, will also describe how spacecraft can use the gravity of one planet to gain a "slingshot" boost toward a more distant destination.

       The 90-minute live webcast, "From Ellipses to Gravity Assist," from NASA's Jet Propulsion Laboratory in Pasadena, Calif., will begin at 4:30 p.m. PST (7:30 p.m. EST) at .

       Tuning in requires free pre-registration with LiveOnTheNet at . Questions for Kohlhase may be submitted to . Additional information about the webcast is available at .

       Kohlhase will begin with the simple notion of an ellipse, easily created by young viewers, then move on to Kepler's laws and curves such as parabolas and hyperbolas to slowly build a framework for understanding how mission designers at JPL work out their special flight paths to planets. The gravity-assist strategy was first used in 1973 to send NASA's Mariner spacecraft to Mercury by way of Venus. Six weeks ago, NASA's Cassini spacecraft flew near Jupiter for a gravity assist necessary for getting Cassini to Saturn.

       Kohlhase designed spacecraft missions at JPL, including Mariner, Viking, Voyager and Cassini missions, from the 1960s through the 1990s, twice receiving NASA's Outstanding Leadership Medal, and he continues to consult for JPL. He is also an active artist, author and environmentalist, and has innovated numerous projects and products to communicate space science to the public.

       JPL is managed for NASA by the California Institute of Technology, Pasadena.

02/09/01 GW