JPL'S STONE STEPPING DOWN.

Byline: Usha Sutliff Staff Writer

LA CANADA FLINTRIDGE - Ed Stone will retire as director of the Jet Propulsion Laboratory today, handing over the position he's held for the past decade to Charles Elachi, a 30-year veteran of the lab.

Stone, who was out of town Monday, announced his intention to retire last May, following a tradition established by previous JPL directors who retired around their 65th birthdays. Stone turned 65 on Jan. 23.

California Institute of Technology President David Baltimore said in May that Stone has done a ``terrific job'' leading the lab and doesn't have a reason other than the age tradition to step down. Caltech manages JPL for the National Aeronautics and Space Administration.

``People might think that this somehow might be connected to the Mars failures, but it has no connection at all,'' Baltimore said, alluding to the failed Mars Climate Orbiter and Mars Polar Lander missions.

Stone plans to return to teaching and doing research at Caltech, where he is the David R. Morrisroe professor of physics.

He became JPL director and Caltech vice president - jobs that go hand in hand - in January 1991 and led the laboratory through a decade that saw triumphs, including the Mars Pathfinder mission, and high-profile failures.

A National Medal of Science winner, Stone has been a principal investigator on nine NASA spacecraft missions and a co-investigator on five other NASA missions. During the 1970s, he was in charge of 11 teams of scientists during the twin Voyager missions.

Elachi, Stone's replacement, has held a number of research and management positions at JPL, most recently as director of the lab's Space and Earth Science Programs Directorate.

An Altadena resident, Elachi is considered a leading expert in remote sensing, a technology that uses satellite instruments to learn about planets' topography.

He grew up in Lebanon and said that when he was an 11-year-old he read a newspaper article about the JPL-managed Explorer 1 satellite mission. It inspired him to pursue a career in space exploration.

``I vividly remember reading in the newspaper about the launch of a small spacecraft by a place called JPL somewhere in California,'' he said during a Jan. 31 news conference. ``That spacecraft was Explorer 1. That spacecraft basically launched the United States into the space age, and that occurred 42 years ago today ... Maybe that's a good omen for me.''

Elachi holds degrees from the University of Grenoble, France, the Polytechnic Institute in Grenoble, and Caltech.

The author of more than 200 publications on space and planetary exploration, he has taught ``the physics of remote sensing'' at Caltech since 1982.