Tech Search

According to his family, he was in the early stages of Alzheimer's disease and suffered debilitating injuries in November, when he was struck by a car while walking on a street near his home at night.

Dr. Schnetzler joined the space agency's scientific branch in Greenbelt in 1963, and his work ranged across many fields of the planetary sciences.

After the Apollo lunar missions began to bring moon rocks back to Earth in 1969, Dr. Schnetzler was among the first scientists to examine them. His analysis showed that the rocks had a density and composition unlike any materials found on Earth.

In the early 1970s, Dr. Schnetzler grew interested in studying environmental changes on Earth and recruited a cadre of NASA scientists to study the problem. He helped devise methods to interpret data gathered by NASA's Landsat satellites on variations in vegetation and other environmental factors. As a result, he became one of the first experts in the new science of remote sensing, or collecting information about Earth from space.

"He was one of the scientists who started that kind of monitoring of the Earth," said Jim Garvin, NASA's chief scientist, who worked with Dr. Schnetzler for 22 years. "He was doing the research but also building the teams at NASA to make things happen."

In the late 1970s, Dr. Schnetzler helped design the experiments used aboard Magsat, a NASA satellite that collected information used in mapping the Earth's magnetic fields. His ideas about monitoring environmental changes on Earth helped lead to the development of NASA's Earth Observing System, a network of orbiting laboratories. The system, which now consists of more than a dozen satellites, measures alterations in the Earth's land mass, atmosphere and oceans, giving scientists a more complete picture of environmental change.

Dr. Schnetzler did research on craters and made key discoveries regarding tektites, or glassy rocks with no crystal structure. The rocks were previously thought to have broken off from meteorites or possibly the moon, but Dr. Schnetzler showed that they were formed from rock vaporized by blazing-hot comets or asteroids striking the Earth's surface. The vaporized rock rose into the atmosphere as a gas then fell back to Earth and in a new, glassy state.

In later years, Dr. Schnetzler examined the effects of volcanoes on climate history and helped design experiments used on the space shuttle and satellites flying past Mars. He received NASA's Exceptional Achievement Medal in 1992.

"He was the catalyst," Garvin said. "That was his hallmark. It was the way he built teams that made him so rare."

Charles Carter Schnetzler was born June 3, 1930, in Whiting, Ind., and grew up in Neodesha, Kan. He graduated from the University of Kansas in 1952, spent four years in the Navy and received a doctorate in geochemistry from the Massachusetts Institute of Technology in 1961.

After retiring from Goddard in 1991, Dr. Schnetzler was a research scientist at the University of Maryland for four years, then worked until 2005 for SAIC, a research and technology firm.

He was a member of the Unitarian Universalist Church in Silver Spring and volunteered with Meals on Wheels and the Howard County General Hospital.

His marriage to Sammy Johnson Schnetzler ended in divorce.

Survivors include his wife of 29 years, Beverly Hassler Schnetzler of Columbia; four children from his first marriage, Margaret Jones of Westminster, Md., Robert Schnetzler of Middletown, William Schnetzler of Lusby and Ann Ackerman of Manchester, Md.; three stepsons, Jeff Johnston and David Johnston, both of Elkridge, and Peter Johnston of Ellicott City; a brother; 14 grandchildren; and two great-granddaughters.