Ernst Stuhlinger, 94, who played a key role in developing America's space program, has died.

Dr. Stuhlinger, who died Sunday, had been in failing health and missed the 50th anniversary of America in space in February. His last public appearance was in December, when he spoke on his 50 years of work in rocket programs, said Ed Buckbee, a former director of the U.S. Space and Rocket Center in Huntsville, Ala.

Dr. Stuhlinger served as chief scientist for Wernher von Braun and was among the group of German scientists who moved with him to Huntsville in 1950 when the Army established the Ordnance Missile Laboratories.

Ralph Petroff, who helped lead efforts to restore the Space and Rocket Center's original Saturn 5 rocket, said Dr. Stuhlinger's brilliance was unmatched. In the 1950s, he conceived what would eventually become the Hubble Space Telescope. He also spent years exploring the possibilities of electric propulsion ion engines for deep space travel. - AP