SAN ANTONIO -- Robert T. Herres, a high-ranking Air Force official who served as vice chairman of the Joint Chiefs of Staff under Gen. Colin Powell, has died. He was 75.

Herres died Thursday at his home after a two-year battle with brain cancer.

Herres was also a pioneer in the space program and went on to become chief executive for seven years of San Antonio-based insurance company USAA beginning in 1993.

He was credited with transforming USAA, which caters to military members, by expanding eligibility to include enlisted service members. The company now has about 6 million members.

Herres was a Naval officer who went to the Air Force in a move that allowed him to fly right away. The former astronaut in the Manned Orbiting Laboratory program never went into space but served as first commander of U.S. Space Command from 1985 to '87.

Among his other military roles, Herres headed the Strategic Air Command, the 8th Air Force and the North American Aerospace Defense Command.

Herres also was active in the San Antonio community, serving as chairman of the United Way of Bexar County and helping raise millions of dollars for children's health care.