By Johnny Firecloud

Visionary science fiction writer Arthur C. Clarke, who wrote more than 100 books on space, science and the future, died of respiratory failure Wednesday in Sri Lanka, according to an aide. He was 90.

Clarke was best known for writing "2001: A Space Odyssey," which director Stanley Kubrick adapted into a film classic, but he was far more than a science fiction writer.

He developed the concept of geostationary communications satellites back in 1945, decades before they became a reality. Geosynchronous orbits, which keep satellites in a fixed position relative to the ground, are referred to as Clarke orbits.

Clarke also joined American broadcaster Walter Cronkite as commentator on the U.S. Apollo moonshots in the late 1960s.

Clarke had battled post-polio syndrome since the 1960s and sometimes used a wheelchair. He moved to Sri Lanka in 1956 to pursue his interest in marine diving, which he said was as close as he could get to the weightlessness of space. "I'm perfectly operational underwater," he used to say.