Co-author with Stanley Kubrick of Kubrick's film "2001: A Space Odyssey," Clarke was regarded as far more than a science fiction writer. He was credited with the concept of communications satellites in 1945, decades before they became a reality. Geosynchronous orbits, which keep satellites in a fixed position relative to the ground, are called Clarke orbits.
I was REALLY sad when I heard about this. But I suppose he lived a nice long life, didn't he? Clarke accomplished a lot, too. Rest In Peace.