Arthur C. Clarke dies at 90

Arthur C. Clarke has died, reports the New York Times. A science fiction writer and futurist, he's remembered for three things of particular interest to readers of this blog:

Communications Satellites. In 1945, before the first orbital rocket flight, Clarke foresaw the possibility of communications satellites. He realized that an object orbiting the equator at about 22,240 miles up would exactly match the Earth's rotational speed, making it hang motionless in the sky relative to the Earth.

Clarke also explained that such an object could relay signals beamed from a point on the ground back down to a wide swath of the planet. That's how most communications satellites - and satellite TV - work today, which is why DirecTV customers need a clear view of the southern sky to aim their dishes. Speaking of DirecTV, they should do an in memoriam documentary.

Not all satellites are in geosynchronous orbits, by the way. GPS satellites and the satellites that power Iridium satellite phones are in lower, and not necessarily equatorial, orbits. That means that transmitters and receivers on the ground - GPS devices and satellite phones - don't need to be as powerful, but also that locking on to a signal may be more complex.

“2001: A Space Odyssey.” Clarke was the author of this 1968 science fiction novel, which became a celebrated, if somewhat confusing, movie by Stanley Kubrick.

Clarke’s Three Laws. He was also the creator of three aphorisms about technology, of which the most notable was “Any sufficiently advanced technology is indistinguishable from magic.”