“This is a letter from Arthur C. Clarke, the famous sci-fi author. And besides suggesting communications satellites, he notes that you could put three satellites up in the air and use them to plot your position anywhere on earth using something the size of a watch. ¶ It’s from 1956, a year before Sputnik went up. And it turns out that Clarke had proposed a version of this in 1945. ¶ Now the model is somewhat different than the APL version as we’ll see later — in APL they were using doppler shift with Low Earth Orbit (LEO) satellites. Clarke’s idea involves geostationary satellites in a high earth orbit. ¶ So I’m not saying that Clarke had the full idea here. ¶ Still, nowhere in the history can I find any indication that the people working on this had heard of Clarke’s idea — an idea he had had since WWII. ¶ And ultimately, even if they had, this is just one idea among thousands that never saw the light of day. This is the one where we have a record. Who knows how many other ideas about satellite aided GPS were never captured anywhere?” • #стайность - urbansheep@gmail.com