You might think that “space situational awareness” is what a football player needs when he goes up for a pass in a crowd of 300-pound helmeted assassins. But to the Department of Defense, it has a more precise and chilling meaning: namely the need to identify and track the untold hundreds of thousands of objects inhabiting the not-so-empty space around our planet – space junk, missile tests, dead rocket parts, foreign satellites of unknown intent and uncharted asteroids coming in for the kill.

The Air Force operates a globe-girdling network of telescopes, radars and even two satellites to keep track of all this stuff.

Last Tuesday, the latest addition to this sky patrol was unveiled at the White Sands Missile Range in New Mexico: the Space Surveillance Telescope, a 90-ton telescope with engines that deliver 38,000 foot-pounds of torque. Swiveling swiftly and almost silently like a ballerina, it can follow objects as small as a softball as they fly through the sky.