The newest satellites pass over your home

Warner Brothers’ Satellite in the sky.

Warner Brothers’ Satellite in the sky.

Last week this page explored the various kinds of airplanes that fly over our region, and the Victor airways that they follow. We looked at towns that sit directly below such airways and thus see regular overhead air traffic (Woodstock) and places that don’t (Kingston). Now let’s look higher – much higher – to the satellites.

They’re mostly hidden this month, because they fly in darkness. Starting in April, however, the region 300 miles overhead stands in sunlight for the first 90 minutes after sunset, so the satellites stand out brilliantly against the starry background, and you see one every minute or two through September.

The highest-up are always hidden. Those are the geostationary orbiters used by folks with satellite TV dishes. They’re located 22,236 miles high, always right above the Equator (which is why your dish aims to the south or southwest). That location alone gives them a speed of 6,878 miles per hour yielding an orbital period of 23 hours, 56 minutes to match our planet’s spin. Hence it hovers above the same place. The Geostational Operational Environmental Satellites (GOES) that track weather are parked in geostationary orbits, too. At that height they’re all much too distant to be seen, even if they weren’t virtually stationary against the background stars.

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Stepping down to half that height, or 11,000 miles, brings us to the Global Positioning System or GPS satellites. That constellation of two dozen, weighing 1 ½ tons apiece, each slowly crosses the sky twice a day, so that there are always at least four above your horizon. Since becoming fully operational in 1994, they broadcast nonstop time signals, using solar panels to generate more than 700 watts of electricity. The receiver in your car knows the right time, recognizes how “wrong” or late is the time signal from each satellite that it’s receiving, then, knowing the speed of light, calculates where you must be located to be that precise distance from each one. This triangulation is continually updated to deliver your speed and direction. It may be the coolest thing that the US military has ever done.

Coming down much closer, we get to various communications, navigation and science satellites, like the Polar Operational Environmental Satellites (POES): weather- and aurora-watching craft that orbit 14 times a day. Also found here are the privately funded Iridium orbiters that let people use satellite phones to make calls from anywhere, no matter how remote. These, plus the spy satellites that we’ll get to in a moment, are the only ones that are large enough and low enough to stand out to the naked eye. Many flash brilliantly as their solar panels momentarily catch the sun.

Now we get to the spy satellites, in non-circular obits that range from 200 to 600 miles up. The Onyx series, known by the code name Lacrosse, employ radar imaging. But the most famous reconnaissance satellites – of which there are always four flying at any given time – are the KH-11. First launched 37 years ago, the latest version blasted into orbit in 2011. Variously named Kenan (or Kennen) and Crystal, they’re usually referenced by the codename Key Hole.

The KH-11 are launched and used by the National Reconnaisance Office (NRO), and replaced the old film surveillance with high-resolution digital, to provide real-time optical observations. A later-model KH-11 (designated KH-12 in most reports) identified and kept an eye on Osama Bin Laden’s lair prior to the raid.

These are large telescopes with mirrors between eight and 9 ½ feet across. The early versions matched the Hubble Space Telescope’s optics, while the newer ones slightly exceed it – except, of course, they’re aimed downward. Their orbital height of about 280 miles would theoretically produce a six-inch resolution if our planet were airless. In practice they have a reported resolution of 11 inches. They can see people and cars, but not identify gender or license plate numbers. Actual KH-11 photos are available online.

The current survey of operational satellites shows 1,016 in orbit, of which 443 are American. Another 2,000 continue to orbit even though they no longer work. Quite a jump from that first Sputnik in 1957 that us old-timers still remember!

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