Wednesday, September 29, 2010

Spy Sat - spies on satellites.

By Michael Mecham

SAN FRANCISCO — Into clear, balmy skies, an Orbital Sciences Minotaur IV lifted the U.S. Air Force’s Space-Based Space Surveillance satellite into a 335-mi. high orbit inclined 98-deg. from Vandenberg AFB, Calif., on Sept. 25.

Built by Boeing and Ball, SBSS weighs close to 2,200 lb. and features a gimbaled telescope on a beryllium mount that provides a high degree of agility for its 2.4 megapixel focal plane shutter to slew across the sky to image spacecraft and space debris without obstruction or vibration.

Although other space assets have occasionally been employed to observe satellites or debris, SBSS represents the first Air Force asset dedicated to that purpose. Being in space, SBSS is not constrained by weather, daylight or being blanked out by line-of-sight issues.

The launch was an important check-off for Orbital Science’s Minotaur IV. SBSS required its full four-stage configuration.

The first three solid-propellant stages are derived from Peacekeeper-class intercontinental ballistic missiles while the fourth is a commercial Orion-38 from Alliant.

The launcher’s first use came in April from Vandenberg when it boosted a Hypersonic Test Vehicle for the Defense Advanced Research Projects Agency, but that was a suborbital mission.

The SBSS launch has suffered repeated delays due to launcher issues, the latest in July. It required a reload and test of software for the guidance system.

But when it came, the Sept. 25 liftoff was reported nominal. Separation from the upper stage came at 9:55 p.m. PDT, 14 min. 50 sec. after the 9:41 p.m. liftoff. A Boeing executive later reported that the “satellite is healthy.”

The satellite now enters a checkout period expected to last 210 days before handover to Air Force Space Command’s 1st Space Operations Squadron.

Much of the interest in the launch has focused on its ability to track space debris that poses a threat to government and commercial spacecraft. But SBSS also will play a major role in assessing the capabilities of secret satellites and tracking the movements of other nations’ reconnaissance spacecraft.

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