A new generation of electro-optical imaging satellites to be built by Lockheed Martin pending congressional approval will have an aperture size of 2.4 meters, a senior U.S. intelligence official said.

James R. Clapper, undersecretary of defense for intelligence, disclosed the aperture size — or diameter of the satellite’s primary imaging mirror — of the Next-Generation Optical satellite system Oct. 19 during a keynote address here at the Geoint 2009 Symposium. Technical details and capabilities of the nation’s spy satellites typically are closely guarded secrets.

Aperture size and altitude are the two factors that determine a satellite’s imaging resolution, which is the size of ground objects or features that can be distinguished in the imagery. The GeoEye-1 commercial imaging satellite, for example, has a 1.1-meter aperture and can distinguish ground objects as small as half a meter across from an orbital altitude of 681 kilometers. According to an industry source, a satellite with a 2.4-meter aperture orbiting at 600 kilometers could distinguish ground objects about 15 centimeters across.

Lockheed Martin Space Systems of Sunnyvale, Calif., is doing preacquisition work on the Next-Generation Optical System, and the National Reconnaissance Office (NRO), which buys and operates the nation’s spy satellites, expects to award the company the full-scale development contract in late 2011. The two-satellite system will be an evolutionary upgrade of the satellites Lockheed Martin has been building for decades.

However, Congress has yet to approve the Next-Generation Optical system, and Sens. Dianne Feinstein (D-Calif.) and Christopher Bond (R-Mo.), chairwoman and vice chairman, respectively, of the Senate Select Committee on Intelligence, want the NRO to pursue an alternative system they say is less costly and less risky.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...