Delta 4 Launches Space Surveillance Satellites for the U.S. Air Force

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WASHINGTON — The U.S. Air Force launched three satellites July 28 that are expected to provide a significant boost to the service’s space surveillance capabilities, particularly of the geosynchronous-orbit belt high above the equator.

The mission, known as AFSPC-4, short for Air Force Space Command-4, launched aboard a United Launch Alliance Delta 4 rocket from Cape Canaveral Air Force Station in Florida around 7 p.m. The launch followed delays on several previous attempts due to weather and technical issues.

The rocket’s primary mission was to deploy two satellites that will serve as the first-generation of the Geosynchronous Space Situational Awareness Program (GSSAP), a previously classified space surveillance system first disclosed in February by Gen. William Shelton, commander of Air Force Space Command.

Orbital Sciences Corp. of Dulles, Virginia, is the GSSAP program’s general contractor.

According to an Air Force fact sheet, the two-satellite system will operate in a “near-geosynchronous orbit regime” to provide accurate tracking and characterization of man-made orbiting objects. Satellites with missions including communications and missile warning operate in the geosynchronous-orbit belt roughly 36,000 kilometers above the equator.

Shelton has repeatedly stressed the importance of space surveillance as the orbital environment becomes more congested and potential threats grow.

Currently, assets in geosynchronous orbit are tracked as points of light, Shelton told reporters in a July 22 press conference. These objects typically are tracked by ground-based telescopes whose view can be obscured by clouds, the Air Force fact sheet said.

The GSSAP system, from its unobstructed orbital perspective, collects “literal images” of those objects, Shelton said. “Through our points of lights and various other means, we make inferences on what a particular satellite can do,” Shelton said. “Well, to paraphrase, a picture is worth a thousand inferences. We can see literally what that satellite looks like and you can effectively reverse engineer and understand what the capabilities are.”

The fact sheet said the satellites will perform rendezvous and proximity maneuvers to allow close-up looks at nearby spacecraft. Data from the system will help with “satellite collision avoidance,” the fact sheet said.

Years ago, “you could build relatively fragile spacecraft,” Shelton said. “You didn’t have to worry about necessarily defending them, other than potential collisions. That’s not true now. … It’s a perfect reason for why we’re launching GSSAP.”

Shelton has previously said two GSSAP replacement satellites would launch in 2016.

Asked about the Defense Department’s decision to disclose the existence of the previously classified GSSAP system, Shelton said, “There is a desire on our part to be transparent.” He called the satellites’ capability “an inherent right.”

However, when asked, Shelton said the Air Force would not provide the two-line element sets that delineate the orbits of satellites. The Air Force typically makes this information available for nonmilitary satellites.

The rocket also carried the Automated Navigation and Guidance Experiment for Local Space, or ANGELS, satellite. Managed by the Air Force Research Lab at Kirtland Air Force Base in New Mexico, the satellite is intended to test multiple techniques “for providing a clearer picture of the environment around our vital space elements,” according to an Air Force ANGELS fact sheet.

The satellite will begin with experiments to monitor the spent upper stage of its launch vehicle from a distance of about 50 kilometers and then gradually move closer to within a few kilometers. The mission is expected to last one year.

The Orbital-built satellite also includes high-performance accelerometers that will be used to examine ways to reduce the probability of on-orbit collisions, according to the Air Force fact sheet.

ULA said the mission was the first use of the Evolved Expendable Launch Vehicle secondary payload adapter on a Delta 4 rocket. The seldom-used adapter ring, developed at Kirtland, enables a rocket to carry multiple small satellites in addition to its primary payload.