U.S Air Force Enlists SETI Telescope Array To Track Space Junk


GOLDEN, Colo. — U.S. Air Force Space Command’s Space Surveillance Network — a global web of radar and optical sensors that detect and track satellites and orbital debris — has enlisted some unlikely help: the Search for Extraterrestrial Intelligence (SETI) Institute’s Allen Telescope Array.

The 42-dish Allen Telescope Array, built by the SETI Institute and the University of California with major funding from Microsoft co-founder Paul Allen, is part of the Hat Creek Radio Observatory. Located nearly 500 kilometers northeast of San Francisco, Hat Creek is surrounded by volcanic mountains that keep out interference such as television and radio signals and cellular phone transmissions.

Under a deal announced in April, management of Hat Creek is shifting from the University of California, Berkeley, to SRI International, a nonprofit research organization based in Menlo Park, Calif.

SRI said in an April 13 press release announcing its new role that it also has been awarded a contract by the U.S. Air Force to use the Allen Telescope Array to conduct space situational awareness and detect space debris.

The Allen Telescope Array’s primary mission, like that of SETI, is to listen for any signals that could be from an intelligent civilization among the stars. The 6-meter dishes that comprise the Allen Telescope Array can operate in multiple frequency bands while its digital hardware runs scientific experiments, such as creating images of the sky.

According to Air Force Space Command’s Space Innovation and Development Center, the Allen Telescope Array can augment the extensive sensors of the Space Surveillance Network. Initial demonstrations showed the Allen Telescope Array’s ability to track transmitting satellites in low Earth orbit, medium Earth orbit and even geosynchronous orbit — the highly trafficked orbital belt 36,000 kilometers above the equator that is home to most of the world’s most expensive and vital satellites.

A SETI official said the Allen Telescope Array’s new Air Force duties will not interfere with the array’s primary mission.

“Because we have planetary systems across the sky, we can effectively share the ATA [Allen Telescope Array] with the Space Situational Awareness mission,” said Jill Tarter, director of the Center for SETI Research at the SETI Institute in Mountain View, Calif.

SETI researchers are targeting their searches on extrasolar planets discovered by NASA’s Kepler Space Telescope.

“We are using our SonATA — SETI on the ATA — automated signal detection system to observe the thousands of Kepler worlds and exoplanets that have been discovered in the past few years,” Tarter said. “Life as we know it is a planetary phenomenon, so we are interested in exploring planets.”

Tarter said the equipment can be pointed at known planetary systems and explore the terrestrial microwave window from 1 to 10 gigahertz in search of radio emissions from distant technological civilizations.

SRI, meanwhile, is on the lookout for new ways to use the Allen Telescope Array.

Scott Seaton, SRI vice president of engineering research and development, said in a statement that SRI is “look[ing] forward to expanding the use of the Allen Telescope Array to support the wider scientific and technical community in radio astronomy and space science.”

SRI has managed scientific facilities for decades, including National Science Foundation radio telescope facilities. In the early 1960s, for example, SRI designed and built a 45-meter radio reflector antenna for the U.S. Defense Department near Palo Alto, Calif., that has been used for satellite calibration, spacecraft command and telemetry, and radio astronomy measurements. In 2011, SRI was awarded a five-year cooperative agreement by the National Science Foundation to operate and maintain Puerto Rico’s Arecibo Observatory, the world’s largest and most sensitive single-dish radio telescope.