U.S. Laser Telecomm Demo Could Support Operations
WASHINGTON — A new laser communications demonstration satellite that the U.S. Air Force may pursue would pick up one of the primary missions that was abandoned when the service’s Transformational Satellite (T-Sat) program was terminated earlier this year.
An advanced programs group at the Air Force Space and Missile Systems Center has requested information from industry by Oct. 2 for a geostationary communications satellite that would use lasers to transmit data at high speeds to aerial platforms. If the Air Force moves forward with the program, it will be directly enabled by the $2.5 billion the service invested in developing T-Sat, government and industry officials say.
“U.S industry is capable of doing this, and enough government agencies are around that can provide assistance if needed,” said Steve Townes, communications systems and research manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “I think it’s infinitely doable. You need to have some of the testing and demonstrations first to really convince people that it works.”
The T-Sat system was envisioned as the U.S. military’s all-in-one next-generation communications platform. It would have featured radio-frequency communications payloads similar to those on today’s military communications satellites, as well as several new technologies. Laser links were a cornerstone of T-Sat: each of the five geostationary satellites would have been connected via laser beams to share information around the globe without the need for terrestrial relays. The satellites also would have used laser links to relay loads of data to and from aerial platforms such as F-22 fighter jets and Global Hawk unmanned aerial vehicles.
The Lasercom Technical Demonstration (LTD) would use a medium-sized geostationary satellite platform to host a laser payload by itself or along with other government or commercial payloads, according to an Aug. 18 posting on the Federal Business Opportunities Web site. The laser payload would simultaneously support four aerial platforms with data rates of several gigabits per second. The Air Force may seek to begin an acquisition in 2011 with the goal of having the satellite on orbit in 2015 for a one-year demonstration period, the posting said. An operational capability of four additional years is desired.
While the United States has never publicly acknowledged demonstrating laser-optical communications in space — industry officials say the technology has been developed in classified programs — other nations have. In 2006, a European Space Agency satellite called Artemis demonstrated laser links from geostationary orbit to an airplane in flight with a data rate of 50 megabits per second. Japan has demonstrated high-speed laser communications between two low Earth orbiting satellites.
The laser technology that LTD would use has been certified to be low-risk and ready for operational use, said Stuart Linsky, vice president for satellite communications atof Los Angeles. Northrop Grumman was developing the communications payloads on the Lockheed Martin team that was competing against Boeing to build T-Sat. Northrop Grumman’s laser terminals demonstrated data rates of tens of gigabits per second over simulated distances of twice the distance from the ground to geostationary orbit.
“It’s a common misconception that lasercom technology is still experimental,” Linksky said. “What we were able to achieve on T-Sat was a completely integrated lasercom terminal operating at multiple tens of gigabits that was certified by [the Massachusetts Institute of Technology’s] Lincoln Laboratories and the Government Accountability Office to be at [Technological Readiness Level] 6,” meaning it has been demonstrated in a relevant environment.
The need for laser communications in space is being driven by the development of next-generation sensors for unmanned aerial vehicles, said Steve Harford, chief technologist for component technologies at Ball Aerospace and Technologies Corp. of Boulder, Colo. New sensors that will fly in coming years on the Air Force’s fleet of Global Hawk, Predator and Reaper unmanned aerial vehicles will be capable of collecting vast amounts of data that would quickly eat up all of the bandwidth on satellites that use radio frequency, Harford said. The near-infrared wavelengths used for laser-optical communications would enable data rates around 1,000 times faster than most radio frequency bands, he said. Laser communications beams are also much more narrowly focused than radio frequency transmissions and would allow spectrum to be reused by aerial platforms operating just hundreds of meters away from each other, Harford said.
Ball Aerospace was on the Boeing T-Sat team and would have provided the gimbaled laser terminals for the satellites. Ball’s hardware was demonstrated under the same conditions and received the same certifications as the Northrop Grumman hardware.
Air Force Space and Missile Systems Center spokesman Bruce Bender was unable to arrange an interview with LTD program officials by press time.