SAN DIEGO — The cost savings potential of replacing the U.S. Air Force’s current fleet of satellites with all-electric versions apparently has piqued the service’s interest, at least enough to invite industry in to discuss the idea.
According to Jay Penn, an engineer with the Aerospace Corp., David Madden, executive director of the Air Force Space and Missile Systems Center, has invited industry experts to come to the El Segundo, California, facility Aug. 21. The invitation was prompted, Penn said, by an Aerospace report saying replacing the Air Force’s navigation, communications and missile-warning satellites with all-electric versions would cut the life-cycle costs of the combined fleet by 15 percent.
Penn presented a summary of the report, “Re-Imagining SMC’s Fleet with High-Power Solar Arrays and Solar Electric Propulsion,” Aug. 6 here at the American Institute of Aeronautics and Astronautics’ Space 2014 conference. The Aerospace Corp. of El Segundo is an Air Force engineering think tank specializing in military space.
The term “all-electric” typically refers to satellites that use electric rather than conventional chemical propellant to reach their operational orbit, which for geostationary satellites is 36,000 kilometers above the equator. Although the orbit-raising process for all-electric satellites typically takes substantially longer — months as opposed to days or weeks — the satellites themselves are much lighter than chemical-propellant satellites of similar capability.
“You can get down to either a much smaller launch vehicle or do two-plus satellites on a given, existing launch vehicle,” Penn said.
Besides having lower mass, all-electric satellites with high-power solar arrays can change orbital planes after launch and still have plenty of fuel left over for their primary missions, Penn said. “That way an adversary wouldn’t know exactly what you were launching by what orbit you’re going to,” he said.
All-electric satellites burst on the commercial scene in early 2012 when Boeing Space and Intelligence Systems of El Segundo landed a contract to build two such craft each for two different operators — Asia Broadcast Satellite of Bermuda and Mexico’s Satmex, which now is owned by Paris-based Eutelsat. Since then other manufacturers have unveiled similar offerings, and the product is beginning to catch on more broadly with satellite operators.
This has not gone unnoticed by the U.S. national security community. Earlier this year, Boeing officials disclosed that the company had sold three all-electric satellites to an undisclosed U.S. government customer.
The Air Force is examining sweeping changes to its current satellite constellation architecture with an eye toward saving money and reducing vulnerability. If adopted, these changes would begin to take place over the next five or so years.
Penn conceded that switching to all-electric propulsion for some or all of its mainstream missions would require the Air Force to invest in things like dual-launch adapters and advanced solar arrays capable of supporting a given satellite’s propulsion and payload requirements. But by ordering these satellites in bulk, the Air Force could still save 15 percent across its fleets even after accounting for these nonrecurring engineering costs, he said.
Penn said the Air Force could leverage NASA investments in advanced solar arrays for its proposed Asteroid Redirect Mission, which aims to divert an asteroid into an orbit near the Moon using a robotic spacecraft featuring solar-electric propulsion. ATK Space Components and Deployable Solar Systems, both of Goleta, California, are working on that technology, he said.
The spacecraft could be launched two at a time on Falcon 9 rockets built by Space Exploration Technologies Corp. and currently undergoing certification to carry military payloads, Penn said. The satellites being built by Boeing for ABS and Satmex are slated for dual launches on Falcon 9 rockets.
