Europe eyes commercial demo of electric propulsion
BY STEPHEN CLARK
Posted: November 26, 2012
The European Space Agency will pursue a public-private partnership to develop and demonstrate all-electric propulsion on a commercial communications satellite, answering a call from operators seeking lower launch costs and longer satellite lifetimes.
The member states agreed on a framework for a public-private partnership between ESA and industry on the Electra program, an initiative to develop a telecommunications satellite bus with fully electric propulsion.
"Electric propulsion will be a big step forward for the satellite business, by advancing miniaturization and reducing business risk," ESA member states said in a communique issued after the decision.
SES of Luxembourg, one of the world's largest commercial satellite operators, is internally discussing a proposal for a low-mass communications satellite relying entirely on electric propulsion, according to a company official.
ESA would contribute public financing through the Advanced Research in Telecommunications Systems program, which provides financial and technical support toward research, experimentation, and communications satellites incorporating innovative technologies. ESA member states approved a new section of the ARTES program last week, allowing for industry-proposed programs like Electra.
The public-private partnership would funnel ESA funding into the program to reduce the financial risk taken by SES and OHB AG, the probable contractor for the Electra program.
"This is a very broad and fundamental innovation for geostationary satellites," said Mario Fuchs, CEO of OHB AG of Bremen, Germany. "What is new now is it is being implemented in the commercial world."
Ion propulsion has powered interplanetary probes, Earth observation satellites, and it has been employed for stationkeeping maneuvers on geostationary communications satellites.
Commercial communications satellites today carry several tons of liquid propellant to propel themselves into geostationary orbit over the equator, where a satellite's speed matches the rate of Earth's rotation, making the craft appear to hover over a fixed location.
After launching from Earth on a large rocket, communications satellites are usually released in temporary oval-shaped, elliptical parking orbits because most launchers are not powerful enough to deploy a sizable craft in its operating position 22,300 miles up.
Next-generation satellites with all-electric propulsion will not carry liquid propellant or conventional rocket jets, but they will use ion thrusters fueled by xenon gas to reach operating posts in geostationary orbit.
Satellite builders can remove fuel tanks and plumbing from all-electric platforms, making more room for communications payloads or allowing the spacecraft to fly on smaller, less expensive rockets.
Boeing's satellite division announced in March the first contract for an all-electric version of its Boeing 702 satellite platform. Each of the Boeing satellites will weigh about 4,000 pounds, or less than 2 metric tons.
The first two confirmed all-electric Boeing 702 satellites - Satmex 7 and ABS-3A - will launch together from Cape Canaveral, Fla., on a single SpaceX Falcon 9 rocket in late 2014 or early 2015.
Two other unidentified satellites for Satmex and Asia Broadcast Satellite could launch together in 2015 on another Falcon booster.
One drawback of an all-electric satellite is the time required for orbit-raising with ion thrusters, which are more efficient but generate much less thrust than conventional chemical propulsion engines.
Instead of arriving at an operating post several weeks after launch, all-electric communications satellites will take up to six months to reach geostationary orbit.
Fuchs said OHB expects to be the prime contractor for the Electra satellite program, with SES as its first commercial operator. According to Fuchs, the all-electric satellite would be based on a new small geostationary satellite bus named Small GEO under development by OHB in a separate public-private partnership with ESA.
The first Small GEO satellite, built in partnership with Spanish operator Hispasat, will launch with conventional propulsion in late 2014 on an Ariane 5 rocket.