PARIS — Satellite fleet operator SES on July 17 said it had selected Airbus Defence and Space to build a large Ku-/Ka-band broadcast satellite for East Asia that will use electric propulsion both for in-orbit station-keeping and initial orbit-raising.
The satellite, SES-12, will carry a backup chemical propellant system but nonetheless puts Luxembourg-based SES firmly on the still-small list of companies that are using electric propulsion to shave hundreds of kilograms of launch weight from large-capacity satellites. The lightweight electric propulsion systems replace chemical thrusters for the orbit-raising phase between a satellite’s separation from its launch vehicle and its arrival in geostationary position.
SES-12 will be based on Airbus’ Eurostar E3000 satellite platform. It is scheduled for launch in late 2017 on a rocket yet to be selected. Operating at 95 degrees east, SES-12 will both add new capacity to this SES slot and replace the NSS-6 satellite there now. SES-8, also at that orbital slot, will be co-located with SES-12.
Airbus said the new satellite would weigh about 5,300 kilograms at launch. An SES official said the same satellite — carrying 68 high-powered Ku-band transponders and eight Ka-band transponders, with 19 kilowatts of power to the payload and eight antennas — would weigh well over 6,000 kilograms if it used only chemical propellant. Lowering a satellite’s launch mass usually affords savings in launch costs.
Airbus said that depending on which launch vehicle is selected, it will take SES-12 between three and six months to climb from the rocket’s drop-off point to final geostationary position, compared to just a couple of weeks using chemical propellant.
“We have been using electric propulsion for station-keeping for 10 years now and have equipped 10 Eurostar E3000 satellites with this technology, which we are now also offering for initial orbit raising,” Airbus Space Systems Director Francois Auque said in a July 17 statement. “The resulting weight savings will enable us to combine two high-capacity missions equivalent to two conventional satellites into one satellite.”
The satellite will combine a conventional direct-to-home television broadcast mission with a high-throughput mission employing frequency reuse with multiple spot beams in both Ku- and Ka-band.
SES said the wide-beam mission includes 54 transponders — measured in 36-megahertz equivalents, rather than in physical transponders — to replace NSS-6 and allow for growth in the satellite television business in India, Indonesia and other markets in the Asia-Pacific region.
A second mission of the 70 Ku-band spot beams and 11 Ka-band spot beams, with a total throughput capacity of more than 14 gigahertz, will be enterprise broadband, mobility and government services. For these applications, the satellite will employ a digital transparent transponder to permit SES to move bandwidth around to avoid signal jamming and to allocate capacity depending on customer demand.