Following the success of the Dawn Spacecraft in exploring the asteroids, I suppose that it was inevitable that ion propulsion would hit the commercial satellite industry:

It’s no secret that Boeing’s space systems unit is aggressively pricing bids in an effort to grow its commercial business segment as government spending flags. But even the most bullish observers were taken aback by an estimated $400 million deal just signed with Asia Broadcast Satellite (ABS) and Satellites Mexicanos (SatMex) to build the first all-electric commercial telecom spacecraft intended for launch to geostationary orbit.

The technology—which uses light-weight xenon-fueled ion thrusters rather than conventional chemical propulsion to maneuver a spacecraft into position—is promising. Imagine cutting in half a satellite’s weight, and subsequently its launch costs, which can top $100 million depending on the size of the spacecraft. All-electric satellites could potentially save fleet operators hundreds of millions of dollars in annual launch expenditures, with potentially no impact to their satellites’ capability or performance.

The downside is that while most commercial communications spacecraft are expected to be on station and making money within a few weeks of launch, new all-electric satellites could spend up to six months using slow pulses from ionic propulsion systems to maneuver into their final orbital slot—months when the spacecraft is not generating any revenue. This might not pose a problem for large operators with established revenue streams who can accommodate the lag in revenue as they incorporate new satellites into fleet-replenishment programs. But it could put small companies at a disadvantage as they sacrifice up to half a year’s income waiting for the spacecraft to enter service.

In either case, employing an all-electric spacecraft requires getting an early start on the capital-spending cycle to accommodate the lengthy orbit-raising process.

“It is easier for a company with a large fleet that has to anticipate replacement satellites several years in advance to tolerate the several months it takes for an electric satellite to reach position once it has separated in orbit,” says Romain Bausch, chief executive of Luxembourg-based SES, the world’s second-largest fleet operator by revenue.

Basically, chemical maneuvering thrusters have something like a hundred times more thrust, but have about 100x lower ISP (fuel efficiency).

The downside to ion propulsion close to earth is time, but the lines cross for anything farther the earth-moon system.