PARIS — SES Chief Executive Romain Bausch used to draw blank stares when he said, year after year, that launch vehicle reliability remains the single most worrisome aspect of his job managing the world’s second-largest commercial satellite fleet.

The spectacular July 2 failure of a Proton rocket carrying three Russian Glonass navigation satellites, the fourth Proton launch anomaly in two years, only drives home Bausch’s point. And yet despite SES’s attempt to insulate itself from launch risks by diversifying its launch sources, SES finds itself now with launch issues that will be difficult to overcome.

Luxembourg-based SES joins London-based Inmarsat among the commercial customers awaiting Proton launches later this year, a prospect that almost certainly disappeared in the fireball that engulfed Proton shortly after liftoff from the Baikonur Cosmodrome in Kazakhstan. Inmarsat’s entire next-generation high-speed mobile communications product offer is booked on three Proton launches.

Given that it was launch over land and overflies populated areas, the July 2 crash is perhaps the most frightening launch failure since the 1996 inaugural-flight failure of Europe’s Ariane 5 rocket.

In both cases, heavy-lift rockets full of fuel showed highly erratic behavior in the second after liftoff and in full view of those attending the launch. In Proton’s case, videos show the rocket shifting from side to side before going horizontal. It then began to break up under the stress before being engulfed in flames and crashing 2.5 kilometers from the launch pad.

SES had been next on Proton’s manifest, with the Astra 2E telecommunications satellite already at the Baikonur Cosmodrome awaiting a launch later this month. Astra 2E will replace an existing Astra direct-broadcast television satellite in orbit but will also add 12 new transponders that SES plans to use to expand its business.

SES’s alternatives for Astra 2E are unclear. The company’s multilaunch agreement with Europe’s Arianespace launch consortium has come to an end and has not been replaced with another that might allow SES to jump the existing queue for Ariane 5 launches.

SES is also waiting for a successful inaugural flight of Space Exploration Technologies Corp.’s Falcon 9 v1.1 rocket, which includes many changes from the Falcon 9 used to launch to the international space station. Hawthorne, Calif.-based SpaceX has postponed the inaugural mission, carrying a Canadian research satellite, on multiple occasions.

The SES-8 satellite, carrying 21 transponders – all aimed at new business – is to follow the inaugural flight of the upgraded Falcon 9. When that flight will occur remains unknown; the latest estimates are sometime this fall. 

London-based mobile satellite services operator Inmarsat knew it took a risk when it decided to book all three of its next-generation Global Xpress Ka-band mobile communications satellites on three Proton rockets in 2013 and 2014.

But booking three Protons gave Inmarsat an attractive per-launch price, and the company expressed confidence that Proton builder Khrunichev of Moscow had got to the bottom of the December anomaly and was ready to launch the Global Xpress satellites starting this autumn.

Like SES, Inmarsat does not have obvious alternatives to waiting out the Proton failure review. The Ariane 5 manifest is full for the rest of the year and into 2014, although Evry, France-based Arianespace may be able to add an Ariane 5 flight to its manifest in 2014 if the market demands one.                  

Peter B. de Selding was the Paris Bureau Chief for SpaceNews.