PARIS — Commercial satellite operators awaiting launches this year on Russian Proton rockets saw their plans literally go down in flames July 2 with the spectacular failure of a Proton-M vehicle carrying three Russian Glonass navigation satellites.

The failure, which occurred 17 seconds after liftoff from the Baikonur Cosmodrome in Kazakhstan, was the fourth Proton anomaly in two years. The workhorse rocket, which was flying a government mission, is built by the Khrunichev State Research and Space Production Center of Moscow.

Among the operators almost certain to be affected by the latest mishap are SES of Luxembourg, whose Astra 2E satellite was next on the vehicle’s manifest, and Inmarsat, which booked Proton launches for its next-generation Ka-band mobile broadband system. It is unclear what alternatives the companies have at this point for getting their satellites into orbit.  

Given that Proton is launched 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 seconds after liftoff and in full view of those attending the launch. Videos of the Proton launch 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 in a massive explosion 2.5 kilometers from the launch pad.

International Launch Services (ILS), the company that sells Proton launchers on the global commercial market, said there appeared to have been no injuries at Baikonur following the mishap and that damage to spaceport infrastructure appears minimal.

ILS has conducted four commercial missions so far this year and had scheduled two more by September as it regained the market’s confidence following a December 2012 anomaly of Proton’s Breeze-M upper stage. A large Russian telecommunications satellite was placed into a bad orbit but ultimately climbed into the correct position.

In a July 2 statement, ILS said it will create its own failure-review oversight board to examine the findings of the Russian government-mandated commission that will investigate the cause of the latest failure.

Reston, Va.-based ILS also sought to distance the Proton Phase 3 vehicle it uses for commercial launches from the older-version rocket that failed July 2. ILS has long told customers that these differences go beyond the fact that government Proton missions typically use the Block DM upper stage built by RSC Energia of Kaliningrad, Russia, whereas commercial versions use the Khrunichev built Breeze-M.

“The Glonass mission was launched using the Phase 1 Proton-M vehicle configuration that first flew in 2004,” ILS, which is owned by Khrunichev, said in its statement. “This Phase 1 Proton was powered by the RD-276 engines on [the] first stage, which [were] introduced with the Phase 2 upgrades and were used on a small number of Phase 1 Protons. The hardware for this mission was previously stored, then used for this mission.

“For commercial missions, the standard Phase 3 vehicle configuration is utilized for every mission.”

In its mission planners’ guide, which is posted on the company’s website, ILS nonetheless says that the basic Proton first-stage engine, which may or may not ultimately be identified as the cause of the July 2 failure, is the same for all Protons.

“Other than the changes to the propellant flow control valves, pressure feedback sensor and gas generator, the engines on the first stage of the Proton M [launch vehicle] are unchanged in their design and manufacture since 1965,” the mission planners’ guide says.

When the failure occurred, SES’s Astra 2E telecommunications satellite was already at Baikonur awaiting a launch later in July. 

Besides Proton, SES’s options for launching 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 Chief Executive Romain Bausch has frequently cited rocket reliability as his single biggest concern in managing the world’s second-largest satellite fleet, and has worked hard to diversify the company’s stable of available launchers. For example, the SES 8 satellite is scheduled to be the first geostationary-orbiting satellite to fly aboard the Falcon 9 v1.1 rocket developed by Space Exploration Technologies Corp. (SpaceX) of Hawthorne, Calif. 

SES is waiting for a successful inaugural flight of the Falcon 9 v1.1, which includes many changes from the Falcon 9 version that has flown successfully several times. SpaceX has postponed the upcoming mission, carrying a Canadian research satellite, on multiple occasions. When the SES-8 launch will occur remains unknown; the latest estimates are sometime this fall. 

London-based mobile satellite services operator Inmarsat, meanwhile, 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.

The deal gave Inmarsat an attractive per-launch price, and the company expressed confidence Khrunichev had gotten to the bottom of the December anomaly and was ready to launch the Global Xpress satellites starting this fall.

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.