ROME — The investigation into why one of the two solar panels on Intelsat’s IS-19 telecommunications satellite failed to deploy following launch May 31 is focusing on what happened under the Sea Launch rocket’s fairing during liftoff and whether vibration there may have been the cause, industry officials said June 7.

While no formal conclusions have yet been reached, satellite fleet operator SES of Luxembourg on June 6 approved the restart of the campaign to launch its SES-5 telecommunications satellite June 20. SES-5, like IS-19, uses a platform built by Space Systems/Loral (SS/L) of Palo Alto, Calif.; the satellites feature similar solar array deployment mechanisms.

SES spokesman Yves Feltes said June 7 that the company had already performed special verifications of the solar array deployment system before SES-5 left the SS/L factory and was shipped for launch.

SES, which is known as one of the industry’s most conservative fleet operators, performed those checks because an SS/L satellite in mid-2011 also failed to deploy one of its solar arrays. An investigation concluded that the failure was caused by a problem on the deployment mechanism.

Feltes said additional tests of SES-5’s solar array system were performed at the Baikonur Cosmodrome spaceport in Kazakhstan after the problem with IS-19 manifested itself.

“We are satisfied after having performed these additional checks that our satellite is ready to go,” Feltes said. “We are authorizing it to be fueled in preparation for a launch June 20 Baikonur time.”

The satellite will be launched by an International Launch Services Proton M rocket.

Feltes stressed that SES had no information on what happened with IS-19 and was basing its decision to proceed with the launch solely on the tests it and Loral performed on SES-5.

Also awaiting launch is the EchoStar 17 Ka-band consumer broadband telecommunications satellite owned by Hughes Network Systems of Germantown, Md., which is a subsidiary of EchoStar of Englewood, Colo.

EchoStar 17, formerly named Jupiter, is an SS/L-built satellite that is scheduled for launch along with Europe’s MSG-3 geostationary-orbiting meteorological satellite aboard a European Ariane 5 rocket.

That launch had been set for early to mid-June but the campaign was suspended to give SS/L time to verify a subsystem that had nothing to do with the solar array release system, according to industry officials.

That issue had been settled and a new launch date of June 29 was about to be announced when the IS-19 event occurred. An industry official said June 7 that given what is now known, or at least suspected, about the IS-19 situation, and following additional checks on EchoStar 17 at the launch base in French Guiana, the launch would be rescheduled for the first week of July.

Dianne J. VanBeber, Intelsat vice president for investor relations and communications, said June 7 that it is too early to pinpoint what happened to IS-19. But VanBeber said in an interview that “the team is now looking very carefully at the data that came from Sea Launch. But we are at a very, very early stage.”

Telemetry data indicating the environment inside the rocket’s fairing from the vehicle’s climb through the atmosphere to the point at which it releases the satellite into orbit can take a couple of days to gather.

VanBeber said IS-19 is now making its way from the drop-off transfer orbit to its final geostationary-orbit operating position. Early indications are that the satellite would be able to provide at least 50 percent of its planned capacity. VanBeber said it remained unclear whether there would be a significant reduction in IS-19’s operating life. A satellite with one solar array still in folded position can be more difficult, and less fuel-efficient, to fly than one whose panels have deployed normally, and this can cut into service life.

Sea Launch AG of Bern, Switzerland, launched IS-19 from its floating platform in the Pacific Ocean on the equator using a Zenit 3SL rocket.

Sea Launch President Kjell Karlsen said early analysis of the telemetry from the IS-19 launch showed no out-of-bounds pressure or other problem. In a June 7 interview, Karlsen said Sea Launch’s fairing carries perhaps the most sophisticated set of sensors of any in the commercial launch industry. If there was any problem during the launch, he said, it will show up in the telemetry data that Sea Launch is now evaluating. It will take several days to cull the data, Karlsen said.

SS/L informed its customers, Hughes Network Systems/EchoStar and SES, that they could proceed with their launch campaigns based on SS/L testing before the IS-19 launch and based on the modifications it has made to its solar array deployment system in recent years.

SS/L President John Celli said he had no evidence that would clearly point to the Sea Launch fairing as the culprit. But he said teams monitoring the IS-19 launch noticed that, after the fairing separated and the satellite was flying in open space — attached to the Sea Launch upper stage — there was loss of electrical current coming from the solar array that ultimately failed to deploy.

The array was still in folded position against the satellite’s body. When the upper stage carrying the satellite flew into sunlight, the array’s exposed outer panel should have delivered a current to a sensor located in the satellite’s body. This current was noticeably less than expected.

In 2004, an SS/L-built satellite named Estrela do Sol-1/Telstar 14 failed to deploy one of its solar arrays after a Sea Launch liftoff. An investigation into the cause was inconclusive. But Celli said U.S. Air Force images of the satellite in orbit showed massive damage to the affected array, confirming that an explosion — which was picked up by Sea Launch sensors — had occurred.

Sea Launch and SS/L never agreed about what happened in that launch. In the June 7 interview, however, Celli said: “I do not believe in coincidences in this industry. We had a problem in 2004, and we have a problem now. My understanding is that Sea Launch’s telemetry ultimately will tell us what happened.”

Peter B. de Selding was the Paris bureau chief for SpaceNews.