Initial Silence Prompts Tense Moments for Successful Pleiades 1A Launch

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KOUROU, French Guiana — The successful launch Dec. 17 of the French Pleiades 1A high-resolution civil/military optical Earth observation satellite was accompanied by several minutes of tense silence as mission control at Europe’s Guiana Space Center here awaited word from Moscow that Pleiades had been released into orbit.

In one of many examples of what it means to import Russia’s Soyuz rocket for use at Europe’s spaceport, it is Moscow, and not the launch control facility here, that received telemetry confirmation from the vehicle’s Fregat upper stage that the satellite was separated as planned into a 700-kilometer polar low Earth orbit.

“We were a little on edge for a few minutes there when there was no word about successful separation of Pleiades despite the fact that mission chronology clearly showed separation should have occurred,” one French military official attending the launch said.

The Jupiter Control Center here, which manages Ariane 5 launches and now Soyuz — and early in 2012 will add the Vega small-satellite launcher to its portfolio — eventually did announce that Pleiades had been released, producing visible signs of relief in the control room’s audience. Confirmation that the satellite was healthy in orbit soon followed.

The delay in announcing the successful conclusion of the Pleiades launch stood in contrast to the normal procedure at Jupiter Mission Control, where a rocket’s trajectory and related milestones — separation of boosters, rocket stages and the payload fairing, and then the separation of the satellites — is announced as they occur by the director of operations and broadcast to all those witnessing the launch from the control center.

Satellite owners and others attending the launches follow the sequence with written minute-by-minute mission scenarios, and can compare the rocket’s actual trajectory with the planned mission through the help of a large video screen that superimposes the vehicle’s path over the intended one.

The Fregat upper stage, built by Lavochkin Association of Moscow, continued its mission with a total of four separate ignition sequences, placing France’s four Elisa electronic-intelligence demonstration satellites into orbit some four minutes after Pleiades. Nearly two and one-half hours later, Fregat placed Chile’s SSOT medium-resolution Earth observation satellite into its correct orbit, about 100 kilometers lower than the Pleiades and Elisa operating orbits.

Jean-Yves Le Gall, chairman of the Arianespace launch consortium that operates the Ariane 5 and Soyuz and will perform the same function for Vega, confirmed after the launch that Fregat’s mission status is sent to Moscow, where mission controllers then call their Jupiter Mission Control to inform them.

“In this case, we had information from Pleiades itself that it had received the order to separate,” Le Gall said. “But actual confirmation of separation comes from our Russian partners.”

The Dec. 17 launch was the second mission for the Europeanized version of Soyuz and came less than two months after the inaugural launch, which placed two European Galileo positioning, navigation and timing satellites into medium Earth orbit. Le Gall said that few had believed Arianespace would be able to conduct a second Soyuz launch in 2011, so soon after the first.

In addition to demonstrating that the Guiana Space Center is at ease with Soyuz operations, conducting the second flight in 2011 will help Evry, France-based Arianespace’s financial accounts for 2011, a year in which late-arriving satellites limited it to five launches of the heavy-lift Ariane 5, instead of the planned six.

Le Gall said the next launch of the Europeanized Soyuz is likely to be of the two remaining Galileo in-orbit-validation satellites. It is scheduled for the first half of 2012, he said.

Arianespace is also a shareholder in the French-Russian Starsem company, which conducts Soyuz commercial launches from Russia’s Baikonur Cosmodrome in Kazakhstan. Arianespace and Starsem launched six Globalstar mobile-communications satellites from there Dec. 28.

 

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