The lift-off went perfectly, however. There were no delays in the countdown, no warning lights and no worries. Arianespace, the European consortium that makes and launches the Ariane spacecraft, has lost only one rocket in the past eight years.
At 6.37pm local time, right on cue, the tiny rocket climbed above the tree line of the Guianese jungle, the brightness of its flame startling against the evening sky.
A minute or so after launch the boosters were jettisoned. A couple of minutes later plumes of smoke showed that separation of the first stage of the rocket had taken place.
In the press centre downstairs, monitors showed what was going on in the control room. Now that the rocket was on its way, the atmosphere became calm. 'Everything looks nominal. The telemetry tells us that the satellite is right on its calculated track,' the English commentary trilled.
On the screen, a diagram showed the planned path into orbit with a dotted line representing the rocket's inexorable progress. The second stage had fired successfully and the third ignited correctly. The rocket was doing what it was supposed to.
The first hint that something was wrong came from Geoff Baines, editor of What Satellite magazine. 'That's too low. That doesn't look right,' he said. On the screen, a circle indicated that the rocket had dropped below its expected line. As we watched, the line of dots curved farther downwards. Perhaps it was just the track of the discarded second stage. The commentator was saying that everything was 'nominal', but then stopped. 'We seem to have a deviation from the nominal trajectory,' he said.
There was little commentary after that. Two minutes later, Charles Bigot, chairman of Arianespace, stood up in the control room. On the screen, speaking in French, he seemed so calm that at first the non-French speakers in the audience could not be sure anything was wrong. But it soon became clear that he was saying the third stage had cut out and the rocket and its two satellites had been lost.
When Louis Gallois, chairman of Aerospatiale, the manufacturer of the launcher and both satellites, stood to speak, he was obviously in shock. 'Space is a high-technology venture, which can't go on without this sort of accident,' he said.
As we waited for news, there was an air of sadness throughout the building. Many journalists had openly hoped for a failure - disasters are easier stories to sell - but the reality of the loss was felt by everyone.
Almost 25 years after men first walked on the Moon, sending rockets into space and building satellites to operate there are still at the far reaches of our engineering ability. A successful project requires a commitment bordering on love from some of those involved. When a launch fails it is not surprising that the sense of grief can be very real.