The final countdown is underway for Arianespace's second Ariane 5 flight of 2007, with the dual-payload mission's liftoff scheduled at the start of a 44-minute launch window that opens today at 7:29 p.m. in French Guiana (22h29 GMT, 00:29 a.m. in Paris and 6:29 p.m. in Washington, D.C.).

Today's flight will orbit a total mass of 9,402 kg. – a record performance for a mission to standard geostationary transfer orbit. This includes the weight of the two satellite payloads, their installation hardware, as well as Ariane 5's multiple deployment system that enables the launcher to perform its efficient dual-spacecraft launches.

The mission's upper payload, ASTRA 1L for SES ASTRA, will be deployed first in the flight sequence, separating from Ariane 5 approximately 27 minutes after liftoff. It will be followed by the Intelsat Galaxy 17 spacecraft, which is to be released about three minutes later.

ASTRA 1L weighs 4,505 kg. at launch, and will be located at 19.2° East – ASTRA's prime position for delivering broadcast services to continental Europe. The spacecraft also is to extend ASTRA's coverage from the Canary Islands in the West to the Russian border in the East, and it will further strengthen SES ASTRA's unique in-orbit back-up scheme.

Galaxy 17 is designed for a 15-year operational life, providing television and telecommunications services for customers of the international Intelsat organization. This satellite weighs in at 4,100 kg. for today's liftoff.

The weather concerns have to do with the ground-level and upper-level winds and the possibility of lightning as the Ariane ascends through the clouds.

The count is holding at T-7:00, the point where the "synchronized sequence" begins the automatic final countdown for launch. We are holding at this point to wait and see if the weather will permit a liftoff today or if tghe launch will be delayed 24 hours.

6:45 p.m. EDT at T-7:00 and Holding. The weather isn't going to clear in time to launch during today's window, which expires at 7:14. Ariane launch control has just called a scrub for today's attempt. The next launch attempt will be made tomorrow. We will have a full story later this evening.

Tomorrow's launch will occur at about the same time as today's window.

The final countdown has resumed for Arianespace's heavy-lift mission with SES ASTRA's ASTRA 1L and Intelsat's Galaxy 17 satellites, which is set for a 44-minute launch window this evening that opens at 7:29 p.m. in French Guiana (22h29 GMT, 00:29 a.m. in Paris and 6:29 p.m. in Washington, D.C.).

Yesterday's countdown was stopped before liftoff because of high-altitude winds over French Guiana, which exceeded the established safety margins. The Ariane 5 remained in the ELA-3 launch zone overnight, allowing the mission to be rescheduled for today.

This flight will be Arianespace's second dual-payload mission of 2007, and is to loft a total mass of 9,402 kg. – a record performance for a mission to standard geostationary transfer orbit. The combined weight includes the two satellite payloads, their installation hardware, as well as Ariane 5's multiple deployment system that enables the launcher to perform its efficient dual-spacecraft launches.

The Ariane 5 rocket is undergoing fueling right now at 6:18 p.m. EDT as Arianespace prepares to make a second launch attempt this evening. The skies are still cloudy and rain has fallen in the area, so the launch team is monitoring the weather, particularly the upper-level winds which must be favorable and not forecast to potentially carry debris from a launch accident onto populated areas.

T-10:00 and the count is proceeding normally. The final automated launch sequence will begin at T-7:00 with the start of the "Synchronized Sequence".

T-:7:15 Coming up on the start of the synchronized sequence.

T-7:00 and the Synchronized Sequence has started.