BY SPACEFLIGHT NOW

Follow the preparations and launch of the Arianespace Ariane 5 rocket carrying the Helios 2A reconnaissance spacecraft. Reload this page for the latest on the mission.

1738 GMT (12:38 p.m. EST)

Arianespace confirms today's launch has successfully placed its seven payloads into the right orbit.

1734 GMT (12:34 p.m. EST)

Plus+68 minutes, 30 seconds. SPACECRAFT SEPARATION! The upper stage has ejected the French Parasol science satellite, completing this 20th flight of Ariane 5, the third and final this year.

Parasol is designed to characterize the radiation and microphysical properties of clouds and aerosols.

1733 GMT (12:33 p.m. EST)

Plus+67 minutes. SPACECRAFT SEPARATION! The cluster of four ESSAIM microsatellites and the Nanosat have been deployed from Ariane.

ESSAIM is an experimental French military program aimed at proving space-based detection of electromagnetic transmitters. The Spanish Nanosat will test solar and magnetic sensors amd communications nano-technologies.

1727 GMT (12:27 p.m. EST)

Plus+60 minutes, 45 seconds. SPACECRAFT SEPARATION! The 9,240-pound French Helios 2A reconnaissance satellite has been released from the Ariane 5 rocket's upper stage.

1724 GMT (12:24 p.m. EST)

Plus+58 minutes. The Dongara tracking station in Australia is now following the rocket to relay live confirmation of deployment for the seven payloads today.

1658 GMT (11:58 a.m. EST)

Plus+32 minutes. Release of Helios 2A is expected 60 minutes and 8 seconds into flight. The tiny secondary payloads are ejected from a ring on the Ariane 5 upper stage starting at +66 minutes, 15 seconds with deploy of NanoSat, followed by ESSAIM 1 and 4 at +66 minutes, 36 seconds and ESSAIM 2 and 3 one second later. Parasol is expected to be released at +68 minutes, 34 minutes to complete today's launch.

1653 GMT (11:53 a.m. EST)

Plus+27 minutes. The upper stage has shut down to complete powered flight for the launch. The stage has entered a half-hour coast before deployment of the payloads.

1652 GMT (11:52 a.m. EST)

Plus+26 minutes, 15 seconds. Altitude is 677 km, velocity is 7.54 km/sec.

1651 GMT (11:51 a.m. EST)

Plus+25 minutes. The Svalbard tracking station in Norway is acquiring the rocket. Altitude is 686 km, velocity is 7.39 km/sec.

1650 GMT (11:50 a.m. EST)

Plus+24 minutes. Altitude is 698 km, velocity is 7.25 km/sec.

1649 GMT (11:49 a.m. EST)

Plus+23 minutes, 5 seconds. Altitude is 711 km, velocity is 7.1 km/sec.

1648 GMT (11:48 a.m. EST)

Plus+22 minutes, 15 seconds. Altitude is 724 km, velocity is 6.9 km/sec.

1647 GMT (11:47 a.m. EST)

Plus+21 minutes. The rocket is now giving up a bit of altitude in order to gain speed. Altitude is 742 km, velocity is 6.7 km/sec.

1646 GMT (11:46 a.m. EST)

Plus+20 minutes, 15 seconds. Altitude is 750 km, velocity is 6.6 km/sec.

1645 GMT (11:45 a.m. EST)

Plus+19 minutes, 15 seconds. Altitude is 756 km, velocity is 6.52 km/sec.

1644 GMT (11:44 a.m. EST)

Plus+18 minutes. Altitude is 753 km, velocity is 6.4 km/sec.

1643 GMT (11:43 a.m. EST)

Plus+17 minutes, 25 seconds. Altitude is 746 km, velocity is 6.37 km/sec.

1643 GMT (11:43 a.m. EST)

Plus+17 minutes. The upper stage has another 10 minutes in this firing.

1641 GMT (11:41 a.m. EST)

Plus+15 minutes, 30 seconds. Altitude is 706 km, velocity is 6.32 km/sec.

1640 GMT (11:40 a.m. EST)

Plus+14 minutes. Altitude is 643 km.

1639 GMT (11:39 a.m. EST)

Plus+13 minutes. The Canadian St. Hubert tracking station has picked up the rocket's signal.

1638 GMT (11:38 a.m. EST)

Plus+12 minutes. Altitude is 525 km, velocity is 6.48 km/sec.

1637 GMT (11:37 a.m. EST)

Plus+11 minutes, 20 seconds. Altitude is 477 km, velocity is 6.55 km/sec.

1636 GMT (11:36 a.m. EST)

Plus+10 minutes, 30 seconds. The upper stage of Ariane 5G+ -- the storable propellant stage -- has ignited for its long-duration burn.

1636 GMT (11:36 a.m. EST)

Plus+10 minutes, 20 seconds. The main cryogenic stage's Vulcain engine has cut off and the spent stage has separated. It will fall back into the atmosphere prior to completing an orbit of Earth.

1635 GMT (11:35 a.m. EST)

Plus+9 minutes. Coming up on main stage shutdown in about one minute. Altitude is 293 km.

1634 GMT (11:34 a.m. EST)

Plus+8 minutes. The main stage engine continues to fire. Altitude is 205 km, velocity is 4.5 km/sec.

1633 GMT (11:33 a.m. EST)

Plus+7 minutes, 15 seconds. Altitude is 230 km, velocity is 4.0 km/sec.

1632 GMT (11:32 a.m. EST)

Plus+6 minutes, 20 seconds. Altitude is 210 km, velocity is 3.4 km/sec.

1631 GMT (11:31 a.m. EST)

Plus+5 minutes, 10 seconds. Altitude is 183 km, velocity is 2.8 km/sec.

1630 GMT (11:30 a.m. EST)

Plus+4 minutes, 20 seconds. Altitude is 160 km, velocity is 2.5 km/sec.

1629 GMT (11:29 a.m. EST)

Plus+3 minutes, 32 seconds. Arianespace says the protective payload fairing enclosing the satellite has been separated from the Ariane 5.

1629 GMT (11:29 a.m. EST)

Plus+3 minutes, 15 seconds. Altitude is 118 km, velocity is 2.21 km/sec.

1628 GMT (11:28 a.m. EST)

Plus+2 minutes, 30 seconds. The solid rocket boosters have been jettisoned from the Ariane 5 rocket's core stage. The liquid-fueled Vulcain 1 main engine continues to fire to propel the vehicle and its satellite payload to space.

1628 GMT (11:28 a.m. EST)

Plus+2 minutes, 10 seconds. Altitude 62 km, velocity 2.04 km/sec.

1627 GMT (11:27 a.m. EST)

Plus+1 minute, 30 seconds. About one minute left in the burn by the solid rocket boosters. The boosters are providing 90 percent of the liftoff thrust. Altitude is 25 km.

1627 GMT (11:27 a.m. EST)

Plus+60 seconds. The vehicle is on the proper trajectory as it rides the power of the twin solid rocket boosters and main stage liquid-fueled engine.

1626 GMT (11:26 a.m. EST)

Plus+30 seconds. Rocket has completed its pitch and roll maneuvers as it heads northward from the South American coast for the 68-minute flight to deliver Helios 2A and six small satellites into polar orbit.

1626 GMT (11:26 a.m. EST)

LIFTOFF! Liftoff of the Arianespace Ariane 5 rocket launching a next-generation reconnaissance satellite for France.

1625 GMT (11:25 a.m. EST)

Minus-40 seconds. The vehicle is switching to internal power.

1625 GMT (11:25 a.m. EST)

Minus-1 minute. A fast-paced series of events leading to launch will begin at Minus-37 seconds when the automated ignition sequence is started. The water suppression system at the launch pad will start at Minus-30 seconds. At Minus-22 seconds, overall control will be given to the onboard computer. The Vulcain main engine will be readied for ignition with hydrogen chilldown starting at Minus-18 seconds. The residual hydrogen burn flares will fire beneath the Vulcain engine at Minus-6 seconds to burn away any free hydrogen gas. At Minus-3 seconds, onboard systems take over and the two inertial guidance systems go to flight mode. Vulcain main engine ignition occurs at Minus-0 seconds with checkout between Plus+4 and 7 seconds. If there are no problems found, the solid rocket boosters are ignited at Plus+7.0 seconds for liftoff at Plus+7.3 seconds.

1624 GMT (11:24 a.m. EST)

Minus-2 minutes. The Vulcain 1 main engine supply valves are being opened. Also, the ground valves for engine chilldown are being closed.

1623 GMT (11:23 a.m. EST)

Minus-3 minutes. The scheduled launch time has been loaded into the rocket's main computer system. The main stage tank pressures should now be at flight level.

1622 GMT (11:22 a.m. EST)

Minus-4 minutes. Pressurization is now underway for the main cryogenic stage's liquid oxygen and hydrogen tanks. Also, final pyrotechnic arming is starting.

1620 GMT (11:20 a.m. EST)

Minus-6 minutes and counting. Liquid hydrogen and liquid oxygen supplies of the main cryogenic stage are being verified at flight level. Also, the pyrotechnic line safety barriers are being armed.

1619 GMT (11:19 a.m. EST)

Minus-7 minutes and counting. The Synchronized Sequence has started. Computers are now in control of this final segment of the launch countdown to prepare the rocket and ground systems for liftoff. There are two computers running the countdown -- one aboard the Ariane 5 and a redundant one at the ELA-3 launch complex.

1615 GMT (11:15 a.m. EST)

Minus-11 minutes and counting. Status panels in the control center are green, indicating all systems are "go" for liftoff today.

1610 GMT (11:10 a.m. EST)

Minus-16 minutes and counting. The Ariane 5G rocket's main stage has been fueled with its super-cold liquid hydrogen and liquid oxygen propellants and the countdown is proceeding on schedule for liftoff at 1626 GMT from French Guiana on South America's northeastern coastline. The rocket will head on a northward trajectory to reach an orbit around Earth's poles for its seven payloads today.

SATURDAY, DECEMBER 18, 2004

A French spy satellite and six small secondary payloads will ride a European Ariane 5 rocket into polar orbit today. The rare daytime liftoff from the Guiana Space Center in South America is scheduled for 1626 GMT (11:26 a.m. EST).

The Helios 2A reconnaissance satellite is the first of a new-generation observation spacecraft built by EADS Astrium. This new satellite offers enhanced resolution, infrared capability, expanded imaging capacity and shorter image transmission times.

This will be the third Ariane 5 rocket launch in 2004 and the 20th overall since the inaugural mission in 1996. It is known as Arianespace Flight 165.

Watch this page for updates during the final countdown and launch of the Ariane 5 rocket.