BY SPACEFLIGHT NOW

Follow the preparations and launch of the Ariane 5 rocket carrying the European Space Agency's Envisat environmental research satellite. Reload this page for the very latest on the mission.

0240 GMT (9:40 p.m. EST)

The Envisat environmental monitoring satellite was successfully delivered into orbit this evening from the Guiana Space Center in South America, marking the return of Europe's Ariane 5 rocket some seven months after a botched flight that grounded the heavy-lift booster.

Turning night to day at the jungle launch site, the Ariane 5 blasted off at 0108 GMT (8:08 p.m. EST) and headed north over the Atlantic Ocean to a sun-synchronous orbit around Earth's poles.

Less than 27 minutes later, the European Space Agency's 8,111 kg (17,844 pound) Envisat satellite, costing 2.3 billion euros (approximately $2 billion), was released from the rocket's upper stage.

After arriving in orbit, ESA ground controllers at the space operations center in Darmstadt, Germany, assumed control of Envisat -- the most complex satellite ever built in Europe.

"This has been a particularly exciting day for ESA and the European space community as a whole," said Jose Achache, ESA's Director of Earth Observation. "Europe is taking an important lead in global observations for worldwide environmental needs and Envisat is going to make a significant impact on the future of remote sensing of the Earth."

"The ten instruments on board Envisat, more than on any other satellite, cover a wide spectrum of phenomena, delivering evidence of the interactions between the atmosphere, the ocean, the polar ice caps, the vegetation as well as human activity at the surface of the Earth. We will be able to trace the smallest changes to the Earth's surface anywhere on the globe. The importance of this mission has triggered great interest in the Earth-science community, both at a European level and worldwide."

Jacques Louet, ESA's Envisat Program Manager, admitted that there was risk to pack so much into one satellite. "However, if we want to have a comprehensive understanding, we must follow this path," he said.

Envisat is expected to be declared operational following a few weeks of testing, once its payload is has been checked out and the various data-recovery links set up. Then the satellite's six-month long commissioning phase will begin, ensuring that the ten instruments are operating as specified and that we can start delivering validated products to our users.

"Now Envisat is in orbit, the culmination of many years' work really begins and we are looking forward to the environmental benefits the satellite is going to bring to Europe," added Achache.

For Arianespace, attention now turns to the launch of a Japanese telecommunications satellite and European direct broadcast spacecraft aboard an Ariane 4 rocket in the second-half of March.

Arianespace's backlog now stands at 39 satellites to be launched, plus 9 cargo missions for the International Space Station.

0140 GMT (8:40 p.m. EST)

Arianespace has just declared success for the launch of Envisat aboard the Ariane 5 rocket. This was the first flight of heavy-lift rocket since its failure last July.

So Envisat is on its way for a five-year mission. The massive satellite, weighing 8,111 kg (17,844 pounds) is the largest single spacecraft ever carried by an Ariane rocket.

Envisat -- the most ambitious Earth observation satellite -- will uses its suite of 10 instruments to study the environment from space, specifically focusing on global warming and climate change research, as well as monitoring pollution and natural disasters.

0134 GMT (8:34 p.m. EST)

Plus+26 minutes, 35 seconds. SPACECRAFT SEPARATION! The European Space Agency's Envisat environmental research satellite has been released into space from the Ariane 5 rocket.

We'll stand by for Arianespace to verify success in tonight's return of Ariane 5.

0133 GMT (8:33 p.m. EST)

Plus+25 minutes. The upper stage has shut down to complete powered flight for the launch. The stage will provide proper pointing pointing for deployment of the Envisat satellite. Altitude 795 km, velocity is 7.54 km/sec.

0131 GMT (8:31 p.m. EST)

Plus+23 minutes, 30 seconds. About two minutes left in the propulsion from the upper stage. Altitude 793 km, velocity is 7.39 km/sec. The vehicle has leveled out in altitude.

0129 GMT (8:29 p.m. EST)

Plus+21 minutes, 20 seconds. Altitude 785 km, velocity is 7.1 km/sec.

0128 GMT (8:28 p.m. EST)

Plus+20 minutes, 30 seconds. Altitude 777 km, velocity is 7.0 km/sec.

0125 GMT (8:25 p.m. EST)

Plus+17 minutes. Altitude currently 716 km, velocity is 6.68 km/sec.

0124 GMT (8:24 p.m. EST)

Plus+16 minutes. About 10 minutes left in the burn of the Ariane 5 rocket's upper stage. Altitude currently 675 km, velocity is 6.63 km/sec.

0123 GMT (8:23 p.m. EST)

Plus+15 minutes, 30 seconds. Vehicle parameters still reported normal by Arianespace.

0122 GMT (8:22 p.m. EST)

Plus+14 minutes. Altitude 609 km, velocity is 6.60 km/sec.

0120 GMT (8:20 p.m. EST)

Plus+12 minutes. The NASA tracking station at Wallops Island, Virginia, has acquired the rocket's signal as it travels north to polar orbit. Altitude 506 km, velocity is 6.6 km/sec.

0119 GMT (8:19 p.m. EST)

Plus+11 minutes. Altitude currently 443 km, velocity is 6.6 km/sec.

0118 GMT (8:18 p.m. EST)

Plus+10 minutes, 15 seconds. The main cryogenic stage's Vulcain engine has cut off and the stage has separated. It will fall back into the atmosphere and fall into into the Arctic Ocean. The upper stage, the storable propellant stage, has now ignited.

0117 GMT (8:17 p.m. EST)

Plus+9 minutes. Coming up on main stage shutdown in about one minute. Altitude currently 300 km, velocity is 5.9 km/sec.

0115 GMT (8:15 p.m. EST)

Plus+7 minutes, 30 seconds. Main stage continues to fire. Altitude is 241 km, velocity is 4.2 km/sec.

0114 GMT (8:14 p.m. EST)

Plus+6 minutes, 30 seconds. The rocket's system parameters reported normal. Altitude is 225 km, velocity is 3.7 km/sec.

0113 GMT (8:13 p.m. EST)

Plus+5 minutes. Altitude is 194 km, velocity is 2.6 km/sec.

0112 GMT (8:12 p.m. EST)

Plus+4 minutes. Altitude is 150 km, velocity is 2.42 km/sec.

0111 GMT (8:11 p.m. EST)

Plus+3 minutes, 30 seconds. The protective payload fairing enclosing the Envisat satellite has been separated from the Ariane 5.

0111 GMT (8:11 p.m. EST)

Plus+3 minutes. Altitude is 108 km, velocity is 2.12 km/sec.

0110 GMT (8:10 p.m. EST)

Plus+2 minutes, 30 seconds. The solid rocket boosters have been jettisoned from the Ariane 5 rocket's core stage. The boosters provided 90 percent of the liftoff thrust. The liquid-fueled Vulcain main engine continues to fire to propel the vehicle and its satellite payload to orbit.

0109 GMT (8:09 p.m. EST)

Plus+1 minute, 30 seconds. About one minute left in the burn by the solid rocket boosters.

0109 GMT (8:09 p.m. EST)

Plus+1 minute. Vehicle parameters are reported normal.

0108 GMT (8:08 p.m. EST)

Plus+30 seconds. Rocket has completed its pitch and rolls maneuvers as it heads north from the South American jungle for an orbit around Earth's polar regions.

0108 GMT (8:08 p.m. EST)

LIFTOFF! The Ariane 5 rocket returns to flight with the Envisat satellite to study the Earth's environment from space.

0107 GMT (8:07 p.m. EST)

Minus-40 seconds. Vehicle now on internal power.

0107 GMT (8:07 p.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 7 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.

0105 GMT (8:05 p.m. EST)

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

0104 GMT (8:04 p.m. EST)

Minus-4 minutes. Pressurization now underway for the main cryogenic stage's liquid oxygen and hydrogen tanks. Also, final pyrotechnic arming has started. Liftoff remains planned for 0108 GMT (8:08 p.m. EST).

0103 GMT (8:03 p.m. EST)

Minus-5 minutes and counting. Today's launch will be the third Arianespace flight in 2002 and the 148th in the entire Ariane program. It will be the 11th Ariane 5 mission.

0101 GMT (8:01 p.m. EST)

Minus-7 minutes and counting. Synchronized Sequence start. 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.

0100 GMT (8:00 p.m. EST)

Minus-8 minutes and counting. The Synchronized Sequence will begin in the next minute to control the countdown through liftoff.

The final weather update has verified that conditions will be acceptable for launch at 0108 GMT.

0056 GMT (7:56 p.m. EST)

Minus-12 minutes and counting. A network of tracking stations are standing ready to relay data from the Ariane 5 rocket to engineers in Kourou. The early portion of flight will be monitored through the Kourou and Cayenne stations in French Guiana. About 12 minutes after launch the Wallops Island tracking station in Virginia will pick up the rocket's signal as the vehicles heads north to a sun-sunchronous polar orbit. At Plus 24 minutes the Svalbard, Norway site will acquire to cover through spacecraft separation.

0053 GMT (7:53 p.m. EST)

Minus-15 minutes and counting. The countdown is proceeding on schedule for launch of Ariane 511 with the Envisat spacecraft. The status panel in the Jupiter Control Center is all green with no indication of any technical problems and the weather conditions are acceptable. Liftoff is targeted for 0108 GMT.

0038 GMT (7:38 p.m. EST)

Now 30 minutes away from the scheduled blastoff time for the Ariane 5 rocket. Arianespace will begin providing countdown status reports from the Guiana Space Center in Kourou, French Guiana, starting in about 10 minutes.

THURSDAY, FEBRUARY 28, 2002
2300 GMT (6:00 p.m. EST)

The Ariane 5 rocket stands fully fueled for launch of the European Space Agency's Envisat environmental research satellite just over two hours from now. Officials report the weather is favorable for launch from the Guiana Space Center in Kourou, French Guiana on South America's northeastern coastline.

2145 GMT (4:45 p.m. EST)

The main cryogenic stage of the Ariane 5 rocket is being loaded with super-cold liquid hydrogen and liquid oxygen at the ELA-3 launch pad at this hour as the countdown continues for this evening's scheduled 8:07:59 p.m. EST (0107:59 GMT) liftoff.

1700 GMT (12:00 p.m. EST)

High winds caused one of the umbilicals connecting the Ariane 5 rocket to its mobile launch table to be pulled out last night. Officials were forced to roll the rocket back to its final assembly building overnight to reconnect the line, which is a flexible tube that provides ventilation air for the rocket's equipment bay. The vehicle was rolled back to the launch pad this morning.

Arianespace says the extra trip shouldn't delay tonight's launch.

0001 GMT (7:01 p.m. EST Wed.)

The Ariane 5 rocket was rolled to the launch pad Wednesday at the Guiana Space Center. Arianespace says all activities remain on track for launch Thursday evening at 8:07:59 p.m. EST (0107:59 GMT Friday).

Watch this page for updates during the final countdown and flight of the Ariane 5 carrying the Envisat Earth observation spacecraft.

WEDNESDAY, FEBRUARY 27, 2002

Seven months after a failed launch that placed two satellites in the wrong orbit, Arianespace's Ariane 5 rocket is poised to return to flight Thursday evening carrying a massive and costly European environmental research spacecraft.

Liftoff of the Ariane 511 rocket on Arianespace Flight 145 is scheduled for precisely 8:07:59 p.m. EST (0107:59 GMT Friday) from ELA-3 at the Guiana Space Center situated on South America's northeast coast. There will be just an instant in time to get the rocket airborne each day.

Thursday's launch will mark the first flight since July when an Ariane 5 failed to deliver the European Space Agency's Artemis experimental communications satellite and the Japanese BSAT-2b telecommunications craft into the intended geosynchronous transfer orbit due to an upper stage engine problem. Artemis has almost fully recovered from its low orbit and is expected to make it to geostationary orbit. BSAT-2b was declared a total loss by its owners and a replacement spacecraft named BSAT-2c is being built.

An investigation of the mishap uncovered that water left in the fuel lines of the Ariane 5's upper stage caused the Aestus engine's poor performance and early shutdown. The team looking into the failure called for better cleaning processes and an improved ignition sequence for future Aestus powerplants, both of which were incorporated into Thursday's Ariane 5 upper stage during a lengthy testing campaign in Europe over the past few months.

This will be 11th flight of the Ariane 5 rocket, designed as the next-generation launcher for Arianespace. The booster, however, has suffered two complete failures and a partial failure on another mission in its near-six-year history.

The maiden launch in June 1996 ended in disaster 40 seconds after liftoff when a guidance problem caused the launcher to go out of control and explode. The second flight ended up in a low orbit in October 1997 because of an early first stage engine cutoff, resulting in a partial failure.

After the 1997 incident, the vehicle amassed seven consecutive successes until the most recent failure occurred in July 2001.

Just seven more of the venerable and older Ariane 4 rockets remain to be flown before Arianespace, which has dominated the commercial launch market, scales down to only Ariane 5 early next year.

Ariane 5 makes its return with the launch of the European Space Agency's Envisat science satellite.

Costing 2.3 billion euros (approximately $2 billion) through the program's history, Envisat is the largest and most complex Earth-observation satellite in ESA's history. The craft is expected to make more complete observations than any other environmental satellite in the world has to date, officials say.

Designed to operate for at least 5 years, and possibly many more, Envisat will use ten instruments to study environmental changes on Earth. Such investigations will focus on global warming, ozone problems, general climate change, natural disasters, and ocean life, among other things.

Officials admit that it is risky to put so many instruments on one satellite. "However, if we want to have a comprehensive understanding, we must follow this path," said Michael Rast, a scientist in ESA's Earth observation program.

Envisat builds upon the success of two earlier European environment-monitoring satellites -- ERS-1 and ERS-2. Many Envisat instruments and payloads can trace their heritage these two missions.

Envisat will set records for the being the heaviest and one of the largest payloads ever launched aboard an Ariane rocket. Built by a consortium of contractors led by Astrium in Europe, it is approximately 30 feet long at launch and weighs in at 17,844 pounds. Once in orbit, its solar panel will stretch nearly 80 feet from tip-to-tip.

With such a large spacecraft, Flight 145 features the first use of the Ariane 5 long fairing. This larger payload envelope provides more room for payloads and increases the overall height of the launcher by over 12 feet.

The Ariane 511 will place Envisat into a near-polar sun-synchronous orbit inclined at 98 degrees. The satellite will circle the Earth from an altitude of 800 kilometers, which will providing near global coverage every three days and an exact revisit capability around every 35 days.

Preparations for Flight 145 began on March 20, 2001, when the first parts of Envisat arrived via aircraft at the launch site in Kourou, French Guiana. The final piece of the craft touched down in Kourou on May 16.

On June 8, 2001, the payload and service modules of the Envisat spacecraft were integrated.

After the July Ariane 5 failure, the satellite processing campaign was put on hold until January 4 of this year.

The Ariane 5's first stage was lifted and placed into position above the launch table on September 11, followed the next day by the positioning of the rocket's twin solid rocket boosters beside the first stage. The two boosters were attached on September 13.

A lengthy stand-by period for the launcher processing flow began on October 6 and lasted until January 7 when the Ariane 5 rolled from the launcher integration building to the final assembly building. From then, another stand-by order was given.

On January 9, Envisat's solar generator was integrated onto the satellite bus.

The newly tested storable propellant upper stage for Ariane 5 arrived in Kourou from Europe in early February and was hoisted atop the first stage on February 4. The vehicle equipment bay, or the "brains" of the Ariane 5, was placed on top of the upper stage the next day.

Envisat was transported to the fueling center at the Guiana Space Center on February 5. Maneuvering propellant was then loaded aboard the spacecraft on February 7 and 8. Envisat was attached to the payload adapter on February 16.

The payload was taken to the final assembly building on February 18 for mating to the launcher on February 19. The new long fairing was placed around the payload on the 20th.

Fueling operations for the Ariane 511 upper stage's attitude control system took place last Friday.

Most recently, the upper stage has been fueled with its load of monomethyl hydrazine and nitrogen tetroxide on Friday and Monday respectively. A launch rehearsal was successfully conducted on Monday as well.

On Tuesday, a launch readiness review cleared Flight 145 for flight. Also, workers armed the launcher's pyrotechnic systems and made final mechanical preparations of the rocket.

The Ariane 511 is expected to roll out on dual rail tracks to the ELA-3 launch zone on Wednesday, followed on Thursday by the final countdown.

Looking ahead to the events of launch day, the final countdown will commence at 1608 GMT (11:08 a.m. EST). A check of electrical systems will occur at 1738 GMT (12:38 p.m. EST). Liquid hydrogen and liquid oxygen will begin to flow into the launcher's first stage at 1948 GMT (2:48 p.m. EST). Small amounts of super-cold cryogenic fuel will be cycled through the Vulcain main engine for a chilldown process at 2148 GMT (4:48 p.m. EST). At 2353 GMT (6:53 p.m. EST), a check of connections between the launcher and telemetry, tracking, and command systems will take place. At around seven minutes before liftoff, the synchronized sequence will start. Following that crucial point are a series of fast-paced events that will culminate with the ignition of the Vulcain main first stage engine at T-0. Liftoff will occur immediately after the solid rocket boosters ignite seven seconds later.

The two solid rocket boosters will burnout and separate almost 2 minutes, 30 seconds after launch. The protective payload fairing will be jettisoned at around 3 minutes, 14 seconds after liftoff. The cryogenic first stage will continue its long burn until a cutoff at a point almost 10 minutes after launch, followed immediately by separation. The upper stage then comes to life a few moments later and burns for a little over 15 minutes before shutting off. Envisat is planned to separate from the upper stage at T+26 minutes, 58 seconds.

Stay with Spaceflight Now for complete play-by-play coverage of the countdown and launch of this highly important flight of the Ariane 5 rocket.