The launch team in the Jupiter control room at the Guiana Space Center has confirmed a successful separation of the Pleiades 1B satellite.

One more ignition of the Fregat engine will come later to de-orbit the stage.

T+plus 53 minutes. Separation of Pleiades 1B is about two minutes away.

T+plus 46 minutes, 30 seconds. The Fregat upper stage has shut down, and the vehicle will now maneuver to the correct attitude for deployment of Pleiades 1B, which is expected at about 0258 GMT (9:58 p.m. EST).

T+plus 42 minutes. The Fregat engine has ignited for the second burn during tonight's launch sequence. This four-minute burn will place Pleiades 1B into an injection orbit with an altitude of 431 miles and an inclination of 98.2 degrees.

T+plus 39 minutes. A ground station in South Korea has acquired radio signals from the Fregat upper stage, and the vehicle is re-orienting for its second firing, which begins in less than three minutes.

T+plus 30 minutes. The Fregat and its payload are flying over the Arctic now.

T+plus 18 minutes. The Fregat upper stage and its Pleiades 1B passenger are now flying out of communications of launch controllers. This is a planned loss of communication.

T+plus 14 minutes, 30 seconds. Arianespace has received confirmation of the completion of the first Fregat upper stage burn and the rocket is now in orbit. The second burn comes at 0245 GMT (9:45 p.m. EST)

T+plus 10 minutes, 30 seconds. The Fregat upper stage should now be firing for the first of three burns during this launch. This first ignition is designed to place the rocket and its payloads in a temporary parking orbit above Earth.

Follow along with this timeline of the launch sequence.

T+plus 9 minutes. The Soyuz third stage and Fregat upper stage have now separated.

T+plus 7 minutes. The Soyuz is now flying 134 miles high at a speed of 11,600 mph.

T+plus 5 minutes. At an altitude of 102 miles and a velocity of 8,500 mph, the Soyuz rocket's second stage has shut down and separated. Third stage ignition is also confirmed.

T+plus 3 minutes, 40 seconds. The rocket's 13.5-foot ST-type nose fairing has jettisoned now that the launcher is out of the lower atmosphere.

T+plus 2 minutes. The four strap-on boosters of the Soyuz rocket have separated at an altitude of approximately 37 miles. The core stage continues firing.

LIFTOFF of the Soyuz with the Pleiades 1B reconnaissance satellite, serving the armed forces of France and commerical users around the world.

T-minus 15 seconds. Ignition of the Soyuz rocket's engines.

T-minus 1 minute. The Soyuz will transition to internal power 40 seconds before liftoff.

T-minus 2 minutes. The upper umbilical mast servicing the Soyuz rocket's six satellite payloads is being disconnected from the launcher.

T-minus 4 minutes. The exact liftoff time is 0202:50 GMT (9:02:50 p.m. EST; 11:02:50 p.m. local time).

T-minus 6 minutes. The launch key has been installed inside the launch control center, beginning the Soyuz rocket's synchronized countdown sequence.

T-minus 8 minutes. The Soyuz rocket family has flown 1,796 times since the 1950s, and this is the fourth time the venerable launcher will fly from outside the territory of the former Soviet Union.

After liftoff today, the Soyuz rocket's communications signals will be picked up by ground stations near the French Guiana launch site, Bermuda, South Korea and Perth, Australia.

T-minus 10 minutes. All systems are reporting a "go" status for an on-time launch this evening.

It is currently 10:53 p.m. in French Guiana.

T-minus 14 minutes and counting. With the mobile gantry now retracted, the Soyuz rocket glows bright white with frost. Its propellant tanks are full of cryogenic liquid oxygen stored at almost -300 degrees Fahrenheit.

T-minus 24 minutes. The Soyuz countdown sequence begins 6 minutes, 10 seconds prior to liftoff, then the Fregat upper stage will transition to internal power five minutes before launch.

The umbilical arm servicing the upper stage and payloads will pull away at T-minus 2 minutes, 25 seconds. The Soyuz rocket is operating on internal power at T-minus 40 seconds, and the final servicing mast retracts from the rocket 20 seconds later.

The ignition sequence of the Soyuz rocket's kerosene-fueled core stage and four strap-on boosters begins 17 seconds before liftoff, and all engines should be at full thrust three seconds before launch.

T-minus 27 minutes. Some statistics on today's flight:

• 1,797th Soyuz rocket launch
• 4th Soyuz launch from French Guiana
• 2nd launch of a Pleiades satellite
• 13th Soyuz of 2012

T-minus 60 minutes. The countdown continues as the launch team finishes loading kerosene and liquid oxygen propellant into the three-stage Soyuz rocket. A Fregat upper stage, which will guide the Pleiades 1B satellite into a 432-mile-high orbit, burns storable propellant which is already on-board.

The 174-foot-tall mobile gantry, a unique structure for Soyuz launch operations, will be moved shortly to the launch position. Soyuz launch pads in Russia and Kazakhstan do not have such a gantry.

The second countdown has begun to launch the Pleiades 1B reconnaissance satellite.

The meeting of the Russian State Commission concluded with a "go" to begin the final countdown for launch of a Soyuz rocket at 0202:50 GMT (9:02:50 p.m. EST).

Fueling of the rocket's three core stages will begin in a few minutes.

The launch team will load more than 500,000 pounds of liquid oxygen and kerosene propellant into the rocket this evening, plus hydrogen peroxide to drive the engines' gas turbines and liquid nitrogen to keep the propellant tanks pressurized.

After replacing a faulty electrical unit, which was responsible for scrubbing a launch attempt Friday night, engineers are preparing for a second try to launch a Russian Soyuz rocket from French Guiana.

The replacement electrical unit passed a test, and weather forecast calls for good conditions tonight.

The Russian State Commission will meet at 2130 GMT (4:30 p.m. EST) to give the "go" to enter the final countdown. Fueling of the Soyuz rocket will begin around 2200 GMT (5 p.m. EST).

Liftoff remains set for 0202:50 GMT (9:02:50 p.m. EST) from the Guiana Space Center in French Guiana.

Arianespace, the commercial operator of the Soyuz, says the launch is now set for 0202:50 GMT Sunday (9:02:50 p.m. EST Saturday).

"The launch vehicle and its satellite payload will remain in a safe standby mode for a resumption of the final countdown," Arianespace says in a statement.

SCRUB. Tonight's launch has been called off, according to Arianespace. The launch has been reset for no earlier than Saturday.

The launch team has loaded more than 500,000 pounds of liquid oxygen and kerosene propellant into the rocket this evening, plus hydrogen peroxide to drive the engines' gas turbines and liquid nitrogen to keep the propellant tanks pressurized.

The Soyuz countdown sequence begins 6 minutes, 10 seconds prior to liftoff, then the Fregat upper stage will transition to internal power five minutes before launch.

The umbilical arm servicing the upper stage and payloads will pull away at T-minus 2 minutes, 25 seconds. The Soyuz rocket is operating on internal power at T-minus 40 seconds, and the final servicing mast retracts from the rocket 20 seconds later.

The ignition sequence of the Soyuz rocket's kerosene-fueled core stage and four strap-on boosters begins 17 seconds before liftoff, and all engines should be at full thrust three seconds before launch.

Weather at the Soyuz launch site looks acceptable for liftoff.

The European-funded, Russian-built pad is located about eight miles northwest of the Ariane 5 and Vega launch pads at the Guiana Space Center. Engineers selected the Soyuz launch site based on terrain, geology and a location away from Ariane facilities to ensure they did not interfere with each other.

It took three years and cost European governments $800 million to build the Soyuz launch facility, which is known by its French acronym ELS. Other than the 17-story mobile servicing tower, the launch pad is modeled after the Soyuz launch pad at the Baikonur Cosmodrome in Kazakhstan.

The Soyuz pad includes blue and yellow umbilical arms and hold-down petals at the base of the rocket. On the back side of the pad is a deep flame trench dug out of granite bedrock. The facility also houses living quarters for Russian workers and a launch control center.

The Soyuz site lies closer to the town of Sinnamary than Kourou, which is more typically associated with the spaceport.

Topping of the Soyuz propellant tanks with liquid oxygen and liquid nitrogen pressurant continues, and filling of the rocket's kerosene tanks is complete.

Fueling of the three Soyuz core stages continues with no problems.

Some statistics on today's flight:

• 1,797th Soyuz rocket launch
• 4th Soyuz launch from French Guiana
• 2nd launch of a Pleiades satellite
• 13th Soyuz of 2012

The launch team has begun loading propellant into the three core stages of the Soyuz rocket. The fueling process should be complete about two hours before launch. The State Commission meeting of senior launch officials concluded this afternoon with a "go" for the final countdown.

The final countdown has begun to launch a Russian Soyuz rocket from French Guiana tonight.

The weather forecast continues to look favorable for liftoff at 0202:50 GMT (9:02:50 p.m. EST) from the European-controlled spaceport on the northeast coast of South America.

The only concern is a slight chance of lightning, which would violate weather rules for launch of the 151-foot-tall Soyuz rocket.

Fueling of the three-stage rocket with kerosene and liquid oxygen should begin soon.

Launching from the Guiana Space Center at the edge of the Amazon jungle, a Russian Soyuz rocket is set for liftoff Friday with a sharp-eyed Earth observation satellite to collect high-resolution imagery for French and European security services.

The rocket's French-owned payload, the Pleiades 1B satellite, will serve the French military, other European governments and commercial customers for the next five years.

Read our full story.