BY JUSTIN RAY

Follow the countdown and launch of the Delta 2 rocket with second COSMO-SkyMed radar imaging satellite for Italy. Reload this page for the very latest on the mission.

1140 GMT (6:40 a.m. EST; 3:40 a.m. PST)

A collection of launch images is posted here.

0400 GMT (11:00 p.m. EST; 8:00 p.m. PST)

The second in a series of Italian radar satellites rocketed away from Earth on Saturday night, achieving a spot-on delivery into polar orbit aboard a Delta 2 rocket launched from California.

COSMO-SkyMed spacecraft thundered off the Vandenberg Air Force Base launch pad at exactly 6:31:42 p.m. local time (9:31:42 p.m. EST; 0231:42 GMT).

The 12-story booster quickly arced its trajectory southward, climbing toward space as it raced downrange. Twelve minutes after liftoff, the rocket's second stage engine completed its initial firing to arrive in a parking orbit.

Delta and its COSMO 2 passenger quietly cruised high above the South Pacific before crossing Antarctica and then proceeding northbound toward Africa. The engine reignited for 12 seconds over Madagascar to reach a near-circular polar orbit 340 miles above the planet.

Latches opened and the two-ton satellite payload was cast free from the rocket at 7:29 p.m. Vandenberg time (10:29 p.m. EST; 0329 GMT), some 58 minutes after blastoff as they passed over the eastern shoreline of Africa.

The liftoff was precisely timed to put the craft in the same orbital plane as the COSMO 1 satellite, which was successfully hauled into orbit by a United Launch Alliance Delta 2 rocket in June.

COSMO stands for Constellation of Small Satellites for Mediterranean basin Observation.

Developed by Thales Alenia Space Italia for the Italian Space Agency and the Italian Ministry of Defence, the COSMO-SkyMed system is a dual civilian and military Earth-imaging program that will use a fleet of four satellites to be launched over the next few years.

Each spacecraft is equipped with an X-Band Synthetic Aperture Radar instrument for environmental monitoring, resource management and territorial surveillance.

The Italian Space Agency president calls COSMO-SkyMed the most ambitious space program his country has ever undertaken. The radar satellites can observe and image the planet in daylight or darkness and pierce clouds and weather.

United Launch Alliance conducted Saturday's rocket flight while Boeing managed the commercial contract for the Italian customer. ULA was formed last December to merge Boeing's Delta and Lockheed Martin's Atlas rocket families under one joint venture to cut the cost for U.S. government space launches. The parent companies have retained the ability to sell the rockets on the commercial marketplace.

A Delta 2 rocket has won the commercial contract to launch the COSMO 3 satellite in the second half of 2008.

The rights to loft COSMO 4 in 2009 is still up for grabs.

"Arianespace has been very vocal about also wanting an opportunity to bid for that particular mission so we'll see just how that goes," said Ken Heinly, vice president of Boeing Launch Services.

Saturday's launch came a week after ULA marked its first birthday.

"One year ago, we officially opened our doors with our stated mission of providing the best expendable launch systems and services to assure access to space for our customers at a lower cost," said Mike Gass, president and chief executive officer of ULA.

"We have made great progress during our first year, and in executing our launches with 100 percent mission success we have helped to protect our nation, explore the universe and enable the commerce of space."

ULA launched 11 times during its first year, including seven Delta 2 vehicles, three Atlas 5 rockets and one Delta 4-Heavy.

"Operationally, we are off to a great start, having met the challenges of moving people and assets from Southern California, executing on our transition and consolidation plans, being 100 percent compliant with the regulatory oversight we must meet, and not missing a beat with mission success," said Dan Collins, ULA's chief operating officer.

"There are always challenges to starting a new company, but by bringing together the most knowledgeable and talented teams in the business, we have created the strongest launch vehicle company in the world."

The second year of operations that began with Saturday's successful COSMO 2 launch foresees nearly two dozen Atlas and Delta missions scheduled through 2008. In fact, two more launches are planned from Cape Canaveral just this month. An Atlas 5 flight carrying a classified spy satellite will launch either Monday or Tuesday afternoon depending on when the shuttle Atlantis lifts off from neighboring Kennedy Space Center and a Delta 2 with a new Global Positioning System spacecraft is slated to fly on December 20.

0359 GMT (10:59 p.m. EST; 7:59 p.m. PST)

T+plus 88 minutes. The fuel depletion burn by the second stage just occurred, bringing to a close the flight of the ULA Delta 2 rocket.

This firing by the rocket engine uses up remaining propellant to safe the stage until its eventual natural re-entry into the atmosphere. Such depletion maneuvers are performed because excess fuel left in rockets can cause explosions resulting giant clouds of dangerous space debris.

0350 GMT (10:50 p.m. EST; 7:50 p.m. PST)

T+plus 79 minutes. The second stage has successfully completed the burn to move out of the orbital plane of COSMO. This is known as the evasive burn, and it put the rocket into an elliptical orbit of about 339.03 by 93.953 miles and inclination of 97.86 degrees.

0341 GMT (10:41 p.m. EST; 7:41 p.m. PST)

T+plus 70 minutes. Ground controllers have established contact with COSMO 2 following the craft's successful trek into orbit tonight.

0337 GMT (10:37 p.m. EST; 7:37 p.m. PST)

T+plus 66 minutes. "This was the second successful COSMO-SkyMed launch from Vandenberg Air Force Base this year. It takes a great deal of communications and teamwork to make a launch happen and the use of the Western Range by our Italian partners is rewarding for Team Vandenberg," Col. Steve Tanous, 30th Space Wing commander at Vandenberg, said in a post-launch press release.

0332 GMT (10:32 p.m. EST; 7:32 p.m. PST)

T+plus 61 minutes. This is the 78th consecutive successful Delta 2 rocket launch dating back to May 1997. The Delta 2's overall history since debuting in 1989 has achieved 131 successes in 133 flights.

The next Delta 2 rocket launch is planned for December 20 from Cape Canaveral, Florida. The vehicle will carry out a Global Positioning System satellite deployment mission for the Air Force. The day's 14-minute launch window will open at 2:59 p.m. EST.

0329 GMT (10:29 p.m. EST; 7:29 p.m. PST)

T+plus 58 minutes, 4 seconds. SPACECRAFT SEPARATION! The COSMO 2 spacecraft has been released from the Delta 2 rocket's second stage, completing tonight's launch!

Developed by Thales Alenia Space Italia for the Italian Space Agency and the Italian Ministry of Defence, the COSMO-SkyMed system is a dual civilian and military Earth-imaging program that will use a fleet of four satellites to be launched over the next few years. Each spacecraft will be equipped with an X-Band Synthetic Aperture Radar instrument for environmental monitoring, resource management and territorial surveillance.

A Delta 2 rocket successfully launched the COSMO 1 satellite in June and COSMO 3 will fly aboard another Delta in the second half of 2008.

0328 GMT (10:28 p.m. EST; 7:28 p.m. PST)

T+plus 57 minutes. The deployment of COSMO from the Delta second stage is a two-step process. The payload attach fitting's clampband will be released at T+plus 57 minutes, 30 seconds. A set of secondary latches then disengage at T+plus 58 minutes, allowing the satellite to physically separate from the rocket.

The second stage then performs a retro maneuver to back away from COSMO. That will be followed by a firing of the stage's engine to move the rocket further away from the spacecraft and then another firing to deplete the remaining fuel supply as a safety measure.

0328 GMT (10:28 p.m. EST; 7:28 p.m. PST)

T+plus 56 minutes, 30 seconds. The second stage has achieved the correct orbit with an apogee of 341.04 miles, perigee of 334.73 miles and inclination of 97.86 degrees to the equator. All of those values are right on target.

0327 GMT (10:27 p.m. EST; 7:27 p.m. PST)

T+plus 56 minutes. The rocket is orienting itself to the proper position for release of COSMO.

0325 GMT (10:25 p.m. EST; 7:25 p.m. PST)

T+plus 53 minutes, 44 seconds. SECO 2. Confirmation has been received that the orbit adjustment burn was completed as planned over Madagascar.

0325 GMT (10:25 p.m. EST; 7:25 p.m. PST)

T+plus 53 minutes, 30 seconds. The second stage engine has ignited for the 12-second firing to propel its 4,200-pound spacecraft payload into the proper polar orbit.

0323 GMT (10:23 p.m. EST; 7:23 p.m. PST)

T+plus 51 minutes, 30 seconds. The second stage has completed its BBQ roll.

0321 GMT (10:21 p.m. EST; 7:21 p.m. PST)

T+plus 50 minutes. Hartebeesthoek has picked up the rocket's signal as it flies northbound.

0319 GMT (10:19 p.m. EST; 7:19 p.m. PST)

T+plus 48 minutes. The second stage will be reigniting its engine for 12 seconds over Madagascar.

0314 GMT (10:14 p.m. EST; 7:14 p.m. PST)

T+plus 43 minutes. The next firing by the Delta rocket's second stage is coming up in 10 minutes. The Hartebeesthoek tracking station in South Africa should acquire the rocket in about six minutes. The site will relay the rocket's signal back to Vandenberg to provide confirmation of the second stage burn and release of the COSMO satellite.

0311 GMT (10:11 p.m. EST; 7:11 p.m. PST)

T+plus 40 minutes. The Range liftoff time was 0231:42.118 GMT.

0306 GMT (10:06 p.m. EST; 7:06 p.m. PST)

T+plus 35 minutes. The rocket is crossing Antarctica now as it flies in a polar orbit around Earth. A map of the rocket's planned flight path is available here.

0301 GMT (10:01 p.m. EST; 7:01 p.m. PST)

T+plus 30 minutes. The rocket is coasting until the second stage restarts its engine at T+plus 53 minutes, 27 seconds for a brief 12-second firing to put the vehicle into a near-circular orbit 340 miles above Earth. Deployment of COSMO from the launch vehicle is expected 58 minutes after liftoff.

0251 GMT (9:51 p.m. EST; 6:51 p.m. PST)

T+plus 20 minutes. As the rocket coasts in this parking orbit, it performs a "BBQ roll" maneuver to keep the thermal conditions on the vehicle equal. This maneuver was scheduled to start at about T+plus 19 minutes, 20 seconds and conclude at T+plus 51 minutes, 25 seconds.

0245 GMT (9:45 p.m. EST; 6:45 p.m. PST)

T+plus 14 minutes. As the rocket passes out of range from the tracking plane, a data blackout is created until the Delta's signal is acquired via a South African ground station a half-hour from now.

0243 GMT (9:43 p.m. EST; 6:43 p.m. PST)

T+plus 11 minutes, 52 seconds. SECO 1 has been confirmed by the P-3 aircraft. The second stage's Aerojet-made engine completed its initial burn for the launch. Delta has reached orbit.

0243 GMT (9:43 p.m. EST; 6:43 p.m. PST)

T+plus 11 minutes, 30 seconds. Standing by for confirmation from the P-3 tracking aircraft that the second stage engine shutdown has occurred as planned.

0241 GMT (9:41 p.m. EST; 6:41 p.m. PST)

T+plus 9 minutes, 30 seconds. About two minutes remain in this burn of the second stage engine to achieve the intended parking orbit.

0240 GMT (9:40 p.m. EST; 6:40 p.m. PST)

T+plus 9 minutes. A P-3 instrumented aircraft over the Pacific is tracking the rocket's telemetry signal as the Delta flies beyond Vandenberg's horizon. However, that data is not being relayed live to the launch site.

0239 GMT (9:39 p.m. EST; 6:39 p.m. PST)

T+plus 7 minutes, 45 seconds. Delta remains on course. Velocity has increased to 12,500 mph.

0238 GMT (9:38 p.m. EST; 6:38 p.m. PST)

T+plus 7 minutes, 10 seconds. The Delta 2 rocket is 585 miles south from the launch pad, 100 miles in altitude and traveling at 12,000 mph.

0237 GMT (9:37 p.m. EST; 6:37 p.m. PST)

T+plus 6 minutes, 15 seconds. The second stage is firing normally.

0237 GMT (9:37 p.m. EST; 6:37 p.m. PST)

T+plus 6 minutes. Delta is 89 miles in altitude, 400 miles downrange from the launch pad and traveling at 11,200 mph.

0237 GMT (9:37 p.m. EST; 6:37 p.m. PST)

T+plus 5 minutes, 25 seconds. The Delta 2 rocket is 78 miles in altitude, 307 miles downrange, traveling over 10,700 mph.

0236 GMT (9:36 p.m. EST; 6:36 p.m. PST)

T+plus 4 minutes, 45 seconds. The rocket's nose cone enclosing the spacecraft has been jettisoned.

0236 GMT (9:36 p.m. EST; 6:36 p.m. PST)

T+plus 4 minutes, 40 seconds. The Delta's second stage engine has ignited!

0236 GMT (9:36 p.m. EST; 6:36 p.m. PST)

T+plus 4 minutes, 36 seconds. MECO. The first stage main engine cutoff is confirmed, and the spent stage has been jettisoned!

0235 GMT (9:35 p.m. EST; 6:35 p.m. PST)

T+plus 3 minutes, 45 seconds. The vehicle is 43 miles in altitude, 88 miles downrange from the launch pad and traveling at 6,200 mph.

0235 GMT (9:35 p.m. EST; 6:35 p.m. PST)

T+plus 3 minutes, 30 seconds. The first stage main engine continues to burn normally. The Pratt & Whitney Rocketdyne powerplant consumes kerosene fuel and liquid oxygen to produce about 200,000 pounds of thrust.

0234 GMT (9:34 p.m. EST; 6:34 p.m. PST)

T+plus 2 minutes, 50 seconds. The vehicle is 20 miles in altitude, 26 miles downrange from the launch pad and traveling at 3,200 mph.

0233 GMT (9:33 p.m. EST; 6:33 p.m. PST)

T+plus 2 minutes, 15 seconds. The first stage main engine continues to burn normally.

0233 GMT (9:33 p.m. EST; 6:33 p.m. PST)

T+plus 1 minute, 30 seconds. The ground-lit boosters have jettisoned from the first stage. They remained attached until the rocket cleared off-shore oil rigs.

0233 GMT (9:33 p.m. EST; 6:33 p.m. PST)

T+plus 1 minute, 20 seconds. The Delta 2 rocket is 10 miles in altitude and 7 miles downrange from the launch pad.

0232 GMT (9:32 p.m. EST; 6:32 p.m. PST)

T+plus 1 minute, 5 seconds. All four ground-start solid rocket boosters have burned out. The Delta 2's first stage RS-27A main engine is providing the sole thrust for the next few minutes.

0232 GMT (9:32 p.m. EST; 6:32 p.m. PST)

T+plus 50 seconds. The rocket has flown through the area of maximum aerodynamic pressure in the lower atmosphere.

0231 GMT (9:31 p.m. EST; 6:31 p.m. PST)

T+plus 15 seconds. Delta 330 has cleared the tower and started maneuvering on course to place the COSMO 2 satellite in the proper orbital plane. The vehicle is riding the power of its first stage main engine and the four strap-on boosters.

0231:42 GMT (9:31:42 p.m. EST; 6:31:42 p.m. PST)

LIFTOFF! Liftoff of the Delta 2 rocket with the second COSMO-SkyMed spacecraft, continuing the assembly of Italy's Earth-observation satellite constellation.

0231:12 GMT (9:31:12 p.m. EST; 6:31:12 p.m. PST)

T-minus 30 seconds. SRB ignitors will be armed at T-minus 11 seconds.

The launch ignition sequence will begin at T-minus 2 seconds when a launch team member triggers the engine start switch. The process begins with ignition of the two vernier thrusters and first stage main engine start. The four ground-lit solid rocket motors then light at T-0 for liftoff.

0230:42 GMT (9:30:42 p.m. EST; 6:30:42 p.m. PST)

T-minus 1 minute. The Range has given its final clear-to-launch.

0229:22 GMT (9:29:22 p.m. EST; 6:29:22 p.m. PST)

T-minus 80 seconds. First stage liquid oxygen topping to 100 percent is underway.

0229:57 GMT (9:29:57 p.m. EST; 6:29:57 p.m. PST)

T-minus 1 minute, 45 seconds. The launch pad water suppression system is being activated.

0229:42 GMT (9:29:42 p.m. EST; 6:29:42 p.m. PST)

T-minus 2 minutes. The first stage liquid oxygen vents are now being closed so the LOX tank can be pressurized for launch. Puffs of vapor from a relief valve on the rocket will be seen in the remainder of the countdown as the tank pressure stabilizes.

0229:12 GMT (9:29:12 p.m. EST; 6:29:12 p.m. PST)

T-minus 2 minutes, 30 seconds. The COSMO payload have been declared "go" for launch.

0228:57 GMT (9:28:57 p.m. EST; 6:28:57 p.m. PST)

T-minus 2 minutes, 45 seconds. Vehicle ordnance is being armed.

0228:42 GMT (9:28:42 p.m. EST; 6:28:42 p.m. PST)

T-minus 3 minutes. All remains "go" for launch.

0227:57 GMT (9:27:57 p.m. EST; 6:27:57 p.m. PST)

T-minus 3 minutes, 45 seconds and counting. The Delta 2 rocket's systems are now transferring to internal power for launch. And the launch pad water system is being enabled.

0227:42 GMT (9:27:42 p.m. EST; 6:27:42 p.m. PST)

T-minus 4 minutes and counting! Clocks are ticking down the final moments for liftoff of Delta 330 with the second COSMO-SkyMed spacecraft. Launch is set for 6:31 p.m. local time from Vandenberg Air Force Base, California.

0226:42 GMT (9:26:42 p.m. EST; 6:26:42 p.m. PST)

Now five minutes from launch! The "go" has been given for release of the hold in one minute.

0223 GMT (9:23 p.m. EST; 6:23 p.m. PST)

All systems are reported "ready" by the launch team.

0222 GMT (9:22 p.m. EST; 6:22 p.m. PST)

The final pre-flight poll of the launch team is underway.

0221:42 GMT (9:21:42 p.m. EST; 6:21:42 p.m. PST)

Now 10 minutes from launch. This will be:

• The 330th Delta rocket launch since 1960
• The eighth Delta of 2007
• The 133rd Delta 2 rocket mission since 1989
• The seventh Delta 2 of the year

0217:42 GMT (9:17:42 p.m. EST; 6:17:42 p.m. PST)

T-minus 4 minutes and holding. The countdown has entered the final planned built-in hold. This is a scheduled 10-minute pause leading to today's liftoff time of 6:31:42 p.m. local time (9:31:42 p.m. EST; 0231:42 GMT) for the Delta 2 rocket with COSMO 2.

The weather is acceptable, upper level winds are within limits and there have been no reports of any technical constraints.

During the hold, officials will poll the various team members in the "soft blockhouse," Range Operations Control Center and Mission Directors Center to verify all systems are ready to enter into the final phase of the countdown.

0216 GMT (9:16 p.m. EST; 6:16 p.m. PST)

The COSMO 2 spacecraft is undergoing final configuring for launch.

0215 GMT (9:15 p.m. EST; 6:15 p.m. PST)

The launch weather officer reports conditions are "go" for liftoff.

0213 GMT (9:13 p.m. EST; 6:13 p.m. PST)

The first stage kerosene fuel tank is being pressurized for flight.

0206:42 GMT (9:06:42 p.m. EST; 6:06:42 p.m. PST)

T-minus 15 minutes and counting. Countdown clocks are running again following the planned 20-minute hold. The count will continue to the T-minus 4 minute mark where another hold is scheduled. Launch remains set to occur at 6:31:42 p.m. local time (9:31:42 p.m. EST; 0231:42 GMT).

0204 GMT (9:04 p.m. EST; 6:04 p.m. PST)

Upper level wind conditions are continuing to be acceptable.

0202 GMT (9:02 p.m. EST; 6:02 p.m. PST)

The launch team members were just polled. All responded with a "ready" to press ahead with the countdown this evening.

0156 GMT (8:56 p.m. EST; 5:56 p.m. PST)

Now half-way through this built-in hold at T-minus 15 minutes. Once the countdown resumes, clocks will tick down to the T-minus 4 minute mark where a 10-minute hold is planned.

0146:42 GMT (8:46:42 p.m. EST; 5:46:42 p.m. PST)

T-minus 15 minutes and holding. Clocks have entered the first of two planned hold periods during the final quarter of the Terminal Countdown for today's launch. This pause will last 20 minutes in duration.

These holds are designed to give the launch team a chance to deal with any problems and catch up on work that could be running behind schedule.

0142 GMT (8:42 p.m. EST; 5:42 p.m. PST)

The first stage engine steering checks are complete.

0138 GMT (8:38 p.m. EST; 5:38 p.m. PST)

The second stage engine slews are complete. First stage tests have begun.

0136 GMT (8:36 p.m. EST; 5:36 p.m. PST)

The launch team is beginning the "slew" or steering checks of the first and second stage engines. These are gimbal tests of the nozzles on the first stage main engine and twin vernier engines and second stage engine to ensure the rocket will be able to steer itself during launch.

0131 GMT (8:31 p.m. EST; 5:31 p.m. PST)

Now one hour until launch. The second stage helium and nitrogen system pressurization has been accomplished. And the fuel and oxidizer tanks, which were filled with storable propellants a few days ago, have been pressurized for flight.

0127 GMT (8:27 p.m. EST; 5:27 p.m. PST)

Inhibited checks are now beginning for the Range Safety command destruct receivers that would be used in destroying the Delta rocket should the vehicle veer off course or malfunction during the launch.

0121 GMT (8:21 p.m. EST; 5:21 p.m. PST)

T-minus 40 minutes and counting. Countdown clocks are continuing to the T-minus 15 minute mark where a 20-minute built-in hold is planned. A final 10-minute hold at T-minus 4 minutes will lead to the target liftoff time of 6:31:42 p.m. local time (9:31:42 p.m. EST; 0231:42 GMT).

0119 GMT (8:19 p.m. EST; 5:19 p.m. PST)

The latest weather balloon update shows the upper level winds continue to be OK at the present time.

0114 GMT (8:14 p.m. EST; 5:14 p.m. PST)

Loading of the Delta 2 rocket's first stage liquid oxygen tank was completed at 0114:20 GMT. The operation took 26 minutes and 16 seconds today. The tank will be replenished through the countdown to replace the super-cold liquid oxygen that naturally boils away.

The rocket is now fully fueled for launch. The vehicle's first stage was successfully loaded with RP-1 kerosene fuel earlier today. The second stage was filled with its storable nitrogen tetroxide and Aerozine 50 fuels a few days ago. And the four strap-on booster rockets are solid-propellant.

0108 GMT (8:08 p.m. EST; 5:08 p.m. PST)

Liquid oxygen loading has been underway for 20 minutes. A bright white plume of vapors have begun streaming from a vent on the rocket and the bottom of the vehicle is icing over as the super-cold liquid oxygen continues to flow into the first stage.

Once the first stage tank is 95 percent full, the "rapid load" valve will be closed and the slower "fine load" phase will continue to fill the rocket.

0101 GMT (8:01 p.m. EST; 5:01 p.m. PST)

Liftoff of COSMO 2 is just 90 minutes away.

No weather rules are being violated right now. But Air Force meteorologists are still saying there is a 60 percent chance of rule violation at launch time due to clouds, rain and winds.

The launch time outlook predicts stratocumulus clouds at 1,500 feet and cumulus clouds at 3,000 feet, visibility of seven miles, light rainshowers in the area, a temperature around 48 degrees F and pad winds from the northwest at 15 to 20 knots with gusts to 25 knots.

0058 GMT (7:58 p.m. EST; 4:58 p.m. PST)

Now 10 minutes into this approximate 25-minute process to fill the first stage liquid oxygen tank.

0048 GMT (7:48 p.m. EST; 4:48 p.m. PST)

Cryogenic liquid oxygen, chilled to Minus-298 degrees F, has started flowing from a 28,000-gallon storage tank at Space Launch Complex-2 West, through plumbing and into the bottom of the Delta 2 rocket. The LOX will be consumed by the first stage main engine during the first four-and-a-half minutes of flight along with the 9,900 gallons of RP-1 kerosene already loaded aboard the vehicle.

0046 GMT (7:46 p.m. EST; 4:46 p.m. PST)

The latest weather balloon shows upper level winds are still acceptable.

0042 GMT (7:42 p.m. EST; 4:42 p.m. PST)

The launch team has a "go" to begin preparations for loading the rocket's first stage liquid oxygen tank as planned.

0031 GMT (7:31 p.m. EST; 4:31 p.m. PST)

Now two hours from launch.

0020 GMT (7:20 p.m. EST; 4:20 p.m. PST)

Upper level winds remain "go" based on weather balloon data. Clouds moving in and out of the area, plus some approaching rainshowers, continue to be watched.

At this point in the count, the launch team is working through the pressurization of first and second stage helium and nitrogen systems and second stage fuel and oxidizer tanks.

2352 GMT (6:52 p.m. EST; 3:52 p.m. PST)

The launch pad has been cleared of all workers, allowing hazardous operations to commence. Pressurization of the vehicle's helium and nitrogen systems has begun.

2331:42 GMT (6:31:42 p.m. EST; 3:31:42 p.m. PST)

T-minus 150 minutes and counting. The Terminal Countdown has been initiated for today's launch of the COSMO 2 spacecraft aboard the Delta 330 vehicle.

Pre-flight activities are proceeding apace for the evening liftoff from Vandenberg Air Force Base in California. The site is on the Pacific coastline, about 140 miles northwest of Los Angeles.

Following liftoff, the vehicle will head southward as it climbs into orbit on a 58-minute flight to deploy the Italian satellite cargo.

The countdown clocks currently stand at T-minus 150 minutes and counting. Two planned holds -- at the T-minus 15 minute and the T-minus 4 minute points -- will give the launch team some time to catch up on any work running behind. The first hold will last 20 minutes in duration, the second extends 10 minutes.

Today's instantaneous launch window occurs at 6:31:42 p.m. local time (9:31:42 p.m. EST; 0231:42 GMT).

2323 GMT (6:23 p.m. EST; 3:23 p.m. PST)

The launch team has been polled to ensure all stations are manned and systems are ready to proceed with the countdown. Workers are busily buttoning up the pad and stowing equipment following rollback of the tower.

2317 GMT (6:17 p.m. EST; 3:17 p.m. PST)

"Man stations for Terminal Count." That was the message just announced to the launch team in preparation for starting the Terminal Countdown some 15 minutes from now.

2311 GMT (6:11 p.m. EST; 3:11 p.m. PST)

Pad crews have moved the mobile service tower away from the Delta, revealing the rocket for today's countdown. The overcast skies have given way to sunny conditions, and the initial weather balloon report indicates upper level winds are acceptable right now.

The 177-foot tall mobile gantry was used to stack the two-stage vehicle, the four strap-on solid rocket motors and the COSMO 2 payload atop the pad's launch mount. The tower also provided the primary weather protection and worker access to the rocket during its stay at the oceanside complex on North Vandenberg.

Ground teams will get the pad secured for the Terminal Countdown. Launch remains targeted for exactly 6:31:42 p.m. local time (9:31:42 p.m. EST; 0231:42 GMT).

2307 GMT (6:07 p.m. EST; 3:07 p.m. PST)

Rollback of the mobile service tower at the Space Launch Complex-2 West pad has begun.

2231 GMT (5:31 p.m. EST; 2:31 p.m. PST)

T-minus 150 minutes and holding. The countdown has just entered a planned 60-minute built-in hold at Vandenberg Air Force Base in California. The Terminal Countdown will begin once this hold is concluded. Launch remains scheduled for 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT), pending acceptable weather.

Rollback of the gantry is anticipated shortly.

The weather outlook for this evening continues to predict a 40 percent chance of acceptable conditions. Clouds, rain and winds are among the concerns.

2138 GMT (4:38 p.m. EST; 1:38 p.m. PST)

The Delta 2 rocket's Redundant Inertial Flight Control Assembly guidance computer is being activated.

2131 GMT (4:31 p.m. EST; 1:31 p.m. PST)

Now five hours away from liftoff. This evening's launch time is 6:31:42 p.m. local (9:31:42 p.m. EST; 0231:42 GMT).

The launch is precisely timed to put the COSMO-SkyMed 2 spacecraft in the same orbital plane as the COSMO 1 satellite, which was successfully hauled into orbit by a Delta 2 rocket in June. That requirement dictates an "instantaneous" launch window for the vehicle, meaning there is just one second for the liftoff to happen tonight.

2118 GMT (4:18 p.m. EST; 1:18 p.m. PST)

About 9,900 gallons of the kerosene propellant have been pumped into the base of the Delta 2 rocket from storage tanks at the pad for today's launch.

Loading of super-cold cryogenic liquid oxygen into the first stage will begin around 4:45 p.m. local time. The kerosene and liquid oxygen will be consumed by the stage's Pratt & Whitney Rocketdyne RS-27A main engine and twin vernier steering thrusters during the initial four-and-a-half minutes of flight.

Mission managers are continuing to monitor the wind conditions at the pad for the upcoming rollback of the protective mobile service gantry. Tower retraction needs to be underway by around 3:15 p.m. to support a launch attempt today.

2107 GMT (4:07 p.m. EST; 1:07 p.m. PST)

The first stage tank is half full, with 5,000 gallons aboard now.

Once the tank is filled to 98 percent, the "rapid load" valve will be closed and the slower "fine load" phase will continue to top off the tank.

2100 GMT (4:00 p.m. EST; 1:00 p.m. PST)

Fueling of the Delta 2 rocket first stage with about 10,000 gallons of highly refined kerosene propellant has just gotten underway. Tanking will take about 20 minutes to complete.

1815 GMT (1:15 p.m. EST; 10:15 a.m. PST)

United Launch Alliance is gearing up for another try at sending its Delta 2 rocket into orbit tonight for delivery of the Italian second COSMO-SkyMed spacecraft. Liftoff time is 6:31 p.m. local (9:31 p.m. EST; 0231 GMT).

But just like yesterday, officials are expecting strong winds at Vandenberg Air Force Base to pose a stiff challenge to the countdown. Current plans call for the rocket's first stage to be reloaded with kerosene fuel this afternoon, followed by rollback of the mobile service tower around 3 p.m. local. However, the tower removal depends on ground winds being low enough.

FRIDAY, DECEMBER 7, 2007
2330 GMT (6:30 p.m. EST; 3:30 p.m. PST)

Uncooperative weather today at Vandenberg Air Force Base has forced a postponement in launching the second COSMO radar imaging satellite for Italy aboard a United Launch Alliance Delta 2 rocket.

Strong winds blowing across the Central California area prevented the mobile service tower from being retracted during the countdown. Officials kept the tower in position to shroud the rocket from the winds as long as possible in hopes the gusts would ease, but time ran out for a launch attempt tonight.

"Obviously, the ground winds have been an issue all morning and afternoon here. We cannot ascertain that we would be below the 31-knot limit for rolling the tower. We also have rainshowers coming at us within the next hour or so. And the upper level winds, right now, look like they would also be close," the chief launch conductor radioed the launch team.

"So with all of this information it has been determined by the (launch director) and (mission director) and (flight director) we are scrubbed for the day. We are setting up for a 24-hour turnaround."

Liftoff on Saturday would occur at 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT).

The forecast calls for similar conditions on Saturday, with a 40 percent chance of acceptable weather at liftoff time. The outlook predicts stratocumulus clouds at 1,500 feet and cumulus clouds at 3,000 feet, visibility of five miles, light rainshowers, a temperature in the low 50s F and pad winds from the northwest at 20 to 25 knots with gusts to 30 knots.

2320 GMT (6:20 p.m. EST; 3:20 p.m. PST)

SCRUB. Launch has been postponed for today due to weather.

2317 GMT (6:17 p.m. EST; 3:17 p.m. PST)

"Man stations for Terminal Count." That was the message just announced to the launch team in preparation for starting the Terminal Countdown some 15 minutes from now. Liftoff of the Delta 2 rocket is scheduled for 6:31:41 p.m. local time (9:31:41 p.m. EST; 0231:41 GMT), if the weather cooperates.

2305 GMT (6:05 p.m. EST; 3:05 p.m. PST)

A weather briefing to mission managers is predicting a 40 percent chance of acceptable conditions at liftoff time due to cumulus clouds, winds and precipitation concerns. The latest outlook calls for stratocumulus clouds at 1,500 feet and cumulus clouds at 3,000 feet, visibility of five miles, light rainshowers in the vicinity, a temperature in the low 50s F and pad winds from the northwest at 15 to 20 knots with gusts to 25 knots.

2301 GMT (6:01 p.m. EST; 3:01 p.m. PST)

Now 30 minutes into this scheduled hold period. The team is still awaiting a "go" for tower rollback.

2231 GMT (5:31 p.m. EST; 2:31 p.m. PST)

T-minus 150 minutes and holding. The countdown has just entered a planned 60-minute built-in hold at Vandenberg Air Force Base in California. The Terminal Countdown will begin once this hold is concluded. Launch remains scheduled for 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT).

Launch pad crews are still waiting for approval to begin moving the service tower away from the rocket. The structure remains in place around Delta, giving the vehicle shielding from the winds.

2215 GMT (5:15 p.m. EST; 2:15 p.m. PST)

The Delta 2 rocket's first stage has been filled with its supply of a highly refined kerosene propellant for tonight's launch. And the vehicle's Redundant Inertial Flight Control Assembly guidance computer is being activated.

2040 GMT (3:40 p.m. EST; 12:40 p.m. PST)

Gusty winds at Vandenberg Air Force Base have prompted the launch team to load the Delta 2 rocket's first stage kerosene fuel tank early, a procedure designed to give the vehicle added weight once the mobile service tower is retracted and leaves the rocket exposed to the weather.

The winds have been blowing at the upper limit for rolling the tower. Once the fueling is completed, a process to pump 10,000 gallons of the propellant into the rocket, crews would move the tower by around 3 p.m. local time, if the winds are acceptable. If the rollback is delayed much longer than that, it would be nearly impossible for the launch team to catch up with work and still hit the planned liftoff time this evening.

The weather outlook does call for the winds to ease as the day goes on and be acceptable by launch time.

1930 GMT (2:30 p.m. EST; 11:30 a.m. PST)

United Launch Alliance is counting down to tonight's planned liftoff of the Delta 2 rocket carrying Italy's COSMO 2 radar imaging satellite. It is a windy, overcast day at the Vandenberg launch base.

Rollback of the mobile service tower has not yet occurred. The structure needs to be wheeled into the launch position by about 2 p.m. for the countdown to proceed, officials have said.

Liftoff is targeted for 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT).

THURSDAY, DECEMBER 6, 2007

Technicians have completed repairs to the cork insulation on the United Launch Alliance Delta 2 rocket, clearing the way for another liftoff attempt on Friday evening from Vandenberg Air Force Base, California.

A small area of debonded cork was found during post-scrub inspections of the vehicle after Wednesday night's launch postponement. Officials said new cork was added and sealed to the area, which is near where one of the solid rocket boosters attaches to the first stage.

Weather could be a factor for Friday's countdown due to a storm system moving into the area.

Friday's launch time will be 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT).

1630 GMT (11:30 a.m. EST; 8:30 a.m. PST)

Launch of the Delta 2 rocket with COSMO 2 has been pushed back at least another day. Following last night's scrub, inspections of the rocket uncovered an area of debonded cork insulation on the vehicle. Cork is used as thermal protection on the Delta's outer skin.

United Launch Alliance says the liftoff will occur no sooner than Friday evening at 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT), pending resolution of the cork problem.

0250 GMT (9:50 p.m. EST; 6:50 p.m. PST)

To recap, today's shot at launching a Delta 2 rocket from California's Vandenberg Air Force Base carrying the second in a series of Earth-imaging radar satellites for Italy was scrubbed a little more than two minutes prior to liftoff.

Countdown clocks were ticking toward an on-time liftoff only to be halted when upper level wind data from the last pre-launch weather balloon was reported into the launch team.

"We just went red on the L-5 balloon," an engineer announced to the team.

"We have a hold condition. Hold. Hold. Hold. We have red winds," the flight director responded as the countdown clocks stopped.

The winds had been "no go" earlier in the countdown. But subsequent weather balloons dispatched to measure wind speeds and directions had found conditions were safe for the Delta to control its ascent and not exceed the structural limits of the rocket, lending hope that the launch would go off as planned.

Yet when the final balloon data was posted, the wind situation was deemed "no go."

The launch window was just an instant in time, a one-second opportunity to get the Delta rocket airborne and place the second COSMO-SkyMed spacecraft in the same orbital plane as the COSMO 1 satellite, which was successfully hauled into orbit by a Delta 2 rocket in June.

The "instantaneous" window meant there was no chance to pause the countdown and wait for the wind situation to clear. The launch postponement was called and the team began safing the rocket and its payload.

Another launch try is possible Thursday evening at 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT).

Weather forecasters are predicting a 60 percent chance that an incoming storm system will violate the launch rules.

0233 GMT (9:33 p.m. EST; 6:33 p.m. PST)

The COSMO 2 spacecraft is switching back to external power.

0231 GMT (9:31 p.m. EST; 6:31 p.m. PST)

The launch team has started the normal scrub procedures to safe the Delta 2 rocket, COSMO 2 spacecraft and pad equipment.

0229 GMT (9:29 p.m. EST; 6:29 p.m. PST)

Data from the final weather balloon that just came into the launch team found "no go" conditions aloft. This has resulted in an automatic scrub for tonight because the launch opportunity lasted just one second. There is no time to wait for the winds to improve this evening.

0229 GMT (9:29 p.m. EST; 6:29 p.m. PST)

HOLD! The countdown has been stopped.

0229:13 GMT (9:29:13 p.m. EST; 6:29:13 p.m. PST)

T-minus 2 minutes, 30 seconds. The COSMO payload have been declared "go" for launch.

0228:58 GMT (9:28:58 p.m. EST; 6:28:58 p.m. PST)

T-minus 2 minutes, 45 seconds. Vehicle ordnance is being armed.

0228:43 GMT (9:28:43 p.m. EST; 6:28:43 p.m. PST)

T-minus 3 minutes. All remains "go" for launch.

0227:58 GMT (9:27:58 p.m. EST; 6:27:58 p.m. PST)

T-minus 3 minutes, 45 seconds and counting. The Delta 2 rocket's systems are now transferring to internal power for launch. And the launch pad water system is being enabled.

0227:43 GMT (9:27:43 p.m. EST; 6:27:43 p.m. PST)

T-minus 4 minutes and counting! Clocks are ticking down the final moments for liftoff of Delta 330 with the second COSMO-SkyMed spacecraft. Launch is set for 6:31 p.m. local time from Vandenberg Air Force Base, California.

0226:43 GMT (9:26:43 p.m. EST; 6:26:43 p.m. PST)

Now five minutes from launch! The "go" has been given for release of the hold in one minute.

0224 GMT (9:24 p.m. EST; 6:24 p.m. PST)

Today's launch will be:

• The 330th Delta rocket launch since 1960
• The eighth Delta of 2007
• The 133rd Delta 2 rocket mission since 1989
• The seventh Delta 2 of the year

0223 GMT (9:23 p.m. EST; 6:23 p.m. PST)

All systems are reported "ready" by the launch team.

0222 GMT (9:22 p.m. EST; 6:22 p.m. PST)

The countdown is half-way through this 10-minute built-in hold. Standing by for the final pre-flight poll of the launch team.

0221:43 GMT (9:21:43 p.m. EST; 6:21:43 p.m. PST)

Now 10 minutes from launch. All appears to be ready for tonight's liftoff. Upper level winds are "go" based on the last two weather balloons.

0217:43 GMT (9:17:43 p.m. EST; 6:17:43 p.m. PST)

T-minus 4 minutes and holding. The countdown has entered the final planned built-in hold. This is a scheduled 10-minute pause leading to today's liftoff time of 6:31:43 p.m. local time (9:31:43 p.m. EST; 0231:43 GMT) for the Delta 2 rocket with COSMO 2.

During the hold, officials will poll the various team members in the "soft blockhouse," Range Operations Control Center and Mission Directors Center to verify all systems are ready to enter into the final phase of the countdown.

0217 GMT (9:17 p.m. EST; 6:17 p.m. PST)

The COSMO 2 spacecraft is undergoing final configuring for launch.

0216 GMT (9:16 p.m. EST; 6:16 p.m. PST)

The launch weather officer reports conditions are "go" for liftoff.

0206:43 GMT (9:06:43 p.m. EST; 6:06:43 p.m. PST)

T-minus 15 minutes and counting. Countdown clocks are running again following the planned 20-minute hold. The count will continue to the T-minus 4 minute mark where another hold is scheduled. Launch remains set to occur at 6:31:43 p.m. local time (9:31:43 p.m. EST; 0231:43 GMT).

0205 GMT (9:05 p.m. EST; 6:05 p.m. PST)

Data from another weather balloon just came in. And conditions were found to be within acceptable limits now.

0202 GMT (9:02 p.m. EST; 6:02 p.m. PST)

The launch team members were just polled. All responded with a "ready" to press ahead with the countdown this evening. The only issue being monitored involves the upper level wind conditions. Earlier weather balloons found the conditions aloft to be slightly out of limits. But a few more balloon results are expected between now and launch time.

0156 GMT (8:56 p.m. EST; 5:56 p.m. PST)

Now half-way through this built-in hold at T-minus 15 minutes. Once the countdown resumes, clocks will tick down to the T-minus 4 minute mark where a 10-minute hold is planned.

0146:43 GMT (8:46:43 p.m. EST; 5:46:43 p.m. PST)

T-minus 15 minutes and holding. Clocks have entered the first of two planned hold periods during the final quarter of the Terminal Countdown for today's launch. This pause will last 20 minutes in duration.

These holds are designed to give the launch team a chance to deal with any problems and catch up on work that could be running behind schedule.

0142 GMT (8:42 p.m. EST; 5:42 p.m. PST)

The first stage engine steering checks are complete.

0138 GMT (8:38 p.m. EST; 5:38 p.m. PST)

The second stage engine slews are complete. First stage tests have begun.

0136 GMT (8:36 p.m. EST; 5:36 p.m. PST)

The launch team is beginning the "slew" or steering checks of the first and second stage engines. These are gimbal tests of the nozzles on the first stage main engine and twin vernier engines and second stage engine to ensure the rocket will be able to steer itself during launch.

0131 GMT (8:31 p.m. EST; 5:31 p.m. PST)

Now one hour until launch. The second stage helium and nitrogen system pressurization has been accomplished. And the fuel and oxidizer tanks, which were filled with storable propellants a few days ago, have been pressurized for flight.

0127 GMT (8:27 p.m. EST; 5:27 p.m. PST)

Inhibited checks are now beginning for the Range Safety command destruct receivers that would be used in destroying the Delta rocket should the vehicle veer off course or malfunction during the launch.

0121 GMT (8:21 p.m. EST; 5:21 p.m. PST)

T-minus 40 minutes and counting. Countdown clocks are continuing to the T-minus 15 minute mark where a 20-minute built-in hold is planned. A final 10-minute hold at T-minus 4 minutes will lead to the target liftoff time of 6:31:43 p.m. local time (9:31:43 p.m. EST; 0231:43 GMT).

The only issue being discussed involves the upper level wind conditions. Weather balloons being dispatched from Vandenberg this afternoon are finding winds loft that could be a concern for the Delta 2 rocket to safely fly through. The winds are evaluated to determine how they will impact the vehicle's ability to control its ascent and the structural loads that would be placed on the rocket. The newest weather balloon data shows "no go" conditions for both controls and loads for the portion of flight between 20,000 and 52,000 feet.

0115 GMT (8:15 p.m. EST; 5:15 p.m. PST)

Loading of the Delta 2 rocket's first stage liquid oxygen tank was completed at 0114:31 GMT. The operation took 26 minutes and 40 seconds today. The tank will be replenished through the countdown to replace the super-cold liquid oxygen that naturally boils away.

The rocket is now fully fueled for launch. The vehicle's first stage was successfully loaded with RP-1 kerosene fuel earlier today. The second stage was filled with its storable nitrogen tetroxide and Aerozine 50 fuels a few days ago. And the four strap-on booster rockets are solid-propellant.

0112 GMT (8:12 p.m. EST; 5:12 p.m. PST)

The latest weather balloon update shows the upper level winds continue to be slightly out of limits.

0110 GMT (8:10 p.m. EST; 5:10 p.m. PST)

Liquid oxygen loading has been underway for 22 minutes. Once the first stage tank is 95 percent full, the "rapid load" valve will be closed and the slower "fine load" phase will continue to fill the rocket.

0105 GMT (8:05 p.m. EST; 5:05 p.m. PST)

As darkness falls on Vandenberg, a bright white plume of vapors have begun streaming from a vent on the rocket and the bottom of the vehicle is icing over as the super-cold liquid oxygen continues to flow into the first stage.

0101 GMT (8:01 p.m. EST; 5:01 p.m. PST)

Liftoff of COSMO 2 is just 90 minutes away.

0058 GMT (7:58 p.m. EST; 4:58 p.m. PST)

Now 10 minutes into this approximate 25-minute process to fill the first stage liquid oxygen tank.

0048 GMT (7:48 p.m. EST; 4:48 p.m. PST)

Cryogenic liquid oxygen, chilled to Minus-298 degrees F, has started flowing from a 28,000-gallon storage tank at Space Launch Complex-2 West, through plumbing and into the bottom of the Delta 2 rocket. The LOX will be consumed by the first stage main engine during the first four-and-a-half minutes of flight along with the 9,900 gallons of RP-1 kerosene already loaded aboard the vehicle.

0042 GMT (7:42 p.m. EST; 4:42 p.m. PST)

The launch team has a "go" to begin preparations for loading the rocket's first stage liquid oxygen tank as planned.

0035 GMT (7:35 p.m. EST; 4:35 p.m. PST)

Weather conditions at the launch pad are favorable for a liftoff tonight. However, officials are taking a look at the results from weather balloons that measure upper level winds. The most recent balloon showed the winds just slightly out of limits. Several more balloons will be sent up during the remainder of the count to monitor wind speeds and directions to determine if conditions aloft are safe for the Delta's ascent.

0020 GMT (7:20 p.m. EST; 4:20 p.m. PST)

The countdown is continuing normally and without any problems to speak of. At this point in the count, the launch team is working through the pressurization of second stage helium and nitrogen systems and the fuel and oxidizer tanks.

0004 GMT (7:04 p.m. EST; 4:04 p.m. PST)

Pressurization of the first stage helium and nitrogen systems has been completed. And the rocket's guidance and control system has been brought online.

2356 GMT (6:56 p.m. EST; 3:56 p.m. PST)

Typically at this point in a Delta 2 rocket countdown, the launch team begins loading 10,000 gallons of highly refined kerosene fuel into the first stage. However, this operation was completed earlier in the day prior to rollback of the mobile service tower.

The early fuel loading was performed to give the rocket added weight and stability in the high wind conditions experienced after the tower was retracted, leaving the Delta exposed to the weather.

The kerosene, called RP-1, will be guzzled along with liquid oxygen by the first stage RS-27A main engine and twin vernier steering thrusters during the initial four-and-a-half minutes of flight.

Filling of the stage with cryogenic liquid oxygen will begin about an hour from now.

2331 GMT (6:31 p.m. EST; 3:31 p.m. PST)

T-minus 150 minutes and counting. The Terminal Countdown has been initiated for today's launch of the COSMO 2 spacecraft aboard the Delta 330 vehicle.

Pre-flight activities are proceeding apace for the evening liftoff from Vandenberg Air Force Base in California. The site is on the Pacific coastline, about 140 miles northwest of Los Angeles.

Following liftoff, the vehicle will head southward as it climbs into orbit on a 58-minute flight to deploy the Italian satellite cargo.

The countdown clocks currently stand at T-minus 150 minutes and counting. Two planned holds -- at the T-minus 15 minute and the T-minus 4 minute points -- will give the launch team some time to catch up on any work running behind. The first hold will last 20 minutes in duration, the second extends 10 minutes.

Today's instantaneous launch window occurs at 6:31:43 p.m. local time (9:31:43 p.m. EST; 0231:43 GMT).

2323 GMT (6:23 p.m. EST; 3:23 p.m. PST)

The launch team has been polled to ensure all stations are manned and systems are ready to proceed with the countdown. No problems were reported.

2316 GMT (6:16 p.m. EST; 3:16 p.m. PST)

"Man stations for Terminal Count." That was the message just announced to the launch team in preparation for starting the Terminal Countdown some 15 minutes from now. Liftoff of the Delta 2 rocket remains targeted to occur ontime at 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT).

2303 GMT (6:03 p.m. EST; 3:03 p.m. PST)

The launch pad water pumps were successfully brought online for the count.

2301 GMT (6:01 p.m. EST; 3:01 p.m. PST)

Now 30 minutes through this scheduled hour-long hold in the countdown.

2250 GMT (5:50 p.m. EST; 2:50 p.m. PST)

A couple of photos of the Delta rocket on the launch pad today can be seen here.

2233 GMT (5:33 p.m. EST; 2:33 p.m. PST)

The SLC-2W launch pad is confirmed to be clear of all personnel for the rest of the countdown.

2231 GMT (5:31 p.m. EST; 2:31 p.m. PST)

T-minus 150 minutes and holding. The countdown has just entered a planned 60-minute built-in hold at Vandenberg Air Force Base in California. The Terminal Countdown will begin once this hold is concluded. Launch remains scheduled for 6:31 p.m. local time (9:31 p.m. EST; 0231 GMT).

2215 GMT (5:15 p.m. EST; 2:15 p.m. PST)

Mission managers are arriving at their consoles in the directors' center to oversee today's launch operation. At the pad, final touches are being put on the facility before all workers clear the area for the hazardous portion of the count.

2131 GMT (4:31 p.m. EST; 1:31 p.m. PST)

Five hours and counting down to liftoff. The 177-foot tall mobile service tower has been retracted from the ULA Delta 2 rocket at Vandenberg Air Force Base's Space Launch Complex-2 West pad, completing a crucial step in the preparations for liftoff later this evening.

The gantry was used to stack the two-stage vehicle, the four strap-on solid rocket motors and the COSMO 2 payload atop the pad's launch mount. The tower also provided the primary weather protection and worker access to the rocket during its stay at the oceanside complex on North Vandenberg.

Ground teams will spend the next couple of hours getting the pad secured in advance of the Terminal Countdown. Launch remains targeted for exactly 6:31:43 p.m. local time (9:31:43 p.m. EST; 0231:43 GMT).

2115 GMT (4:15 p.m. EST; 1:15 p.m. PST)

Rollback of the mobile service tower at the Space Launch Complex-2 West pad just got underway. Crews are moving the tower into its launch position, revealing the Delta 2 rocket for today's countdown.

2100 GMT (4:00 p.m. EST; 1:00 p.m. PST)

The Delta 2 rocket remains enclosed within the launch pad's protective service tower. Pad crews hope to begin tower rollback shortly. Officials have been waiting for more suitable wind conditions before pulling back the tower to reveal the rocket. Winds are quite gusty at Vandenberg today but forecasters say they are expected to ease later in the afternoon.

1900 GMT (2:00 p.m. EST; 11:00 a.m. PST)

Countdown preparations are underway at Vandenberg Air Force Base for this evening's launch of the Delta 2 rocket carrying the COSMO 2 spacecraft for Italy. Launch pad workers have readied the mobile service tower for its rollback from around the rocket. However, the retraction has not yet occurred due to the wind conditions at the Central California site.

The Terminal Countdown is scheduled to begin at 3:31 p.m. local (6:31 p.m. EST; 2331 GMT), some three hours prior to the targeted liftoff time.

TUESDAY, DECEMBER 4, 2007

A Delta 2 rocket has a split second to launch Wednesday evening from California's Vandenberg Air Force Base and continue the in-space assembly of an Italian satellite constellation that began six months ago.

Liftoff of the United Launch Alliance booster is scheduled for 6:31:43 p.m. local time (9:31:43 p.m. EST; 0231:43 GMT).

Bolted aboard the 12-story rocket is the second in a set of four COSMO-SkyMed spacecraft. The satellites are equipped to image the Earth's surface for commercial and military uses.

Developed by Thales Alenia Space Italia for the Italian Space Agency and the Italian Ministry of Defence, the COSMO-SkyMed system features X-Band Synthetic Aperture Radar instruments on the satellites for environmental monitoring, resource management and territorial surveillance.

Wednesday's launch is precisely timed to put the craft in the same orbital plane as the COSMO 1, which was successfully hauled into orbit by a Delta 2 rocket in June.

But the "instantaneous" launch window offers engineers little margin to wrestle with last-minute problems.

"It doesn't give you an opportunity to move the launch if there is a Range, or a vehicle or spacecraft problem that you can't clear in the built-in holds. So that's a little less opportunity," Kris Walsh, United Launch Alliance's director of NASA and commercial programs for the Delta rocket, said in an interview Tuesday.

The Delta team goes into Wednesday's countdown well rehearsed in dealing with such brief windows to get a rocket airborne. Some NASA science spacecraft launches flown on Delta rockets, including missions to Mars, often have just instants in time each day to lift off.

The countdown has three holds already planned to give technicians time to resolve any issues that crop up and to ensure activities are completed in time before clocks enter the crucial final minutes.

Weather forecasters anticipate favorable conditions on Wednesday for the launch, with gusty high winds posing only a 20 percent chance of violating the liftoff rules.

"A decaying cold front moves through the region in the early morning hours on the day of launch. There will be mid-level cloudiness with this system but in a narrow band and will quickly move out of the region by late morning. Precipitation and thick clouds will not be an issue for T-0," Air Force meteorologists reported Tuesday.

Stiff northerly winds behind that weather front will increase during the day as gusts reach upwards of 30 knots at the pad.

"Strongest winds of the day should be late morning to early afternoon then gradually diminish as we approach T-0. This could impact timing of (mobile service tower) removal but should not violate launch constraints as they diminish to the low 20s by T-0," the Air Force weather team reported.

Launch officials hope to take full advantage of Wednesday's liftoff opportunity. A looming storm system is predicted to push into the Vandenberg area by Thursday, bringing a thick cloud cover, rain and an 80 percent likelihood of breaking the launch guidelines.

"Tomorrow is going to be our best opportunity for awhile," Ken Heinly, vice president of Boeing Launch Services, said in an interview Tuesday afternoon.

"Right now, as we sit, no issues are being worked. Everything is in place. The team has done these instantaneous launches before and we're looking forward to having one tomorrow."

United Launch Alliance is conducting the rocket flight while Boeing manages the commercial contract for the Italian customer. ULA was formed last December to merge Boeing's Delta and Lockheed Martin's Atlas rocket families under one joint venture to cut the cost for U.S. government space launches. The parent companies have retained the ability to sell the rockets on the commercial marketplace.

Wednesday's launch activities begin with retraction of the protective mobile service gantry from around the Delta rocket at the Space Launch Complex-2 West pad. Rollback is expected to occur between 8 and 10 a.m., but the timing could depend on the wind conditions.

By launch time, the weather outlook calls for a few high cirrus clouds around 30,000 feet, good visibility, northerly winds of 18 to 22 knots with gusts to 25 knots and a temperature in the low 50s F.

The Delta rocket will be flying in its configuration known as the 7420-10 vehicle. The two-stage launcher is fitted with four strap-on solid-propellant motors and a 10-foot diameter composite nose cone.

After quickly climbing away from its coastal pad, the rocket will soar southward over the Pacific Ocean. The four solid boosters burn out and separate less than 90 seconds into the flight, leaving the kerosene-powered main engine to continue pushing the rocket to an altitude of 60 miles. The spent stage then jettisons to let the hydrazine-fueled second stage ignite.

Within 12 minutes, the vehicle settles into an initial parking orbit along a trajectory the cruises above the South Pacific before crossing Antarctica and then proceeding northbound toward Africa. The second stage reignites its engine for 12 seconds over Madagascar to reach a near-circular polar orbit 340 miles above the planet.

The 4,200-pound payload is expected to be released from the rocket 58 minutes after blastoff.

Watch this page for live updates throughout the final hours of the countdown and COSMO 2's trek to orbit aboard the Delta rocket.