BY JUSTIN RAY

Follow the countdown and launch of the Boeing Delta 2 rocket with the U.S. Air Force's latest GPS navigation spacecraft. Reload this page for the very latest on the mission.

MONDAY, SEPTEMBER 26, 2005

A Boeing Delta 2 booster pierced the night sky Sunday evening, successfully launching the first modernized Global Positioning System satellite to build a bridge from the navigation network of today to the advancements of tomorrow. Read our full launch story.

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VIDEO: DELTA ROCKET LIFTS OFF WITH GPS 2R-M1 QT
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0402 GMT (12:02 a.m. EDT)

The official launch time was 11:37:00.531 p.m. EDT -- right at the opening of tonight's window after a flawless and trouble-free countdown.

0401 GMT (12:01 a.m. EDT)

T+plus 24 minutes, 30 seconds. SPACECRAFT SEPARATION! The U.S. Air Force's NAVSTAR Global Positioning System Block 2R-M1 spacecraft has been released from the Boeing Delta 2 rocket's third stage to complete tonight's launch from Cape Canaveral.

This concludes our live play-by-play coverage of today's mission. Check back later for a wrap-up story, pictures and a movie clip of the launch.

0359 GMT (11:59 p.m. EDT Sun.)

T+plus 22 minutes, 32 seconds. The third stage has burned out of its solid fuel, ending the Delta 2 rocket's powered flight for the launch of the GPS 2R-M1 spaeccraft. Separation of the payload is about two minutes away.

About two seconds after release of the satellite, a small "yo" will be strung out from the third stage put the motor into a tumble and keep it from running into the GPS spacecraft.

0358 GMT (11:58 p.m. EDT Sun.)

T+plus 21 minutes, 45 seconds. Good chamber pressure on the third stage is reported.

0358 GMT (11:58 p.m. EDT Sun.)

T+plus 21 minutes, 10 seconds. Third stage ignition! The Thiokol Star 48B motor is firing to propel the GPS 2R-M1 satellite into its targeted orbit for this launch.

0357 GMT (11:57 p.m. EDT Sun.)

T+plus 20 minutes, 30 seconds. The solid-fueled third stage has spun up.

As the launch sequence continues with the third stage burn and subsequent deployment of the GPS 2R-M1 satellite, the second stage will conduct one additional engine firing to deplete its remaining fuel supply and lower its orbital inclination. This is designed to minimize the amount of land that the stage flies over during its natural fall from orbit and future reentry.

0357 GMT (11:57 p.m. EDT Sun.)

T+plus 20 minutes, 30 seconds. The SECO 2 orbit looks normal.

0356 GMT (11:56 p.m. EDT Sun.)

T+plus 19 minutes, 40 seconds. SECO 2. The second stage has completed its second burn of this launch. In the next minute, tiny thrusters on the side of the rocket will be fired to spin up the vehicle in preparation for jettison of the second stage.

0356 GMT (11:56 p.m. EDT Sun.)

T+plus 19 minutes, 29 seconds. The Delta 2 rocket's second stage engine has restarted to boost the vehicle into a higher orbit.

0355 GMT (11:55 p.m. EDT Sun.)

T+plus 18 minutes, 15 seconds. Second stage engine restart is about one minute away.

0353 GMT (11:53 p.m. EDT Sun.)

T+plus 16 minutes. As this coast phase of the launch continues, you can see a map of the rocket's planned track here.

0351 GMT (11:51 p.m. EDT Sun.)

T+plus 14 minutes. The rocket has successfully achieved a parking orbit with an apogee of 601 miles, perigee of 94 miles and inclination of 37.78 degrees. That is right on the pre-planned orbit parameters.

0349 GMT (11:49 p.m. EDT Sun.)

T+plus 12 minutes, 30 seconds. Restart of second stage engine is expected at about T+plus 19 minutes, 19 seconds. The stage will fire for approximately 7.6 seconds to raise the orbit's high point, or apogee, by nearly 100 miles. That will be followed by separation between the second and third stages. The upper stage will burn to inject GPS into the intended transfer orbit. Deployment of the payload to complete the launch is expected just before T+plus 25 minutes.

0348 GMT (11:48 p.m. EDT Sun.)

T+plus 11 minutes, 40 seconds. SECO 1. The second stage engine cutoff has occurred, completing the motor's first firing of the day. The Delta 2 rocket with GPS 2R-M1 has arrived in a preliminary orbit around Earth following launch tonight from Cape Canaveral. The vehicle will coast for the next eight minutes before the second stage is re-ignited.

0347 GMT (11:47 p.m. EDT Sun.)

T+plus 10 minutes, 40 seconds. Speed has increased to 16,450 mph.

0346 GMT (11:46 p.m. EDT Sun.)

T+plus 9 minutes, 40 seconds. Good chamber pressure on the second stage engine. The Delta 2 rocket is 97 miles in altitude, 1,300 miles downrange from the launch pad, traveling nearly 15,000 mph.

0345 GMT (11:45 p.m. EDT Sun.)

T+plus 8 minutes. The second stage engine is still firing, consuming a hydrazine propellant mixture and nitrogen tetroxide oxidizer. This burn is needed to achieve a parking orbit around Earth.

0344 GMT (11:44 p.m. EDT Sun.)

T+plus 7 minutes, 30 seconds. The Delta 2 rocket is 93 miles in altitude, 840 miles downrange from the launch pad, traveling over 14,000 mph.

0343 GMT (11:43 p.m. EDT Sun.)

T+plus 6 minutes, 50 seconds. Data is being received at the Cape telemetry lab again. The second stage engine is firing normally.

0343 GMT (11:43 p.m. EDT Sun.)

T+plus 6 minutes. This initial firing of the second stage should last another five-and-a-half minutes.

0342 GMT (11:42 p.m. EDT Sun.)

T+plus 5 minutes. Boeing says staging happened, along with nose cone separation.

0341 GMT (11:41 p.m. EDT Sun.)

T+plus 4 minutes, 35 seconds. Staging should have occurred. But no telemetry means confirmation cannot be made.

0341 GMT (11:41 p.m. EDT Sun.)

T+plus 4 minutes. Coming up on first stage engine cutoff.

0340 GMT (11:40 p.m. EDT Sun.)

T+plus 3 minutes, 25 seconds. Still waiting to restore the telemetry data stream from the rocket.

0339 GMT (11:39 p.m. EDT Sun.)

T+plus 2 minutes, 20 seconds. The three air-ignited solid rocket boosters have burned out and separated. The rocket is now flying solely on the power generated by the liquid-fueled first stage main engine.

That confirmation was received via the long range tracking via cameras. However, no data is being received from the rocket.

0338 GMT (11:38 p.m. EDT Sun.)

T+plus 1 minute, 40 seconds. The Delta 2 rocket is tracking the proper course. No live data is being received in the telemetry station at the Cape.

0338 GMT (11:38 p.m. EDT Sun.)

T+plus 1 minute, 20 seconds. All six ground-start solid rocket boosters have burned out of propellant and separated from the Delta 2's first stage. A moment before the jettison occurred, the three remaining motors strapped to rocket ignited to continue assisting the rocket's RS-27A main engine on the push to space.

0337 GMT (11:37 p.m. EDT Sun.)

T+plus 56 seconds. The Delta 2 rocket has passed through the region of maximum aerodynamic pressure during its atmospheric ascent.

0337 GMT (11:37 p.m. EDT Sun.)

T+plus 40 seconds. The vehicle has broken the sound barrier as it accelerates rapidly on the combined power from the kerosene- and liquid oxygen-fed main engine and six solid-propellant motors.

0337 GMT (11:37 p.m. EDT Sun.)

T+plus 30 seconds. The six solid rocket motors ignited on the launch pad have surpassed their period of maximum thrust. Each of the Alliant Techsystems-made boosters generate roughly 100,000 pounds of thrust.

0337 GMT (11:37 p.m. EDT Sun.)

T+plus 20 seconds. The Delta 2 rocket is on its way carrying the GPS 2R-M1 satellite, roaring into the Florida nighttime sky. The vehicle has maneuvered to the correct eastward trajectory from the Cape Canaveral's coastline for the flight downrange.

0337 GMT (11:37 p.m. EDT Sun.)

LIFTOFF! Liftoff of the Boeing Delta 2 rocket launching the first modernized Global Positioning System satellite -- building a bridge from the navigation network of today to the advancements of tomorrow.

0336 GMT (11:36 p.m. EDT Sun.)

T-minus 30 seconds. The launch ignition sequence will begin in the final two seconds of the countdown when a Boeing engineer pushes the engine start switch. The process begins with ignition of the two vernier engines and first stage main engine start. The six ground-lit solid rocket motors then light at T-0 for liftoff.

0336 GMT (11:36 p.m. EDT Sun.)

T-minus 1 minute. The Delta 2 rocket's second stage hydraulic pump has gone to internal power after its pressures were verified acceptable.

0335 GMT (11:35 p.m. EDT Sun.)

T-minus 75 seconds. The Range has given its final clear-to-launch.

0335 GMT (11:35 p.m. EDT Sun.)

T-minus 2 minutes. Pressurization of the first stage liquid oxygen is now beginning. Puffs of vapor from a relief valve on the rocket will be seen in the remainder of the countdown as the tank pressure stabilizes.

0334 GMT (11:34 p.m. EDT Sun.)

T-minus 2 minutes, 30 seconds. The GPS 2R-M1 spacecraft has been declared "go" for launch. The $75 million satellite is the first in a new breed of modernized craft that will introduce two new military signals as well as a second civilian signal for the Global Positioning System. The signals promise greater accuracy, added resistance to interference and enhanced performance for military and civilian users around the world.

0334 GMT (11:34 p.m. EDT Sun.)

T-minus 3 minutes and counting. The rocket's third stage safe and arm devices are being armed.

0333 GMT (11:33 p.m. EDT Sun.)

T-minus 3 minutes, 45 seconds. The Delta 2 rocket's systems are now transferring to internal power for launch.

0333 GMT (11:33 p.m. EDT Sun.)

T-minus 4 minutes and counting! The final phase of the countdown is underway for launch of the Delta 2 rocket and the GPS 2R-M1 military navigation satellite at 11:37 p.m. EDT from pad 17A at Cape Canaveral Air Force Station in Florida.

0332 GMT (11:32 p.m. EDT Sun.)

Standing by to resume the countdown in one minute. This has been an extremely smooth countdown tonight with no significant problems discussed by the launch team.

0330 GMT (11:30 p.m. EDT Sun.)

The Air Force management poll has been conducted with no concerns voiced.

0329 GMT (11:29 p.m. EDT Sun.)

The Boeing launch conductor has polled the team for a "go" to proceed with the countdown. No problems were reported. The team is now receiving final instructions on countdown procedures.

0328 GMT (11:28 p.m. EDT Sun.)

Launch team polling is about to begin. The countdown is half-way through this built-in hold.

0327 GMT (11:27 p.m. EDT Sun.)

Time to launch is 10 minutes. Everything continues to look good.

0323 GMT (11:23 p.m. EDT Sun.)

T-minus 4 minutes and holding. The countdown has entered the final planned hold point for tonight's launch attempt. During this planned 10-minute hold, officials will poll the various team members in the soft blockhouse, Range Operations Control Center and Mission Directors Center. If all systems are "go," the countdown will resume for liftoff at 11:37 p.m. EDT (0337 GMT).

0321 GMT (11:21 p.m. EDT Sun.)

The Air Force launch weather officer says conditions are "go" for liftoff tonight.

0320 GMT (11:20 p.m. EDT Sun.)

The liquid oxygen tank is being topped off to 100 percent.

0318 GMT (11:18 p.m. EDT Sun.)

The spacecraft safe and arm devices are armed.

0317 GMT (11:17 p.m. EDT Sun.)

T-minus 10 minutes and counting. The Lockheed Martin-built GPS spacecraft payload is now confirmed to be on internal battery power for flight.

0315 GMT (11:15 p.m. EDT Sun.)

The Range safety checks have been completed. Data analysis is underway.

0313 GMT (11:13 p.m. EDT Sun.)

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 and malfunction during the launch.

0312 GMT (11:12 p.m. EDT Sun.)

The GPS 2R-M1 spacecraft cargo atop the Delta 2 rocket is now switching to internal power for launch.

0307 GMT (11:07 p.m. EDT Sun.)

T-minus 20 minutes and counting. The planned hold in the countdown has been released. Clocks will now tick down to T-minus 4 minutes where the final hold is scheduled.

0303 GMT (11:03 p.m. EDT Sun.)

The launch team has been polled for "ready" status to resume the countdown. The clocks will resume counting at the end of the hold as scheduled.

0257 GMT (10:57 p.m. EDT Sun.)

Now half-way through this built-in hold at T-minus 20 minutes. Launch team and management polls will be coming up shortly. Once the countdown resumes, clocks will tick down to the T-minus 4 minute mark where a 10-minute hold is planned.

0247 GMT (10:47 p.m. EDT Sun.)

T-minus 20 minutes and holding. The countdown has entered the 20-minute built-in hold. This pause is designed to give the launch team a chance to work any problems or catch up on activities that might be running behind schedule. Engineers will also have time to examine all the data from the just-completed steering tests.

0245 GMT (10:45 p.m. EDT Sun.)

The first stage steering checks are finished. Coming up on the T-minus 20 minute hold.

0241 GMT (10:41 p.m. EDT Sun.)

The second stage engine slews have been completed.

0239 GMT (10:39 p.m. EDT Sun.)

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.

0232 GMT (10:32 p.m. EDT Sun.)

Coming up in about five minutes, engine steering tests will be conducted on the Delta 2 launch vehicle.

0219 GMT (10:19 p.m. EDT Sun.)

Loading of the Delta 2 rocket's first stage liquid oxygen tank has been completed. The tank will be replenished through the countdown to replace the super-cold liquid oxygen that naturally boils away. The operation took 26 minutes and 11 seconds tonight.

The rocket is now fully fueled for launch. The vehicle's first stage was successfully loaded with RP-1 kerosene fuel along with the liquid oxygen over the past hour. The second stage was filled with its storable nitrogen tetroxide and Aerozine 50 fuels a few days ago. The nine strap-on booster rockets and third stage use solid-propellants.

0213 GMT (10:13 p.m. EDT Sun.)

Now passing the 20-minute mark of this approximate 25-minute cryogenic tanking process for the Delta rocket's first stage.

Once the liquid oxygen tank reaches the 95 percent full level, the "rapid load" valve will be closed and the slower "fine load" phase will continue to fill the tank.

0207 GMT (10:07 p.m. EDT Sun.)

The countdown is entering the final 90 minutes to launch.

0203 GMT (10:03 p.m. EDT Sun.)

Now 10 minutes into liquid oxygen loading. The bottom of the Boeing Delta 2 rocket is icing over as the super-cold liquid oxygen continues to flow into the first stage.

0153 GMT (9:53 p.m. EDT Sun.)

Super-cold liquid oxygen is beginning to flow into the first stage of the Boeing Delta 2 rocket as the countdown continues for tonight's 11:37 p.m. EDT (0337 GMT) launch.

The liquid oxygen, chilled to Minus-298 degrees F, is being pumped from a storage tank at pad 17A, through plumbing and into the bottom of the rocket. The LOX and the RP-1 kerosene fuel -- loaded aboard the vehicle in the past hour -- will be consumed by the first stage main engine.

0149 GMT (9:49 p.m. EDT Sun.)

The launch team has received approval to begin preps for loading the first stage liquid oxygen tank.

0142 GMT (9:42 p.m. EDT Sun.)

The launch team has completed work to turn on and configure the Delta's onboard guidance computer -- called the Redundant Inertial Flight Control Assembly, or RIFCA.

0136 GMT (9:36 p.m. EDT Sun.)

The launch weather officer has completed his briefing to the management team in advance of loading liquid oxygen into the Delta 2 rocket's first stage. All conditions are acceptable at this time and there's an 80 percent chance of favorable weather during tonight's launch window extending from 11:37 p.m. to 12:05 a.m. EDT. Clouds and rainshowers drifting over the pad from the Atlantic Ocean pose the only worry tonight.

0124 GMT (9:24 p.m. EDT Sun.)

The first stage fuel tank of the Boeing Delta 2 rocket has been fully loaded for tonight's planned 11:37 p.m. launch. The tank was filled with a highly refined kerosene, called RP-1, during a 19-minute, 10-second process that concluded at 9:24:25 p.m. EDT.

The next major task in the count will be loading super-cold cryogenic liquid oxygen into the first stage starting just before 10 p.m.

0122 GMT (9:22 p.m. EDT Sun.)

Rapid-loading of the RP-1 tank has concluded as 9,800 gallons have been pumped into the rocket. Fine load is continuing.

0117 GMT (9:17 p.m. EDT Sun.)

The launch team has computed that the full load for the first stage fuel tank is 9,971 gallons.

Once the tank is filled to 98 percent or 9,770 gallons, the "rapid load" valve will be closed and the slower "fine load" phase will continue to top off the tank.

0115 GMT (9:15 p.m. EDT Sun.)

Now 10 minutes, or half-way, through this 20-minute process to load the rocket's first stage with kerosene fuel. Some 6,000 gallons have been loaded to this point.

The propellant will be used along with liquid oxygen -- to be pumped into the rocket a little later -- by the first stage Rocketdyne RS-27A main engine and twin vernier steering thrusters during the initial four-and-a-half minutes of flight.

0105 GMT (9:05 p.m. EDT Sun.)

Fueling of the Delta 2 rocket's first stage has begun for tonight's launch. About 10,000 gallons of a highly refined kerosene propellant, called RP-1, are being pumped into the base of the rocket from a storage tank at pad 17A.

0100 GMT (9:00 p.m. EDT Sun.)

Preparations for loading the Delta 2 rocket's first stage RP-1 fuel tank are beginning. After verifying valves, sensors, flow meters and equipment are ready, the highly-refined kerosene fuel will start flowing into the vehicle a few minutes from now.

0040 GMT (8:40 p.m. EDT Sun.)

Activation of the rocket's guidance system is starting.

0037 GMT (8:37 p.m. EDT Sun.)

T-minus 150 minutes and counting. The Terminal Countdown is now underway for tonight's launch of the Delta 2 rocket and the Global Positioning System 2R-M1 satellite. The next three hours will be spent fueling the rocket, activating systems and performing final testing before liftoff at 11:37 p.m. EDT (0337 GMT) from pad 17A at Cape Canaveral Air Force Station in Florida.

The Complex 17 area is verified cleared of workers. A warning horn will be sounded three times at the seaside complex as a precaution to alert any remaining personnel in the vicinity that they should leave immediately.

The pad clear status will allow the start of hazardous operations such as the pressurization of helium and nitrogen storage tanks inside the rocket's first and second stages, along with the second stage fuel and oxidizer tanks.

The countdown currently stands at T-minus 150 minutes. However, there are a pair of holds -- totaling 30 minutes in duration -- planned at T-minus 20 minutes and T-minus 4 minutes.

0028 GMT (8:28 p.m. EDT Sun.)

The launch team members have been polled for a "ready" status to resume the countdown as planned at the end of this hold. No issues were reported. Clocks will start ticking again at 8:37 p.m. EDT as the Terminal Countdown begins.

0005 GMT (8:05 p.m. EDT Sun.)

We have posted a gallery of pictures taken by Boeing photographer Carleton Bailie from this afternoon's rollback of the mobile service tower at launch pad 17A. See the pictures here.

SUNDAY, SEPTEMBER 25, 2005
2337 GMT (7:37 p.m. EDT)

T-minus 150 minutes and holding. Clocks are entering a planned 60-minute built-in hold in the countdown. Holds are scheduled into the count to give workers a chance to catch up on any activities that may be running behind.

Over the next hour, all launch team members and management officials will be seated at their consoles. A series of polls will be conducted to verify everyone is ready to enter Terminal Count at end of the built-in hold.

Liftoff of the Delta 2 rocket remains scheduled for 11:37 p.m. EDT from Cape Canaveral, Florida.

2315 GMT (7:15 p.m. EDT)

The sun is setting and the bright lights of launch pad 17A are coming on. Countdown preps continue to go well, a Boeing spokesperson says.

2237 GMT (6:37 p.m. EDT)

Five hours and counting. The launch team is gathering inside the control center at Cape Canaveral. A readiness poll of the members will be conducted shortly before 8:30 p.m. in advance of starting the Terminal Countdown.

2220 GMT (6:20 p.m. EDT)

The launch weather forecast has improved to an 80 percent chance of acceptable conditions for this evening's liftoff. Earlier forecasts predicted a 70 percent chance.

"Surface and upper level high pressure centered well north of the state will be the main influence on local weather conditions today. Onshore flow and an isolated coastal shower may develop during the countdown. Launch window concerns will be westward moving cumulus clouds and showers over the near coastal waters," the weather team reported today.

The launch time forecast calls for scattered cumulus clouds at 3,000 feet, scattered cirrus clouds at 25,000 feet, visibility of 10 miles, easterly winds at 10 gusting to 15 knots, a temperature of 78-80 degrees F and showers in the vicinity.

2137 GMT (5:37 p.m. EDT)

The countdown is now entering its final six hours to launch of a Boeing Delta 2 rocket and the GPS satellite for the U.S. Air Force. Work continues at pad 17A to configure the launch complex for fueling the rocket and launch.

2105 GMT (5:05 p.m. EDT)

A Boeing spokesman says all systems remain "go" for tonight's 11:37 p.m. EDT launch of the Delta 2 rocket and GPS 2R-M1 satellite.

2020 GMT (4:20 p.m. EDT)

The mobile service tower is in motion right now, wheeling back to its park position away from the Delta 2 rocket at pad 17A. The tower is used to assemble the rocket on the pad and provide access for workers during the booster's stay on the seaside complex.

Once the tower is fully retracted over the next few minutes, workers will get the structure locked down and proceed with the other activities to ready the pad for launch.

1610 GMT (12:10 p.m. EDT)

The Delta rocket is still set to fly tonight from Cape Canaveral. Launch crews are gearing up to start the countdown this afternoon.

Watch this page for live updates throughout the evening's countdown and launch.

SATURDAY, SEPTEMBER 24, 2005

The first step to upgrading the Global Positioning System begins Sunday evening by launching a spacecraft designed to transmit more military and civilian navigation signals than ever before.

Liftoff of the GPS 2R-M1 satellite aboard a Boeing Delta 2 rocket remains scheduled for 11:37 p.m. EDT (0337 GMT) from pad 17A at Cape Canaveral Air Force Station, Florida.

Countdown activities start Sunday afternoon with retraction of the mobile service gantry from around the 125-foot tall rocket. The Terminal Count picks up three hours before launch time -- 8:37 p.m. EDT -- in advance of fueling the vehicle's first stage with a highly fined kerosene propellant and supercold liquid oxygen.

Air Force weather forecasters predict at least a 70 percent chance that conditions will be acceptable for liftoff during the evening's 28-minute launch window, which runs to 12:05 a.m. EDT. The main worry will be small rainshowers forming over the Atlantic Ocean and drifting near the launch pad via an easterly wind.

"As long as you have an east wind off the ocean, we do have the chance for rain and showers," launch weather officer Joel Tumbiolo told reporters at today's pre-launch news conference. "Those will be few and far between, so I am optimistic."

The outer fringes of Hurricane Rita brought stormy conditions to the Cape for several days earlier this week. But clearing skies finally returned to spaceport on Friday.

"Hurricanes are basically large sucking vortices where they take all of the atmospheric moisture in the area and concentrate it around the storm. As the storm moved further and further to the west, all of the rain we had in the middle part of the week basically was taken to the west with it and it has left us with a day, day-and-a-half now of good weather. And I do expect that good weather to continue over the next two or three days at least," Tumbiolo said.

This launch was planned to occur on Wednesday. But problems with a battery in the rocket's self-destruct safety system and a last-minute concern with the payload forced the delay, Air Force officials said.

"A procedural error in battery processing caused the need to remove and replace a suspect (flight termination system) battery," the Space and Missile Systems Center explained.

"This mission has been a long time coming. We received the first components of the booster on August 6, 2004 and erected the vehicle on (pad) SLC-17A on March 22," Air Force launch director Lt. Col. L.C. Coffey said Saturday.

The $75 million GPS 2R-M1 satellite will introduce two new military signals as well as a second civilian signal for the spaceborne navigation system, promising greater accuracy, added resistance to interference and enhanced performance.

"We are right on the brink of a major step in continuing to modernize the GPS constellation and services to provide new capabilities for military and civilian users worldwide," said Col. Allan Ballenger, GPS system program director at the Space and Missile Systems Center.

Within a few days of launch, ground teams will begin testing the satellite's new signals and the original features carried on previous GPS spacecraft to verify the modernization has worked as planned. The Lockheed Martin-built satellite is expected to enter service by year's end, joining the 28 other GPS craft operating above Earth.

"We're all excited. Our whole team is waiting for this one to go up," said Dave Podlesney, Lockheed Martin's GPS 2R program director. "We're waiting to get on-orbit, and we really want to see the performance."

Seven additional updated GPS 2R satellites will be launched over the next couple of years. What's more, a dozen next-generation 2F spacecraft with even more enhancements are slated to start launching in 2007.

THURSDAY, SEPTEMBER 22, 2005

A Boeing Delta 2 rocket will try again this weekend to launch the first modernized Global Positioning System satellite from Cape Canaveral, but why the liftoff was postponed earlier this week remains a mystery.

Air Force officials on Thursday evening were still unable to answer any questions about the delay, four days after being asked by the news media. It is unknown if the problems involved the rocket, satellite or ground equipment.

Launch is scheduled for Sunday evening at 11:37 p.m. EDT. A 28-minute window extends to 12:05 a.m.

The weather outlook calls for generally favorable conditions.

1600 GMT (12:00 p.m. EDT)

Preparations are resuming for the delayed launch of Boeing's Delta 2 rocket with the latest GPS military navigation satellite. Liftoff is targeted for 11:37 p.m. EDT on Sunday night.

The Air Force has still not explained why the launch was postponed several days.

The weather forecast for Sunday's launch attempt calls for a 70 percent chance of acceptable conditions. See the full forecast here.

MONDAY, SEPTEMBER 19, 2005

Launch is being re-targeted for no earlier than Sunday night. Liftoff that day will be possible between 11:37 p.m. and 12:05 a.m. EDT.

1525 GMT (11:25 a.m. EDT)

DELAY. Wednesday's planned launch has been postponed, Boeing announced this morning. No further details have been released on the cause or how long the delay will last.

SUNDAY, SEPTEMBER 18, 2005

The first modernized Global Positioning System satellite featuring additional navigation signals to benefit military and civilian users around the world will be launched Wednesday night aboard a Boeing Delta 2 rocket.

Liftoff from pad 17A at the Cape Canaveral spaceport is scheduled for 11:53 p.m. EDT, the opening of a 28-minute window that extends past midnight to 12:21 a.m. EDT (0353-0421 GMT).

The Lockheed Martin-built GPS 2R-M1 spacecraft has spent seven months undergoing launch testing and preparations at the Cape, twice as long as originally envisioned. Concerns about internal components on the satellite and delays building Range Safety batteries for the Delta booster postponed the mission from May.

Read our launch preview story.