BY JUSTIN RAY

Follow the countdown and launch of the ULA Delta 2 rocket with a GPS navigation spacecraft. Reload this page for the very latest on the mission.

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WEDNESDAY, OCTOBER 17, 2007

A Global Positioning System satellite with enhanced qualities is flying high after successfully soaring into space Wednesday to reinvigorate a corner of the precision navigation network.

Read our full launch story.

A gallery of launch photos is posted here.

1345 GMT (9:45 a.m. EDT)

Official confirmation received -- the U.S. Air Force's Global Positioning System Block 2R-17 spacecraft has been released from the Delta 2 rocket's third stage to complete this morning's launch from Cape Canaveral. Controllers have established contact with the satellite, which is headed for the orbiting GPS navigation constellation to replace an aging craft when it enters service in a couple of weeks.

1334 GMT (9:34 a.m. EDT)

T+plus 71 minutes. Satellite ground controllers anticipate acquiring the first signals from the GPS spacecraft in about 10 minutes. That would confirm the craft's location and health following the launch.

1331 GMT (9:31 a.m. EDT)

T+plus 68 minutes, 15 seconds. Separation is expected to have taken place by this point. But the lack of live telemtry from the third stage back at the Cape Canaveral engineering facilities makes confirmation of a good third stage burn and deployment of the GPS not possible.

1329 GMT (9:29 a.m. EDT)

T+plus 66 minutes, 30 seconds. The third stage should have burned out of its solid fuel by now, ending the Delta 2 rocket's powered flight for the launch of the GPS 2R-17 spaeccraft. Separation of the payload is about two minutes away. Still waiting on live telemetry back at the Cape from Guam.

1328 GMT (9:28 a.m. EDT)

T+plus 65 minutes. Third stage ignition should have occurred. However, live telemetry at the Cape is not available at the moment via Guam. The Thiokol Star 48B motor will propel the GPS 2R-17 satellite into its targeted orbit for this launch.

1327 GMT (9:27 a.m. EDT)

T+plus 64 minutes, 45 seconds. The solid-fueled third stage has separated.

As the launch sequence continues with the third stage burn and subsequent deployment of the GPS 2R-17 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.

1326 GMT (9:26 a.m. EDT)

T+plus 63 minutes, 30 seconds. 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.

1326 GMT (9:26 a.m. EDT)

T+plus 63 minutes, 5 seconds. The Delta 2 rocket's second stage burn is in progress to boost the vehicle into a higher orbit, data from the Guam tracking site says.

1323 GMT (9:23 a.m. EDT)

T+plus 60 minutes. The Delta 2 rocket should be coming within the Guam tracking station's coverage zone in the next two minutes.

1313 GMT (9:13 a.m. EDT)

T+plus 50 minutes. The rocket continues in the coast phase of the mission as it soars over the Indian Ocean.

1308 GMT (9:08 a.m. EDT)

T+plus 45 minutes. The thermal conditioning roll of the rocket will end in about 11 minutes. Ignition of the second stage is up coming in 17 minutes.

1258 GMT (8:58 a.m. EDT)

T+plus 35 minutes. Today's official liftoff time was 8:23:00.258 a.m. EDT.

1253 GMT (8:53 a.m. EDT)

T+plus 30 minutes. The vehicle just passed out of range from the Ascension Island tracking site in the central Atlantic Ocean. The next station to acquire the rocket's signal will be Guam a half-hour from now.

As this coast phase of the launch continues, you can see a map of the rocket's planned track here.

1246 GMT (8:46 a.m. EDT)

T+plus 23 minutes. Ascension Island is relaying data from the rocket to engineers at Cape Canaveral. The vehicle has entered the slow rolling motion designed to keep the thermal conditions even across the rocket.

1243 GMT (8:43 a.m. EDT)

T+plus 20 minutes. Restart of second stage engine is expected at about T+plus 62 minutes, 29 seconds. The stage will fire for approximately 42 seconds to raise the orbit's high point, or apogee. 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 at T+plus 68 minutes.

1238 GMT (8:38 a.m. EDT)

T+plus 15 minutes. The rocket has successfully achieved a parking orbit with an apogee of 110.56 miles, perigee of 93.99 miles and inclination of 37.50 degrees. That is right on the pre-planned orbit parameters.

1237 GMT (8:37 a.m. EDT)

T+plus 14 minutes. The rocket has flown out of range from the Antigua tracking station. The next site to acquire signal will be Ascension Island in about six minutes.

1234 GMT (8:34 a.m. EDT)

T+plus 11 minutes, 10 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-17 has arrived in a preliminary orbit around Earth following launch today from Cape Canaveral. The vehicle will coast for about 52 minutes before the second stage is re-ignited.

1233 GMT (8:33 a.m. EDT)

T+plus 10 minutes. About a minute left in this initial firing of the second stage.

1232 GMT (8:32 a.m. EDT)

T+plus 9 minutes, 55 seconds. The rocket is 97 miles in altitude, 1,380 miles downrange from the launch pad and traveling at 16,021 mph.

1232 GMT (8:32 a.m. EDT)

T+plus 9 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.

1231 GMT (8:31 a.m. EDT)

T+plus 8 minutes, 10 seconds. Altitude now 95 miles, downrange distance 990 miles and speed 14,600 mph.

1230 GMT (8:30 a.m. EDT)

T+plus 7 minutes, 20 seconds. Good chamber pressure reported on the second stage engine.

1229 GMT (8:29 a.m. EDT)

T+plus 6 minutes, 50 seconds. The Air Force's downrange tracking station on Antigua Island has acquired the rocket's signal.

1229 GMT (8:29 a.m. EDT)

T+plus 6 minutes, 30 seconds. The rocket is 660 miles downrange from the launch pad and traveling at 13,550 mph.

1228 GMT (8:28 a.m. EDT)

T+plus 5 minutes, 10 seconds. The rocket is 70 miles in altitude, 429 miles downrange from the launch pad and traveling almost 13,000 mph.

1228 GMT (8:28 a.m. EDT)

T+plus 5 minutes. The rocket's nose cone enclosing the spacecraft has been jettisoned.

1227 GMT (8:27 a.m. EDT)

T+plus 4 minutes, 40 seconds. The spent first stage has been jettisoned and the Delta's second stage engine has ignited!

1227 GMT (8:27 a.m. EDT)

T+plus 4 minutes, 24 seconds. MECO. The first stage main engine cutoff is confirmed.

1226 GMT (8:26 a.m. EDT)

T+plus 3 minutes, 35 seconds. The vehicle is 45 miles in altitude, 178 miles downrange from the launch pad and traveling at 8,500 mph.

1226 GMT (8:26 a.m. EDT)

T+plus 3 minutes, 15 seconds. The main engine is still firing normally, burning a mixture of highly refined kerosene fuel and supercold liquid oxygen.

1225 GMT (8:25 a.m. EDT)

T+plus 2 minutes, 50 seconds. The vehicle is traveling at 6,200 mph.

1225 GMT (8:25 a.m. EDT)

T+plus 2 minutes, 15 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.

1224 GMT (8:24 a.m. EDT)

T+plus 1 minute, 45 seconds. Delta continues its steep climb. All appears normal with the vehicle.

1224 GMT (8:24 a.m. EDT)

T+plus 1 minute, 12 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.

1223 GMT (8:23 a.m. EDT)

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

1223 GMT (8:23 a.m. EDT)

T+plus 40 seconds. The vehicle is now breaking through the sound barrier.

1223 GMT (8:23 a.m. EDT)

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.

1223 GMT (8:23 a.m. EDT)

T+plus 20 seconds. All six ground-lit solid boosters and the first stage main engine are firing to give the Delta a quick get-away from pad 17A on this 68-minute ascent to deploy the GPS 2R-17 satellite.

1223 GMT (8:23 a.m. EDT)

LIFTOFF! Liftoff of the Delta 2 rocket, launching another modernized spacecraft to enhance the Global Positioning System. And the vehicle has cleared the tower!

1222 GMT (8:22 a.m. EDT)

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

The launch ignition sequence will begin in the final two seconds of the countdown when a ULA 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.

1222 GMT (8:22 a.m. EDT)

T-minus 1 minute. Sixty seconds from launch. The vehicle's second stage hydraulic pump has gone to internal power after its pressures were verified acceptable.

1221 GMT (8:21 a.m. EDT)

T-minus 75 seconds. The Air Force's Eastern Range has given the all-clear to launch.

1221 GMT (8:21 a.m. EDT)

T-minus 100 seconds. First stage LOX topping to 100 percent is underway.

1221 GMT (8:21 a.m. EDT)

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.

1220 GMT (8:20 a.m. EDT)

T-minus 2 minutes, 30 seconds. The GPS spacecraft has been declared "go" for launch.

1220 GMT (8:20 a.m. EDT)

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

1219 GMT (8:19 a.m. EDT)

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

1219 GMT (8:19 a.m. EDT)

T-minus 4 minutes and counting! The Delta 2 rocket is ready to launch the GPS 2R-17 military navigation satellite at 8:23 a.m. EDT from pad 17A at Cape Canaveral Air Force Station in Florida.

1218 GMT (8:18 a.m. EDT)

Standing by to resume the countdown in one minute. All systems are "go" for launch.

1217 GMT (8:17 a.m. EDT)

Two minutes remain in the built-in hold.

1216 GMT (8:16 a.m. EDT)

The Air Force launch poll has been conducted with no problems reported.

1214 GMT (8:14 a.m. EDT)

The entire launch team has given a "go" for liftoff at 8:23 a.m. EDT.

1214 GMT (8:14 a.m. EDT)

Launch team readiness polling is underway.

1213 GMT (8:13 a.m. EDT)

Time to launch is 10 minutes. The spacecraft safe and arm devices are being armed.

1209 GMT (8:09 a.m. EDT)

T-minus 4 minutes and holding. The countdown has entered the final planned hold point for this afternoon'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 8:23 a.m. EDT.

1207 GMT (8:07 a.m. EDT)

The launch weather officer confirms conditions remain "go" for liftoff.

1204 GMT (8:04 a.m. EDT)

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

1202 GMT (8:02 a.m. EDT)

The Lockheed Martin-built GPS spacecraft payload is now confirmed to be on internal battery power for flight.

1158 GMT (7:58 a.m. EDT)

T-minus 15 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.

1157 GMT (7:57 a.m. EDT)

The GPS 2R-17 spacecraft cargo atop the Delta 2 rocket is now switching to internal power for launch.

1153 GMT (7:53 a.m. EDT)

The launch team is being polled for "ready" status to resume the countdown at the end of the hold as scheduled.

1148 GMT (7:48 a.m. EDT)

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. Activitites are going smoothly for this morning's 8:23 a.m. liftoff of the Delta 2 rocket with the GPS 2R-17 spacecraft.

Today's launch will be:

• The 328th Delta rocket launch since 1960
• The 6th to fly this year
• The 132nd Delta 2 rocket mission since 1989
• The 56th GPS satellite to launch
• The 45th time a Delta 2 has launched a GPS satellite
• The 17th GPS Block 2R satellite and 4th modernized

1139 GMT (7:39 a.m. EDT)

The weather officer reports all conditions remain acceptable for launch. Concerns about showers continues to decrease. Skies over the pad are clear as the sun rises.

1138 GMT (7:38 a.m. EDT)

T-minus 15 minutes and holding. The countdown has entered the 20-minute built-in hold. The 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.

1133 GMT (7:33 a.m. EDT)

The first stage steering checks are finished.

1131 GMT (7:31 a.m. EDT)

The second stage engine slews have been completed.

1128 GMT (7:28 a.m. EDT)

Technicians are 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.

1125 GMT (7:25 a.m. EDT)

The weather team is keeping eye on any showers developing around the launch pad this morning. Right now, conditions are perfect at the Cape for a launch. The official odds of acceptable conditions at liftoff time have improved to 60 percent.

1121 GMT (7:21 a.m. EDT)

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.

1117 GMT (7:17 a.m. EDT)

Good morning from Cape Canaveral Air Force Station where the United Launch Alliance Delta 2 rocket has been fueled up for this morning's liftoff carrying the next modernized Global Positioning System satellite.

Over the past hour, the launch team completed the job of loading supercold liquid oxygen into the rocket's first stage. The operation took 27 minutes and was finished at 7:06 a.m.

Chilled to Minus-298 degrees F, the cryogenic oxidizer was pumped from the storage reservoir at Complex 17, 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 10,000 gallons of RP-1 kerosene already loaded aboard the vehicle.

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.

At this point, all remains on schedule for a liftoff at 8:23 a.m. EDT. The countdown is progressing smoothly and no technical problems are being addressed.

1009 GMT (6:09 a.m. EDT)

The first stage fuel tank of the Delta 2 rocket has been fully loaded for this morning's planned 8:23 a.m. EDT launch. The tank was filled with a highly refined kerosene, called RP-1, during a 19-minute, 35-second process that concluded at 6:09:05 a.m. EDT.

The latest weather forecast is predicting a 40 percent chance of conditions being acceptable for a liftoff during this morning's 8:23 to 8:38 a.m. EDT window. All of the weather rules are "go" right now.

The outlook predicts levels of broken clouds at 3,000, 12,000 and 25,000 feet, seven miles of visibility, easterly winds of 10 to 15 knots and a temperature around 78 degrees F.

There is the possibility of some isolated rainshowers or thunderstorms in the area.

We'll be pausing our countdown updates for the next hour or so. The live reports will resume once we get in position at the Cape Canaveral press site.

1006 GMT (6:06 a.m. EDT)

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

1002 GMT (6:02 a.m. EDT)

The launch team has computed that the full load for the first stage fuel tank is 9,994 gallons.

Once the tank is filled to 98 percent or 9,800 gallons, the "rapid load" valve will be closed and the slower "fine load" phase will continue to top off the tank.

0955 GMT (5:55 a.m. EDT)

First stage propellant loading has passed the 3,000-gallon mark. This process to load the kerosene fuel takes about 20 minutes.

0953 GMT (5:53 a.m. EDT)

The countdown is entering the final two-and-a-half hours to liftoff of the GPS 2R-17 spacecraft aboard the Delta 2 rocket.

0949 GMT (5:49 a.m. EDT)

About 10,000 gallons of the kerosene propellant, called RP-1, are pumping into the base of the rocket from storage tanks at pad 17A as fueling of the Delta 2's first stage begins for today's launch.

0944 GMT (5:44 a.m. EDT)

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.

0943 GMT (5:43 a.m. EDT)

First stage helium and nitrogen pressurization is complete. Now standing by for the start of fueling.

0927 GMT (5:27 a.m. EDT)

The launch team has started activation of the rocket's guidance system, as well as the pressurization steps for the first and second stage helium and nitrogen systems and second stage fuel tanks.

0923 GMT (5:23 a.m. EDT)

BEGIN COUNT. The Terminal Countdown has been initiated for today's launch of the Global Positioning System 2R-17 satellite aboard the Delta 2 rocket.

The next three hours will be spent fueling the rocket, activating systems and performing final testing before liftoff at 8:23 a.m. EDT from pad 17A at Cape Canaveral Air Force Station in Florida.

No technical concerns have been reported by the launch team and activities are progressing on schedule. But the odds of acceptable weather during this morning's 15-minute launch window is just 30 percent due to cloud cover and rainshowers.

Workers have cleared the Complex 17 area in advance of the hazardous portion in today's launch operation. But a warning horn is now being 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 activities such as pressurizing the helium and nitrogen storage tanks inside the rocket's first and second stages, along with the second stage fuel and oxidizer tanks.

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.

0914 GMT (5:14 a.m. EDT)

The launch team has been polled to ensure all stations are manned and systems are prepared to proceed with the countdown. Everyone reported "ready."

Liftoff of the Delta 2 rocket remains targeted to occur ontime at 8:23 a.m. this morning.

0823 GMT (4:23 a.m. EDT)

T-minus 150 minutes and holding. Clocks are entering a planned 60-minute built-in hold in the countdown. 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.

0415 GMT (12:15 a.m. EDT)

Retraction of the service gantry from around the Delta 2 rocket at pad 17A is now underway.

The tower was used to stack the multi-stage vehicle atop the pad's launch mount, attach the nine strap-on solid motors and hoist the payload aboard the rocket. The tower also provided the primary weather protection and worker access to the rocket during its stay on the oceanside complex.

The next few hours will be spent configuring launch pad equipment and securing the site.

The Terminal Countdown begins at 5:23 a.m. EDT, followed about 20 minutes later by loading the first stage with kerosene propellant.

0030 GMT (8:30 p.m. EDT Tues.)

Early steps in the countdown are getting underway at Cape Canaveral's pad 17A for Wednesday morning's planned launch of the Delta 2 rocket. Crews will be retracting the mobile service tower in the next couple of hours, buttoning up the launch complex overnight and then starting the Terminal Countdown at 5:23 a.m. EDT.

Wednesday's launch time remains targeted for 8:23 a.m. EDT (1223 GMT).

MONDAY, OCTOBER 15, 2007

An updated Global Positioning System satellite will be launched high above Earth on Wednesday morning, rocketing into orbit aboard a Delta 2 booster from Cape Canaveral to replace an old spacecraft in the navigation network.

Liftoff of the United Launch Alliance rocket is scheduled for 8:23 a.m. EDT (1223 GMT) from pad 17A. The morning's available launch window extends 15 minutes to 8:38 a.m. EDT (1238 GMT).

The weather outlook calls for a 40 percent chance of favorable conditions. Cloud cover and rainshowers will be the main concerns. See the full forecast here.

A final round of launch readiness meetings were held Monday and all systems were deemed "go" for the mission.

"Hopefully everything continues this smoothly," said Dave Podlesney, the GPS programs director at satellite-builder Lockheed Martin.

Satellite technicians were spending Monday uploading flight software to the GPS 2R-17 spacecraft now shrouded inside the rocket's nose cone. The craft is the fourth in a series of eight with enhanced features designed to rejuvenate the GPS constellation.

"It's pretty much a carbon-copy of our other modernized (satellites). Those that have launched have been exceeding all of the performance requirements," Podlesney said. "We're quite pleased."

The modernized satellites transmit additional signals and feature improvements aimed at greater accuracy, tougher resistance to interference and enhanced performance for users around the world.

The new civilian signal removes navigation errors caused by the Earth's ionosphere. The military advancements will provide a more robust jam-resistant signal and enable better targeting of GPS-guided weapons in hostile environments.

"We take great pride in our partnership with the Air Force on this vitally important system," said Don DeGryse, Lockheed Martin's vice president of Navigation Systems. "We look forward to extending our excellent record of delivering advanced navigation capabilities that better serve our warfighters and civil users around the globe."

An hour after sunrise Wednesday, spectators will see the 12-story Delta 2 rocket zoom off the launch pad with its kerosene-fueled main engine and six strap-on solid-propellant boosters firing to generate over 700,000 pounds of thrust.

A minute into the ascent, the rocket will already be 10 miles up as those six solid motors extinguish and separate. Three remaining solids are ignited for their minute-long firing.

The slender blue first stage keeps its RS-27A engine roaring through the initial four-and-a-half-minutes, climbing about 60 miles over the Atlantic Ocean before being jettisoned. That allows the hypergolic second stage engine to ignite and push the vehicle into a preliminary orbit stretching 111 miles at its high point and 94 miles at its lowest.

The second stage will settle into the parking orbit about 11 minutes after liftoff and begin a quiet coast to the other side of the planet where the launch sequence resumes about 50 minutes later over the western Pacific Ocean.

Another firing of the second stage, this time lasting just 42 seconds, begins the process of shaping the orbit for the GPS satellite cargo. The end result of this burn will be an orbit 670 miles at apogee and 103 miles at perigee.

Tiny thrusters then ignite to rapidly "spin up" the third stage and attached satellite to 55 rpm. The second stage separates from the spinning duo some 64 minutes after liftoff.

The solid-fuel third stage is lit moments later, delivering a minute-and-a-half of thrust to propel the 4,500-pound satellite into a highly elliptical orbit reaching 11,000 miles at the high point, 104 miles at the lowest and inclined 40 degrees to the equator.

The satellite is cast free from the spent rocket 68 minutes into the ascent, completing the Delta 2 vehicle's job.

If all goes well, another solid-propellant kick motor on the satellite itself will fire late Friday to circularize its orbit at 11,000 miles and increase the inclination to 55 degrees where the GPS constellation flies.

Controllers will maneuver the $75 million craft into the Plane F, Slot 2 position of the constellation to replace the aging GPS 2A-14 satellite, which was launched in July 1992 with a seven-year design life.

The orbiting network currently has 30 operational satellites, which emit continuous navigation signals that allow users to find their position in latitude, longitude and altitude and determine time.

"The improved signals provided by the GPS satellites will continue to provide around the Earth precise positioning, navigation and timing service any time, any place, right time and right place supporting both the warfighter and the growing needs of our global economy," said Col. David Madden, commander of the Global Positioning Systems Wing.

Watch this page for live updates throughout Wednesday morning's countdown and launch!