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The Mission

Rocket: Delta 2 (7925)
Payload: GPS 2R-19
Date: March 15, 2008
Window: 2:09-2:23 a.m. EDT (0609-0623 GMT)
Site: SLC-17A, Cape Canaveral, Florida
Satellite feed: Galaxy 26, Transponder 9, C-band, 93° West

Mission Status Center

Launch events timeline

Ground track map

Delta 2 fact sheet

The GPS system

Pre-launch flow

Launch Complex 17

Archived Delta coverage


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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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Using one of its final Delta 2 rockets, the U.S. Air Force continued a year-long launch surge of new Global Positioning System satellites with a successful blastoff from Cape Canaveral over the weekend.

Read our full launch story.

0920 GMT (5:20 a.m. EDT)

A gallery of launch photos is posted here.

0725 GMT (3:25 a.m. EDT)

This is the 80th consecutive successful Delta 2 rocket launch dating back to May 1997. The Delta 2's overall history since debuting in 1989 has achieved 133 successes in 135 flights.

The next Delta 2 rocket launch from Cape Canaveral is scheduled for May 16 during a window extending from 11:45 a.m. to 1:40 p.m. EDT. Flying in its Heavy configuration with larger strap-on solid rocket boosters, vehicle will haul NASA's Gamma-ray Large Area Space Telescope (GLAST) observatory into orbit.

The next GPS launch is planned for the end of June.

0721 GMT (3:21 a.m. EDT)

Spacecraft separation confirmed! The U.S. Air Force's Global Positioning System Block 2R-19 spacecraft has been released from the Delta 2 rocket's third stage to complete this late-night launch from Cape Canaveral.

The deploy occurred at 2:18:03 a.m. EDT this morning.

0718 GMT (3:18 a.m. EDT)

T+plus 68 minutes, 30 seconds. Standing by for confirmation of spacecraft separation. Telemetry engineers at the Cape are waiting for data via the Guam tracking station.

0716 GMT (3:16 a.m. EDT)

T+plus 66 minutes, 14 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-19 spaeccraft. Separation of the payload is about two minutes away.

0715 GMT (3:15 a.m. EDT)

T+plus 65 minutes, 30 seconds. Third stage burn continuing to look good.

0715 GMT (3:15 a.m. EDT)

T+plus 65 minutes, 4 seconds. Good chamber pressure on the third stage.

0714 GMT (3:14 a.m. EDT)

T+plus 64 minutes, 53 seconds. Third stage ignition! The Thiokol Star 48B motor is firing to propel the GPS 2R-19 satellite into its targeted orbit for this launch.

0714 GMT (3:14 a.m. EDT)

T+plus 64 minutes, 17 seconds. The solid-fueled third stage has spun up and separated.

As the launch sequence continues with the third stage burn and subsequent deployment of the GPS 2R-19 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.

0713 GMT (3:13 a.m. EDT)

T+plus 63 minutes, 18 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.

0712 GMT (3:12 a.m. EDT)

T+plus 62 minutes, 42 seconds. Confirmation now received that Delta 2 rocket's second stage burn is in progress to boost the vehicle into a higher orbit. The Guam tracking site is providing the live telemetry relay from the rocket back to Cape Canaveral.

0710 GMT (3:10 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.

0700 GMT (3:00 a.m. EDT)

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

0655 GMT (2:55 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.

0640 GMT (2:40 a.m. EDT)

T+plus 30 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.

0636 GMT (2:36 a.m. EDT)

T+plus 26 minutes, 10 seconds. 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.

0630 GMT (2:30 a.m. EDT)

T+plus 20 minutes, 30 seconds. 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.

0626 GMT (2:26 a.m. EDT)

T+plus 16 minutes. The rocket has successfully achieved the intended parking orbit. The orbit is right on the pre-planned parameters.

0623 GMT (2:23 a.m. EDT)

T+plus 13 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 seven minutes.

0622 GMT (2:22 a.m. EDT)

T+plus 12 minutes, 15 seconds. The rocket is 97.6 miles in altitude, 1,904 miles downrange from the launch pad and traveling over 16,686 mph.

0620 GMT (2:20 a.m. EDT)

T+plus 10 minutes, 56 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-19 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.

0620 GMT (2:20 a.m. EDT)

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

0619 GMT (2:19 a.m. EDT)

T+plus 9 minutes, 30 seconds. 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.

0619 GMT (2:19 a.m. EDT)

T+plus 9 minutes. Altitude now 96 miles, downrange distance 1,167 miles and speed 15,116 mph.

0618 GMT (2:18 a.m. EDT)

T+plus 8 minutes, 30 seconds. Second stage engine chamber pressure continues to look good.

0617 GMT (2:17 a.m. EDT)

T+plus 7 minutes. The Air Force's downrange tracking station on Antigua Island has acquired the rocket's signal.

0616 GMT (2:16 a.m. EDT)

T+plus 6 minutes, 30 seconds. The vehicle is 86 miles in altitude, 688 miles downrange from the launch pad and traveling at 13,560 mph.

0615 GMT (2:15 a.m. EDT)

T+plus 5 minutes, 25 seconds. The vehicle is 74 miles in altitude, 491 miles downrange from the launch pad and traveling over 12,000 mph.

0615 GMT (2:15 a.m. EDT)

T+plus 5 minutes, 4 seconds. The rocket's nose cone enclosing the spacecraft has been jettisoned.

0614 GMT (2:14 a.m. EDT)

T+plus 4 minutes, 47 seconds. The spent first stage has been jettisoned and the Delta's second stage engine has ignited!

0614 GMT (2:14 a.m. EDT)

T+plus 4 minutes, 30 seconds. MECO. The first stage main engine cutoff is confirmed.

0614 GMT (2:14 a.m. EDT)

T+plus 4 minutes. A half-minute remaining in the first stage burn. Everything is reported normal aboard the vehicle.

0613 GMT (2:13 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.

0612 GMT (2:12 a.m. EDT)

T+plus 2 minutes, 40 seconds. The vehicle is 28 nautical miles in altitude, 79 miles downrange from the launch pad, traveling at 5,400 mph.

0612 GMT (2:12 a.m. EDT)

T+plus 2 minutes, 17 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.

0611 GMT (2:11 a.m. EDT)

T+plus 1 minute, 10 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.

0610 GMT (2:10 a.m. EDT)

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

0610 GMT (2:10 a.m. EDT)

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

0610 GMT (2:10 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.

0610 GMT (2:10 a.m. EDT)

T+plus 20 seconds. All six ground-lit solid boosters and the first stage main engine are firing to power the Delta away from pad 17A on this 68-minute ascent to deploy the GPS 2R-19 satellite.

0610 GMT (2:10 a.m. EDT)

LIFTOFF! Liftoff of the Delta 2 rocket launching another modernized Global Positioning System satellite and taking the next step to improve the accuracy of the world's premier navigation network!

0609 GMT (2:09 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.

0609 GMT (2:09 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.

0608 GMT (2:08 a.m. EDT)

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

0608 GMT (2:08 a.m. EDT)

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

0608 GMT (2:08 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.

0607 GMT (2:07 a.m. EDT)

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

0607 GMT (2:07 a.m. EDT)

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

0606 GMT (2:06 a.m. EDT)

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

0606 GMT (2:06 a.m. EDT)

T-minus 4 minutes and counting! The Delta 2 rocket is ready to launch the GPS 2R-19 military navigation satellite at 2:10 a.m. EDT from pad 17A at Cape Canaveral Air Force Station in Florida.

0605 GMT (2:05 a.m. EDT)

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

0604 GMT (2:04 a.m. EDT)

Two minutes remain in the built-in hold.

0602 GMT (2:02 a.m. EDT)

A provisional "go" to continue the countdown has been given by the launch director, pending a final approval from the Range.

0601 GMT (2:01 a.m. EDT)

Launch team readiness polling is underway.

0600 GMT (2:00 a.m. EDT)

Liftoff is 10 minutes away.

0555 GMT (1:55 a.m. EDT)

T-minus 4 minutes and holding. The countdown has entered the final planned hold point for today's launch attempt. During this planned 11-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 2:10 a.m. EDT.

0553 GMT (1:53 a.m. EDT)

The launch weather officer reports that all of the cloud rules are "go" for launch now. The thick cloud and anvil cloud rules had been "no go" over the course of the evening. But the conditions have improved in the last few minutes.

0553 GMT (1:53 a.m. EDT)

Upper level winds are "go" for launch, a ULA spokesman says.

0551 GMT (1:51 a.m. EDT)

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

0548 GMT (1:48 a.m. EDT)

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

0544 GMT (1:44 a.m. EDT)

The GPS 2R-19 spacecraft cargo atop the Delta 2 rocket is now switching to internal power for launch.

0544 GMT (1:44 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 leading to liftoff at 2:10 a.m. EDT.

0540 GMT (1:40 a.m. EDT)

The launch team is being polled for "ready" status to resume the countdown at the end of the hold as scheduled. As the clouds improve, another concern -- strong upper level winds -- could become a factor in the final count, an Air Force spokesperson says.

0534 GMT (1:34 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 an 11-minute hold is planned to sync up with today's revised launch time of 2:10 a.m. EDT (0610 GMT) for the Delta 2 rocket with the GPS 2R-19 spacecraft.

Today's launch will be:

  • The 332nd Delta rocket launch since 1960
  • The 1st to fly this year
  • The 135th Delta 2 rocket mission since 1989
  • The 58th GPS satellite to launch
  • The 47th time a Delta 2 has launched a GPS satellite
  • The 19th GPS Block 2R satellite and 6th modernized

0529 GMT (1:29 a.m. EDT)

The first and second stage engine steering checks have been completed.

0524 GMT (1:24 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 catch up on activities running behind schedule, which is handy tonight because of the weather-induced delay for first stage liquid oxygen loading has pushed back the timeline of work.

0523 GMT (1:23 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.

0517 GMT (1:17 a.m. EDT)

Range Safety is performing inhibited checks of the command destruct receivers. The CRDs would be used in destroying the Delta rocket should the vehicle veer off course or malfunction during the launch.

0512 GMT (1:12 a.m. EDT)

The launch weather officer reports the conditions continue to improve here at the Cape. In fact, he has increased the odds of acceptable weather for today's launch window from 40 percent all the way up to 80 percent. The rain has moved through, the back edge of the thick clouds should pass clear of the pad shortly and winds remain within limits.

The cloud cover is "no go" right now. But those clouds should be out of the area in the next 15-20 minutes and the weather would then be "go" for launch.

0505 GMT (1:05 a.m. EDT)

NEW LAUNCH TIME. Mission managers are going to adjust the target launch time to 2:10 a.m. EDT, one minute later than planned. This is due to a COLA, or Collision Avoidance, period that prohibits liftoff in the initial minute of today's window, ensuring the rocket isn't launched on a trajectory that would pass too close to an object already in space.

0504 GMT (1:04 a.m. EDT)

Loading of the Delta 2 rocket's first stage liquid oxygen tank has concluded. The filling process took 24 minutes and 17 seconds, ending at 1:04:16 a.m. The tank will be replenished through the countdown to replace the supercold liquid oxygen that naturally boils away.

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

0501 GMT (1:01 a.m. EDT)

The first stage liquid oxygen tank just reached the 95 percent full level. The "rapid load" valve was closed, with the slower "fine load" phase continuing to fill the tank.

0448 GMT (12:48 a.m. EDT)

Now 10 minutes into this approximate 25-minute process to fill the first stage liquid oxygen tank. The outer skin of the rocket is beginning to ice over as the supercold oxidizer pumps into the vehicle.

0439 GMT (12:39 a.m. EDT)

Now 90 minutes to launch. There is plenty of margin in the countdown timeline to catch up with the liquid oxygen loading without impacting the planned 2:09 a.m. EDT liftoff time.

0438 GMT (12:38 a.m. EDT)

LOX LOADING BEGINS. Cryogenic liquid oxygen, chilled to Minus-298 degrees F, has started flowing from the storage reservoir at Complex 17, through plumbing and into the bottom of the ULA 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.

0437 GMT (12:37 a.m. EDT)

The official "go" has been given by the launch director to start filling the rocket's first stage with liquid oxygen.

0434 GMT (12:34 a.m. EDT)

The rain has moved through the pad area and weather is now "go" for liquid oxygen loading.

0427 GMT (12:27 a.m. EDT)

The heaviest rain in this passing shower has already moved east of the launch pad. Conditions should be acceptable for fuel loading in about five minutes or so.

0421 GMT (12:21 a.m. EDT)

Initial preps for liquid oxygen loading are starting. The actual filling of the rocket's tank will have to wait until weather conditions at the pad are deemed acceptable. There is a rainshower moving over Complex 17 right now.

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

The launch team has completed work to turn on and configure the Delta's onboard guidance computer.

0410 GMT (12:10 a.m. EDT)

Cloud cover and rain have been issues throughout the evening, but the launch weather officer's latest update gives hope that conditions will be improving as the countdown nears liftoff time.

The weather reconnaissance aircraft is flying around the Cape area to evaluate conditions and relay observations to the weather team.

Anvil and thick clouds remain a worry. However, The thick clouds overhead seem to be thinning and moving through quickly.

A rainshower is passing over the pad right now. Although officials may need to delay the start of liquid oxygen loading until the shower passes, it should be gone within the next half-hour and the radar shows no further precipitation expected through the launch time.

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

The next major task in the count will be loading super-cold cryogenic liquid oxygen into the first stage starting in about 30 minutes.

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.

0354 GMT (11:54 p.m. EDT Fri.)

The first stage fuel tank of the Delta 2 rocket has been fully loaded for tonight's planned 2:09 a.m. EDT launch. The tank was filled with a highly refined kerosene, called RP-1, during a 19-minute, 32-second process that concluded at 11:53:14 p.m.

0350 GMT (11:50 p.m. EDT Fri.)

Rapid-loading of the RP-1 tank has concluded as 9,875 gallons have been pumped into the rocket. Fine load is continuing.

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

First stage propellant loading has passed the 9,000-gallon mark. This process to load the kerosene fuel takes about 20 minutes.

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

The launch team has computed that the full load for the first stage fuel tank is 10,078 gallons.

Once the tank is filled to 98 percent or 9,875 gallons, the "rapid load" valve will be closed and the slower "fine load" phase will continue to top off the tank.

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

The countdown is entering the final two-and-a-half hours to liftoff of the GPS 2R-19 spacecraft aboard the Delta 2 rocket. Fueling is underway, the launch team is not reporting any significant technical issues with the vehicle and the weather continues to move on through the area.

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

FUELING BEGINS. 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 tonight's launch.

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

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.

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

First stage helium and nitrogen pressurization is complete. And the "go" has been given for the start of fueling.

0314 GMT (11:14 p.m. EDT Fri.)

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.

0309 GMT (11:09 p.m. EDT Fri.)

BEGIN COUNT. The Terminal Countdown has been initiated for tonight's launch of the Global Positioning System 2R-19 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 2:09 a.m. EDT from pad 17A at Cape Canaveral Air Force Station in Florida.

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.

0300 GMT (11:00 p.m. EDT Fri.)

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 2:09 a.m. EDT.

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

A collection of beautiful photos from this evening's rollback of the mobile service tower is posted here.

0209 GMT (10:09 p.m. EDT Fri.)

T-minus 150 minutes and holding. The countdown has just entered a planned 60-minute built-in hold at Cape Canaveral Air Force Station. The Terminal Countdown will begin once this hold is concluded.

A persistent drizzle has been falling on the Space Coast this evening. But the rain seems to be passing through, so there's hope weather will be acceptable when the 2:09 a.m. EDT launch time rolls around.

FRIDAY, MARCH 14, 2008
2330 GMT (7:30 p.m. EDT)

The gantry is arriving at its launch position where it will be secured. Now, workers will turn their attention to configuring the pad and putting the final touches on equipment and the rocket before clearing Complex 17 later tonight. The three-hour Terminal Countdown will begin at 11:09 p.m.

Liftoff remains on schedule for 2:09 a.m. EDT, weather permitting. Skies are overcast and a wide area of rain is passing over Central Florida this evening.

2320 GMT (7:20 p.m. EDT)

The tower has moved clear of the rocket now and accelerated its speed.

The initial part of tower retraction is slow-going, with the structure rolling only a short distance to allow workers to tighten lanyards and ensure good clearance. Now, the tower is headed to driving to its launch position.

2249 GMT (6:49 p.m. EDT)

With liftoff time about just over seven hours away, the pad 17A mobile service gantry is starting to slowly roll away from the Delta 2 rocket.

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. This cocoon-like structure wraps around the Delta to offer weather protection and full access for workers during the pre-launch flow.

2215 GMT (6:15 p.m. EDT)

Under gray skies, the sliding doors on the backside of the pad 17A mobile service tower have been opened for the upcoming retraction of the gantry. The doors enclose the cleanroom area where Delta payloads get attached to the rockets during the campaigns leading up to launch.

The GPS spacecraft launching tonight was delivered to the pad on March 3, then hoisted into the cleanroom and bolted to its Delta for the ride to orbit. The rocket's two-piece nose cone to shroud the satellite during ascent through the atmosphere was installed around the GPS craft last Friday.

1930 GMT (3:30 p.m. EDT)

Preparations are underway at launch pad 17A this afternoon to ready the mobile service tower for its rollback a little later today. Pad workers are retracting access platforms and stowing gear in the tower in advance of the structure wheeling away from the Delta 2 rocket for tonight's countdown and launch.

1530 GMT (11:30 a.m. EDT)

The odds of acceptable weather tonight have worsened slightly in the latest forecast issued this morning. There's now a 60 percent chance that conditions will permit an on-time launch. Thick clouds and rain are the main worries for violating the launch rules.

"Upper level disturbance moving across northern Florida will increase cloud cover while producing showers and possibly a thunderstorm over the northern half of Florida this afternoon and evening," the weather team said this morning. "A second and stronger low pressure system over the south central U.S. although void of moisture will produce surface south-southwest flow over Florida over the next couple of days. Cold front associated with this system expected to pass through on Sunday afternoon.

"During the countdown and launch window the main concerns will be for the thick layered clouds and precipitation associated with the previously mentioned upper level disturbance."

Meteorologists are predicting scattered cumulus clouds at 3,000 feet, scattered altocumulus clouds at 8,000 feet and a broken deck of cirrus clouds at 25,000 feet, good visibility, southwesterly winds 10 gusting to 15 knots, a temperature around 64 degrees F and showers in the vicinity.

Should the launch be delayed 24 hours for some reason, the chances of good weather improves to 80 percent. Cumulus clouds, rain and ground winds would be factors for a Sunday morning launch try.


Another Global Positioning System satellite is about to launch into space, replacing a craft more than 15 years old.

Liftoff from pad 17A at Cape Canaveral aboard a United Launch Alliance Delta 2 rocket is scheduled for early Saturday morning at 2:09 a.m. EDT (0609 GMT). The day's available launch window extends 14 minutes to 2:23 a.m. EDT (0623 GMT).

"The Delta 2 and GPS programs are ready for this year's first launch, which will be our fourth Air Force Delta mission over a busy five-month span," said Col. Jim Planeaux, the mission director. "I am honored to lead such a talented and dedicated team of launch and satellite professionals."

The weather outlook calls for a 70 percent chance of acceptable launch conditions. Thick clouds and rain will be the concerns.

Meteorologists are predicting scattered cumulus clouds at 3,000 feet, scattered altocumulus clouds at 8,000 feet and broken cirrus clouds at 25,000 feet, good visibility, southwesterly winds 10 gusting to 15 knots, a temperature around 67 degrees F and showers in the vicinity.

The GPS 2R-19 spacecraft is the sixth in a series of eight with enhanced features designed to rejuvenate the GPS constellation.

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 are extremely proud of the increased capabilities these advanced spacecraft are providing to our warfighters as well as civil users worldwide," said Don DeGryse, Lockheed Martin's vice president of Navigation Systems.

The Terminal Countdown commences at 11:09 p.m. EDT, followed shortly thereafter by loading kerosene fuel and then supercold liquid oxygen into the first stage.

The 12-story Delta 2 rocket is propelled off the launch pad with its 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 Lockheed Martin-built 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 in a few days 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 A, Slot 4 position of the constellation to take the place of GPS 2A-15. That aging satellite, which was launched in September 1992 with a seven-year design life, will become an in-space spare.

The orbiting network emits continuous navigation signals that allow users to find their position in latitude, longitude and altitude and determine time.

"GPS provides users throughout the world with precise positioning, navigation and timing information. The improved capabilities of the GPS 2R-M satellites takes us a step closer to delivering and sustaining global navigation and timing service for our military, civil, and commercial users around the globe," said Col. David Madden, commander of the Space and Missile Systems Center's Global Positioning Systems Wing.

Watch this page for live updates throughout the countdown and launch!

Copyright 2008, all rights reserved.

Ares patch
The Ares Project will develop two new rockets to launch astronauts back to the Moon under NASA's Vision for Exploration. The Ares 1 will employ a single space shuttle solid rocket booster to loft the Orion crew capsule. The gigantic Ares 5 will haul the equipment and cargo needed for such lunar voyages. This is the Ares emblem.
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Project Orion
The Orion crew exploration vehicle is NASA's first new human spacecraft developed since the space shuttle a quarter-century earlier. The capsule is one of the key elements of returning astronauts to the Moon.
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