BY JUSTIN RAY
May 11, 2000 -- Follow the countdown and launch of a Boeing Delta 2 rocket with the U.S. Air Force's GPS 2R-4 navigation satellite. Reload this page for the very latest on the mission.
THURSDAY, MAY 11, 2000
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Over the coming month, activities to prepare the satellite for service will include deploying its solar arrays in order to generate power and recharge onboard batteries, manuevers to circularize the orbital altitude and testing and of the spacecraft bus and communications payload.
Check back later tonight for a full report on the launch, movie clips and images.
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The launch ignition sequence will begin at T-minus 2 seconds when a Boeing engineer triggers the engine start switch. The process begins with ignition of the two vernier engines and first stage main engine start. The six ground-start solid rocket motors then light at T-0 for liftoff.
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The U.S. Air Force has declared the NAVSTAR Global Positioning System 2R-4 spacecraft is officially "go" for launch this evening. The spacecraft will join 27 other operational GPS satellites in space to provide precision navigation and timing information to military forces and civilians on land, in the air and at sea around the globe. Officials are launching the craft to replace an older GPS satellite that has malfunctioned after reaching the end of its extended life.
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Over the past few minutes, the rocket's first stage RP-1 fuel tank was pressurized and the third stage telemetry system was turned on.
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For these NAVSTAR GPS launches, Boeing uses a model 7925-9.5 Delta 2 rocket. The expendable launch vehicle consists of three stages, nine strap-on solid rocket boosters and a 9.5-foot diameter payload fairing. The rocket stands 126 feet tall.
The rocket's first stage is powered by the liquid-fueled RS-27A main engine built by Rocketdyne, a division of Boeing. The engine will fire for the first 4 minutes, 20 seconds of flight, consuming the RP-1 kerosene and liquid oxygen loaded aboard the rocket early this evening. The first stage also features nine Alliant Techsystems solid-propellant thrust augmentation motors. Six will be ignited at liftoff and burn for 63 seconds. The remain three motors will be lit in flight 65 seconds after launch. At T+plus 66 and 67 seconds, the spent ground-start casings will separate in two groups of three to fall into the Atlantic Ocean. The air-start motors will be jettisoned 2 minutes, 11 seconds into flight.
Some 4 minutes, 30 seconds after liftoff, the first stage will be jettisoned and the second stage will take over. The Aerojet AJ10-118K engine will ignite for the first time at T+plus 4 minutes, 34 seconds, beginning 6-minute, 9-second firing. The engine burns Aerozine-50 fuel and nitrogen tetroxide oxidizer. The oxidizer and propellant were loaded aboard the rocket on April 19. The payload fairing will be jettisoned 4 minutes, 50 seconds into flight. Following the cutoff of the second stage engine, the second stage with the third stage and attached GPS spacecraft will coast for about nine minutes before another firing will occur. That 35-second burn will set up a fast-paced sequence of events to deliver GPS 2R-4 into its planned orbit. Following the second stage's second burn, at T+plus 21 minutes, 19 seconds, the stage will separate from the third stage. The Thiokol-built Star 48B solid-fuel third stage will then ignite 40 seconds later. The stage will fire for one minute and 26 seconds. Spacecraft separation will complete this 278th Delta mission at T+plus 25 minutes and 19 seconds.
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The Navigation Signal Timing and Ranging Global Positioning System (NAVSTAR GPS) was established in the 1970s to provide the military with navigation data for ground, sea and air forces. The first 11 satellites, known as Block 1, were launched from 1978 through 1985 and served to test the fundamentals behind the GPS concept. Beginning in 1989, the Block 2 and 2A series satellites began flying to form the current constellation that provides precise navigation data not only to the military but civilians as well.
In 1997 a newer, more advanced series of GPS satellites, the Block 2R, debuted. However, the first was lost in a launch failure. The second was successfully launched in July of that year. This evening, the fourth of 21 is scheduled to leave the Earth aboard the Delta 2 rocket. The craft are considered to be operational replenishment satellites and are developed by Lockheed Martin. They will carry GPS into the next century. Block 2R satellites are designed to provide at least 14 days of operation without contact from controllers and up to 180 days of operation when operating in the autonomous navigation (AUTONAV) mode. The spacecraft maintain their accuracy by communicating with other Block 2R satellites in orbit. This so-called cross-link ranging will be used to estimate and update the parameters in the navigation message of each Block 2R satellite without contact from ground control. Other enhancements include reprogrammable micro-processors for upgrading in-flight, additional radiation protection, greater fuel capacity, the ability to determine their own position and two atomic clocks working at all times, providing a "hot backup."
The GPS constellation is comprised of 24 primary satellites divided into six orbital planes with four spacecraft in each. They circle in formation about 10,900 nautical miles above Earth every 12 hours in orbits inclined 55 degrees to the equator.
The continuous navigation signals sent from the satellites allow users to find their position in latitude, longitude and altitude and measure time. A GPS user receiver measures the time delay for the signal to reach the receiver, which is the direct measure of the apparent range to the satellite. Measurements collected simultaneously from four satellites are processed to solve for the three dimensions of position, velocity and time. Military users can determine their location to within feet, speed within a fraction of a mile per hour and time to within a millionth of a second. Positioning accuracy for military users is nominally 16 meters, while accuracy for civilian users is nominally 100 meters.
Countless uses have been found for the revolutionary GPS system. Everyday, GPS guides U.S. military troops, aircraft, submarines and ships around the globe. Troops also relied on the system extensively in the featureless desert battlefield of the Gulf War. Weapons can use GPS data for guidance. GPS also found its way into the civilian commercial market - assisting planes, automobiles, boats, hikers and map makers.
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The second stage was loaded with its storable nitrogen tetroxide and Aerozine 50 fuels on April 19; and the third stage and strap-on booster rockets are solid-propellant.
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WEDNESDAY, MAY 10, 2000
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Once the countdown gets underway, the launch team will begin pressurizing the first and second stage helium and nitrogen systems and second stage fuel tanks. In addition, the rocket's guidance computer will be turned on. Loading of 10,000 gallons RP-1 fuel, a highly refined kerosene, into the first stage is slated to start in about 20 minutes, and liquid oxygen tanking will follow at about 8 p.m. EDT.
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At pad 17A, the 12-story mobile service tower has been retracted to the launch position and final work is underway to prepare the complex for liftoff. Tower rollback occurred at about 4:15 p.m. EDT, nearly four hours later than planned due to the threat of local thunderstorms.
The terminal countdown will be started at 6:48 p.m. EDT at the T-minus 150 minute mark. Two holds are scheduled into the countdown -- 20 minutes at T-minus 20 minutes and 10 minutes at T-minus 4 minutes.
The rocket will deploy the NAVSTAR Global Positioning System 2R-4 military navigation satellite into orbit for the Air Force some 25 minutes after launch.
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TUESDAY, MAY 9, 2000
Launch attempts for the Delta 2 and its U.S. Air Force Global Positioning System Block 2R-4 satellite cargo on April 21 and 22 were scrubbed by a problem with ground support equipment and then by a last-minute concern with the payload.
The equipment glitch was fixed after the first night's delay. But Air Force officials called off the second try a few hours before the launch window opened to allow engineers time to conduct a precautionary assessment of the solar array deployment mechanism used by the Lockheed Martin-built GPS satellite.
"A potential issue was identified while inspecting another spacecraft being prepared for launch which led the Air Force to stand down from the launch and conduct an analysis," the Air Force said in a statement to Spaceflight Now.
"Additional data was collected from all the satellites in storage. That data was reviewed along with design requirements. The resulting assessment is that the satellite currently awaiting launch is ready to go into orbit."
The $42 million satellite will be put to work soon after reaching space to replace a sister-craft that failed on March 26 when its onboard reaction wheels, which are need for orienting in orbit, shut down. The now-decommissioned satellite was 11 years old and had well exceeded its design life. It was the first operational GPS spacecraft launched to construct a network of 24 orbiting satellites that provide precision location and timing information for U.S. military forces around the globe. Civilians can also use the GPS system.
The flurry of recent launches and related tests at Cape Canaveral have extended the wait before another launch opportunity was possible for the Delta 2 rocket. And with even more launches scheduled over the next two weeks, officials have only Wednesday and Thursday night to get the rocket airborne or else delay until around May 20.
Launch pad technicians on Tuesday were making final preparations for Wednesday's countdown and mission. Steering checks of the rocket's bell-shaped engine nozzles were performed, along with loading ordnance aboard the vehicle and sealing the protective nose cone enclosing the GPS satellite atop the Delta 2, a Boeing spokesman reported.
Senior officials held a brief Flight Readiness Review Update to discuss the status of the rocket, satellite, Range, weather and other factors associated with the launch. With no significant problems addressed, managers cleared the mission preparations to continue.
Meteorologists are calling for generally favorable conditions for liftoff with a 70 percent chance of meeting the launch weather rules. The main threats will be thunderstorm anvil and debris clouds approaching the rocket's flight path. Launch Weather Officer Joel Tumbiolo gave this overview on Tuesday:
The launch time forecast calls for a few clouds at 3,000 feet and scattered clouds at 12,000 and 25,000 feet, visibility of 10 miles or better, southerly winds at 10 gusting to 15 knots, a temperature between 74 and 76 degrees F, relative humidity of 50 percent and isolated thunderstorms in the vicinity.
Should the launch be delayed to Thursday evening for some reason, there is an 80 percent chance of good conditions with the same weather concerns. The 29-minute launch window that night will open at 9:44 p.m. EDT.
On Wednesday, the 12-story mobile service tower at pad 17A will be rolled away from the rocket just after 12 noon EDT. The terminal countdown is slated to get underway at 6:48 p.m. EDT.
We will provide live extensive coverage of the launch throughout the day tomorrow with play-by-play reports during the final three hours of the countdown and 25-minute-long launch. In addition, Spaceflight Now will offer a live QuickTime streaming video broadcast of the launch beginning at about 9 p.m. EDT.
WEDNESDAY, APRIL 26, 2000
The spacecraft is now due for launch on May 10 at 9:48 p.m. EDT (0148 GMT on 11th) aboard a Boeing Delta 2 rocket. Liftoff will occur from pad 17A at Cape Canaveral Air Force Station in Florida.
The Air Force decided to delay the launch to make sure an issue recently uncovered with the deployment mechanisms on similar Lockheed Martin Space Systems-built satellites still at the factory would not affect the $42 million spacecraft once in Earth orbit.
Officials said this week the concern was put to rest and the GPS 2R-4 satellite was ready for flight. It will replace the very first GPS satellite launched into the Air Force's space-based navigation system 11 years ago.
The new launch date could have been sooner but the Air Force-controlled Range is booked with other launches and tests that will preclude the Delta from trying before May 10.
SATURDAY, APRIL 22, 2000
"The decision to delay the launch was made to ensure the spacecraft is absolutely prepared for launch," said Lt. Col. Blaise Kordell, Air Force Launch Director.
A ground power supply problem that originally cancelled Friday night's attempt has been resolved.
When the next launch try will be made is not yet known. The Air Force-run Eastern Range that governs all Cape Canaveral and Kennedy Space Center launches in Florida previously needed 48 hours between flights of different space vehicles to reconfigure its tracking, communications and safety systems.
However, recent upgrades that went into effect April 1, now allow the range to switch its networks within 24 hours for different rockets, Air Force spokeswoman Lt. Alana Austin said.
The space shuttle Atlantis has reserved the Range for Monday's planned launch, with backup attempts on Tuesday and Wednesday. In addition, the Air Force plans to conduct a mission rehearsal involving a Titan 4 rocket on Friday.
We will provide additional information on this launch when it becomes available.
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The next major event leading up tonight's flight will be starting the Terminal Countdown at 8:01 p.m. EDT. Officials scrubbed the launch last night before starting the count.
The launch time remains set for 11:01 p.m. EDT, the opening of a 29-minute window. Weather forecasters say there is less than a 10 percent chance conditions would halt the launch.
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If the launch is cleared, liftoff will occur during a window of 11:01 to 11:30 p.m. EDT (0301-0330 GMT). Air Force weather forecasters are predicting near-perfect conditions tonight.
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Engineers are working to correct the problem and officials hope to make another try at launching the rocket in 24 hours. Saturday's launch window extends from 11:01 to 11:30 p.m. EDT (0301-0330 GMT Sunday).
"The Air Force launch director is very confident" the problem will be resolved in time for an attempt on Saturday night, Air Force spokeswoman Lt. Alana Austin said.
Air Force weather forecasters say there is a 90 percent chance of good weather Saturday night. The only slight concern is gusty ground winds.
If the Delta does not fly tomorrow, the Air Force will have to delay the mission until at least the middle of next week because of the upcoming space shuttle launch on Monday. Exact availability of the Air Force-run Eastern Range that governs all Cape launches was not immediately known, Austin said. However, it might be possible for the Delta to squeeze in another try on Wednesday provided the shuttle launches on schedule. A mission rehearsal is planned involving a Titan 4 rocket on April 28 and an Atlas rocket is slated for launch on May 3. The Range needs 48 hours between events to reconfigure its systems.
Be sure to watch our time-lapsed movie of today's mobile service tower retraction from around the Delta 2 rocket at launch pad 17A.
We will update this page as events dictate on Saturday. When the launch does occur, you can follow the final hours of the countdown and the 25-minute flight through our play-by-play reports.
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FRIDAY, APRIL 21, 2000
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The weather forecast looks good for tonight's 11:05 p.m. EDT (0305 GMT Saturday) liftoff, with meteorologists reporting only a 10 percent chance of a weather-related delay.
Check back later today for photos of the tower rollback, continuous countdown updates, and live streaming video coverage of the liftoff.
THURSDAY, APRIL 20, 2000
Boeing and Air Force officials this morning completed the traditional Launch Readiness Review to determine if the rocket, satellite and ground systems were prepared for the mission. No significant problems were uncovered and the launch was cleared to go forward as planned.
Liftoff is planned for 11:05 p.m. EDT Friday (0305 GMT Saturday) from pad 17A at Cape Canaveral Air Force Station in east-central Florida. There will be a 30-minute window extending to 11:35 p.m. in which to launch the rocket before having to wait 24 hours.
Weather forecasters are optimistic conditions will allow the launch to go off on schedule. There is only a 20 percent chance of weather problems. The main concern will be thunderstorm anvil clouds, which might develop near a weather front expected to approach the Cape late Friday. If the clouds move within 10 nautical miles of the rocket's flight path, the launch would have to be delayed. Such electrically-charged clouds are troublesome because they could cause the rocket to trigger lightning, potentially destroying itself.
At liftoff time, Air Force Launch Weather Officer Joel Tumbiolo predicts a few clouds at 3,000 feet and scattered clouds at 25,000 feet, visibility of 10 miles or better, west-southwesterly winds 15 gusting to 20 knots, a temperature of 74 to 76 degrees F and relative humidity of 50 percent.
If the launch is delayed until Saturday night for some reason, there is a 90 percent chance of acceptable conditions with the only concern being gusty ground winds.
The passenger for this 278th Delta rocket launch is formally known as the Navigation Signal Timing and Ranging Global Positioning System Block 2R-4 satellite. More simply put, it is NAVSTAR GPS 2R-4.
The $42 million craft is the fourth in a series of advanced GPS satellites built by Lockheed Martin Space Systems to replace older spacecraft in the Air Force's navigation constellation. The GPS network relies on 24 primary satellites orbiting 10,900 miles above Earth, providing highly accurate position, speed and timing information to military forces around the world.
GPS 2R-4 is slated to take over for the failed GPS 2-1 satellite, which reached the end of its life on March 26 after suffering a shutdown of its onboard reaction wheels need for orienting in space. The Air Force decommissioned the satellite -- the first GPS spacecraft launched to form the current constellation 11 years ago -- on April 14.
Read our launch preview story for further details on the satellite, rocket and the mission. This will be Boeing's third launch in 2000 and second to occur from Cape Canaveral.
On Friday, Boeing workers plan to retract the 12-story mobile service tower from around the rocket at about 3 p.m. EDT. The terminal countdown will be started at T-minus 150 minutes at 8:05 p.m. EDT. Two built-in hold are scheduled at T-minus 20 minutes and T-minus 4 for a total duration of 30 minutes. That will lead to the opening of the launch window at 11:05 p.m. EDT.
Check back on Friday for updates throughout the day and live continuous reports during the final three hours of the countdown and 25-minute long launch.
Launch - Images of the Delta 2 rocket from the countdown and launch.
The Boeing Delta 2 rocket lifts off on May 10 from pad 17A at Cape Canaveral carrying the GPS 2R-4 satellite for the U.S. Air Force.
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The Delta 2 rocket's three air-lit solid rocket boosters are ignited and the six ground-start motors are jettisoned.
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A time-lapsed movie shows the 12-story mobile service tower being rolled away from the Boeing Delta 2 rocket at launch pad 17A on April 21.
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Animation depicts the GPS satellites and the Global Positioning System orbital constellation.
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The mission patch designed by the U.S. Air Force. "Sparky" is a nickname given to the satellite because of electrical problems it experienced previously.
Flight Data File
Vehicle: Delta 2 (7925)
Payload: GPS 2R-4
Launch date: May 11, 2000
Launch window: 0148-0217 GMT (9:48-10:17 p.m. EDT on 10th)
Launch site: SLC-17A, Cape Canaveral, Fla.
Launch Preview - Our story gives a complete report on the upcoming launch.
Launch timeline - Chart with times and descriptions of events to occur during the launch.
Orbit trace - A map shows the launch track for the mission.
Delta 2 rocket - Overview of the Delta 2 7925-model rocket used to launch GPS satellites.
Global Positioning System - Description of the U.S. Air Force's space-based navigation network.
GPS constellation - Chart shows the current status of the orbiting GPS satellite fleet.
Explore the Net
Delta 2 - Official Web site of Boeing's Delta 2 expendable launch vehicle program.
GPS - Global Positioning System Joint Program Office at U.S. Air Force.
LMMS - Lockheed Martin Missiles & Space built GPS 2R-4.
1st Space Launch Squadron - Oversees Delta rocket launches and facilities at Cape Canaveral Air Force Station in Florida.
History of Delta - A private Web site devoted to past Delta launches with valuable facts and figures.