Delta 3 rocket falls short but still a success, Boeing says
BY JUSTIN RAY
Posted: August 24, 2000 at 1959 GMT
The $85 million booster lofted a satellite mockup in the demonstration launch aimed at proving the reliability of the Delta 3 after two earlier failures.
Mission planners had expected the Delta 3 to achieve an orbit with a low point of 100 nautical miles and high point of 12,637 miles. However, the actual result was a looping orbit going from 97.6 miles to 11,174 miles. The allowable margin of error was an orbit no lower than 10,973 miles.
Earlier today, rumors and speculation ran rampant throughout the aerospace and insurance industries that the Delta 3 had failed again.
Although the orbit reached was lower than planned, officials said it was within the margin of error.
"We were within the expected range," said Jay Witzling, Boeing's vice president of the Delta 3 program.
The rocket's second stage fired until it sensed the lack of fuel and then cut off, a procedure called Propellant Depletion Shutdown (PDS). This often times results in a higher-than-planned orbit by consuming all available propellant. The alternative is the rocket commanding the engine to shut down at a certain point.
With such a PDS engine shutdown planned, the orbit range can vary based upon pre-launch predictions, Witzling said.
Taking into account fuel temperatures, a prevailing head wind and other atmospheric conditions, Wednesday's launch remains a successful placement of the dummy satellite payload into space, said Witzling.
"If this had been a commercial communications satellite, it would have been within an acceptable orbit," company spokeswoman Christine Nelson said.
For every launch, satellite operators determine how high their craft should be delivered into a geosynchronous transfer orbit by the launch vehicle. The satellite then fires its own kick engine to raise and circular the orbit to geostationary altitude 22,300 miles high.
The desired altitude range serves as the bull's-eye for the rocket. But lesser rocket accuracy is accepted up to a point, ensuring the satellite doesn't have to use up its precious onboard fuel supply to compensate for a botched orbit.
Nelson said the orbit achieved by the Delta 3 would not have reduced a satellite cargo's life expectancy.
The payload launched by the Delta 3, however, was just an instrumented satellite simulator and not a real communications spacecraft.
Future Delta 3 missions will employ the Propellant Depletion Shutdown so the commercial payloads can reach the highest possible transfer orbit. This will save the fuel supply of satellites by using all of the rocket's propellant.
The Delta 3 rocket's first two launches in 1998 and 1999 both ended in failure. The first due to a software error that resulted in the vehicle losing control and exploding a minute into flight; then the second try ended when an upper stage engine malfunction caused a communications satellite to be stranded in a worthless orbit.
Boeing has 18 more Delta 3 launches ordered with the next planned sometime next summer, officials said before Wednesday's flight.
Flight Data File
Vehicle: Delta 3 (8930)
Launch date: August 23, 2000
Launch window: 1100-1500 GMT (7:00-11:00 a.m. EDT)
Launch site: SLC-17B, Cape Canaveral, Fla.
The Boeing Delta 3 rocket lifts off August 23 from Cape Canaveral carrying a simulated satellite cargo for a demonstration launch.
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The six solid rocket motors ignited on the launch pad burn out and separate from the Boeing Delta 3 rocket some 80 seconds after liftoff.
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The three air-start solid rocket motors separate from the Boeing Delta 3 rocket over 2 1/2 minutes into the launch.
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A video camera mounted on the second stage shows the spent first stage separate and nozzle extension deploy and ignition of the RL10B-2 engine.
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Animation shows a typical Boeing Delta 3 rocket launch from liftoff through spacecraft deployment.
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The inaugural Boeing Delta 3 rocket launches from Cape Canaveral on August 26, 1998 but explodes just over a minute into the flight.
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A close-up view of the Delta 3 rocket exploding in 1998 as captured from a long range tracking camera.
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The second Delta 3 rocket lifts on May 4, 1999 from Cape Canaveral with the Orion 3 satellite.
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Launch timeline - Chart with times and descriptions of events to occur during the launch.
Delta 3 rocket - Overview of the Delta 3 8930-model rocket.
Rocket diagram - Illustration shows the various components of the Delta 3.
Payload simulator - Description of the satellite mockup to be launched by Delta 3 and its research mission.
Orbit trace - A map shows the launch track for the mission.