Air Force says plenty of good came from Delta 4 test
BY JUSTIN RAY
Posted: December 22, 2004
While stressing the positives of Tuesday's demonstration flight of the Boeing Delta 4-Heavy rocket and the mountain of data generated about the big booster's actions, Air Force officials on Wednesday acknowledged an "anomaly" occurred during the first stage and two university-built nanosats were lost after not reaching orbit.
The Air Force purchased this test launch as a dress rehearsal for the Delta 4-Heavy rocket before costly national security missions begin flying atop the vehicle next year. The rocket offers the largest payload-carrying capacity currently available in the Evolved Expendable Launch Vehicle (EELV) program that includes Lockheed Martin's Atlas 5.
"The Air Force/Boeing team will spend the next two months going through the pre-planned review of flight data in preparation for the next launch," the Air Force's Space and Missile Systems Center said in a statement Wednesday.
But the under-performance from the early shutdown of the Common Booster Cores left the upper stage to compensate, forcing its RL10 engine to fire longer and use more fuel than planned.
The exact duration of the upper stage burn was not immediately announced in real-time as live telemetry from rocket being relayed to Cape Canaveral broke up during a handover from one tracking site to another.
When the next station acquired the vehicle's signal a couple of minutes later, the burn was over. The nanosats were to be deployed in low-Earth orbit, but the Air Force said Wednesday that the tiny craft were released at far too low of an altitude to survive.
"The Nanosats were released at the proper time, demonstrating a new low-shock separation system, which will be used in future systems. In addition, the Nanosats were successfully integrated onto the DemoSat in a remarkably short four-month period, thus providing a successful demonstration of a responsive space mission," the Air Force statement said.
"However, the early shutdown resulted in separation at an altitude of approximately 57 miles, which was not sufficient to achieve orbit."
The upper stage then re-ignited for the second of three scheduled firings during the launch to reach the intended geosynchronous orbit. This burn was expected to produce an orbit with a high point of 19,650 nautical miles, low point of 148 nautical miles and inclination of 27.3 degrees. Although the exact numbers of the actual orbit reached were not formally released, Boeing indicated the altitude was close to the projections.
The rocket then began a five-hour coast to reach the orbit's high point where the final burn would occur to circularize the orbit at 19,623 nautical miles above the planet at an inclination of 10 degrees for deployment of the DemoSat primary test payload.
But the stage's fuel supply was greatly impacted by the extended maneuvers to overcome the first stage problem. Instead of firing for more than three minutes to achieve the proper orbit, the stage depleted its cryogenic propellants and shut down approximately a minute prematurely.
The result was an orbit featuring a high point of approximately 19,600 nautical miles (36,400 km), low point of 9,600 nautical miles (19,000 km) and inclination of 13.5 degrees. DemoSat was released as programmed into the elliptical orbit with the low point about 10,000 miles short of the target altitude.
"The EELV program office is leading an effort to determine the cause of this anomaly. The Delta 4 flight featured a substantial increase in telemetry over previous first-flight rocket launches. Engineers will be able to use this data to evaluate all aspects of the mission, including the early cutoff of the first stage. The Air Force has no plans to fly another Delta 4-Heavy flight demonstration."
Despite the trouble, the Air Force reported that the demo flight completed these primary flight objectives:
"We are very pleased with the overall performance of the Delta 4-Heavy Demo in meeting these test objectives," said Col. John Insprucker, Evolved Expendable Launch Vehicle program director at the Space and Missile Systems Center and the mission director for this launch.
"The EELV program and Boeing invested in today's demonstration launch to ensure that the Delta 4-Heavy, the only EELV Heavy variant available, is ready to launch our nation's most important national security payloads into space," said Dan Collins, vice president of Boeing Expendable Launch Systems. "While the demonstration satellite did not reach its intended orbit, we now have enough information and confidence in the Delta 4-Heavy to move forward with preparations for the upcoming Defense Support Program launch in 2005."
The first operational Delta 4-Heavy, presently scheduled for August, will carry the final Defense Support Program craft that detects enemy missile launches and nuclear weapon detonations from space. The rocket must fly a trajectory similar to the test flight's intended course to deliver DSP-23 directly into geostationary orbit over the equator. A problem like the one experienced Tuesday would leave the payload within an unusable orbit and uncertain of boosting itself the remaining altitude.
A secret National Reconnaissance Office payload is slated to fly on the second operational Heavy mission next December. What type of orbit this cargo is destined for has not been disclosed.
Beyond next year's two launches, the long-range military outlook for Heavy missions is sparse.
"The NRO still has another heavy satellite that will be ready to launch in about 2008," Col. Insprucker said at the pre-launch news conference earlier this month. "After that we've got a little hiatus, I think, until probably the Transformational Communication Satellite architecture comes forward."
The Delta 4-Heavy can loft payloads comparable in weight to the Titan 4 rocket that has been in service since 1989. But that Lockheed Martin-built booster is being retired after two more flights next year from Florida and California. The Delta promises to provide launches far cheaper than Titan.
Lockheed Martin's heavy-lift Atlas 5 configuration is proceeding through development and would be ready to fly its inaugural flight 30 months from the time one is ordered, the company has said.
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