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Tuesday, January 24, 2012
Old satellite teaching new lessons
by Scott Prater, 50th Space Wing Public Affairs
SCHRIEVER AIR FORCE BASE, Colo. (AFNS) -- Since Jan. 13, the 2nd Space Operations Squadron here has been busy disposing of an old and trusted satellite.
Squadron members could soon refer to the vehicle, known as SVN-30, as the satellite that keeps on giving because crews continues to garner invaluable information concerning how Global Positioning System Block IIA satellites behave as they degrade.
"We still have 12 GPS Block IIA vehicles on orbit," said Lt. Col. Dean Holthaus, the 2nd SOPS director of operations. "In addition to the normal end-of-life test and disposal procedures, we're conducting some tests (that) will help characterize how the other Block IIAs will behave with regard to their sensors, attitude control, etc., during future disposal operations."
The Air Force launched SVN-30 during September 1996 and the vehicle began providing position, navigation and timing data for GPS users worldwide the very next month. Designers placed four atomic frequency standards, or clocks, on the satellite during construction and it took nearly 16 years for all four to degrade beyond their usefulness. Operations crews began noticing that SVN-30's final clock was experiencing trouble during May 2011, so 2nd SOPS crews resurrected a residual satellite, SVN-35, to replace it in the GPS architecture.
That's when the satellite that keeps on giving leapt back into service.
"We've known for some time that SVN-30 was going to present itself as the perfect test bed," said Capt. Jayson Andersen, the 2nd SOPS assistant flight commander, GPS Mission Analysis. "Its navigation payload has degraded to the point where it can't support position, navigation and timing missions anymore, but its bus components are still operating on the primary side and there is plenty of fuel onboard. We have an incredible opportunity to gain some understanding and knowledge about how Block IIAs behave at the end of their operational lives."
More than 50 personnel, including 2nd SOPS and 19th Space Operations Squadron operators and orbital analysts, will coordinate with Boeing and Aerospace contractors to test the satellite before its disposal later this month.
"The major benefit for us is that the information we gain from testing will drive down risk in future disposal operations," Holthaus said. "We know if anything falls outside the norm during future operations, we'll have quantifiable data from SVN-30's disposal for use in a scenario where we can't dispose of a vehicle in the standard fashion."
Andersen contends that the 2nd SOPS is showing forward thinking by trying to protect high-value GPS slots, which could be compromised if a satellite were to become inoperable in place.
"We may not dispose of another vehicle for several years," he said. "But, when we are forced to dispose of it, we want to go into it with high confidence so that we have the lowest risk disposal possible. We want to be able to vacate that slot and bring in a new vehicle."
Final shutdown of SVN-30 will occur at the later stages of the operation, when crews will command the vehicle to fire its thrusters, pushing it out and up to a higher orbit, deplete the vehicle of its remaining fuel, discharge all batteries and open all valves. Telemetry shutdown and final contact with earth is planned for Jan. 27.
In addition to taking safety precautions to ensure a mishap free transition, the 2nd SOPS will also coordinate with external organizations, such as the Joint Space Operations Center, to provide predicted burn vectors and post-burn vectors so crews can conduct collision avoidance operations with other vehicles on orbit.
"I am proud of our team for their innovation and forward thinking in this regard," said Lt. Col. Jennifer Grant, the 2nd SOPS commander. "We are constantly trying to find ways to utilize every satellite on orbit to the best of our ability. This end-of-life testing will pay dividends in planning for future disposal, or contingency operations for future disposal operations."