http://www.schriever.af.mil/news/story.asp?storyID=123030470
6th SOPS says farewell to 'old friend': DMSP F-8 shuts down after 20
years, 100k orbits
by Staff Sgt. Don Branum
50th Space Wing Public Affairs
11/1/2006 - SCHRIEVER AIR FORCE BASE, Colo. -- The 6th Space Operations
Squadron here wished a fond farewell to an old friend Oct. 16.
After nearly 20 years and 100,000 trips around the earth, Satellite F-8
of the Defense Meteorological Satellite Program constellation shut down.
DMSP F-8 was the first satellite in the constellation to carry air and
soil moisture sensors with it into orbit and the third satellite in the
Block 5D-2 series, said 6th SOPS' 2nd Lt. Jeremy Cotton.
Satellite F-8 launched June 19, 1987 from Vandenberg Air Force Base,
Calif. Though its life expectancy was 30 months, it outlived
expectations and continued to perform its weather data-gathering mission
until Aug. 16, 1991, when an anomaly struck its primary sensor.
Maj. Michael Ruff of 6th SOPS was on crew at a 6th SOPS detachment in
Fairchild AFB, Wash., when the Operational Linescan System suffered a
power spike and went dark. The major has been with 6th SOPS for eight
years and has been involved with DMSP for 13.
"It wasn't a shock -- the engineers had indications up to that point
because of a problem with the grease in the bearings," Major Ruff
explained. "They could see some signs up to that point. The (OLS)
freeze-up was the big event."
Like a wheel on a shopping cart, the problem had started with gradual
sticks in the OLS that became worse and worse until the sensor failed
altogether. The OLS provides visual and infrared weather data and
accounts for most of the data DMSP satellites collect.
The OLS failure didn't mean F-8 was no longer useful, however. The Air
Force Research Laboratory and Center for Research Support here used the
ailing satellite as a testbed for research and development, and 6th SOPS
used it as a training platform.
"There are a couple of procedures we got to practice every time," Major
Ruff said. "On every revolution, you'd have to reset the OLS Gain Clock.
It was like anomaly contingency training every revolution if you wanted
it."
Maj. Clifton Stargardt of 6th SOPS attempted to coax F-8's satellite
control authority, or SCA, from the National Oceanic and Atmospheric
Administration, which owns and primarily operates the DMSP constellation
from its satellite operations center in Suitland, Md. The squadron
planned to use the satellite for continued training if they had been
able to gain control.
"We tried to get SCA, but it was just too late to push the process
through and make it happen," Lieutenant Cotton said.
Shortly thereafter, the shutdown process began.
NOAA and 6th SOPS use run command messages, or RCMs, to automate every
series of commands sent to a DMSP satellite, Lieutenant Cotton
explained. Because the satellites reside in low-earth orbits
approximately 550 miles above the earth's surface, operators have only a
handful of minutes to send commands to the satellite before its orbit
carries it beneath the horizon.
In this case, the RCM contained commands that shut F-8 down completely
-- sensors, telemetry and receiving antennas.
"There were commands in that RCM that I had never seen before,"
Lieutenant Cotton said.
Major Ruff said he was saddened to see the satellite go.
"We'll miss the training opportunities," he said. "True anomaly
resolution is what it gave us. You spend a lot of time on the
simulators, but it always feels different when you're working with a
satellite on orbit; with F-8, you got that real-time training experience."
F-8's record -- 19 years on orbit and 99,868 revolutions -- is hard to
match, Lieutenant Cotton said.
"The fact that it went around the earth almost 100,000 times is
phenomenal," he added. "The generation this satellite has spanned is
incredible for a satellite whose operational life is less than three
years."
--
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