|
|
 The NRO conceived a “dual mode” capability for the GAMBIT spacecraft that could operate at two different altitudes.
|
In 1981, the Cold War was heating up. Ronald Reagan had entered
office in January after promising to restore America’s military power
and face down the Soviet Union. The Soviets were continuing a strategic
arms buildup, deploying mobile ICBMs that were nearly impossible to
track and new massive ballistic missile submarines, as well as naval
surface combatants. The United States was also about to deploy the
mobile Pershing II missile in Europe, despite the protests of European
populations.
| The
NRO explored the possibility of modifying the GAMBIT-3 reconnaissance
satellite to operate at a much higher operational altitude, thereby
increasing its ability to see more territory. This new capability was
referred to either as “Highboy” or “Higherboy.” |
But the United States intelligence community was also facing a
dilemma: a gap had opened in its intelligence collection capabilities.
The United States deployed three kinds of photo-reconnaissance
satellites. Two had high-resolution capabilities and the third was able
to image broad areas of territory in a single pass over the Soviet
Union, enabling photo-interpreters to count the number of strategic
bombers deployed at most Soviet airfields and to spot mobile ballistic
missiles in the field. But intelligence officials realized that they
would have no broad-area coverage for nearly a year, and they sought a
stopgap measure to close that gap. The solution was to launch a
specially modified version of the GAMBIT-3 reconnaissance satellite.
The GAMBIT
The GAMBIT was the most powerful reconnaissance satellite ever
produced by the National Reconnaissance Office. Although later
satellites had larger image-resolving mirrors, they flew in higher
orbits and so their resolution of objects on the ground was not as good.
GAMBIT’s large mirror, high-resolution film, and its ability to fly as
low as 72 nautical miles (133 kilometers) above the ground, allowed it
to take very high resolution photos. The United States launched 92
GAMBIT high-resolution reconnaissance missions between 1963 and 1984.
The GAMBIT-1 series entered service in 1963 and was retired by 1967,
superseded in 1966 by the GAMBIT-3 series with a more powerful camera.
The last of 54 GAMBIT-3 missions was launched in April 1984.
Over its 21 years of operational service, GAMBIT-3 underwent numerous
upgrades, gaining additional capabilities and ever-higher resolution.
The upgrades included:
1967: Ultra thin base film
1968: Use of SO-121 color film
1969: Dual Satellite Recovery Vehicles (SRVs), 14-day orbital life
1970: Use of 1414 High definition black and white film
1970: Low coefficient optical materials
1970: Factory to pad operations
1971: 20-day orbital life
1971: Lens formula change R-5
1972: 30-day orbital life
1972: Exposure slit change
1973: Increased film capacity (10,800 feet)
1973: Improved optical quality
1973: Satellite-to-satellite (SSquared) imaging capability
1973: Use of SO-124 high-definition black and white film
1973: Use of SO-131 false color IR film
1974: 45-day orbital life
1977: 9x5-inch dual platen camera
1977: 75-day orbital life
1982: Dual mode capability demonstrated
The last significant development in the GAMBIT program came as the program was nearly over, but it was not a new development.
The photographic system for the dual mode GAMBIT.
|
The origins of dual mode
In the early 1970s, as the National Reconnaissance Office (NRO)
planned to retire the CORONA search satellite and replace it with the
HEXAGON, NRO officials became concerned that HEXAGON schedule slips
would leave the United States without broad area search coverage for a
substantial period of time. So they explored the possibility of
modifying the GAMBIT-3 reconnaissance satellite to operate at a much
higher operational altitude, thereby increasing its ability to see more
territory. This new capability was referred to either as “Highboy” or
“Higherboy.” These were nicknames, not formal codewords, and had the
disadvantage of providing a clue about the satellite operating mode.
Eventually, those involved in the program settled on the ambiguous
designation “dual mode.”
| By
1981 the NRO was facing a dilemma. The next HEXAGON spacecraft would
not be ready to launch until spring 1982, creating a gap of over a year.
This made imagery intelligence analysts worried. |
The technical modifications for dual mode operations included
modifications to the camera system to adjust it for the higher orbit.
For example, at higher altitude, the image of the Earth below would move
through the camera more slowly. The camera had to account for this
moving image in order to prevent image smear on the film, and therefore
dual mode modifications included tweaking the camera to provide the
slower image motion compensation required. Another modification probably
involved one of the GAMBIT’s two Satellite Recovery Vehicles to enable
it to descend from a higher altitude than normal. Originally, dual mode
operations involved 80 days operation at 500 nautical miles (926
kilometers) altitude and 40 days at 75 nautical miles (139 kilometers).
In 1971 the NRO ordered three Higherboy modification kits for
delivery by 1972. HEXAGON eventually launched in June 1971, and the dual
mode GAMBIT-3 was unnecessary. The dual mode equipment was then placed
in storage, but reconnaissance officials were aware of its availability.
By 1981 the NRO was facing a dilemma. HEXAGON Mission 1216 was
launched on June 18, 1980, returning its fourth and last film return
vehicle to Earth in March 1981. But for reasons that remain unclear, the
next HEXAGON spacecraft would not be ready to launch until spring 1982,
creating a gap of over a year. This made imagery intelligence analysts
worried. The Committee on Imagery Requirements and Exploitation, known
by its acronym COMIREX, was responsible for selecting targets for
intelligence satellites. COMIREX officials were concerned that there
would be no broad area search imagery for twelve to fifteen months at a
time when the new president’s defense policies depended upon a good
accounting of Soviet strategic actions.
During this time the NRO had other assets in orbit, the third and
soon fourth KH-11 KENNEN electro-optical imagery satellites. The KENNEN,
unlike GAMBIT and HEXAGON, beamed its images to Earth via a relay
satellite. But KENNEN’s images were not as high-resolution as GAMBIT,
and did not cover as much area as HEXAGON.
The members of COMIREX determined that it was important to gain broad
area coverage of various spots, including the Soviet Union, and in
October 1981 COMIREX, following a presentation from the NRO about the
dual mode mission, recommended that such a mission be flown to close the
gap. The decision was not unanimous, however, and the Navy
representative to COMIREX objected, advocating a standard
high-resolution GAMBIT-3 mission. His specific reasons are not known,
but the Soviet Union was expanding its navy and had a number of large
surface combatants and nuclear powered missile submarines under
construction, and high-resolution imagery was valuable in determining
their construction and capabilities.
The photographic system for the dual mode GAMBIT.
|
The dual mode GAMBIT
In addition to the GAMBIT-3’s standard camera with its nine-inch wide
film, the camera incorporated a device that allowed the image to be
redirected onto a second platen holding five-inch film. This enabled the
GAMBIT-3 to perform its standard mission with the main camera, and to
carry special film, such as infrared or experimental film, in the second
camera. Both rolls of film then went to the two Satellite Recovery
Vehicles at the front of the spacecraft.
| On
March 20, 1982, the first SRV was ordered to disconnect from the
spacecraft and reenter. But an “electro-explosive device” on an
in-flight disconnect unit did not operate. |
GAMBIT Mission 4352 was launched on January 21, 1982, aboard a Titan
IIIB Agena at Vandenberg Air Force Base in California. The goal was a
120-day reconnaissance mission to capture both search and
high-resolution photography. The plan was to fly the first 90 days of
the mission at 300–350 nautical miles (556–648 kilometers)—significantly
below the original 500-nautical-mile design altitude—and the last 30
days at 78 nautical miles (144 kilometers). But because the weather was
excellent over several targets over China, Southeast Asia, the Middle
East, parts of Africa, and one other still-classified area, the
high-mode was extended to 97 days and the low-mode was shortened to 23
days. Film from the first 500 revolutions was stored in the first SRV,
and film from the last 625 revolutions was stored in the second SRV. The
second SRV had imagery from 125 high-altitude revolutions and 248
low-altitude revolutions.
But something went wrong.
On March 20, 1982, the first SRV was ordered to disconnect from the
spacecraft and reenter. But an “electro-explosive device” on an
in-flight disconnect unit did not operate. The device that malfunctioned
was new and had not been flown before, and had not been ground tested
under conditions simulating the high-altitude dual mode mission. The SRV
did not cleanly separate from the spacecraft. Backups to ensure
destruction of the reentry vehicle and its payload did not operate
correctly because of the original failure.
Fortunately, the internal “bucket” that contained the film was
separated from the heat shield and the thrust cone that deorbited the
vehicle. Designers had developed this technique in event an SRV was
stranded in orbit, figuring that the film would slowly degrade in space,
and when it eventually fell to Earth the bucket and its film payload,
lacking a protective heat shield, would burn up.
On the ground, controllers quickly determined that the SRV could not
be successfully recovered. So they decided to focus instead on the rest
of the mission, collecting remaining area search imagery and the
low-altitude mode imagery, and recovering the second SRV.
Ground controllers determined that the first SRV could spend up to 30
years in orbit before falling back to Earth. But they were concerned
that the fate that befell the first SRV could also happen to the second
one. So they devised a procedure to prevent that from happening. They
commanded the entire vehicle to de-orbit boost and then separated the
second SRV. This proved fortunate, because the second SRV’s in-flight
disconnect also malfunctioned. However, the SRV still separated due to
the new procedure and it was successfully air recovered on May 23, 1982.
Unfortunately, the film on the second SRV was degraded. Despite
months of investigation by many different experts inside and outside the
program, nobody could determine the source of the degradation.
HEXAGON Mission 1217 was launched on May 11, 1982, and restored broad
area imagery coverage. The GAMBIT program was nearing its end. GAMBIT-3
Mission 4353 launched on April 15, 1983, and operated successfully for
129 days, making it the longest GAMBIT mission ever flown. GAMBIT-3
Mission 4354 launched on April 17, 1984, ending the highly successful
GAMBIT program.
| On
September 28, 2002, the bucket came down, landing in deep ocean waters
and presumably sinking immediately. No recovery operation was conducted.
The last Higherboy mission, conceived in the early 1970s, was finally
over. |
Mission 4352’s unusual orbit did not go unnoticed by satellite
spotters. Anthony Kenden, who regularly wrote about American military
space efforts and monitored the orbits of American satellites by
obtaining two-line element data directly from NORAD—before the United
States government stopped releasing such data—noticed that the satellite
was unlike previous Titan IIIB Agena’s launched from Vandenberg. He
speculated that it was a radar satellite. Later, famed reporter Bob
Woodward wrote that the United States had launched a radar satellite in
1982 designated INDIGO. However, Woodward may have been referring to an
ongoing radar satellite program with that designation, and simply
confused it with a specific launch.
Ghost from the past
In the summer of 2002 the NRO Flight Safety Working Group learned
that the mission 4352 bucket, containing more than 6,800 feet (2,070
meters) of photoreconnaissance film, was soon going to reenter the
Earth’s atmosphere. By this time, the film was undoubtedly substantially
degraded, and reentry would damage it further or even destroy it. But
it was possible that something from this still-classified mission could
fall to the ground in unfriendly territory.
The NRO requested that Air Force Space Command concentrate its
sensors on the several pieces of debris from the mission that were still
in orbit, determining which one was the wayward bucket. Space Command
used radar and other sensors to track the bucket and determined that it
would reenter the atmosphere in four to five weeks.
The National Reconnaissance Operations Center started monitoring the
payload closely. They could not determine a reentry point until only
approximately four hours before reentry. As reentry grew near, they
determined that it would come down in the South Atlantic near
Antarctica. Radars tracked the bucket and the Aerospace Fusion Center
used data from Defense Support Program (DSP) satellites that detected
the heat of the bucket’s fiery reentry. On September 28, 2002, at 0218
UTC (10:18 pm on the 27th at NRO Headquarters outside Washington, DC),
the bucket came down, landing in deep ocean waters and presumably
sinking immediately. No recovery operation was conducted. The last
Higherboy mission, conceived in the early 1970s, was finally over.
source: http://www.thespacereview.com |
Posts
No comments:
Post a Comment