KH-7, GAMBIT

RECONNAISSANCE IMAGING SPACERAFT

By © Charles P. Vick 2007 All Rights Reserved

05-25-07

Disclaimer

The opinions and evaluations stated here in are only the author’s and cannot be construed to reflect those of any Government agency, company, institute or association. It is based on public information, circumstantial evidence, informed speculation, and declassified U.S. intelligence community documents, official US government documents and histories, oral histories, interviews and engineering analysis. As with all data regarding the intelligence programs of the US intelligence community, this analysis is subject to revision--and represents a work in progress.

KH-7 GAMBIT

KH-7, GAMBIT

The KH-7 was the first high quality "close-look" reconnaissance satellite. The system was designed to work with CORONA to take higher resolution images of a smaller area. The ground footprint for GAMBIT was approximately 10 nm by 12 nm. The mean perigee was 92 miles, with two of the spacecraft dipping as low as 76 and 87 miles. It became operational from July 1963 to June 1967. Flew 38 missions; duration of missions spanned one to eight days. It utilized a single return bucket of film to earth for each mission. Successfully returned film on 34 of 38 missions; usable images obtained from 30 of those 34 missions. Returned 19,000 frames, totaling 43,000 linear ft. "Footprint" on the ground was approximately 10 nm by 12 nm; total ground coverage for all missions was about 6.6 million sq nm. intelligence community's first high-resolution surveillance or "spotting" imaging satellite. Best resolution was initially four ft (1.2 meters) on ground; by 1966, best resolution improved to two ft (.6 meters) Capable of imaging areas 12 nm wide, ranging from 5-400 nm long. Provided key cartographic information for large scale (1:50,000) maps for Department of Defense Priority targets for systems included Soviet and Chinese nuclear installations and ICBM sites.

Spacecraft Description

The KH-7 GAMBIT spacecraft had a maximum diameter of five feet or 60 inches with the standard 20.86 foot long Agena-D rocket stage. The over all spacecraft Agena-D rocket stage length was on the order of 38.9 feet. In most cases the spacecraft was apparently separated from the Agena-D stage leaving it with a mass of 4,410 pounds. The Agena-D stage carried the P-11 class sub-satellite package to orbit while the spacecraft separated from the Agena-D stage was controlled by the (OCV) Orbital Control Vehicle. Each spacecraft carried one primary imaging camera with only one General Electric film return capsule. Both the spacecraft and Agena-D stage carried no solar arrays for longer duration missions. It was launching to an average inclination of 97.21 degrees with and average apogee 186.86 miles and an average perigee 92.22 miles. There were a total of 38 launches with only two losses. It carried the usual assortment of Lockheed sun, earth and horizon sensors.

KH-7, GAMBIT Launches, (Program –AFP-188, AFP-206)

KH-7 GAMBIT Optical System

The KH-7 GAMBIT Kodak advanced lens drive scanning Optical Bar camera system with its forward rotating primary mirror and folding optics created images on large format 9 inch wide film. The improved KH-7 camera was the full development of the KH-6s LANYARD camera potential not otherwise possible with the original KH-6 camera due to payload mass constraints. This produced images with greater detail with a resolution down to between 48 and 24 inches. That is the objects that were of that size of 24 inches or above on a side could readily be identified from the imagery. The multi-position primary mirror had an approximate swath of perhaps less than 120-140 degrees. GAMBIT had a significant technical issue with lateral aiming of the camera. "If one target was directly under the satellite it could be difficult or impossible to move the camera to a target off to the side in the limited time available to get a picture before the spacecraft was out of range. As a result, the KH-7 was 'access limited' and the satellites usually finished their missions with unused film because the consumables needed to keep the spacecraft in orbit ran out before the film" (Richelson, J. "America's Secret Eyes in Space." New York : Ballinger, 1990, p 78.) The camera was actually smaller in diameter as it was mounted with in the five foot 60 inch diameter external airframe with an inner diameter close to 44 inches.

Chart II: Optical Swath Data Parameters for Imaging 06-27-04 © By Charles P. Vick 2004 All Rights Reserved

1. CORONA KH-4B swath was a 70 degree cross span with a maximum of 35 degrees off Nadir angle with a 5 degree width. This provided an imaging area with a minimum of 17.79 km. wide and 268.69 km. long.

2. The average KH-7 GAMBIT Block-I altitude was 148.3820 km is known to have used a maximum of a 140 degrees swath providing a known 741.2 km by 22.2360 km imaging area potential. (3) The average KH-7 altitude yields a 22.2360 x 370.60 km half swath imaging area using trigonometry.

3. When the highly refined KH-8 GAMBIT Block-II imaging system was introduced it provided the best imagery that was to come out of the GAMBIT film-based imaging systems over the KH-7 / GAMBIT Block-I system. While the average KH-8 altitude was 134.5124 km yields a swath imaging area of 739.14 x 20.1579 km. using trigonometry and assuming the same limits of 20 degrees and above elevation minimum view from the target area or 70 degrees off nadir angle from the spacecraft for a 140 degrees total swath potential.

4. The KH-9 imaging capability had known limits of 30 degrees elevation from the target or 60 degrees off nadir angle which yields a 120 degrees swath potential imaging area capability. The KH-9 imaging system apparently used the same KH-7, 8 film used in the CORONA format. The wider frames provided for higher resolution Hexagon images.

Apparent Off Nadir Angle Study
Off Nadir Angle for 140 km re 6371, re6511
Phi + Elevation + Nadir = 90 degrees
Degrees. Degrees Degrees
3 21.1 66.0 = 90 degrees
4 15.3 70.7 = 90 degrees
5 11.5 73.5 = 90 degrees
KH-7 140.00 km 69.58/20.42= 90 degrees
KH-7 148.3820 km 68.51/21.49= 90 degrees
KH-8 134.5124 km 70.00/20.00= 90 degrees
KH-8 134.5124 km 70.43/19.57= 90 degrees

References:

1. McDowell, Jonathan, US Reconnaissance Satellite Programs, Part-1, Quest, Summer 1995 pp. 22-33

2. SSB Satellite Support Bus, Lockheed Missile & Space Company pp. 1-20

3. Commercial Titan-III Users Manuel

4. Bus-1 Implementation Concept for Space Station Alpha, Lockheed Missile & Space Company, Inc., Nov. 25, 1993.,ppp1-4, 17-31, 64.

5. Day, Dwayne Allen, Sensitivity About Gambit And Hexagon Imagery Declassification, History of the Gambit and Hexagon Programs, The Recon Report September 20, 2000, FPSpace, Aug. 30, 2000.

6. Quick Facts about the KH-7 and KH-9 Mapping Imagery

7. Declassified MOL and Gemini – B design details & Declassified MOL Baseline Configuration studies

8. Day, Dwayne A., A Failed Phoenix: The KH-6 LANYARD Reconnaissance Satellite, Spaceflight, Vol. 39, May 1997, pp. 170-174.

9. KH-6 Camera System declassified NPIC document February 1963.

10. Day, Dwayne A, Pushing Iron Spaceflight, Vol. 46, July 2004, pp. 289-293.