RECONNAISSANCE IMAGING SPACERAFT SSB BUS DETAILS
By © Charles P. Vick 2007 All Rights Reserved
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.
Lockheed provided considerable insight into the propulsion support bus for the KH-11 spacecraft when it released the “SSB Satellite Support Bus,” Lockheed, Missile & Space Company Space Systems Division” documentation for space support payloads for satellite support conceptual development. The difference being that the solar array system described for SSB was not applied to the KENNON KH-11 spacecraft. Various details released on the KH-9B spacecraft also contributed to the understanding of the design of the KH-11, Satellite Support Bus SSB. From time to time Images taken by amateur astronomers of the KH-11 have been described to this analyst in addition to the available primary contract vendor literature and trophy award flag illustrations of the spacecraft clarifying the details.
The following details are quoted from the Lockheed, open literature on the SSB:
“SSB -Satellite Support Bus (p.5)
Table 1-1 Summary of SSB Characteristics and CapabilitiesSSB ASSEMBLY
- Diameter: 120-in.; adaptable to Space Shuttle cargo bay
- Length: (including engine) 114-in.; (9.25 feet) Equipment Rack 38-in. Orbit Adjust/Reaction Control Section 38-in., Booster Adapter 17-in. (not required for Shuttle).
- Weight: 3,606-lb. excluding propellants and gases
- Equipment section is 38 inches long and has 12 equal size cargo bays capable of supporting 550-lb. with a total of 12 cubic feet.
- Motor: Hydrazine monopropellant with quad-redundant propellant valves.
- Thrust level: 145- to 230-lb.
- Specific impulse: 230-see minimum.
- Propellant load: 7300-lb hydrazine in a 76.0-in. inside diameter aluminum tank.
- Pressurization: Internal blow down system with external re-pressurization; nitrogen pressurant.
- Propellant Temperature range: 70 to 100 degrees F.
- Passive propellant management device.
- Altitude Reference System
- Altitude determination accuracy for level flight at 100-300 nm using horizon sensor references: Higher altitudes require different Horizon Sensor look angle than presently used minor change.
- 0.24 degrees Roll, 0.28 degrees Pitch, and 0.35degrees Yaw
- Attitude control accuracy, with 0.12 degrees Dead-bands (0.13 in roll) is O.13 degrees in Roll) is 0.37 degrees roll. 0.40 degrees Pitch and 0.47degrees Yaw.
- Altitude control rates are determined by the thruster impulse bit, the vehicle mass distribution and disturbances. Typical values, including a large payload, are less than 0.001 deg/per sec for disturbance-free limn cycles.
- Typical settling time for small disturbances: 6 sec.
- Attitude accuracy for non-level menial night is subject to gyro drift at rates up to 1.0 deg/hr.
- Motors: 16 hydrazine engines in 4 modules.
- Thrust level: 2.5-lb minimum.
- Minimum impulse bit: 0.03- to .18-lb/sec to 1.0 cps.
- Specific impulse: 119 sec at 0.01 cps to 203 sec minimum steady state.
- Solar arrays: 172-sq-ft of active area in two deployable arms of 11 panels each. (Baseline arrays are not retractable.)
- Batteries: Four 60-ampere-hour nickel-cadmium secondary batteries.
- Arrangement: One-fourth of each array arm charges each battery.
- Average power: 600 waits, of which SSB requires 270 watts, with 330 watts available for payload. Peak power 2 kilowatts.
- Provides unregulated 28 v dc to main bus.
- Tracking System
- Compatible with SGLS capabilities and procedures.
- Up-link in 1750 to 1850 MHz band, down-link in 2200 to 2300 MHz band.
- Accuracies at 80 to 1440 nm: per SGLS specifications
- Uses a Stored program and remote sub-multiplexers for flexibility.
- Each of tape recorders can store 45 minutes of 64 kbps data for later readout at 256 kbps.
- Command selection of format and bit rate changes in flight.
- Optional selection based on customer needs.
- Capable of executing real-time and stored commands.
- Digital data link capability.
- 174-lbs weight allowed for the command system.
Table 1-2 Weight Summary (p.2)
|Equipment Rack Assembly||547|
|Battery Modules (2)||502|
|Orbit Adjust System (Dry)||821|
|Reaction Control System (Dry)||725|
|Solar Array Module||317|
|Electrical Distribution and Power Module||103|
|Attitude Reference Module||216|
|Telemetry & Tracking Module||153|
|Total SSB Dry Weight||3,606|
|OAS/RCS Pressurizarion Gas (Nitrogen)||79|
Ref. (SSB Satellite Support Bus, Lockheed Missile & Space Company. Space Systems Division)”
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