Purpose of the flight and payload description
The objective of the flight was to perform a stratospheric drop test of a DISCOVERER satellite nosecone to evaluate the parachute and retrofiring systems of a capsule intended to reenter from orbit. DISCOVERER was a program started in 1958 presented to the public as a scientific project aimed at developing and acquiring biomedical data on animals, but its real purpose was to provide a cover story for the highly classified CORONA photoreconnaissance satellite program, designed to obtain images of Soviet and Chinese strategic military assets. The program was part of a complex effort directed by multiple agencies and involving various military and civilian contractors, including the U.S. Air Force, the Air Force Systems Command (AFSC), the Air Force Ballistic Missile Division (AFBMD), and the Central Intelligence Agency (CIA). General Electric (GE) supplied the recovery system for the capsules, including the thermal protection, retrorocket, and attitude control system.
During 1959 and 1960, the Discoverer program attempted ten orbital capsule recoveries, all unsuccessful. Seeking to address the failures, it was decided to test the problematic components by dropping a replica of the satellite nosecone from a stratospheric balloon reproducing every step of the recovery procedure. Originally planned for nine drops during April and May 1960 at Holloman Air Force Base in New Mexico, the program was expanded to a total of 31 drops, concluding with the final test in February 1961.
At left we can see a close-up of the test capsule and the telemetry equipment that provided flight data and received the release command. The equipment varied over time according to the specific test performed or the modifications introduced as the program advanced. For each test, the capsule (equipped with telemetry systems to monitor performance) was carried by a stratospheric balloon to about 100,000 feet and then released inside a fairing similar to that of the AGENA vehicle, simulating the critical re-entry and recovery phases. During the retrofiring system drop, an internal ejection programmer activated the spin system, the retrorocket, and the de-spin system in the correct sequence, and it also controlled the parachute deployment. The test capsules were fully instrumented to track internal performance and transmitted data to ground stations, accurately reproducing the Mach and dynamic loading conditions encountered during actual aerial recoveries.
Details of the balloon flight
Balloon launched on: 7/27/1960 at
Launch site: Holloman Air Force Base, Alamogordo, New Mexico, US
Balloon launched by: Balloon Branch, Holloman Air Force Base (HAFB)
Balloon manufacturer/size/composition: Zero Pressure Balloon General Mills 2.940.000 cuft (1.5 Mils. Taped)
Flight identification number: HAFB Nº 1142
End of flight (L for landing time, W for last contact, otherwise termination time): 7/27/1960
Overall weight: 1825 lbs
Extensive examination of the results from DISCOVERER flights I through XI indicated the possibility of tumbling and/or precession of the capsule upon separation from the AGENA vehicle, caused by the failure of one or more spin/de-spin rockets to fire properly. To correct this condition, a "cold gas" spin/de-spin system was incorporated into the DISCOVERER XII payload. The cold-gas system consisted of two separate subsystems, each providing a maximum thrust of 195 pounds with a firing duration of 0.8 seconds. Each subsystem included a gas bottle containing a nitrogen and freon mixture, a manifold, a squib-operated valve, and exhaust jets.
This was the fourth successful balloon drop of the recovery system series. The retro rocket and spin/de-spin systems functioned satisfactorily. It was the third successful dynamic test of the "cold gas" spin system. In the test, chaff was dispensed from the pilot chute deployment bag and did not contact the main chute, indicating that the prior interference problem was solved.
External references
- Balloon Branch Record U.S. National Archives
- GMI balloon performance record at Holloman AFB in Flight Summary Log, Winzen Research Inc. report (1963)
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