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APPENDIX O

MECHANICAL DESIGN CONSIDERATIONS

To assure a higher level of mechanical integrity of the spacecraft hardware for future missions, a thorough recheck of load paths and structural integrity is underway. In particular, a thorough study is being undertaken on vibration transfer functions of specific payload packages and components that may be critical to certain types and amplitudes of vibration stimuli.

However, For example:

The exact flight environment of the TV Subsystem is not completely known. there are several areas where preventive improvements have been made.

1)

2)

Structural modifications have been made to the DCU to reduce vibration
amplifications.

Modifications to the TV transmitter power supply were made to improve the
structural integrity of the transformer mounts and to provide damping.

Further investigations are being made on a shake table to determine vibration levels and frequencies at which critical components exhibit hazardous modes. Steps have been and will continue to be taken to alleviate or minimize the amplitudes of these modes. In particular, investigations of this type have been initiated on the following components:

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In addition, efforts are underway (or have been completed) to reaffirm the integrity of all spot bonding, stiffeners, fasteners, potting, conformal coating, mountings, connectors, cable runs, venting, and insulation of exposed high voltage conductors.

APPENDIX P

PTM TV SUBSYSTEM FAILURE IN A VACUUM THERMAL TEST

On 27 June 1962, the PTM Ranger TV Subsystem, in the original RA-6 through RA-9 configuration, was operated during a vacuum-thermal test approximately 45 minutes after the

start of chamber pump down. The chamber pressure at the start of the test was 1.2 x 10-4 mm Hg. The sequence of events in Table P-1 occurred during this test.

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Tests of individual assemblies following this failure revealed the following:

1) LCVR output to telemetry power supply was 27. 6 v (normal).

2)

3)

4)

Command switch would not step.

All six camera assemblies and the transmitters were not operational
Sequencer operated satisfactorily.

Subsequent investigation concluded that the failure of the PTM in this test was attributable to high voltage DC arcs caused by operation of the TV Subsystem when the pressure in the thermal shield or assemblies was in the critical pressure region. (See Appendix E.)

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Power Control Unit

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Power spectral density: see Section IV

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Proof Test Model: see Section IV

Radio Corporation of America

Radio Frequency

Real Time Command (from ground station to S/C)
(sec): second(s)

Stored Command (from CC&S to other units in S/C)
Spacecraft

Silicon Controlled Rectifier: see Appendix M

Static Phase Error

Establishes warmup/full power interval and sync pulses for

cameras

simulate

The time of Agena separation

Separation of booster engines from Atlas

(see Ledex)

Type Approval (testing): see Section IV

temperature

Refers to area or maneuver when S/C nears its target
Telemetry

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Cable with connector, from S/C to OSE, that separates at launch microsecond(s)

volt(s)

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BIBLIOGRAPHY

Information on the Television Subsystem design criteria and operational characteristics, as well as the Ranger 6 flight sequence and operational plans, are contained in the documents listed.

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