Encyclopedia Astronautica
Gemini Satellite Inspector

Rendezvous with an Unmanned Satellite

Description - The objective of the flight was to rendezvous with a noncooperative target, namely the Pegasus satellite, photograph the meteoroid puncture panels to corroborate telemetered data, and remove and return a piece of one of the panels by extravehicular activity, if possible.

The basic mission plan was to: (i) inject into a low orbit coplanar with the Pegasus orbit for gross catch-up, (2) transfer open loop, based on tracking data, to a slow catch-up orbit slightly lower than the Pegasus orbit, and (3) perform a closed loop rendezvous after contact was made. An alternate plan would be to first rendezvous with an Agena and then use the Agena propulsion for the open loop transfer to the slow catch-up orbit. The Agena would then be discarded and a second closed loop rendezvous performed with Pegasus. The alternate was operationally complicated and would not be considered unless more extensive analysis shows the basic plan unworkable or undesirable.

After rendezvous was completed, a slow pass was to be made to photograph the meteoroid puncture panels. After the photograph run was completed, the two craft would be "docked" and a crewman would secure the specimen of the panel by EVA.

Technical or Scientific Benefit - The greatest benefit of the mission was the accomplishment of rendezvous with a non-cooperative target, thus opening the possibility of obtaining additional data using spacecraft with this capability. The information returned from the Pegasus should provide, in addition to substantiating data received from it by telemetry, direct information of the effects of meteoroid impacts on structures for use in future designs.

Effect on US Space Program - The experience obtained would be directly applicable in the areas of satellite data retrieval, resupply, maintenance, repair, and recovery. The knowledge of meteoroids arid their impact with a spacecraft would be considerably increased, which would benefit the Apollo and other future space programs. The mission would provide information for DOD directly applicable in the areas of satellite interception, inspection, and surveillance.

Prestige Value - The return of a piece of a spacecraft from orbit, a feat which had yet to be accomplished, would demonstrate advanced space skills and carry implications of an ability to exercise access to any orbiting object at will.

Performance Feasibility - Preliminary analysis showed that if the OAMS was augmented by the addition of two sets of tanks and four 45 kgf thrusters, and if some of the additional delta-V capability was used to extend the Gemini Launch Vehicle payload capability, rendezvous with Pegasus was possible. Analysis showed that 390 kg of the 845 kg of propellant loaded in the OAMS at liftoff could be used to inject the Gemini into a 160-185 km orbit. The remaining 455 kg of propellant would be sufficient to complete the mission. The weight change associated with the change in spacecraft configuration and propellant loading, and the use of eight retrorockets for retrograde from the Pegasus orbit, were considered in the analysis.

Extensive analysis of: (i) injection performance, (2) rendezvous with a spacecraft in an elliptic orbit, and (3) of retrograde and re-entry would be required to more definitely establish the delta-V capability of the spacecraft and the delta-V required for rendezvous and retrograde.

Cost Feasibility - The first unit cost was estimated to be $19.75 million with each additional unit costing $1.75 million, plus the coat of the spacecraft and launch vehicle.

Schedule Feasibility - It was estimated that a Gemini could be modified in approximately 20 months.

Operations Feasibility - The effect of the changes required, (OAMS augmentation and possible computer program changes) would make little difference in over-all ground operations. Flight operations would be similar to those for Gemini and were expected to be straightforward.

Radiation hazard over the South Atlantic might require flight operations at the Pegasus altitudes to be performed when the orbit did not enter this tone, according to a radiation analysis conducted using two different radiation models.

Impact on Gemini Program - The impact of the Pegasus mission on the Gemini Program would be principally that of sustaining a fairly sizeable engineering effort to accomplish the propulsion system configuration changes and to insure the integrity of the associated structural changes. In addition, changes to checkout equipment end AGE would have to be made. The magnitude of these changes were not ascertained to date.

Aside from the actual hardware changes, the suitability of: (i) the Gemini scheme of rendezvous when in elliptic orbit, (2) the re-entry control scheme when re-entering from high orbits, and (3) the launch guidance back-up for controlling an OAMS augmented injection would have to be established. If any of the three were to give unsatisfactory performance, a new scheme would have to be devised, programmed, and procedures revised.

Crew Size: 2.

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