TRAAC [US Navy]
TRAAC (Transit Research And Attitude Control) tested gravity gradient stabilisation for the operational Transit satellites. Additionally, it carried Solar Cell Experiments and a Neutron Detector. TRAAC was launched with Transit 4B on a Thor-DM21 Able-Star launch vehicle.
The objectives of the mission were:
Since Satellite 4B met all objectives, the first objective was not necessary. Objectives 3 and 4 were met. TRAAC contained the first gravity gradient stabilization system orbited (Objective No. 2). This system responded to the extension command but, shortly thereafter, a drive motor malfunctioned and the 60-foot gravity gradient stabilization boom did not extend fully. After launch, it was difficult to execute operational commands while the TRAAC doppler transmitters were on, so that this system was maintained in the off position for substantial periods.
TRAAC contributed some early measurement data of the space environment resulting from the Pacific high altitude nuclear tests (Johnson Island). The albedo neutron flux was measured over a nine-month period. The gravity gradient libration damping spring operated satisfactorily.
This satellite was the first to employ electromagnets for temporary magnetic stabilization.
The satellite had an operating life of 270 days. As with Satellite 4-B, the TRAAC power system was greatly affected by artificial radiation and the satellite ceased transmitting 12 August 1962.
|Type / Application:||Technology|
|Contractors:||Johns Hopkins University Applied Physics Laboratory (APL)|
|Power:||Solar cells, batteries|
|Lifetime:||270 days (design)|
|Orbit:||957 km × 1109 km, 32.4°|
|TRAAC||1961 αη 2||15.11.1961||CC LC-17B||Thor-DM21 Able-Star||with Transit 4B|