ORS Mk.3 (ERS)

ORS 3 [USAF]

From 1962 the US Air Force launched a series very small technology satellites called ERS (Environmental Research Satellites). The satellites were built by TRW Systems Group for the United States Air Force Office of Aerospace Research (AFOAR). Depending on the shape, these satellites are also referred to as the Tetrahedral Research Satellite (TRS) or Octahedral Research Satellite (ORS).

The basic configuration of the ORS Mk.3 spacecrafts was a regular octahedron measuring 28 cm on a side. Solar cells mounted on each side of the faces provide sufficient electrical power to operate the experiments and the telemetry system when the satellite is illuminated by the sun. No internal battery or command system were provided. The satellite subsystems consisted of electrical power, antenna, telemetry, experiments, and mechanical structure.

Payloads:

• ORS 3 (ERS 17): Trapped radiation measurements for correlation with Vela data, Cosmic rays, Solar and galactic gamma and X-rays, 5.4 kg, operated for 104 days
• ORS 4 (ERS 18): investigation of the Van Allen belts; carried six Geiger-Müller counters, low- and high-energy photomultiplier detectors, an X-ray detector, a solid state electron and proton detector and a surface barrier proton detector

Orbits:

• ORS 3: 153 km × 112964 km × 34.4°
• ORS 4: 8604 km × 111229 km × 32.8°