Oreol 3 (Auréole 3) or ARCAD 3 (Arctic Aurora Density) was a joint Soviet and French satellite that was part of the Interkosmos Series, subset AUOS-T (automatic universal orbital station terrestrial studies).

The center portion of the spacecraft was a pressurized cylinder 1.6 m in diameter and 2.7 m in height. Extending from the central body and deployed after launch were the telemetry and command antennas, the solar panels, and six booms holding various sensors away from the spacecraft. Magnetic torquing and gravity gradient were utilized to achieve three-axis stabilization. The Z axis of the spacecraft was aimed toward the center of the earth, the × axis was the direction of the spacecraft velocity vector. Both passive and active thermal control were used. Eight solar panels and 28 V batteries provided a maximum power of 250 W, and an average power of 50 W.