Proba-3 infographic: Double spacecraft mission

The two satellites have been designed with maximum commonality in functioning and configuration. Both spacecraft share the same power generation and onboard data handling systems:

Occulter

Weighing about 250 kg, the cube-shaped Occulter bearing a 140-cm diameter disk will fly with the same face toward the Sun at all times. For the mission’s science operations, it casts a precisely controlled shadow onto the Coronagraph spacecraft. The Occulter is responsible for performing the high-accuracy formation control using cold-gas millinewton thrusters, producing minimum force equivalent to a single falling feather. The DARA radiometer is mounted on the Occulter’s Sunward side.

Coronagraph

The 300 kg Coronagraph spacecraft hosts the mission’s main ASPIICS coronagraph instrument. Like the Occulter, the spacecraft is designed to point the same face at the Sun. Flashing LEDs and a retro-reflector for lasers are mounted on the Coronagraph’s face to help guide the Occulter. Because the Coronagraph will often be shaded it possesses a single side-mounted solar panel to generate power. The Coronagraph has monopropellant thrusters to perform newton-scale manoeuvring.