Both the larger Coronagraph and the smaller Occulter satellites are derived from ESA’s standard Proba platform.
The 340 kg coronagraph satellite has a volume of 1100 x 1800 x 1700 mm3. It hosts the coronagraph instrument which will point directly at the Occulter satellite to observe the corona of the Sun. It takes power from a deployable solar array.
Its front panel has an opening for the coronagraph instrument and for optical metrology sensors. The guidance, navigation and control (GNC) system consists of four reaction wheels, 2x3-axis gyroscopes, one three-headed star tracker, six Sun sensors and two GPS receivers. The majority of the formation flying system is housed within the coronagraph satellite which performs most of the manoeuvres.
The 200 kg Occulter satellite has a volume of 900 x 1400 x 900 mm3. Its main task is simply to block the Sun for the coronagraph instrument, with a 1400-mm diameter occulting disk on its face pointing away from the Sun.
The opposite side accommodates the satellite’s solar array. Its GNC system consists of four reaction wheels, three three-axis gyroscopes, one triple-headed star tracker, six Sun sensors and two GPS receivers.