The PROBA-3 mission concept consists of two independent, three-axis stabilized minisatellites flying in a formation with relative position control accuracy of less than 1 mm. The two minisatellites are referred to as CSC (Coronagraph Spacecraft) with a wet mass of ~340 kg and OSC (Occulter SpaceCraft) with a wet mass of ~200 kg. RedWire Space NV is developing the two satellites and is providing the on-board computer for both spacecraft.

The two spacecraft will be controlled in space as if they were two parts of a rigid structure (e.g. telescope optics and detector). This virtual rigid structure will be commanded to rotate and point to any desired direction. It will also be possible to set the relative distance of the two spacecraft from close-rendez-vous to 250 m.

The picture on the right shows the occulter spacecraft (OCS) and was obtained at RedWire Space in Antwerp in spring 2023. Both spacecraft have been integrated and are shown with the final layer of insulation, thus ready for the environmental validation. Please select the image for a high-resolution view. The individual subsystems visible in the photograph are:

  • Metrology to support formation flying
    • WAC (Wide Angle Camera)
    • NAC (Narrow Angle Camera)
    • OPSE (Optical Position Emitter Sensors)
    • FLLS (Fine Lateral and Longitudinal Sensor)
  • Star Trackers
  • S-band antenna
  • GPS (Global Positioning System) antenna
  • Sun sensor

 

 

The second photo shows the coronagraph spacecraft (CSC) was also taken in spring 2023 and shows the fully integrated CSC partly wrapped in multi-layer insulation. The following subsystems are visible on the photograph:

  • S-Band antenna
  • GPS antenna
  • ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigations of the Corona of the Sun)
  • Corner Cube Reflectors
  • InterSat link antenna
  • Sun senor
  • AMU (Acquisition Mire Unit)
  • thrusters

To the left of the photograph the launch adapter ring is visible, and to the right the adapter ring between CSC and OSC is visible.

Each spacecraft contains 4 reaction wheels, the CSC 8 1N mono propellant thrusters, and the OSC 12 10mN Cold Gas Thrusters. The thruster valves indicated in the photograph of the stacked configuration are to tank the cold gas into the OSC.

 

 

 

 

 

 

 

 

 

The two spacecraft in stacked configuration acquired in late 2023 at IABG ready for environmental validation. This is the launch configuration, with the OSC stowed on-top of the CSC and connected by the launch adapter (nicely visible in previous image). The solar array is stowed and shown in the back of the CSC.