Engineers in Belgium have been testing the laser metrology system for Proba-3, the European Space Agency’s mission formation flying.
Later this year, Proba’s two satellites will be launched together into orbit to maintain formation relative to each other down to a few millimetres, creating an artificial solar eclipse in space.
Proba-3’s ‘Occulter’ spacecraft will cast a shadow onto the other ‘Coronagraph’ spacecraft to block out the fiery face of the Sun and make the ghostly solar corona available for sustained observation for up to six hours per 19.5 hour orbit.
However, to maintain the position of a shadow just a few centimeters across on the Coronagraph satellite from the Occulter satellite around 150m (500ft) away, the two satellites rely on a suite of sensors, including inter-satellite radio links, GNSS, visual imaging and – for the most precise positioning at closest range – a laser metrology system.
The metrology system will shoot a laser from the Occulter spacecraft toward a corner cube retroreflector placed on the face of the Coronagraph spacecraft for tracking of relative position and attitude, achieving millimetre precision.
“To calibrate Proba-3’s laser metrology system, its performance was tested within the 60-m long Redwire cleanroom,” says Damien Galano, Proba-3’s mission manager. “The Coronagraph’s laser was reflected off a retroreflector and the resulting positioning measurements checked against absolute ‘ground truth’ using a separate laser tracking system.”
This mission is being put together for ESA by a consortium led by Spain’s Sener, with participation by more than 29 companies from 14 countries.
The Proba-3 platforms have been designed by Airbus Defence and Space in Spain with satellite integration by Redwire in Belgium. GMV in Spain is responsible for Proba-3’s formation flying subsystem while its main coronagraph instrument comes from Belgium’s Centre Spatial de Liège, CSL.
Proba-3 is due to be launched by PSLV-XL launcher from India in September.
