Proba-3’s Coronagraph and Occulter spacecraft get closer to each other in preparation for the world’s first-ever precision formation-flying attempt.
At a safe distance of 200 metres, the Occulter spacecraft captured a series of images of its Coronagraph twin using the Visual Based System – a device equipped with two cameras that will play a crucial role during the mission’s corona observations phase.
In the Occulter’s view of the Coronagraph (bottom right) several features of the spacecraft, including the solar panel and the ASPIICS coronagraph, can be made out (compare with detailed photo in top left).
The European Space Agency’s Proba-3 mission will create artificial solar eclipses in orbit, allowing scientists to study the Sun’s corona for longer periods than would be possible during eclipses observed from Earth.
In their most precise formation, the Coronagraph and the Occulter will be flying 150 m apart, maintaining their relative position down to a single millimetre.
A 1.4-m large occulting disk on the Occulter spacecraft will cover the bright body of the Sun, casting a shadow onto the optical instrument on the Coronagraph spacecraft and allowing it to study the solar corona.
The Occulter first took an image of the Coronagraph when the two were about 4.5 kilometres apart. Following the commissioning phase, the mission control team at ESA’s European Space Security and Education Centre in Belgium has brought them the closest they have been to each other since their in-orbit separation – about 200 metres apart.
With the spacecraft in this position, the next step was to attempt ‘target pointing’ – precisely orienting them to point towards each other. Both cameras of the Visual Based System on the Occulter locked in on the Coronagraph, snapping a photo.
Proba-3 mission manager Damien Galano explains: “This is the ‘first light’ of our Visual Based System sensor, which will be used again later on in the mission, allowing us to see the spacecraft in even more detail.”
Following commands from the operations team, the spacecraft then switched to autonomous mode for the first time, able to keep pointing at each other without any instructions from the ground.
After the successful target pointing attempt, the spacecraft await the operators’ command to begin their formation-flying dance.
Damien adds: “We are now ready for the next step of the formation flying commissioning. The team can’t wait to achieve the first alignment of the Coronagraph in the Occulter’s shadow!”