New space mission to create artificial solar eclipse
21 August 2017
In the next decade, astrophysicists will be viewing eclipses for hours, instead of minutes, thanks to a new ESA space mission.
Proba-3 is due for launch in late 2020; the two small metre-scale satellites will line up to cast a precise shadow across space to block out the solar disc for six hours at a time, giving researchers a sustained view of the sun’s immediate vicinity.
The total solar eclipse that is expected today (Monday 21st) across North America will last for about 160 seconds. While this will reveal features of the sun normally hidden, researchers are constantly seeking new ways to increase this visibility, mainly through ‘coronographs’ – telescopes bearing discs to block out the direct light of the sun.
“The inner extent of the view afforded by standard coronagraphs is limited by stray light,” explains Andrei Zhukov of the Royal Observatory of Belgium, serving as Principal Investigator for Proba-3’s coronagraph.
“Stray light is a sort of light pollution inside an instrument. In coronagraphs it is a kind of bending of the sunlight around the blocking disc.
“This problem can be minimised by extending the coronagraph length, the distance between the camera and the disc, as far as possible – but there are practical limits to coronagraph size.
“Instead, Proba-3’s coronagraph uses two craft: a camera satellite and a disc satellite. They fly together so precisely that they operate like a single coronagraph, 150m long.”
Each six hour artificial eclipse per 19.6 hour Proba-3 orbit of Earth should provide a view close to the sun’s visible surface. The challenge will be keeping the satellites in control and correctly positioned. This will be done using new technologies, like sensors and intelligent software. It will be similar to autonomous driving, but in space!
The structural and thermal model version of the coronagraph is built, ready for its critical design review in the autumn.