How 'jugaad' made Europe's Solar Orbiter see Sun like never before

Scientists have successfully used the Extreme Ultraviolet Imager (EUI) camera on the Solar Orbiter in a new mode to capture images of the Sun's atmosphere at extreme ultraviolet wavelengths. They call it a hack. In India we say 'jugad'.

This feat, previously considered nearly impossible, was achieved through a last-minute modification to the camera, a move that is expected to significantly influence future solar instruments.

The EUI, part of the Solar Orbiter mission jointly operated by the European Space Agency (ESA) and NASA, returns high-resolution images of the Sun's corona, a region of the Sun's atmosphere.

A simple yet ingenious 'hack' during the construction of the EUI allowed it to see deeper into its target region than initially planned.

Frederic Auchere, a member of the EUI team from the Institut d'Astrophysique Spatiale, Universite Paris-Sud, described the modification as a "hack."

The team added a small protruding 'thumb' to the instrument's safety door. When the door slides halfway open, the thumb covers the Sun's bright disk, enabling the EUI to detect the faint ultraviolet light emanating from the surrounding corona, a million times dimmer than the Sun's disk.

This innovative method, referred to as the occulter mode of operation, has been under testing since 2021. The team recently expressed confidence in its successful operation, publishing a paper and video demonstrating the results.

The video showcases an ultraviolet image of the Sun's corona captured using the EUI occulter. An ultraviolet image of the Sun's disk, taken by NASA's STEREO mission, is superimposed in the middle, correlating well with the features in the corona.

Historically, dedicated instruments called coronagraphs were used to capture images of the Sun's corona. However, this new approach allows the coronagraph and the camera to be included in the same instrument, opening up new possibilities for solar imaging.

Daniel M¼ller, ESA’s Project Scientist for Solar Orbiter, stated that the success of this method could lead to the consideration of a new type of instrument capable of imaging both the Sun and its surrounding corona.

India's Aditya L1 has a Visible Emission Line Coronagraph (VELC), which is one of the most advanced instruments that will be used for imaging and spectroscopy of the Sun to better understand the science powering the star.

VELC aims to collect data for solving how the temperature of the corona can reach about a million degrees while the Sun’s surface itself stays just over 6,000 degrees Centigrade.