The European Space Agency’s (ESA) Solar Orbiter spacecraft is on a mission to observe the sun up close and capture detailed images of its corona. To achieve this, the spacecraft is performing a series of flybys of various planets to gradually bring itself closer to the sun. Eventually, it will come within 26 million miles of the sun and even enter the orbit of Mercury, allowing it to get closer to the sun than any camera has before.
While in between close approaches, the Solar Orbiter team has made an interesting discovery. The instrument team for the spacecraft’s Extreme Ultraviolet Imager (EUI) camera has found a new way to make the camera more sensitive to faint extreme ultraviolet light. During the construction phase, engineers made a modification to the camera’s safety door by adding a small weight, known as a thumb. By chance, the team realized that when the door was partially open, the thumb would hang in front of the brightest part of the sun’s disk, enabling them to detect fainter light from the sun’s atmosphere.
This unintended modification turned the camera into something like a makeshift coronagraph, a specialized instrument used to block out the brightest light from a star to observe its surroundings more clearly. Previously, coronagraphs and cameras were separate instruments, but this discovery shows that one instrument can fulfill both functions.
The team tested this concept and found that it worked effectively, allowing the camera to capture images of the sun’s atmosphere, including deep layers that were previously difficult to observe. The images reveal changes in physics and magnetic structures that were previously unexplored.
This unexpected hack has opened doors to new possibilities in solar imaging and has the potential to lead to the development of instruments capable of both imaging the sun and its corona. It is an exciting development for the ESA’s Solar Orbiter mission, providing researchers with a unique opportunity to uncover secrets about the sun’s atmosphere that were previously unknown.