The European Space Agency (ESA) is planning to create its own solar eclipses in order to study the Sun’s corona, a difficult-to-observe part of the Sun’s anatomy. This will involve flying two spacecraft 150 meters apart, with one satellite blocking all but the corona from the other satellite, which will observe it using a coronagraph instrument. The mission will require the two spacecraft to fly in precise formation down to millimeter accuracy, using various technologies such as satellite navigation, radio-based satellite interlinks, cameras, and a laser beam reflected between them.
The Sun’s corona plays a crucial role in our solar system’s weather, as it is mysteriously hotter than the Sun’s surface, contributes to solar wind, and can have effects on Earth such as coronal mass ejections leading to auroras or electrical outages. The ESA’s Proba-3 mission aims to measure the Sun’s total energy output in order to inform climate modeling. By studying the corona, scientists hope to gain a better understanding of its influence on Earth and improve predictions for potential effects.
While there are coronagraphs on Earth and in space, they are limited in what they can accomplish due to light diffraction and spillage over the edge of the light-blocking disk. By placing the occluding disk farther away, the ESA hopes to overcome these limitations and enhance the capabilities of studying the Sun’s corona. NASA previously attempted a similar mission in 1975, using an Apollo capsule to block out the Sun for a Soviet Soyuz spacecraft.
The ESA is targeting a launch date for the Proba-3 mission in September, with the goal of conducting six-hour eclipse observations during each craft’s 19-hour, 36-minute orbit. This mission comes at a time when much of the US is preparing to witness a total eclipse on April 8th, as the Moon traverses the Sun, providing a real-life example of the principles on which the Proba-3 mission is based. By creating artificial solar eclipses, the ESA hopes to unlock new insights into the Sun’s corona and its impact on Earth’s climate and space weather.