ESA space mission wants to simulate a total solar eclipse

Science recognizes four types of solar eclipses: total, partial, annular and hybrid. The following applies: The name describes the type of solar eclipse. During a partial solar eclipse, the sun is only partially covered; During an annular solar eclipse, part of the Sun remains visible around the disk of the Moon and the rest looks like a ring. During the total solar eclipse, the sun is completely covered by the moon and the hybrid solar eclipse is a mixture of annular and total solar eclipses.

Only during total and hybrid solar eclipses can the solar corona, the upper and hottest layer of the solar atmosphere, be seen. It is usually obscured by the Sun’s brighter lower atmosphere.

Only fourteen total and three hybrid solar eclipses have occurred in the 21st century. Usually they only lasted a few minutes. The solar corona now needs to be examined in more detail. That is why the European Space Agency’s (ESA) Proba-3 mission will start in September this year. Two satellites must simulate a total solar eclipse.

One satellite plays the role of the moon and will create an artificial eclipse for the second satellite. However, this will be so small that it will not be observable from Earth. The second satellite is located at a distance of 144 meters from the first ‘Minimoon’ satellite.

The two satellites will then fly in tandem formation for six hours. This process is then repeated several times.

The long-term measurement of the solar corona should provide new insights into the exact yield of the sun’s rays. Joe Zender, ESA project scientist for ‘Proba-3’, adds that accurate measurement of the corona could also provide new insights into the sun’s climate role.

Russell Howard, an astrophysicist at Johns Hopkins University in Baltimore, Maryland, describes the mission as “spectacular.” The main reason for this is the length of the observation time compared to Earth.

The satellites will only simulate an artificial solar eclipse for six hours per orbit; the rest of the track will then be spent in so-called “passive safe drifting”. The respective transition phases from the ‘passive drift phase’ to the ‘solar eclipse simulation phase’ should also provide data that can lead to technical improvements.

Another key part of the ‘Proba-3’ mission is the rendezvous experiment, which tests sensors and algorithms on encounters between human space bodies, such as satellites, in an elliptical orbit. This technology could be used in the future to return Mars samples and land satellites safely from low Earth orbit.