Proba-3: Twin spacecraft launched to cause artificial solar eclipse

The European Space Agency (ESA) aims to create an artificial solar eclipse in space with its upcoming Proba-3 mission, which will help study the Sun and demonstrate extremely precise formation flight down to just a millimeter. It turns out.

Scheduled to launch on December 4 on an Indian PSLV-XL rocket, the mission will consist of two spacecraft. After launch, they will be placed into a highly elliptical orbit around the Earth, bringing them about 600 kilometers (600 kilometers) close to Earth, but at a distance of about 60,000 kilometers (60,000 kilometers) from the Earth.

One of the spacecraft, called Occulter, features a 1.4-meter-wide disc made of carbon fiber and plastic. The other spacecraft will fly about 150 meters behind the first spacecraft and point its camera there. From this vantage point, the occulter’s disk blocks the surface of the Sun, much like the Moon appears to cover the Sun during a total solar eclipse. This will allow imaging probes to observe the solar corona, or the sun’s atmosphere, in more detail than ever before.

“This will be the closest we’ve ever seen the corona to the Sun in visible light,” said Damien Galano, ESA’s Proba-3 mission manager. “This could provide concrete information about the temperature of the corona, the formation of the solar wind, and how the corona expands into space.”

Proba-3 accomplishes this feat by flying with incredible precision. Both spacecraft are equipped with sensors to track their position in space, and Occulter uses 12 nitrogen thrusters to autonomously maintain its position with its partner with millimeter accuracy. The thrusters can deliver just 10 millinewtons of thrust, which is 1/50th the force of human breathing.

To limit the destabilizing effects of Earth’s gravity, the artificial eclipse will last six hours when the spacecraft is furthest from Earth. More than 1,000 solar eclipses are planned during the two-year mission. Galano said this is the first artificial solar eclipse experiment in space since the Apollo-Soyuz test mission in 1975.

The experience gained from the Proba-3 mission could also be applied to things like refueling spacecraft and developing large telescopes in space. “Until now, we’ve only been able to achieve accuracy of one centimeter or better,” said Steve Buckley, Proba-3’s lead engineer at Onsemi, a US company that developed some of the sensors for the mission. “This is 10 times better.”