European satellites launched to create an artificial eclipse

A pair of satellites astronomers hope can create an artificial eclipse were launched from a site in India last week. Beginning in 2025, each satellite will cause a periodic eclipse that lasts for six hours, much longer than the few minutes caused by natural eclipses.

In addition to conducting this experimental maneuver, the so-called ESA’s Proba-3 mission will observe a slice of the Sun’s ethereal corona difficult to perceive from Earth. The pair of satellites are currently orbiting Earth in lockstep with each other, but eventually will separate in a highly precise and technical procedure. Each satellite is smaller than a compact car but stuffed full of probes and other sensors. The larger one, known as the Coronagraph spacecraft, will explore the Sun’s corona, or outer atmosphere, while the smaller spacecraft Occulter will take a voyage through the same region with special navigation sensors and low-impulse thrusters that will allow the Coronagraph to do its job.

Specifically, the Occulter spacecraft will be positioned at the exact correct distance for a 4.6-foot (1.4-meter) disk mounted to Proba-3’s Occulter spacecraft to obscure the surface of the Sun, blocking the star’s glare and casting a shadow 3 inches (8 centimeters) onto the Coronagraph satellite. By doing this, the scientists hope to learn more about the super-heated gases that comprise the solar corona.

The mission has two objectives: Take photographic images of the corona once every two seconds, which will help scientists search for small-scale fast-moving plasma waves that could be super-fueling the corona’s hellish temperatures; and also seek evidence of plasma jets which could play a role in accelerating the solar wind, or a cloud of solar particles emitted by the Sun at speeds of up to 1.2 million mph (2 million km/hr).