Why ESA wants to create artificial solar eclipses

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Aug 26, 2017

So we just witnessed, tweeted, and Instagrammed a solar eclipse, and it was pretty spectacular, even more amazing is that scientists are going to create their own.

The European Space Agency’s DIY eclipse project is the Proba-3 mission, which involves a satellite duo that will create artificial eclipses lasting for hours (and in case you were wondering, the sky won’t black out every time they do it). The larger camera satellite will already be floating in space, equipped with cameras and other instruments on board craft for a field of view. The idea is to get the smaller disc or occulter satellite to fly directly between those instruments and the sun to block all sunlight but that eerie glowing ring of our star’s corona and—there it is—instant eclipse.

This isn’t exactly the astronomical magic trick it sounds like. The sun’s surface light is a million times brighter than that of the corona, which is why you didn’t go blind when you watched totality without those special glasses. Scientists have tried to pull something like this off before by obstructing that blazing light with coronagraphs. These instruments are light-obscuring discs inside telescopes that make the corona visible as it is during a solar eclipse. The problem with coronagraphs is that escaping light can distort the view.

What the Proba-3 satellite duo will look like.

This problem can be minimized by extending the coronagraph length, the distance between the camera and the disc, as far as possible – but there are practical limits to coronagraph size,” said principal investigator for Proba-3’s coronagraph Andrei Zhukov, who emphasized that his team’s goal is to replicate the conditions of a solar eclipse as close to the actual phenomenon as possible.

Proba-3’s camera satellite and occulted satellite will launch together into an elliptical orbit around Earth and team up to operate as if they were one coronagraph. An inter-satellite radio link will connect them. The occulter will keep them both precisely in line with low-power micro thrusters, and the camera satellite will produce an artificial eclipse for 6 hours out of every 19.6 it takes to fly around our planet. It also has incredible vision, able to see features 34,500 miles from the sun, though human observers actually have the advantage on that one, since the corona can be seen more clearly from Earth. Not that any eclipse has ever lasted six hours.

During two years of its nominal mission, Proba-3 will provide around 1,000 hours of coronal observations,” Zhukov said. “This has to be compared with several minutes of duration of ‘natural’ eclipses during the same time. Proba-3 will also be free from disturbances produced by the Earth’s atmosphere in all astronomical observations.”

When it comes to observing the sun’s atmosphere, this just might be the mission to eclipse everything else.

(via Astronomy Now)