Two European satellites have successfully manufactured artificial solar eclipses by maintaining a precise formation in space. This innovative technique offers scientists extended periods of totality on demand.
The European Space Agency unveiled images from these eclipses at the Paris Air Show on Monday. The pair of satellites, launched in late 2023, have been creating simulated solar eclipses since March, while orbiting thousands of miles above the Earth.
The satellites fly 492 feet (150 meters) apart. One satellite blocks the sun, mimicking the moon's role in a natural solar eclipse. The other satellite then focuses its telescope on the corona, the sun's outer atmosphere, which appears as a halo of light.
It's an intricate, prolonged dance requiring extreme precision by the cube-shaped spacecraft, less than 5 feet (1.5 meters) in size. Their flying accuracy needs to be within a mere millimeter, the thickness of a fingernail. This meticulous positioning is achieved autonomously through GPS navigation, star trackers, lasers and radio links.
Dubbed Proba-3, the $210 million mission has generated 10 successful solar eclipses so far during the ongoing checkout phase. The longest eclipse lasted five hours, said the Royal Observatory of Belgium's Andrei Zhukov, the lead scientist for the orbiting corona-observing telescope. He and his team are aiming for a wondrous six hours of totality per eclipse once scientific observations begin.
Scientists already are thrilled by the preliminary results that show the corona without the need for any special image processing, said Zhukov.
"We almost couldn’t believe our eyes,” Zhukov said in an email. “This was the first try, and it worked. It was so incredible.”
Zhukov anticipates an average of two solar eclipses per week being produced for a total of nearly 200 during the two-year mission, yielding more than 1,000 hours of totality. That will be a scientific bonanza since full solar eclipses produce just a few minutes of totality when the moon lines up perfectly between Earth and the sun — on average just once every 18 months.
The sun continues to mystify scientists, especially its corona, which is hotter than the solar surface. Coronal mass ejections result in billions of tons of plasma and magnetic fields being hurled out into space. Geomagnetic storms can result, disrupting power and communication while lighting up the night sky with auroras in unexpected locales.
While previous satellites have generated imitation solar eclipses — including the European Space Agency and NASA's Solar Orbiter and Soho observatory — the sun-blocking disk was always on the same spacecraft as the corona-observing telescope. What makes this mission unique, Zhukov said, is that the sun-shrouding disk and telescope are on two different satellites and therefore far apart.
The distance between these two satellites will give scientists a better look at the part of the corona closest to the limb of the sun.
"We are extremely satisfied by the quality of these images, and again this is really thanks to formation flying” with unprecedented accuracy, ESA’s mission manager Damien Galano said from the Paris Air Show.
