Friday, 17 July 2020

Solar Orbiter Gets Closest-Ever Look at the Sun

NASA and the European Space Agency (ESA) got together earlier this year to launch the aptly named Solar Orbiter spacecraft. The mission recently took up its position near the sun, and the agencies have released the first wave of images from this enviable vantage point. Naturally, the pictures are stunning and unprecedented, but they also show some scientifically relevant “campfires” dotting the surface of our local star

The Solar Orbiter mission began in 2012, suffering several delays along the way. That is, unfortunately, quite common with complex space missions like this. NASA successfully launched the spacecraft in February 2020 from Cape Canaveral. However, the Solar Orbiter almost missed important mission milestones after launch when the COVID-19 pandemic shut down the European Space Operations Center for a week. A skeleton staff was able to complete the necessary systems tests just in time, and the probe has now beamed back its first close-ups of the sun. 

To keep the Solar Orbiter from being roasted, it maintains a highly elliptical orbit around the sun. The probe will orbit the sun every 168 days, shrinking its orbit each time through November 2021. Eventually, it will swing past the sun at a distance of 0.28 AU — 1 AU (92 million miles) is the distance between Earth and the sun. The first images were captured from about 48 million miles out. While some missions like NASA’s Parker Solar Probe have been much closer, they did not have sunward-facing instruments. 

Data from the Extreme Ultraviolet Imager (EUI), one of six instruments the spacecraft will use to study the sun, showed something new. Scientists didn’t expect the EUI to return any critical discoveries in its first pass, but the team has spotted numerous small “campfires” spread across the surface of the sun (see above). Scientists aren’t entirely sure what they’re looking at yet, but there are some hypotheses. They might be a phenomenon known as nanoflares that keep the sun’s corona hotter than the surface. 

Future data sets from the Solar Orbiter should allow researchers to measure the temperature of these campfires. That should help identify them, and if they are nanoflares, to improve our understanding of coronal heating. The spacecraft should also be able to study solar wind structures for the first time. 

The Solar Orbiter mission is expected to last seven years. If the probe is still working at the end of that, NASA and the ESA have committed to extending it by three years.

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