Now We Know How a Solar Storm Took Out a Fleet of Starlinks

upstart writes:

Now We Know How a Solar Storm Took Out a Fleet of Starlinks:

On March 23rd, sky observers marvelled at a gorgeous display of northern and southern lights. It was reminder that when our Sun gets active, it can spark a phenomenon called "space weather." Aurorae are among the most benign effects of this phenomenon.

At the other end of the space weather spectrum are solar storms that can knock out satellites. The folks at Starlink found that out the hard way in February 2022. On January 29th that year, the Sun belched out a class M 1.1 flare and related coronal mass ejection. Material from the Sun traveled out on the solar wind and arrived at Earth a few days later. On February 3, Starlink launched a group of 49 satellites to an altitude only 130 miles above Earth's surface. They didn't last long, and now solar physicists know why.

A group of researchers from NASA Goddard Space Flight Center and the Catholic University of America took a closer look at the specifics of that storm. Their analysis identified a mass of plasma that impacted our planet's magnetosphere. The actual event was a halo coronal mass ejection from an active region in the northeast quadrant of the Sun.

The material traveled out at around 690 kilometers per second as a shock-driving magnetic cloud. Think of it as a long ropy mass of material writhing its way through space. As it traveled, it expanded and at solar-facing satellites-including STEREO-A, which took a direct hit from it-made observations. Eventually, the cloud smacked into Earth's magnetosphere creating a geomagnetic storm.

One of the side effects of space weather that can affect satellites is warming in a region called the "thermosphere". That increased the density of the upper atmosphere over a short amount of time and caused it to swell up. A denser atmosphere causes a phenomenon called "atmospheric drag". Essentially, the thicker atmosphere slows down anything moving through. It also heats things up.

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