As aurora-watchers, we know how unpredictable solar storms can be. Sometimes they arrive early or late or don't even show at all. Rarely do the blasts have disastrous consequences. Until last week.
On Thursday, Feb. 3 at 12:13 p.m. CST, SpaceX launched 49 Starlink satellites to low Earth orbit from the Kennedy Space Center in Florida. When the company first sends a new batch aloft, the satellites briefly spend time in orbits that dip as low as 130 miles (210 km) above Earth's surface before controllers move them to slots in higher orbits. SpaceX does this as a caution in the rare case of a Starlink malfunction. If a problem arises, friction (called drag) with the atmosphere will quickly and safely deorbit the faulty spacecraft. To date, more than 2,000 Starlinks have been launched with some 2,400 more in the pipeline.
By a stroke of bad luck, a significant geomagnetic storm that began on Feb. 2-3 and reverberated for the next two days not only sparked auroras but also took a swing at the Starlinks. Solar storms can also temporarily warm and expand the atmosphere, increasing the amount of drag on orbiting satellites. A satellite otherwise in the clear can suddenly find itself traveling through denser air. Keep in mind that dense is a relative term. At 130 miles altitude, the air is vanishingly thin, but there's just enough there to affect a satellite's orbit.
GPS systems on board the 49 Starlinks suggested that the solar tempest was severe enough to increase drag up to 50 percent higher than during previous launches. To shelter the satellites from the storm, the Starlink team put them in safe-mode, where they would fly edge-on "like a sheet of paper" to minimize air friction. Unfortunately, their efforts came up short. Up to 40 Starlinks will reenter or already have reentered the atmosphere.
Starlinks are designed to pose no collision risk with other satellites on their way down. As well, no parts and pieces are expected to hit the ground. Each satellite measures 10.5 feet (3.2 meters) by 5.25 feet (1.6 meters) across and weighs about 573 lbs. (260 kg). If you're lucky enough to reside under the path of one of these falling spacecraft you'll witness a spectacular, slow-moving swarm of fiery objects resembling a bright, exploding meteor. Already, there are reports of one or more Starlinks reentering over Puerto Rico as seen in the video above.
ADVERTISEMENT
According to Heavens-Above, the Starlink G4-7 launch continues to make passes at dawn for cities in the northern U.S. I don't know if their imminent demise has changed those times. But if you'd like to attempt to see a potential reentry anyway, go to the site and click on the big, blue Get predictions for your location link on the left side of the page.
Here it is a week later, and guess what? The possibility of another geomagnetic storm looms. Wednesday night (Feb. 9-10), space weather forecasters predict a minor G1 storm from a flare in sunspot region AR2940. Should the forecast come true, auroras would be visible across Canada and the northern U.S. The best viewing time will be late at night from roughly 11 p.m. till dawn.
Oh, and while you're out hunting the northern lights, keep your eyes peeled for falling satellites!
"Astro" Bob King is a freelance writer for the Duluth News Tribune.
