Night sky fallings: Spotters document space debris over northern Minnesota
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Just after 6 p.m. on Saturday night, Al Sorensen was in Hayward, Wis., watching a holiday parade. She had her phone out, filming the floats passing by, when she saw something zooming across the night sky overhead.
“It was just this green ball with this trail, and it looked so bright.”
Her first thought was maybe it was something to do with the parade.
"You could see a trail of kind of sparks behind it, but the color was just so surreal. It was just this vivid green with maybe a little bit of a blue tinge to it.”
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Sorensen is an avid night sky watcher of the northern lights and meteor showers. But she had never seen anything like this.
She didn’t think much more about it until she later saw videos and pictures of it on social media.
More than 100 people from Minnesota, Wisconsin, Michigan and Canada reported the sighting to the International Meteor Organization. The group tracks what are called "fireballs" — what people often call shooting stars.
But this was no meteor. It turns out Sorensen saw Starlink satellite #3322 – from Elon Musk’s internet service company – burning up as it reentered the earth’s atmosphere.
Bob King, an amateur astronomer in Duluth known as “Astro Bob,” explained that meteors move much faster across the night sky than satellites.
"It's kind of over and done with in just a few seconds,” said King, who didn’t see the falling satellite but saw videos of it online “that went on for seconds and seconds. And that's typical of a re-entering satellite, it moves more slowly through the atmosphere as it's coming in,” King explained.
The bright green color is produced by copper, said King. “Like the wiring inside the electronics. And when that gets heated to a certain temperature, it just basically becomes a plasma and it glows bright green."
These sightings are still rare. But they’re becoming more common. There are now more than 9,000 Starlink satellites in orbit. This week, the SpaceX subsidiary launched 27 more satellites. The company has deployed more than 3,000 this year alone. And their life span is only about five years, so every day, one or two falls back to earth.
And that's just a tiny portion of the total amount of space debris orbiting around the earth.
"There's a lot of stuff up there,” said John Crassidis, a professor of mechanical and aerospace engineering at the University of Buffalo, New York, who studies so called “space junk.”
Crassidis says there are more than 40,000 objects of softball size or bigger orbiting around the earth.
But “it's the smaller stuff that we're more worried about, between one centimeter and 10 centimeters. It's estimated there could be up to 1.4 million of those objects,” he said.
Those objects are traveling at 17,500 miles per hour to stay in orbit. If they moved any slower they'd get pulled back to earth by gravity. That means something as small as a Cheerio can cause a lot of damage to active satellites or spacecraft. In fact, just last month, 3 Chinese astronauts had to delay their return to earth after their spacecraft was damaged by space junk.
And the amount of debris is constantly growing, because more countries and companies are launching satellites. Amazon has a new satellite internet venture dubbed Leo, with plans to launch more than 3,000 satellites.
Satellites are designed to burn up upon reentering the atmosphere, but on rare occasions, a piece of space debris can penetrate the atmosphere all the way through to the ground. That happened last year, for example, when a battery from the International Space Station smashed into a home in Florida.
But Crassidis advises not to lose sleep over it. “You're got a much bigger chance of getting struck by lightning than you do getting hit by a piece of space debris.”
His bigger concern is that as the amount of space debris grows, the risk of collisions in space may someday be so great that it won't be worth the risk of launching more satellites, or sending astronauts into space.
That’s a theory known as the Kessler Syndrome. Crassidis worries that if action isn’t taken to reduce the amount of space debris accumulating, it could become a reality in the next century.
"If we want to go to the moon and Mars, we have to navigate through that debris field, right? So we're putting our astronauts in much more danger too,” he said.
There's also a much more immediate concern for anyone who loves to observe the night sky: light pollution.
"If you're an astrophotographer and you're taking pictures at night, it’s virtually impossible anymore to not record multiple satellite trails in your images,” said “Astro Bob” King. It’s a phenomenon he calls the "mechanized sky."
King admits he'd love to see an exciting fireball like the one created by the falling Starlink satellite last Saturday. But he says the price we pay is a loss of the pristine night sky.
Satellites “are so commonplace,” King said. “They distract from the experience of being under the stars.”
