Musk's space junk is a threat to us all
Pieces of space junk are falling to earth on a regular basis. On Techtonic this week I spoke with astronomer Samantha Lawler, who has been raising the alarm about this problem for some time:
One of the notable re-entries recently was a piece of a Crew Dragon spacecraft, made by Elon Musk's SpaceX. Pictured below is the hairy chunk that came down from the sky a few months ago and slammed into a field in Saskatchewan, Canada. Lawler tells the whole story in our interview (and in a Scientific American article).
Space junk is falling more frequently as Musk launches more and more Starlink satellites into low earth orbit (for most objects, below 800 km or 500 miles). A few years ago there were about a thousand Starlink satellites in orbit. According to the Economist last month,
the 6,400 or so Starlink satellites launched since 2019 account for around three-quarters of all the active satellites in space . . .
In other words, most of the roughly 10,000 satellites in low earth orbit are owned by one person. And he’s applied to launch tens of thousands more.
Musk isn’t alone. Never one to accept second place, Jeff Bezos has plans to launch his own “mega-constellation” of satellites. And a Chinese project called Qianfan has begun launching and is planned to grow to 15,000 satellites. All told, we’re looking at an explosion of surveillance and communication equipment orbiting our planet in coming years. As a U.S. PIRG report (Aug 8, 2024) puts it:
Researchers have tracked international proposals for over 500,000 satellites in multiple competing constellations from Amazon’s Project Kuiper, OneWeb and others.
500,000?! That’s a lot of stuff coming back at us, since each of the satellites has a shelf life of about five years. If we consider only Musk’s plans, and he achieves his goal of 42,000 Starlink satellites in orbit, that means one of his satellites will re-enter the atmosphere, on average, every hour. (A year has 8,760 hours, about the number of satellites Musk will need to bring down annually.) As PIRG puts it:
Due to the large number of short-lived satellites, at its peak deployment, Starlink’s mega-constellation will require 29 tons of satellites to enter the upper atmosphere every day. That’s nearly equivalent to a car entering our skies every hour.
Vaporizing a car’s worth of aluminum, other metals, and chemicals in the upper atmosphere, every hour, indefinitely? Not good. From a statement (Sep 27, 2024) issued by the American Astronomical Society:
the choice to burn up satellites in the atmosphere may pose a significant risk to the Earth’s climate and the ozone layer, through the resulting alteration of atmospheric chemistry. . . . with a typical satellite weighing of order 1,000 kg [2,200 lb], and being primarily metallic, the steady state injection of metals into the stratosphere by vaporization of satellites would be at least 8,000 tons per year.
And that’s assuming all of the satellites fully burn up. If it turns out some of them have some chunks left over, as in the case of the Crew Dragon object shown above, we’ll have to deal with two problems: potentially catastrophic atmospheric pollution and the dystopian rain of space junk. Perhaps at the end of our daily weather forecast we could get a Starlink precipitation report like this one from Jonathan McDowell:
McDowell also maintains an ongoing list of Dragon 2 trunk re-entries, including the Saskatchewan incident above. Surely there are more re-entries yielding space junk that haven’t been reported.
Here’s a fun graphic showing what happens when a satellite re-enters the atmosphere:
That diagram comes from an article in Aerospace in America (July 2021), which offers a fresh new nightmare scenario: the possibility of space junk striking an airliner at 35,000 feet. As one expert put it,
If a large piece of space debris hits an airplane in flight, it is almost certain to be fatal to everyone on board.
Not fun. But how likely is it that these things will only partially burn up and have chunks left over? One estimate, from way back in 2008, was that
of the 70 space objects with masses of 800 kilograms or more that fell to Earth that year, between 10% and 40% of the mass of each probably survived the fall into the airspace — with as many as 300 fragments that could be lethal to an aircraft.
OK, objects that weigh at least 800 kg are likely to only burn up partially, with the remainder falling to earth. How does that relate to Starlink? According to Space.com (Sep 27, 2024),
The current V2 Starlink satellite version weighs approximately 1,760 lbs (800 kilograms) at launch.
That means that, thanks to Elon’s growth-at-any-cost plans, we’ll soon see a 800-kilogram satellite entering the atmosphere, every hour, with possibly 10% to 40% of that junk coming all the way down, into airliner airspace, and then possibly into your backyard.
My advice? Reinforce your roof, buy a stronger umbrella, and pack a parachute.
Sam Lawler offers much better advice at the end of our interview. Take a listen.
I do hope you’ll join me at Creative Good, a community finding ways to navigate these strange times.
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Until next time,
-mark
Mark Hurst, founder, Creative Good
Email: mark@creativegood.com
Podcast/radio show: techtonic.fm
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