March 2022
The Backyard Astronomer
Adam England

Space Junk

The Earth has been estimated at a total mass of about 5.9722×1024kg, more commonly notated as 1 earth mass (ME). One solar mass — or the mass of the sun, notated as Mo — is approximately 333,000 Earth masses. The whole of the solar system is estimated at 1.0014 solar masses, meaning all the planets, moons, asteroids, and comets make up just 0.0014 the mass of the sun. This all adds up to a lot of stuff floating around in our celestial backyard.

We Earthlings, however, love to produce trash. We have spent vast amounts of time and energy converting earthly resources into products that ultimately lose value and become garbage, subsequently dumped on land and in water, since well before recorded history. Some of the greatest archaeological discoveries of our past come from ancient landfills and latrines. So it’s no surprise that our forays off our planet have also produced large quantities of waste.

Beginning on October 4 1957, Sputnik I launched aboard a modified Russian ICBM to become the first artificial satellite in space. Its orbit decayed over the subsequent weeks and it fell back to Earth on January 4 1958, burning up in the atmosphere on in its way in. March 17 of the same year saw the United States launch the 3.2kg Vanguard I satellite, which still orbits the Earth today, along with the 31kg upper stage of its launch vehicle.

Now 64 years later, the US Space Surveillance Network tracks around 20,000 artificial objects orbiting the Earth, with only 2,218 of those being operational satellites. Those are the most recent numbers, from 2019, and with the rise of private space-industry giants like SpaceX and Blue Origin, and more countries entering the space race every year, those numbers are growing faster than ever.

But these are just the objects large enough to be tracked from ground-based observatories, like the Navy Precision Optical Interferometer outside Flagstaff, which can track objects the size of a quarter. Accounting for even the smallest paint flecks, estimates place the total number upward of 130 million objects made by humans and flying around the Earth at ungodly speeds.

“Space junk” is the colloquial term for all this debris, and generally carries a negative connotation. The International Space Station was recently forced to adjust its orbit and shield the resident scientists in their respective escape capsules when Russia tested a space weapon that destroyed a defunct satellite and created hundreds of thousands of small pieces of debris. Even the smallest piece of metal shaving orbiting at around 15,700 miles per hour could easily pierce through the outer layers of something like the ISS, causing depressurization, major repairs or loss of life.

Despite these astounding numbers, we know that space is a big place. Collisions are not common, even with billions and trillions of micro-meteoroids scattered across the solar system. Impact craters on Earth, the moon, Mars and elsewhere around the solar system tell us that major impacts do happen with relative frequency in the space timeline, but our technology is just advancing to the capability of capturing such events.

Impact flash on Jupiter, Sept. 13 '21, by Jose Luis Pereira with processing by Marc Delacroix

Two such events have been documented, and both were with Jupiter. Astronomers everywhere watched as Comet Shoemaker-Levy 9 flew its Icarus-like path and was torn apart by the immense gravity of Jupiter, crashing into it and leaving a trail of temporary scars in the Jovian atmosphere in July 1994. By comparison, on September 13 2021 a handful of amateur astronomers just happened to be photographing Jupiter when a bright flash appeared, thought to have been caused by an asteroid around 300 feet in diameter.

As we develop new ways of tracking objects across space, such as by Greg Leonard and the team at the Catalina Sky Survey in Tucson, more advance notice of impacts will follow. Many professional observatories are dedicating their clear nights to hunting for unknown comets and asteroids, while amateur astronomers are leading the charge in following the larger objects we have placed in uncontrolled and forgotten orbits.

Recently amateur astronomers found that a junk rocket will impact the far side of the moon on March 4 at around 12:26 UTC, in the first known unintentional collision of a human-made object with the moon.

The vehicle has been tentatively identified as a 3.6-ton SpaceX Falcon 9 booster that launched a weather satellite in 2015 or a Chang’e 5 booster from China, though both those ideas are disputed by their organizations. Either way we’re in for a scientific treat.

Such calculations by amateur astronomers have allowed international space agencies to adjust the orbits of lunar satellites that may be in the way, or even witness impacts.

Sadly, since the impact will be on the far side, we will not be able to observe it with our backyard telescopes. But with record numbers of orbital flights increasing year by year, I’m sure we’ll have more opportunities to witness collisions in space.

And just maybe, in a few thousand years, space archaeologists will look to all these defunct satellites, rocket bodies, landers, rovers, and nuts and bolts to catalog the many long-forgotten adventures of our current era. Or maybe it will just be another pile of orbiting space junk to dodge on our way to colonize

If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at or Facebook @PrescottAstronomyClub to find the next star party, Star Talk, or event.

Adam England is the owner of Manzanita Financial and moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or at