On Apr. 15, an Earth-orbiting object known as #32398 disintegrated, according to the U.S. Air Force. The agency's 18th Space Defense Squadron announced the event via a tweet, saying that 16 parts of space debris associated with the event are currently being tracked.
According to journalist and author Anatoly Zak, who runs RussianSpaceWeb.com, Object #32398 was an ullage motor from a space tug that helped deliver three Russian GLONASS satellites into orbit in 2007. (GLONASS is the Russian equivalent of the GPS navigation system.)
As per astrophysicist and satellite tracker Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics, the GLONASS spacecraft took off atop a Russian Proton rocket, the upper stage of which had two tiny ullage motors.
"The SOZ motors don't use up all their propellant when they fire. And they have an unfortunate tendency to go bang years or decades later, leaving a bunch of debris in a highly elliptical orbit. At least 54 SOZ motors have now exploded," McDowell stated in a tweet.
McDowell clarified in a series of tweets on Tuesday that ullage motors slightly accelerate their parent rocket stages to ensure that the boosters' fuel is properly positioned in the tanks for engine restarts in orbit. (After all, gravity can't pull the propellant down toward the engine.)
These SOZ motors are Proton upper-stage ullage motors, and there are currently 64 of them in Earth orbit, according to McDowell. He explained that the acronym stands for "Sistema Obespecheniya Zapuska," which roughly translates as "Launch Assurance System."
According to McDowell, the SOZ motor that just blew up was sprinting around Earth in a highly elliptical orbit, going as fast as 241 miles (388 kilometers) and as far away as 11,852 miles (19,074 kilometers), and "the debris will take quite a while to reenter."
Space junk is becoming an increasing issue for satellite operators and mission planners. According to the European Space Agency (ESA), approximately 36,500 pieces of debris at least 4 inches (10 centimeters) wide are presently whizzing around the Earth. According to ESA, there are likely 1 million objects in Earth's orbit with diameters ranging from 0.4 to 4 inches (1 to 10 cm).
In November 2021, Russia added to the debris population with a widely criticized anti-satellite (ASAT) test. A missile was used to destroy one of the country's defunct satellites, resulting in a new debris field in the same orbit as the International Space Station (ISS). To avoid Russian ASAT debris, ISS operators had to perform engine burns.
