Sputnik 1 should be the first piece of space debris in existence, and yet it is not: it disintegrated a month after its launch in the Earth’s atmosphere. In fact, it is the second satellite launched by the United States in 1958, Vanguard 1 , the oldest remaining one that is still orbiting the Earth along with many other inactive vehicles or ship remains. This remains is what we call space debris and what NASA calls “orbital debris”, that is, all the artificial objects that orbit the Earth and are no longer useful.
Currently, most of the objects tracked are disused ships, fragments of explosions, collisions or pieces of satellites or rockets. In addition, there is evidence of a large number of remains that are difficult to trace due to their size. The European Space Agency estimates that there are about 900,000 objects larger than 1 cm and 128 million objects larger than 1 mm circling the Earth. Some of these remains are simply objects that astronauts have accidentally lost , such as screws, tools, cables… or that in the early years of the Soviet space station MIR and the International Space Station were launched directly into space, like the urine of astronauts. To this must be added the structural remains of launchers and the deployment of space objects, paint chips, fuel tanks…
The culprits of space debris
Intentionally creating space debris is nothing new. In the 1960s, the United States wanted to launch what they called the West Ford Project of the MIT Lincoln Laboratory for the Air Force. They intended to create a belt in an almost polar orbit, 8 kilometers wide and 45 thick, formed by small pieces of copper wire to achieve an increase in the gain of military communications signals: of the two attempts carried out none were successful, and of the 480 million needles launched in 1963, most remained clumped together, becoming space junk. Years later, 144 groups were tracked, although most of those needles are untraceable due to their diminutive size.
But let’s not be naive and believe that this only happened in the past; In our days things have not gone for the better. In November 2021, Russia decided to conduct an anti-satellite missile test, causing a global environmental emergency due to space debris. These types of tests have been taking place for more than 35 years and in all cases the majority of the debris generated is dispersed by their orbits.
How does space debris affect
The big problem with these wastes is their size. The most problematic are the small ones, as it is very difficult to track them and the orbital speed at which they can go, up to 56,000 km/h, makes them real bullets : a 1 cm piece can disable a spacecraft. If we talk about objects larger than 10 cm, what will occur will be a collision that will create a cloud of dangerous fragments of all kinds that can cause situations like the one that took place in 1983, during the STS-7 mission of the Challenger shuttle. A chip of paint hit one of his windows and made a hole twice its size. During the space shuttle’s first 63 missions, 177 impact marks were found on its exterior windows, and between 1981 and 1998 more than 70 windows had to be replaced. In 2009, an American and a Russian communication satellite, already inactive, collided 770 km away and were completely destroyed. A year later, it was concluded that 20% of the remains would remain in orbit for 30 years, that is, until 2040, and the remaining 70% would begin to fall in 2030.
Garbage growth slowed in 1996 when most countries were aware of the need to tackle the problem, but the Chinese Fengyun series weather satellite incident in 2007 and the collision between Iridium 33 and Cosmos 2251 in 2009 caused the situation to spiral out of control again. In fact, in 2012 the upper stage of a Russian Briz-M rocket, in orbit with half-full fuel tanks, exploded causing around 1,000 trackable fragments and tens of thousands of untrackable ones.
The International Space Station has not been spared from this plague and since its inauguration in 1998 it has suffered 30 accidents. In one of them, a window was hit by various pieces of debris that opened a hole 6.5 mm in diameter. In May 2021, during a routine inspection of the ISS robotic arm (Canadarm2), a 5mm hole was discovered and in November NASA canceled a spacewalk due to the proximity of some debris.
A risk predicted 40 years ago
What is striking is that this situation had already been predicted by various scientists. In 1978, NASA researchers Donald J. Kessler and Burton Cour-Palais published a paper titled “Artificial Satellite Collision Frequency: The Creation of a Debris Belt.” The document was very explicit, explaining that by the year 2000 the density of space debris in orbit would be so great that random collisions could not be avoided. This situation was called the Kessler Syndrome: “satellite collisions will produce fragments in orbit, each one of them will increase the probability of more collisions, which will lead to the appearance of a debris belt around the Earth”. Kessler suggested that the best way to avoid the exponential growth of collisions was to reduce the number of non-operational spacecraft left in orbit. With the passage of time, the Kessler Syndrome has become a reality and it is urgent not only to catalog but also to devise ways to clean the space.
Obviously, both are not easy tasks, but someone has to do it.
References
Parliamentary Office of Science and Technology, Space debris, Postnote, marzo de 2010
M. A. Nixno y J. Michaels, Space Debris and Its Solutions, en el libro Modern English for Aeronautics and Space Technology (pp.149-158), DOI:10.3139/9783446470118.011
