The seven residents of the International Space Station (ISS) were awakened earlier on November 15, when the North American Space Agency (NASA) initiated a security protocol. The objective was to move the astronauts to the spacecraft in which they arrived in space, as a newly detected cloud of garbage would pass close to the Station, putting the crew at risk.
Shortly thereafter, the Pentagon confirmed that the debris had been generated by an anti-satellite test conducted by Russia on the same day. In a statement, the US State Department classified the attitude as “irresponsible” and estimated that so far about 1,500 traceable fragments had been found.
In response, the Russian Ministry of Defense denied the possibility of collision between the test debris and other orbiting objects, including the ISS.
The event, however, is not an isolated case — and this is the main concern of specialists.
“Today our main problem is that we keep putting things into orbit and some things break, stop working or collide with each other, creating other fragments that then collide with other objects”, explains Alice Gorman, space archaeologist and professor at Flinders University, Australia, The CNN.
The trap that can enclose humanity
In a worst-case scenario, the number of collisions would be so large that it would lead to the so-called Kessler syndrome, theorized in 1978 by then NASA scientist Donald J. Kessler.
In this hypothesis, the space debris present in low Earth orbit — up to 1,000 kilometers from the planet’s surface — would be so much that collisions between debris would generate a ripple effect.
As a result, entire layers of low Earth orbit would become unusable, which is a problem, as that is precisely where the satellites used for communication, GPS, Earth monitoring, and other functions are located.
According to Gorman, “We’ve built contemporary life around accessing information from satellites, and the amount of space junk in orbit is putting that at risk.”
There are also those who believe that, if nothing is done to resolve the issue, humans will fall prey to their own trap: the debris around the planet will be so much that it will not be safe to carry out space missions. In other words, in its eagerness to explore the universe, humanity can confine itself to Earth.
The chances of something like that happening, however, are still remote. “When we see images of simulations that show space debris, it seems that the planet is practically surrounded by debris”, comments Naelton Mendes de Araújo, astronomer at the Planetarium Foundation of the City of Rio de Janeiro. “Actually, the vast majority of that debris is very small parts, which are quite far apart.”
The danger of high-speed fragments
Still, the expert emphasizes that accidents are possible. In February 2009, for example, the American satellite Iridium 33 and the Russian satellite Kosmos-2251 collided at a speed of 42,120 km/h, which resulted in the destruction of both, in the creation of at least a thousand fragments larger than ten centimeters and, in 2011, in an ISS maneuver to avoid colliding with the wreckage.
But it’s not these larger pieces that worry scientists. Debris between one and ten centimeters in diameter is much more difficult to detect and, therefore, to avoid colliding with equipment in orbit.
Furthermore, even the smallest of particles can do enormous damage at high speed. “On average, space junk debris is traveling at 8 kilometers per second [28 mil km/h]”, observes Araújo.
In August 2016, for example, a fragment of space debris just one millimeter long hit one of the solar panels on the European Space Agency (ESA) Copernicus Sentinel-1A satellite, creating a crater 40 centimeters in diameter.
See illustrations and images of space junk
Today, NASA estimates that there are about 100 million pieces of space debris more than a millimeter in diameter at different heights in Earth’s orbit.
Astrophysicists fear, however, that this number will grow exponentially, given the thousands of satellites from private companies that will be launched in the next few years.
Starlink alone, owned by South Africa’s Elon Musk, has already received authorization from the US government to place 42,000 satellites into orbit over the next few years, of which nearly 2,000 have already been launched.
The company claims that, after it stops working, the equipment should take between one and five years to disintegrate in the Earth’s atmosphere without major complications and without causing harm to the population.
In fact, the probability that a piece of space junk will resist Earth’s atmosphere and do some damage is very low. According to ESA, the chance of a person being hit by lightning is 60,000 times greater than that of being surprised with a fragment of a rocket falling on his head.
Only one case of this type has ever been registered, in 1997, with the American Lottie Williams, who was not injured.
What worries experts about launching mega-constellations like Starlink is actually the amount of potential space junk being launched into space.
“Satellites stop working for a variety of reasons, and if they’re not working and we can’t control them, they can drift and crash into things,” says Gorman. “A lot of debris is pulled back into the atmosphere, but this can take weeks, months and even years.”
The difficult solutions to clean the space
To speed up this process, the Japanese company Astroscale Inc. works on several commercial spacecraft in charge of “cleaning up” the space.
The aim of the technology is to capture extinct satellites in higher regions of Earth’s orbit and bring them closer to Earth, accelerating the process of re-entry and disintegration of these objects in the atmosphere.
The company plans to put the technology into practice in 2024 and, to that end, began carrying out tests in orbit around the planet in August of this year. The prototype, dubbed Elsa-d, consists of two satellites working together and, in this first phase, it demonstrated the ability of its magnetic system to trap and release debris.
Other solutions to remove space debris have already been proposed by engineers and astrophysicists from different countries.
While options range from rockets with networks to capture retired satellites to equipment with “garbage vaporizers” lasers, none have proven viable so far.
The reason is that creating technologies for conditions as extreme and unstable as those found around the Earth is no easy task. Under these circumstances, even something seemingly simple, like maintaining uninterrupted contact with orbiting equipment for a few minutes, can be quite complex.
As Alison Howlett, a spokeswoman for Astroscale, explains, for the Elsa-d procedure to work, the control system on Earth must remain in contact with the spacecraft for 30 minutes, four times longer than it usually takes to perform routine procedures on satellites.
“Overall, Elsa-d’s mission is very complex,” says Howlett. “But we hope these technical demonstrations will show commercial and government customers that we have the technical resources to provide this service.”
However, eliminating space debris by accelerating its re-entry and disintegration process in the atmosphere is far from the ideal alternative.
Risks to the Earth’s environment
A study released by the Aerospace Corporation in the North American Geophysical Union, in December 2020, indicates that there is great chance that the combustion of materials that make up satellites and rocket parts will harm the environment.
The authors of the research say that little is known about the end of the components of space debris as they are burned in the Earth’s atmosphere, but they estimate that 60% of the rocket bodies and 60% to 90% of the satellite mass disintegrate in the process.
They also believe that aluminum is much of the material that combusts — and that’s where the danger lies.
Elements like aluminum can interact with those already present in the Earth’s atmosphere, heating it and even damaging the ozone layer. However, “without precise modeling, the exact extension [desse problema] is unknown,” the scientists in the study wrote.
Also according to the article, if all the predicted satellites are launched, between 800 and 3,200 tons of garbage will burn into the atmosphere every year, compared to 100 tons annually today.
Space without rules
Another aspect that needs to be taken into account is: not everything up there that doesn’t work is garbage. As Alice Gorman observes, many objects have historical and cultural value.
An example is the American satellite Vanguard 1. Launched in 1958, it is the object that orbits the planet for the longest time. “Technically, it’s a piece of space junk, but its cultural meaning lies in being there,” says Gorman.
According to the Outer Space Treaty drawn up by the United Nations (UN) in 1967, space belongs to everyone. So getting a broader, less nationalistic sense of off-Earth achievement is crucial to resolving issues like space junk—but that’s not always the case.
Apart from the Treaty, the only tool that to some extent guides good practice outside of Earth is the 1972 Convention on Liability for Damage Caused by Space Objects. However, none of them actually regulate space activities, according to Nigerian Timiebi Aganaba, specialist in spatial governance.
“This is the big issue we have with international law, because there is no ‘international police’; there is no authority superior to the State”, explains the researcher, who also teaches at Arizona State University, in the United States. “In this way, the states choose to be linked or not [a tratados e acordos] and choose whether to follow them or not.”
And there isn’t exactly a “punishment” for those who don’t stick to the agreements.
Furthermore, given the millions of fragments of space debris in orbit, it is difficult to pinpoint the culprits for any accidents. The exception is when something like the Russian anti-satellite test done in November happens — and even then, harsher reactions from other governments may not be very convenient.
“All countries want to keep their freedom off Earth and will not be the first to exaggerately condemn an action [como a da Rússia], because they also want to be able to carry them out”, describes Aganaba.
But as occupying the universe — for political reasons or not — seems to be a great interest of several countries, solving the space debris issue should also be.
“Our experience shows us that whenever human activity increases a lot in a given environment, it degrades”, reflects the researcher. “So why not think of solutions now at the start, while we’re just getting started and the risk of accidents is low?”
Reference: CNN Brasil
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