The world’s first human-made satellite, Sputnik-1, was launched by the Soviets in 1957. Since then, more than almost 9,000 satellites have been launched into space by nearly 40 different nations. For decades, government and private space agencies were only focused on exploring the outer space and somewhat establishing dominance in the space race.
But now, we are in a very precarious situation where the future of space travel itself hangs in the balance. Decades of space missions and thousands of satellites have given birth to a new phenomenon known as Space Junk.
Space junk or space debris is a term given for a heap of defunct, man-made objects, such as satellites and unmanned probes orbiting around the Earth. In 2013, the European Space Agency estimated that there are more than 170 million pieces of debris (larger than 1 mm) revolving around the Earth, of which only 29,000 debris is larger than the size of 10 cm. Then in 2016, the United States Strategic Command cataloged 1,419 active satellites above the Earth with a total of 17,852 traceable objects.
The increasing number of dead satellites are a problem not just to new spacecraft but to us, here on the Earth’s surface, as well.
Why Is It Dangerous?
A computer-generated image of space debris around the Earth
The current state of space debris is a serious threat to all the active satellites and spacecraft revolving in the Earth’s orbit. Many artificial satellites sent into space over the years have been severely damaged by orbital debris. One of the earliest confirmed cases occurred in 1996, when Cerise, a French military satellite, was smacked by fragments of an Ariane booster (also manufactured by France), which exploded back in 1986.
Then in 2009, NASA’s scientific research satellite Terra suffered multiple system failures, which were most likely caused by an orbital debris strike. A similar incident caused Aura, NASA’s climate research satellite, to lose power from one of its solar panels. In 2013, NOAA’s weather satellite GOES 13 was struck by a piece of space debris, which temporarily damaged its vital instruments.
In the same year, an MMOD (Micrometeoroids and Orbital Debris) strike threw the Russian BLITS satellite out of its intended orbit and also altered its spin rate. It was suspected that the debris might have been of Chinese origin.
Even the International Space Station is constantly under the threat of a collision with orbital debris. Though the ISS is mostly protected by the Whipple shield technology, many of its crucial instruments like the solar panels cannot be safeguarded without typical space maneuvers. In 2009, the space station barely avoided a collision between space debris, which was believed to be a part of Soviet Kosmos 1275 satellite.
Blazing Returns to The Earth
Officials Inspecting a crashed PAM D module in 2001
The increasing number of inactive and uncontrolled satellites in low earth orbit is a matter of concern for people living on the Earth’s surface as well. There are several instances in which, upon re-entry, a satellite makes an uncontrolled descent towards the Earth’s surface.
Larger debris is much more dangerous than the smaller ones since they can reach the surface mostly intact. Below are a few examples of satellites that have crash-landed in the past.
Skylab: The first major incident of space debris re-entry occurred back in 1979, when the first American space station, Skylab, disintegrated over parts of Western Australia and the Indian Ocean during its uncontrolled descent. Skylab was launched by NASA in 1973 and was part of three crewed missions.
Salyut 7: Launched in 1982, Salyut 7 was the last space laboratory under the Soviet Salyut program, which was replaced by the famous Mir space station in 1986. To complete the transition, the Soviets pushed the Salyut into a much higher orbit to delay its re-entry till 1994.
However, elevated solar activity and increased atmospheric drag caused the structure to charge down the Earth in 1991, three years ahead of schedule. It exploded upon re-entry,
Mir: After Salyut 1, Mir became the largest artificial satellite in the lower earth orbit (LEO). It was launched in 1986 and re-entered the Earth in 2001. Upon re-entry, the massive space station was disintegrated over the South Pacific region near Fiji.
Tiangong-1: China’s first space station Tiangong-1 is the latest addition to this list. After losing contact with the ground control back in 2016, the space station finally re-entered Earth’s atmosphere on 2nd April 2018. The space lab was mostly vaporized; only a few remaining pieces reached the surface harmlessly.
The Kessler Syndrome
The Kessler Syndrome, also known as the Kessler effect, is a scenario in which a collision between two objects in the lower earth orbit generates more debris that increases the possibility of further collisions with other objects.
It creates even more debris or space junks to a point where any space activities in that orbital range become impractical or inconvenient for many future generations. The concept was proposed by astrophysicist Donald J. Kessler in 1978, who also worked for NASA.
Measuring and Tracking The Space Junk
Organizations like NASA, ESA, and the U.S. Strategic Command are mostly responsible for tracking all the potentially dangerous objects revolving in the Earth orbit using ground-based radars, optical detectors, and telescopes.
These organizations have valuable data that are used to move active satellites and probes out of harm’s way. Most of these data come from NASA’s Goldstone Observatory, ESA’s Space Debris Telescope TIRA and EISCAT.
Sling Sat removing the Space debris
The standard, most common approach to address the space junk problem is to relocate all the geostationary satellites to a graveyard orbit at the end of their operational lives. But it does not ensure a debris-free geostationary orbit.
Researchers have come with several possible solutions to this particular problem. Most of them are, however, still in the experimental stage.
These include the Space Infrastructure Service, which would be able to push dead satellites to the graveyard orbit. Another such experimental spacecraft is the Busek ORbital DEbris Remover (ORDER).
Countries like Switzerland, Japan, the USA, and France all have their space junk removal programs. However, most of them might not be cost-effective.
As of now, there is no ironclad international regulatory framework for minimizing space debris in the lower earth orbit except the voluntary guidelines provided by the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) in 2007.
In 2017, the European Space Agency’s Holger Krag stated that not only is there no international regulation on this matter, but no progress is currently taking place at the moment in the respective U.N. body. Professor Joan Johnson-Freese of Naval War College said that there are no laws to salvage debris from space. ‘Even if we had the political will to do so, we cannot carry big pieces of junk because we don’t own them.’
Many researchers believe that the lower orbit might soon become a kill zone for satellites due to space debris and be lost altogether. Some also proposed that space agencies must develop much smaller satellites that can orbit the Earth with a safe distance from the space junks.