Humankind has always been curious to unravel the mysteries of the universe. Artificial #satellites are developed to study the earth, Moon, and various other planets as well. The first artificial satellite Sputnik I, was launched into space on 4 October 1957 and thus began space exploration. Many satellites are launched into the earth's orbit to find answers to several naturally occurring phenomena, and to provide various services. These numerous satellites add to the space traffic. The increasing space traffic makes it necessary to build satellites that can resist collisions, which in turn increases the building cost. Hence, space junk must be cleared to ensure a smooth space exploration. Firstly, let's know a bit about space junk.
Space Junk
Space junk(or Space Debris) are the non-functional objects or parts of a larger satellite that are left in the earth's orbit. They can be fragments of a launch rocket, the components of a non-active satellite, or even the flakes of paint. The collision of an active satellite with an extremely minute particle is dangerous too. There are instances in the past where tiny particles have destroyed massive satellites.
Almost 2600 active satellites are orbiting the earth, and nearly 3000 dead ones are hindering in space. The US Space surveillance network reported that there are over 128 million pieces of debris tinier than 1 cm, 9,00,000 bits of debris that are 1 to 10 cm, and 34,000 items of debris larger than 10 cm. All these can be destructive if they collide with something else. Debris left in the lower orbits returns to the atmosphere of the earth after a period of time. But the trash present in the orbits of higher altitudes(above 36,000 km) continues to circle the earth for hundreds and thousands of years.
The Kessler Syndrome
It is proposed by Donald J. Kessler, a #NASA scientist, in the year 1978. It is a theoretical situation in which when the density of debris in the lower earth orbit is high enough, that the collision between them results in space #debris, thereby rising the possibility of collisions even further. This implies that the future operation of satellites is difficult remarkably. Hence the space junk must be removed to ensure a smoother operation of various satellites.
Several instances of space collisions
The active Iridium 33 and the derelict Kosmos-2252, two communication satellites, collided haphazardly at a speed of 11,700 m/s on February 10, 2009, at an altitude of 789 kilometers.
On October 15, 2020, the pieces of an old rocket(of china) and a dead soviet satellite had a very close encounter. Scientists say that the collision between these two would have engulfed the orbit with space debris.
The International Space Station was smitten by space debris several times.
In addition to these, countries also use Anti-Satellite weapons(ASAT) to destroy or shut down satellites for strategic purposes.
In March 2019, India launched a 3 stage missile that destroyed a military satellite Microsat-R in its trajectory, shattering the satellite into pieces.
Likewise, China and Russia have developed Anti-Satellite weapons that target the satellites in the lower earth orbit.
Removal of Space Junk
The debris present in the lower orbits gradually enters the earth's atmosphere after a period of time. The minute dust particles and the debris present in the higher altitudes cannot reach the earth and hence must be removed by other means. There are no standard means of doing this, but there are several proposals from various companies. The satellites must be dragged into the atmosphere of the earth. This can be done by:
Using magnets to seize it.
Enclosing it in a net and pulling it.
Using fire lasers to heat the satellite, thus increasing its atmospheric drag and hence it comes out of the orbit.
Launching satellites into elliptical orbits that decay fastly, thus releasing the satellites into the earth's atmosphere.
Passivation of Satellites and launch vehicles(Though it doesn't actually reduce the debris, it reduces the chances of satellite destructing others and creating further debris).
Space Traffic Management System
The above graph depicts the number of space crafts launched to space from the year 2010 to 2017. More than 100 space crafts were launched every year from 2010 to 2012. There was an increase in the number of satellite launches from the year 2013. More than 200 satellites are launched into space from 2013. This explains that there will be still more satellites launched into space, in the years to come. Thus it becomes necessary for proper vigilance of all the satellites. The Space #Traffic Management System ensures this smooth operation.
The International Academy of Astronautics defines the Space Traffic Management System as the set of technical provisions and rules that provide safe entry into outer space, smooth migration, and return from space without any physical or radio-interference. United Nations Office for Outer Space Affairs(A bureau of the United Nations Organisation) works on establishing global cooperation and coordinates all countries to avoid collisions of #spacecraft and reduce space debris.
Conclusion
Launching various navigational, communication, and weather #satellites are imminent as they provide crucial information and also warn us about any natural disasters in advance. But consequently, measures must be taken to reduce the space debris by following a set of shielding measures. Nations must ensure that the satellites are removed from the earth's orbit once they are inactive. The earth's orbit equips us in navigation, communication, and many more. Thus, it is our duty to secure the orbit from the accumulation of space debris, thereby supporting future generations to benefit from its advantages.