Introduction
The space beyond the vast blue sky was always a mystery to mankind. We have always tried to reach out into space. On 4th October 1957, the first artificial satellite entered space. From that day hundreds of artificial satellites, rockets, and exploration vehicles were launched to space. All these artificial earth satellites which were launched still revolve around earth even after their functions are stopped. Mankind has been polluting nature in various ways, and after realizing its harmful effects we have tried to reduce the pollution. However, little is known to the public about the celestial landfill that man has created since the early days of the Space Race involving the Russian launching of Sputnik. Ever since then about 6600 satellites were launched into space. These orbiting debris can cause major problems for both research machinery and humans. In recent years there have been studies regarding the issue of space pollution. Various ideas regarding the control and removal of this junk were put forward. In this article, we are going to discuss the origin, effects, and methods for the prevention and removal of this space debris.
Space pollution
Space debris or space pollution is the unusable or non-functioning artificial objects in space (mostly in Earth’s orbit). This includes wrecked spacecraft, mission-related debris, and fragments of rocket bodies, especially on Earth’s orbit. In addition to the fragments of machines and rockets, there are also solidified liquids that were expelled from spacecraft, and unburnt fuel particles from rocket motors. These space debris can cause great risk to spacecraft and exploration vehicles.
According to the report of the US Space Surveillance Network in October 2019, there are nearly 20,000 artificial objects in Earth’s orbit, including 2,218 artificial satellites. These numbers represent large debris, meanwhile, there are more than 128 million pieces of debris smaller than 1 cm, about 900,000 pieces of debris which have a size about 1–10 cm, and around 34,000 pieces that are larger than 10 cm were estimated to be in Earth’s orbit. The smallest objects of artificial space debris are sometimes referred to by space agencies as MMOD (Micrometeoroid and Orbital Debris). This debris may collide with spacecraft to cause accidents. Below 2000km of Earth’s altitude the space debris is denser, most of them are dust from rocket motors, surface erosion debris like paint flakes, or frozen coolant from nuclear-powered satellites.
North American Aerospace Defence Command (NORAD) has been keeping track of all known rocket launches and artificial objects reaching space. The NORAD was aware of other objects in orbit, many of them were the result of in-orbit explosions. Some were caused due to the Anti-satellite weapon (ASAT) test during the 1960s, and others were the result of rocket stages blowing up in orbit. During the 1970s, the database of NORAD became publicly available.
Hazards of Space debris
Space debris that revolves around the Earth at high velocities can cause damage to spacecraft and active satellites. It is theorized that the Orbit of Earth may become impassable and the risk of collisions will be higher. it is said that Lower Earth Orbit would be rendered unusable by orbiting crafts. Even though spacecraft are Whipple shields, parts like the solar panels wear from low mass impacts. Small particles can cause electrical risks to the panels. Spacecrafts that are crewed are more sensitive to debris collisions. Long-term debris wear has occurred on International Space Station and the MIR Space station.
Kessler effect proposed by Donald. J. Kessler (NASA scientist) theorized that the “density of objects in Low Earth Orbit due to Space Pollution is high enough that collisions between objects could cause a cascade in which each collision generates Space debris that increases the likelihood of further collisions”.
Although most of the debris entering the Earth’s atmosphere burns up, some large pieces can reach the ground. These falling debris can cause damage to both life and property. The burning up of the pieces can also cause atmospheric pollution.
Some events that occurred due to space debris are given below:
In 1969 sailors of a Japanese ship were heavily injured due to fallen debris striking on the deck of the ship.
On March 25, 2021, a Falcon 9 second stage made an uncontrolled re-entry over Washington producing a widely seen "light show".
A hole of size 5.5 mm was formed due to debris which had a major impact on the radiator of Space Shuttle Endeavour during STS – 118.
Debris caused the degradation in the performance of the solar panels of the MIR Space Station.
On 10 February 2009, Satellite Kosmos 2251 and the operational satellite Iridium 33 collided. The speed of impact was about 11.7 km/s. Both the satellites were destroyed, creating much new smaller debris.
On 22 January 2013, BLITS (Russian satellite) was struck by debris from the Chinese Anti-Missile Test.
Debris and overcrowding present serious threats to the 335-billion-dollar global space industry and the space-based services on which Countries, governments, businesses, researchers, and individuals around the world rely every day to communicate, navigate, and anticipate the weather and other services. Accidents and collisions that occur in space affect the Space economy. Satellites and space research plays an important role in other industries like shipping, navigation, aviation, agriculture, and national security. It also plays a vital role in the lives of billions of people.
Solutions for Space pollution
Satellites should be designed with the ability to retire themselves after their use, by methods like lowering themselves into the atmosphere to burn up or should be carefully placed in specific orbits in which the effect of gravity of the Moon and Sun will cause them to re-enter the atmosphere.
Satellites after use that is in a higher orbit should push themselves to a higher orbit where there are no useful satellites called Graveyard Orbit.
Advanced spacecraft should be built for the removal of existing debris in space.
A well-known is the use of a remote-controlled vehicle to search, capture, and return debris to a designated station (e.g.: Clearspace one).
Shielding is a widely known method for protecting satellites from small particles.
Manoeuvres for avoiding collisions are the most common method used. By avoiding collisions, we can stop the increase of debris due to collisions. Avoiding collisions depends on detecting debris and predicting its path accurately. The satellite should have enough fuel to conduct the manoeuvre.
Currently, almost all satellites are 'disposable' which means that they cannot be refuelled. So, when the fuel runs out, they become unusable. Advanced spacecraft should be designed for refuelling satellites in orbit.
Use of a specially designed net or harpoons for debris collection and removal (E.g.: Spacenet by JAXA, e. Deorbit by European Space Agency).
Usage of ground-based laser beams which heats up satellites and allows them to get dragged to Earth’s atmosphere.
There should be efficient tracking, monitoring and study regarding Space debris.
Till date there are no specific rules or treaties regarding the mitigation of space debris.
Rules and regulations must be made and implemented in order to minimize the
generation and growth of space junk.
Conclusion
Humanity has been evolving for years finding more knowledge and producing new technology. This helped us to reach where we are. But during our growth, the destruction we caused to our nature and skies is very high. As the ones who have caused such destruction it is our duty and responsibility to clean up the mess, we have caused. We should learn from our mistakes and try to prevent such damages from happening. Mankind needs to use the knowledge that we acquired for the protection of our Earth. We should be aware that if we don’t put an end to this pollution, it is the future generations who are going to face trouble. So, we should start cleaning up the junk we put on the skies so that our future generations will be able to see the stars more brightly.
References
1. https://dailybrief.oxan.com/Analysis/DB238840/Space-debris-threatens-global- economy and-security
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4. https://en.wikipedia.org/wiki/Space_debris
5. https://www.esa.int/Safety_Security/Space_Debris/The_cost_of_space_debris