Tuesday, 14 November 2023 | in Guest Column
GUEST COLUMN
Vir Singh
In today’s era of rapid technological development and space exploration, the world has made significant progress in the exploration of outer space. The space race is about to start after the unprecedented success of India’s moon mission. Along with the achievements of space, another serious problem is also lurking on which the attention of the world community has not yet been focused. That problem is space pollution whose dark shadow is going to fall in the future on the already polluted Earth.
According to the Union of Concerned Scientists (UCS), which keeps records of operational satellites, as of January 1, 2021, there were 6,542 satellites orbiting the Earth, of which 3,372 were active and 3,170 were inactive. According to the United Nations Office for Outer Space Affairs (UNOOSA), which monitors all space activities, as of January 2022, there are 8,261 satellites orbiting the Earth, of which only 4,852 are active.
As more satellites are launched into orbit in the coming decades, the number of collisions and subsequent space debris is likely to increase. There are at least 128 million pieces floating in low Earth orbit (LEO). According to the Natural History Museum in London, about 34,000 of those pieces are more than 10 centimetres in size. Space junk is likely to be uncountable in the future.
We have not only polluted the Earth’s orbit with debris, but also left many objects on the surface of the Earth’s only moon, many kept there as souvenirs or time capsules. Currently, apart from India’s operational pride symbol Vikram Lander and Pragyan at the Shiv Shakti point on the Moon, there is much more on the Moon surface that has now become debris, such as three Moon buggies of Apollo 15, 16 and 17; 54 unmanned vehicles which had crashed on the lunar surface; 19000 kg of material left by astronauts; Soviet Union’s Luna-2 (1959); USA’s Ranger-4 (1969); Japan’s Hiten (1993); Europe’s Smart-1 (2006); India’s Chandrayaan-1 (2008); China’s Chang’e-1 (2009); Israel’s Beresheet (2019), India’s Chandrayaan-2 (2019), Russia’s Luna-25 (2023), etc.
Apart from these, some strange objects have also been left on the Moon, such as a golden olive branch in 1969 (Apollo 11), Andy Warhol’s artwork in 1969 (Apollo 12), three golf balls in 1971 (Apollo 14), an eagle feather in 1971 (Apollo 15), a photo of astronaut Charles Duke’s family in 1972 (Apollo 16), etc.
Operating so many satellites in Earth’s orbit is going to be a big challenge. Collisions are not the only cause of space debris. Prolonged exposure to intense ultraviolet radiation in LEO can also cause satellites to break up.
Space debris has the potential to damage other satellites as well as other spacecraft. In June 2021, the International Space Station was struck by a piece of debris, causing a hole in the robotic arm. Fortunately, the space station and the astronauts inside escaped any major damage.
Ultimately, the number of satellites in LEO could lead to an uncontrolled series of collisions that would scatter space debris all around, to the point that we would be unable to launch new rockets. This possibility is known as Kessler Syndrome and many astronomers fear that if we cannot keep space debris under control it could prevent humanity from becoming a multi-planetary species.
Some objects in low orbits of a few hundred kilometers from Earth can return quickly. After a few years they re-enter the atmosphere and are destroyed by atmospheric friction and are unable to reach the lower atmosphere. But a satellite launched at an altitude of 36,000 kilometers and its resulting debris – where communications and weather satellites are often placed in geostationary orbits – may remain orbiting the Earth for hundreds or thousands of years.
Some space debris results from in-orbit collisions or anti-satellite tests. When two satellites collide, they can break into thousands of new pieces, creating a lot of new debris. It is rare, but several countries, including the United States, China, and India, have used missiles to practice blowing up their own satellites. How much more garbage will spread in space through this process can be imagined.
Fortunately, so far space pollution has not posed any major risk to our space exploration programs. The biggest threat from this is to other satellites working in orbit. The ever-increasing pollution is sure to hinder future space programs. Surviving satellites must be moved out of the way of incoming space debris to ensure they are not hit and potentially damaged.
There has been a rush for space tourism in the last few years, due to which black carbon emissions may more than double in the next three years. The particles emitted by rockets are approximately 500 times more capable of retaining heat in the atmosphere than all other sources of soot, which is likely to increase climate change.
The United Nations mandates that all companies decommission their satellites within 25 years after the end of their missions. This order is difficult to enforce, because satellites can, and often do, fail. To deal with this problem, companies have come up with new solutions. This involves removing dead satellites from orbit and pulling them back into the atmosphere where they will burn up. Techniques by which this is done include using a harpoon to capture the satellite, catching it in a giant net, using magnets to hold it, or even firing a laser to heat the satellite, increasing atmospheric pull, etc. so that it falls out of orbit.
These techniques for removing space junk from Earth’s orbit are suitable for large-sized defunct satellites orbiting the Earth. There is no way to pick up small pieces of debris, such as paint and metal pieces. We just have to wait for them to re-enter Earth’s atmosphere naturally.
Several private companies, notably Space X and Amazon, are planning huge new constellations of satellites, called mega constellations aimed at strengthening the internet system on Earth. These companies are chalking out plans to launch thousands of satellites to achieve global satellite Internet coverage. If these private space companies come out with success, there might be as many as 50,000 additional satellites in orbit. Therefore, more and more measures will have to be taken to avoid space debris.
Earth’s orbit allows us to study our planet, send communications, and much more. In modern times, our life has adapted to the facilities provided by this orbit of the Earth. Therefore, continuing to clear this orbit of useless debris can ensure the benefits of space science for future generations.
(The author is professor emeritus, environmental science at GB Pant University of Agriculture and Technology. Views expressed are personal)
