Let us talk about marine pollution caused by space debris. After sixty years of outer space conquest, orbits around the Earth are becoming a sort of landfill, being increasingly polluted by the countless presence of space debris. There are indeed more than seven hundred thousand pieces of metal and plastic larger than one centimetre that revolve around the Earth. Most often, these are not complete devices but small pieces of satellites, rocket stages or capsule elements which have come loose during accidents or even during the “normal” operation of various space operations.
But the impact of the space debris does not stop there. Although many of them remain in Low Earth Orbit (LEO), some fall back to Earth and create marine pollution. And especially in the oceans. Today, most satellites have a fuel reserve to use when they are near their end of life. This fuel must make it possible to “desorb” the satellite and destroy it in the simplest possible way: by sending it into the Earth’s atmosphere. The friction between the air molecules and the satellite increased by the Earth’s attraction will bring it to temperatures such that, in general, there will be nothing left before any debris can touch the ground. However, there are cases where debris are still present once on Earth and can create marine pollution.
But these fallout are finely planned by those who send these space objects into outer space and in order to minimise the damage caused by the space debris, the “Nemo point”, which takes its name from the famous captain of Twenty Thousand Leagues Under the Sea, is thus referred. Indeed, it is the point of inaccessibility, the most distant place from any land and any human activity. Also known as the “Spacecraft Cemetery” in the South Pacific, located about four thousand kilometers off the coast of New Zealand, it was discovered twenty-six years ago by Canadian-Croatian geographer Hrvoje Lukatela.
Even the fauna is scarce. “There are few fishes in this area because ocean currents do not pass through and do not provide nutrients to this area, which makes marine life scarce” say some specialists. Space objects can therefore crash without risk in this area, before sinking four kilometers deep. “We could also drop them in the Atlantic, but this ocean is narrower, which would make the operation more complicated”.
“There is a low probability that stages, engines or fuselage elements dropped by a launcher could reach a marine animal when they enter the ocean during nominal flight operations. The probability of a shock has been estimated. The results of this analysis indicate that there is an extremely low chance of a launching element striking a sea animal. Less than half a shock with an animal is expected annually, even when all the launch activities are added up, and an addition is made on all species of the Atlantic and Pacific oceans”, according to the “Programmatic Environmental Impact Statement for Licensing Launches”. This cemetery has already hosted two hundred and fifty to three hundred spacecraft at the end of their life. The Soviet Mir station, for example, largely ended its existence in 2001, as did the remains of the Chinese space station Tiangong-1. In a few years, it could be joined by the current International Space Station (ISS), when it is no longer in service, its mission to be completed at the earliest in 2028. These space objects can create a marine pollution.
A “European Code of Conduct for the Mitigation of Space Debris” was established in 2004 and signed by the Italian Space Agency (ASI), the British National Space Center (BNSC), the German Space Center (DLR), the French Space Agency (CNES) and the European Space Agency (ESA). This Code of Conduct clarifies and improves the mitigation measures of the IADC, the Inter-Agency Space Debris Coordination Committee created by NASA, the European Space Agency, the Russian and Japanese space agencies in 1993. This code defines the methods of design and control of spacecraft that are likely to reduce the production of waste. A space waste manager must be designated for each project. He must take care to minimise the damage to the environment when the spacecraft returns to Earth.
For example, fuels must not release particles larger than ten microns into outer space; the design of the devices, their materials and accessories must not generate waste greater than ten microns during the orbiting phase; the return to Earth of a spacecraft must not produce harmful effects on the terrestrial environment, particularly in the radiological, biological and chemical fields. Compliance with this Code of Conduct has been mandatory since April 1, 2008 and the European ATV program, although launched before its entry into force, has applied its recommendations. If the project cannot comply with the objectives of the Code of Conduct, this non-compliance must be justified and recorded. The propellants used as fuel for launchers are often polluting. Some debris falling from their orbit can be dangerous; some satellites carry toxic or radioactive materials, which are not necessarily consumed when crossing the Earth’s atmosphere. An example of this problem is the Kosmos 954 satellite, which used a small nuclear reactor; when it fell on January 24, 1978, it disintegrated over the far Canadian north, dispersing its debris there.
The European Space Agency (ESA) is thus working on the design of a space cargo ship that can carry out a fully controlled re-entry of the atmosphere and a smooth return to Earth using parachutes to recover valuable scientific equipment and waste. In the medium term, the ambition of the European Space Agency (ESA) is to develop and implement vessels capable of capturing space waste.
Contrary to what might be inferred from the use of this area as a space debris cemetery, the biggest source of pollution in this place does not come from this rubble. A study has shown that this region of the South Pacific Ocean has become an open-air plastic dump, where fishing lines and fragments recovered from ships or the coastline float. Because of the rotating current, this debris stagnates and eventually disintegrates into tiny particles. During the last Volvo Ocean Race, the samples taken showed the presence of twenty-six micro-plastics per cubic meter of water. The most isolated place on the planet is also one of the most polluted, and it is due to the debris rejected by humans due to the displacement of plastic waste rejected by civilisations.
While the law banning the use of single-use plastic was voted in France for only 2040, reports, such as this one, are cold in the back and prove that our consumption of plastic is such that this toxic material is found en masse in the most distant places from all civilisation and all humanity. This is what can be said concerning Marine pollution caused by space debris.
This article was written by Solène FAUQUEUX (Paris-Saclay).