• Russia tested a Direct-Ascent Anti-Satellite (DA-ASAT) missile on November 15, that struck its own old satellite (COSMOS 1408) and created a debris field in low-Earth orbit. 

• According to the US Space Command, the debris created by Russia’s DA-ASAT will continue to pose a threat to activities in outer space for years to come, putting satellites and space missions at risk, as well as forcing more collision avoidance maneuvers.

• The Cosmos 1408 satellite, that was destroyed, was launched in 1982 and weighed more than 2,000 kg, creating a significant amount of space debris. The test generated more than 1,500 pieces of “trackable orbital debris” and would likely spawn hundreds of thousands of smaller fragments, the US Space Command said.

• Russia’s test has drawn criticism for endangering the crew of the International Space Station (ISS). Space junk threatened the seven astronauts aboard the ISS and forced them to seek shelter in their docked capsules.

• Apart from Russia, China, the US and India have shot down satellites, creating space debris.

What is space debris?

• Ever since the start of the space age there has been more space debris in orbit than operational satellites.

• The amount of objects, combined mass and combined area has been steadily rising since the beginning of the space age, leading to the appearance of involuntary collisions between operational payloads and space debris. 

• Space debris encompasses both natural meteoroid and artificial (human-made) orbital debris. Meteoroids are in orbit about the Sun, while most artificial debris is in orbit about the Earth (hence the term “orbital” debris).

• Orbital debris is any human-made object in orbit about the Earth that no longer serves a useful function. Such debris includes non-functional spacecraft, abandoned launch vehicle stages, mission-related debris, and fragmentation debris.

• There are approximately 23,000 pieces of debris larger than a softball orbiting the Earth. They travel at speeds up to 28,000 kmph, fast enough for a relatively small piece of orbital debris to damage a satellite or a spacecraft. 

• There are half a million pieces of debris the size of a marble or larger (up to 0.4 inches, or 1 centimeter) or larger, and approximately 100 million pieces of debris about .04 inches (or one millimeter) and larger. There is even smaller micrometer-sized (0.000039 of an inch in diameter) debris.

• Even tiny paint flecks can damage a spacecraft when traveling at these velocities. A number of space shuttle windows were replaced because of damage caused by material that was analysed and shown to be paint flecks. In fact, millimeter-sized orbital debris represents the highest mission-ending risk to most robotic spacecraft operating in low Earth orbit.

• The International Space Station (ISS) orbits Earth at an altitude of just over 400 km. In the two decades since its launch, about 30 ‘collision avoidance manoeuvres’ have been performed in order to dodge space debris, with three taking place in 2020 alone. If a potential collision appears imminent, and there is no time to move the Station, they can take emergency shelter.

• In 1996, a French satellite was hit and damaged by debris from a French rocket that had exploded a decade earlier.

• In February, 2009, a defunct Russian spacecraft collided with and destroyed a functioning US Iridium commercial spacecraft. The collision added more than 2,300 pieces of large, trackable debris and many more smaller debris to the inventory of space junk.

• China’s 2007 anti-satellite test, which used a missile to destroy an old weather satellite, added more than 3,500 pieces of large, trackable debris and many more smaller debris to the debris problem.

• Not only a hazard, space debris increases the cost for satellite operators. Satellite operators in the geostationary orbit have estimated protective and mitigation measures account for about 5-10 per cent of mission costs and for lower-Earth orbits the cost is higher.

How long will orbital debris remain in Earth orbit?

• The higher the altitude, the longer the orbital debris will typically remain in Earth orbit. Debris left in orbits below 600 km normally fall back to Earth within several years. At an altitude of 800 km, the time for orbital decay is often measured in decades. Above 1,000 km, orbital debris will normally continue circling the Earth for a century or more.

• A significant amount of debris does not survive the severe heating that occurs during re-entry. Components which do survive are most likely to fall into the oceans or other bodies of water.

What can be done about orbital debris?

• The most important action currently is to prevent the unnecessary creation of additional orbital debris. This can be done through prudent vehicle design and operations. Cleaning up the environment remains a technical and economic challenge.

• As space debris poses a problem for the near Earth environment on a global scale, only a globally supported solution can be the answer.

• The United Nations Committee on the Peaceful Uses of Outer Space by the United Nations Office for Outer Space Affairs (UNOOSA) has paid particular attention to the issue of preventing and minimising the creation of space debris.

• Japan’s Aerospace Exploration Agency (JAXA) and the European Space Agency have partnered with start-ups to help with removal of space debris. The ESA is working with Swiss start-up ClearSpace for launching a mission in 2025.

• The NASA Orbital Debris Programme officially began in 1979 in the Space Sciences Branch at the Johnson Space Center (JSC) in Houston, Texas. The programme looks for ways to create less orbital debris, and designs equipment to track and remove the debris already in space.

• Ever increasing improvements in space surveillance sensor capabilities during the last decades have brought down the size limits where debris can be reliably tracked and catalogued. This, in turn, implies that we know about significant amounts of space debris, but not all their originating events.

• The problem of managing space debris is both an international challenge and an opportunity to preserve the space environment for future space exploration missions.

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