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Artist’s illustration of space junk orbiting Earth. | Credit: NASA
This article was originally published on The conversation. The publication contributed the article to Space.com Expert voices: opinion pieces and perspectives.
China regularly sends astronauts to and from its space station Tiangong. A crew capsule is about to detach from the station and return to Earth, but its journey back is anything but routine.
THE Shenzhou-20 the capsule will not carry any crew, because one of its windows was hit by space debris. The astronauts noticed an apparent crack on November 5, during pre-return checks.
Space journalist Andrew Jones how experts on the ground had studied images of the damage and concluded that a piece of debris smaller than 1 mm (about 1/25th of an inch) had penetrated from the outer layers to the inner layers of the glass.
Simulations and tests confirmed a low probability that the window would fail during high-temperature reentry into the Earth’s atmosphere. Although this is a worst-case scenario, this scenario was deemed unacceptable by the authorities. A rescue mission – Shenzhou-22 – was launched to bring back the astronauts from the station.
Experts have been warning for years about the threat posed by space debris. The ever-increasing number of space programs run by states and private entities now contributes to an increasingly crowded environment in orbit.
THE European Space Agency estimates that there are over 15,100 tons of material in space that have been launched from Earth. There are 1.2 million pieces of debris between 1 cm and 10 cm and 140 million pieces of debris between 1 mm and 1 cm.
In low orbit, they will travel at about 7.6 km/s (about 17,000 miles per hour), damaging anything they hit. This is how a piece of less than 1 mm was able to penetrate the thick glass of the Shenzhou-20 capsule.
Given the increasing number of objects in orbit, this is likely to become more regular. This is costly in terms of property damage and increasingly poses a threat to life. When debris hits another object in space, it can also create more space debris, making the problem worse.
A number of countries are capable of tracking what is in space, but given that these may include classified satellites, states are reluctant to share details. China’s space program is overseen by its military, consistent with the idea that space is intrinsically linked to national security. This only adds to geopolitical tensions between states around the use of space.
Treaties and responsibilities
The Outer Space Treaty of 1967 sought to define how space should be governed. But it is outdated and does not take into account the increased presence of debris or the proliferation of private space launches. It also does not address responsibilities for sustainable use of space.
In total, 117 states are parties to the treaty, but while efforts are underway to develop new norms around space governance, including the creation of the Interagency Space Debris Coordination Committeethe organization can offer a platform for cooperation and research but does not give rise to binding decisions for state action. The lack of a global agreement on space debris, and especially its repercussions, makes solving the space debris problem even more difficult.
Technology is being developed to combat space debris – but this generally appears as conceptual mission plans with only a few test trials launched anywhere in the world. Examples include the idea of a harpoon to collect large pieces – although the recoil of such an instrument means the spacecraft deploying it could become new debris.
An alternative is the highly technological approach of a large net. This will work in the sense that if you can slow down the debris, it will fall into the atmosphere and burn.
The problem with these methods is the lack of sustainability, sending a satellite to cut just a few pieces consumes fuel, which worsens climate variations. A suitable and effective solution would be a constellation of satellites that would remain in orbit and bring back the debris. Of course, the process still needs to be studied.
A ground solution is laser broomwhich uses laser pulses to slow down objects orbiting Earth, potentially allowing them to re-enter the atmosphere and burn up. However, it remains to be tested and carries its own potential problems such as atmospheric warming and missing its target.
Yet without addressing the geopolitics of space governance, space debris removal is moot because the focus on national interests, security concerns, and the growing presence of the private sector means that pollution in Earth’s orbit is occurring faster than we can clean it up.
Any collision results in the production of many more parts than can be collected, some notable examples include China’s 2007 destruction of its own parts. Fengyun-1C satellite as part of an anti-satellite weapon test. This added about 3,500 pieces to orbit.
In 2009, a Russian satellite called Cosmos 2251 collided with an Iridium communications satellite, generating approximately 2,400 pieces of debris. In 2021, Russia conducted its own anti-satellite missile test, destroying the Cosmos 1408 satellite and generating 1,787 additional coins. Most of these returned through the atmosphere, but 400 pieces remained in orbit.
Whether it is such anti-satellite weapon could be reused for space debris disposal is unlikely but has potential.
This will require global cooperation and concerted efforts to not only indicate which spacecraft states and private companies have in space, but also to commit to deorbiting each future spacecraft at the end of its life, thereby reducing future debris.
The current European Space Agency Space Debris Mitigation Standards emphasize that any satellite must be decommissioned within 25 years of the end of its operations. Although this is also intended to apply to miniatures”cubesats” – the process to bring them down has not yet been demonstrated.
Ultimately, this debris will cause problems for all space launch agencies and private companies because there is a limit to our ground-based tracking and warning capabilities. It is therefore crucial to address global space governance. However, it may take several expensive satellites to be decommissioned, or potentially suffer human casualties, for this issue to be taken seriously.
