Space Cleaning: Reducing Pollution, Ensuring Safety

Space is getting crowded. With the increase in space exploration and activity, there is now a growing amount of space debris in orbit, posing a significant threat to spacecraft and satellites. The issue of space junk is one of the biggest challenges facing the space industry, and it is only getting worse as more objects are launched into orbit. The risk of collisions is ever-present, and the potential consequences are dire. To address this issue, various methods have been proposed, ranging from technological solutions such as laser systems and space tugs to policy interventions like international agreements and orbital-use fees. While there is no easy solution, it is clear that reducing space pollution is crucial to ensuring the safety and sustainability of space exploration and the long-term health of the planet.

Create international agreements to charge operators orbital-use fees for satellites

The issue of space debris is a pressing one, with an estimated 20,000 objects, including defunct satellites and space debris, currently crowding low-Earth orbit. This number does not include the more than 100 million smaller pieces of space debris. Even these tiny pieces pose a threat to objects in orbit due to their high orbital speeds, and several spacecraft have already been damaged or destroyed as a result.

A team of researchers from the University of Colorado Boulder has proposed an innovative solution to address this issue: implementing an international agreement to charge operators "orbital-use fees" for each satellite they put into orbit. This approach is different from a launch fee and would incentivize operators to properly manage and dispose of their satellites at the end of their lifetimes.

The orbital-use fee would function similarly to a carbon tax or fisheries management fee, and all countries launching and operating satellites would need to participate. The fee would be calculated based on the cost to the industry of putting another satellite into orbit, including the costs of collision risk and space debris production. It could also be orbit-specific, with higher charges for satellites in crowded orbits with a higher risk of collision.

The researchers estimate that an annual fee of approximately $235,000 per satellite, increasing at a rate of 14% per year, would quadruple the value of the satellite industry by 2040. This increase in value is attributed to the reduction in collisions and associated costs, such as launching replacement satellites.

By addressing the issue of space debris through this international agreement, the long-term value of the satellite industry can be significantly enhanced, and the risks associated with space debris can be mitigated.

Implement guidelines for responsible behaviour in outer space

The issue of space pollution, particularly the accumulation of space debris, is a pressing concern that threatens the sustainability of outer space activities and global security. While various solutions have been proposed, from technological fixes to policy changes, a comprehensive approach that addresses the root causes and involves all stakeholders is necessary. Implementing guidelines for responsible behaviour in outer space is a crucial step towards mitigating space pollution and ensuring the long-term viability of space exploration and utilisation. Here are several key considerations for establishing and enforcing such guidelines:

International Cooperation and Collaboration:

Addressing space pollution requires a global effort due to the international nature of space activities. The United Nations, through its Committee on the Peaceful Uses of Outer Space (COPUOS), has played a pivotal role in fostering dialogue and consensus among nations. The development of voluntary guidelines by COPUOS, in collaboration with major spacefaring nations, is a significant step forward. However, to be truly effective, these guidelines must be widely adopted and implemented by all countries and organisations involved in space activities.

Binding Agreements and Enforcement:

While voluntary guidelines are a start, the lack of enforceability may limit their impact. The complexity of space activities, involving multiple actors with competing interests, underscores the need for binding agreements with clear consequences for non-compliance. The Outer Space Treaty (OST) of 1967 serves as a foundational document, but it needs to be updated to address modern challenges, including space pollution. Negotiating new treaties or amending existing ones to include specific provisions for responsible behaviour and pollution mitigation will be essential to establishing a robust regulatory framework.

Incentivising Responsible Behaviour:

Economic incentives can play a crucial role in encouraging responsible behaviour. The concept of "orbital-use fees" or "taxes" on satellites has been proposed, where operators are charged for each satellite placed into orbit. Such fees would account for the costs imposed on other operators due to collision risks and space debris production. This approach not only generates revenue to address the space junk problem but also incentivises operators to reduce future satellite launches, minimising collision risks and debris generation.

Technological and Managerial Solutions:

While the primary focus is on behavioural guidelines, technological and managerial solutions are complementary. Tenet 2 of the US Guidance on Responsible Behaviour in Space, for example, emphasises the importance of designing, operating, and maintaining space objects to limit the generation of long-lived space debris. This includes considering end-of-life disposal options, such as deorbiting satellites at the end of their operational lifespan. Additionally, collision avoidance systems and safe trajectories can help prevent accidental collisions and mitigate the creation of new space debris.

Private Sector Engagement:

The increasing involvement of the private sector in space activities adds complexity to the regulatory landscape. Corporations play a significant role in providing space services and products, and their participation in establishing responsible behaviour guidelines is crucial. Engaging with private sector entities to identify threats, risks, and responsible practices can help develop more comprehensive and practical guidelines. Additionally, encouraging the adoption of best practices and providing incentives for responsible behaviour within the private space industry will be essential.

Education and Awareness:

Raising awareness about the space debris problem and promoting responsible behaviour at all levels are vital. Educational initiatives targeting space operators, policymakers, and the general public can foster a culture of responsible space stewardship. This includes sharing knowledge about the potential consequences of irresponsible behaviour, such as the risks posed by the Kessler Syndrome, where low Earth orbit becomes increasingly congested and unusable.

Develop debris-cleaning tech like ground laser nudges, space tugs, and space lasers

The problem of space junk is a pressing issue that needs to be addressed. There are several proposed solutions, including the use of debris-cleaning technologies such as ground laser nudges, space tugs, and space lasers.

Ground-based laser systems, or "laser brooms", have been proposed to sweep up smaller space debris. The laser heats up one side of the debris, altering its trajectory so that it falls into the atmosphere. This method is intended to be used on debris between one and ten centimetres in diameter, preventing collisions that could cause significant damage to satellites and create even more secondary debris. The laser would operate in a pulsed fashion to avoid the target from self-shielding through its ablated plasma. The power levels required for this method are well below those of anti-satellite weapons. A ground-based laser system could offset the orbits of dozens of pieces of debris daily at a reasonable cost.

Space-based lasers have also been proposed, with a project planned to be installed on the International Space Station in 2003. Laser-nudging the top 50 objects of concern would be beneficial, according to a NASA report, although higher-cost options such as rocket nudges could be faster.

Another option is the use of space tugs, which are being considered by NASA for removing larger pieces of space debris. A $1 billion space tug has been announced to safely remove the International Space Station when it concludes operations in 2030.

While these technologies show promise, it is important to note that the solutions to the space debris problem are not solely technological. An international agreement to charge operators "orbital-use fees" for every satellite put into orbit has been proposed as a way to reduce future satellite and debris collision risk. This approach addresses the incentive problem, where operators launch more satellites without considering the costs their launches impose on other satellite operators.

Make satellites reusable and manoeuvrable to avoid collisions

The number of satellites in low-Earth orbit is increasing, and with it, the risk of collisions. To avoid collisions, satellites need to be manoeuvrable, and one way to achieve this is by using an electric propulsion system. Accion Systems has developed a commercial electrospray propulsion system made of tiny chips that provide thrust for small satellites. This technology is particularly useful for small satellites, which otherwise lack viable propulsion systems. Without a propulsion system, small satellites cannot accurately point cameras or change orbit, and they usually crash and burn within a few months.

Accion's electrospray propulsion system, called MAX-1, is about the size of a pack of gum and can be placed anywhere on a satellite. It has a plastic tank that stores a nontoxic, non-volatile, liquid-salt propellant. Above the reservoir are chips, each with a porous substrate with about 500 pointed tips, and above that, an extractor grid with small holes. When a high voltage is applied between the tips and the grid, charged ions burst through the holes, propelling the satellite in the opposite direction.

This technology is much cheaper than other propulsion systems, and it doesn't require pressurised tanks, bulky valves, or neutralising cathodes. It has a higher thrust-to-mass ratio than low-power, plasma-based ion engines, meaning it packs more punch. This technology could enable low-cost satellites to become more viable for commercial and research applications, including advanced imaging and communications.

In addition to making satellites manoeuvrable, it is also important to consider making them reusable. Reusable launch vehicles have parts that can be recovered and reflown, reducing launch costs. While the benefits of reusability may be diminished by the cost of recovery and refurbishment, reusable systems can still significantly impact the space industry. For example, SpaceX routinely recovers and reuses the first stages of its Falcon 9 rockets.

By making satellites both reusable and manoeuvrable, we can avoid collisions and reduce space pollution.

Prioritise removing small debris, which is harder to track but no less dangerous

The issue of space debris is a pressing one, with the potential to affect space innovation and invention in the coming decades if not addressed. While there are various methods to manage and mitigate debris, from legislative and regulatory efforts to technological solutions, the challenge remains a complex one.

One of the most critical aspects of space debris is the presence of small debris, which is harder to track due to limitations in current technology. These tiny objects, ranging from 1 millimetre to 10 centimetres in size, pose a significant risk to spacecraft. Despite their small size, the speed at which objects move in Low Earth Orbit (LEO) can cause even a small object like a ping pong ball to inflict significant damage or completely shatter existing infrastructure, creating more fragments. Therefore, prioritising the removal of small debris is crucial.

NASA's recent financial analysis highlights the importance of addressing small debris. Their models indicate that removing non-trackable debris can have immediate benefits, and it would take only 3-4 years to make up for the initial costs of removing trackable debris. Additionally, removing smaller debris demonstrates faster results and is more financially feasible than tackling larger debris.

To effectively remove small debris, innovative solutions are required. Current tracking methods are insufficient for detecting and monitoring these tiny objects. A more robust and scalable system is necessary for successful detection, tracking, and remediation. NASA's Detect, Track, and Remediate: The Challenge of Small Space Debris competition aims to address this issue by inviting participants to contribute groundbreaking concepts.

Some proposed solutions for remediating small space debris include designing satellites for controlled deorbiting and implementing active debris removal missions. However, these approaches pose significant challenges in terms of cost and time due to the vast amount of small debris in LEO. Therefore, it is essential to explore cost-effective and practical strategies for reducing the overall debris population, mitigating collision risks, and maintaining the sustainability of orbital space.

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