Climate footprint of Space Exploration

As the world increasingly depends on space technologies for vital functions like climate monitoring, concerns about the environmental impact of space activities are growing. The rapid rise in the number of satellites and space missions is leading to two main issues:

• Pollution from rocket emissions
• Orbital debris

Environmental Impact of Space Activities

Space activities, particularly rocket launches, have environmental consequences:

• Rocket emissions: Every rocket launch releases gases like carbon dioxide (CO2), black carbon, and water vapour into the atmosphere. Black carbon is particularly harmful as it absorbs sunlight and contributes more to global warming than CO2.
• Ozone depletion: Some rocket propellants, especially chlorine-based chemicals, damage the ozone layer, which protects Earth from harmful ultraviolet radiation. This leads to increased UV exposure and disruptions in atmospheric circulation, affecting global climate.
• Satellite production: Building satellites is an energy-intensive process that involves extracting and processing metals, which contributes to carbon emissions. Satellites also use propulsion systems that emit additional pollutants.
• Space mining: While not yet active, extracting resources from asteroids could further increase industrial activities both in space and on Earth, adding to environmental concerns.

Risks of Orbital Debris (Space Junk)

Orbital debris refers to defunct satellites, rocket stages, and broken-up pieces of satellites floating in Low Earth Orbit (LEO).

• As of September 2024, there are about 19,590 satellites in orbit, with 13,230 still in space. Around 10,200 of these are functional.
• Space debris poses risks to both active satellites and space missions. Even small pieces of debris, traveling at speeds up to 29 km/s, can damage satellites, disrupting services like communication, navigation, and climate monitoring.
• The increasing amount of debris makes it harder to avoid collisions, adding costs to space missions due to the need for protective measures like shielding satellites and performing costly manoeuvres.

Barriers to Space Sustainability

Currently, there are no clear international regulations on space emissions or debris, which complicates efforts to ensure sustainability:

• Lack of regulation: Space activities are not covered by agreements like the Paris Agreement, which addresses climate change. Without clear regulations, emissions from rockets and satellites could worsen global warming.
• Crowded orbits: The growing number of satellites and debris in LEO increases the risk of collisions, which raises the costs of future missions and makes space less accessible.
• Need for international cooperation: Bodies like the Committee on the Peaceful Use of Outer Space (COPUOS) can help create global standards, but current efforts lack enforceability.

Solutions for Sustainable Space Exploration

Achieving sustainability in space requires technological advancements and regulatory changes:

• Reusable rockets: Companies like SpaceX and Blue Origin have developed rockets that can be reused, reducing manufacturing waste and mission costs. However, these rockets are heavier and consume more fuel, which complicates scaling the technology.
• Clean fuels: Using liquid hydrogen or biofuels could reduce harmful emissions. However, hydrogen is currently produced using non-renewable energy, which limits its environmental benefits. Cryogenic fuels offer more power but are expensive and complex to use.
• Biodegradable satellites: Designing satellites with materials that can disintegrate when they re-enter Earth's atmosphere could help reduce space debris. However, these materials are not yet durable enough for space conditions.
• Autonomous debris removal: Technologies like robotic arms and laser systems could help remove space junk, but they are expensive and need clearer legal frameworks before they can be used effectively.
• Space traffic management: A global system to track satellites and debris could help avoid collisions and optimize the use of orbits. However, data-sharing challenges, particularly due to security and commercial concerns, hinder progress.

What Needs to Be Done?

• Regulations and international agreements: Governments must create binding agreements to set limits on emissions, manage debris, and improve data-sharing. This can be done through COPUOS and other international bodies.
• Funding for green technologies: Governments and private companies should invest in clean technologies, debris removal systems, and biodegradable satellites to reduce space's environmental footprint.
• Incentives for sustainable practices: Financial rewards, subsidies, or penalties could encourage companies to adopt more sustainable practices.