How dangerous is space debris? | DW Documentary

Key Concepts

Space debris, Kessler syndrome, satellite course correction, laser momentum transfer, hypervelocity impacts, space servicing vehicles, controlled re-entry, mega constellations, space sustainability, light pollution.

The Growing Problem of Space Debris

The video highlights the increasing problem of space debris, caused by decades of space exploration and a lack of regulation. Millions of pieces of waste, including old rocket parts, defunct satellites, and fragments from collisions, are orbiting Earth at speeds of up to 7 kilometers per second, posing a significant threat to operational satellites, the International Space Station (ISS), and potentially even the Earth's surface.

• Speed and Danger: Space debris travels at extremely high speeds (ten to twenty times faster than a bullet), making even small pieces capable of causing significant damage upon impact.
• ISS Incident: The video recounts a 2021 incident where the ISS crew had to take shelter due to a cloud of debris created by a Russian anti-satellite missile test. The risk of losing the ISS due to debris impact is estimated at 1 in 8 over a 10-year period.
• Visualization of Space Objects: The video shows a visualization of the space object population, highlighting the concentration of debris in two main regions: a shell up to 2,000 kilometers and the geostationary orbit at 36,000 kilometers.
• Lack of Regulation: There are currently no international laws to penalize polluters of space, contributing to the problem.

Historical Context and Key Events

The video traces the history of space debris back to the launch of Sputnik 1 in 1957, marking the beginning of the space race and the accumulation of waste in orbit.

• Sputnik 1: The launch of Sputnik 1 and its launch rocket marked the beginning of space debris.
• Chinese Anti-Satellite Test (2007): China's destruction of one of its derelict orbiting satellites created thousands of new pieces of debris in a fraction of a second.
• Iridium-33 Collision (2009): The accidental collision between the operational satellite Iridium-33 and a derelict Soviet Cosmos 22-51 satellite significantly increased the amount of space debris. This event was a "watershed" moment, raising awareness of the need for space sustainability.

Monitoring and Tracking Space Debris

The US military and private companies are actively involved in tracking and monitoring space debris to mitigate the risk of collisions.

• US Military Tracking: The US military tracks debris larger than 10 centimeters.
• Private Radar Systems: Companies like the one operating the radar on Santa Maria Island in the Azores use advanced radar systems to track objects as small as two centimeters. These radars can track up to a thousand objects per hour.
• Congested Zones: Data from these systems reveals heavily congested zones, particularly at an altitude of about 900 kilometers, where numerous large objects pose a collision risk.

Kessler Syndrome and Collision Avoidance

The video explains the concept of Kessler syndrome, a chain reaction where collisions create more debris, leading to further collisions and making near-Earth orbit unusable.

• Kessler Syndrome: Each collision in orbit creates new debris, which in turn, increases the risk of further collisions.
• Satellite Course Correction: Space agencies employ teams to monitor conjunctions (close approaches between objects) and perform course corrections to avoid collisions. The French space center CNES has a team of 15 people working 24/7 on this task.
• Increased Maneuvers: The number of required maneuvers is increasing due to the "democratization of space" and the advent of mega constellations like Starlink.

Potential Solutions and Technologies

Scientists and engineers are exploring various technologies to address the space debris problem, including laser momentum transfer and debris removal missions.

• Laser Momentum Transfer: The ESA is investigating the possibility of using lasers to maneuver space debris from the ground. This involves using a powerful laser to apply a small force to the debris, gradually altering its trajectory.
• Micro-Debris and Hypervelocity: The video discusses the dangers of micro-debris (small fragments) and the phenomenon of hypervelocity impacts, where collisions at high speeds create clouds of new projectiles.
• Gas Gun Experiments: Engineers use gas guns to simulate hypervelocity impacts and develop protective measures for satellites and space suits.
• ClearSpace-1 Mission: The European Space Agency (ESA) is planning the ClearSpace-1 mission, which will use a robot with articulated arms to capture a piece of debris (the "Vespa" rocket section) and bring it back to Earth to burn up in the atmosphere. The mission has a budget of 100 million euros.

Preventing Future Debris

The video emphasizes the importance of preventing the creation of new debris through responsible space practices and international cooperation.

• International Code of Conduct: An international code of conduct recommends that operators remove their satellites from low Earth orbit within 25 years and exile old satellites to a "graveyard orbit."
• Space Servicing Vehicles: Companies are developing space servicing vehicles that can refuel and repair defective satellites, extending their operational life and reducing the need for replacements.
• Sustainable Satellite Design: Engineers are designing new satellites with features like controlled re-entry capabilities, ensuring they do not become debris at the end of their lives. The SWOT satellite, developed by NASA and CNES, is an example of this approach.
• French Law: France is the first country to have passed a law that aims to reduce the amount of space junk.

Light Pollution and Re-entry Risks

The video also touches on the issues of light pollution caused by satellites and the risks associated with debris re-entering the Earth's atmosphere.

• Light Pollution: Mega constellations like Starlink contribute to light pollution, affecting astronomical observations.
• Re-entry Risks: Objects in orbit at under 500 kilometers altitude will fall back to Earth's surface within 25 years. While most debris burns up in the atmosphere, larger pieces can survive and pose a risk to populated areas.
• Chinese Rocket Debris: The video mentions instances of Chinese rocket debris falling back to Earth, including an incident where debris landed near a village in Côte d'Ivoire.

Conclusion

The video concludes that the space debris problem is a growing threat that requires urgent action. While cleaning up existing debris is important, preventing the creation of new debris through responsible space practices, international cooperation, and sustainable satellite design is crucial for ensuring the long-term accessibility and sustainability of space. The video emphasizes that we still have time to act and keep space accessible to future generations.