Why satellite space junk may be bad news for the environment/What is Satellite space junk?

Why satellite space junk may be bad news for the environment

More than 10,000 active satellites are in orbit around the planet today. This number is estimated to shoot up to more than 100,000 by the 2030s, and possibly half a million in the decades to follow.

Most satellites, at the end of their life-cycle, fall to a fiery death through Earth’s atmosphere. As they disintegrate, however, they leave all kinds of pollutants in the upper atmosphere. As the number of satellites goes up, so will this pollution. And some scientists are very worried.

 Polluting satellites:

• Daniel Murphy, an atmospheric scientist at the US National Oceanographic and Atmospheric Administration (NOAA), and others presented definitive evidence that “10% of the aerosol particles in the stratosphere contain aluminum and other metals that originated from the burn-up of satellites, and rocket stages during reentry”(‘Metals from spacecraft reentry in stratospheric aerosol particles’, 2023).
• Connor Barker, an atmospheric chemist from the University College of London, and others found that emissions of aluminum and nitrogen oxides from satellite reentries significantly increased from 3.3 billion grams in 2020 to 5.6 billion grams in 2022. Also on the rise were emissions from rocket launches, which leave pollutants such as black carbon, nitrogen oxides, carbon monoxide, aluminum oxide and a variety of chlorine gases (‘Developing inventories of by-products from satellite megaconstellation launches and disposal to determine the influence on stratospheric ozone and climate’, 2024).

 Impact of satellite pollution:

• While pollution from burnt-up satellites high up in the atmosphere is seemingly a distant concern for humans, it might lead to ripple effects that will change the chemistry of the atmosphere. This is not good news. Life on Earth has evolved over billions of years to adjust to the planet’s specific environment, and even miniscule changes could trigger massive chaos on the planet.
• Scientists are particularly concerned about the impact of this pollution on the ozone layer in Earth’s stratosphere. This layer absorbs up to 99% of ultraviolet rays from the Sun, which would otherwise harm living organisms on Earth’s surface.

But pollutants from burnt-up spacecraft are likely already harming it. Aluminum oxide, for instance, is a known catalyst for ozone depletion. This would be major new threat to the ozone layer especially in the light of the success of the Montreal Protocol of 1987, which banned production and emissions of known ozone-destroying chemicals such as chlorofluorocarbons (CFCs), previously used as a common refrigerant.

Murphy also notes many other ways in which spacecraft pollutants might impact the atmospheric composition. He told Science News: “Soot emitted from rocket engines absorbs solar energy, which can warm the atmosphere. Copper and other metals released during the incineration of spacecraft wiring and alloys are known to be powerful catalysts for chemical reactions in the atmosphere. Among other things, those metals could promote the creation of the tiny particles that act as the seeds of clouds.”

What is Satellite space junk?

Satellite space junk, also known as space debris or orbital debris, refers to the collection of defunct artificial objects in Earth’s orbit. These include non-functional satellites, spent rocket stages, fragments from collisions, and other discarded items from human activities in space. Space junk poses significant risks to operational satellites, the International Space Station (ISS), and future space missions.

Sources of Satellite Space Junk:

1. Defunct Satellites:
   • Satellites that have exceeded their operational life span and are no longer functioning.
2. Rocket Stages:
   • Parts of rockets, such as upper stages, left in orbit after launching satellites or other payloads.
3. Fragmentation Events:
   • Breakup of satellites or rocket stages due to collisions, explosions, or structural failures.
4. Microparticles:
   • Small debris like paint flecks, insulation fragments, or solid rocket fuel particles.

Classification of Space Junk

1. Large Debris:
   • Includes inactive satellites and spent rocket stages.
   • Easily trackable by ground-based radar and optical systems.
2. Small Debris:
   • Fragments smaller than 10 cm, such as bolts, screws, or chips of paint.
   • Difficult to track but still dangerous due to high speeds.
3. Microscopic Debris:
   • Particles smaller than 1 cm, including dust or particles from solid rocket fuel.

Challenges and Risks of Space Junk

1. Collision Risks:
   • High-speed collisions with operational satellites or spacecraft can cause damage or create more debris (Kessler Syndrome).
2. Threat to Human Life:
   • Endangers astronauts aboard the ISS or crewed missions due to potential impacts.
3. Increased Costs:
   • Space debris increases the cost of satellite launches due to the need for collision-avoidance maneuvers.
4. Impact on Future Space Exploration:
   • Growing debris can make certain orbits unsafe for future missions.
5. Difficulty in Removal:
   • Retrieving or deorbiting space junk is technologically challenging and expensive.

Current Mitigation Efforts

1. Space Debris Tracking:
   • Organizations like NASA, ESA (European Space Agency), and private entities monitor space debris using radar and optical telescopes.
2. Collision Avoidance:
   • Satellites and spacecraft perform maneuvers to avoid debris.
3. End-of-Life Disposal:
   • Guidelines require satellites to deorbit (burn up in Earth’s atmosphere) or move to a “graveyard orbit” after their operational life.
4. International Guidelines:
   • The UN Outer Space Treaty and Space Debris Mitigation Guidelines of the UN Office for Outer Space Affairs (UNOOSA) set frameworks for managing space debris.
5. Active Debris Removal:
   • Emerging technologies like nets, harpoons, and robotic arms are being tested to remove debris.
6. Design Improvements:
   • Designing satellites and rockets to minimize debris generation (e.g., reducing fragmentation risks).

Examples of Space Junk Events

1. 2007 Chinese Anti-Satellite Test:
   • China destroyed one of its satellites, creating over 3,000 pieces of trackable debris.
2. 2009 Satellite Collision:
   • Iridium 33 (a U.S. satellite) and Cosmos 2251 (a defunct Russian satellite) collided, generating thousands of debris fragments.
3. ISS Debris Avoidance Maneuvers:
   • The ISS frequently adjusts its orbit to avoid collisions with tracked debris.