Space Debris

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    In News

    • Recently, the debris from the last stage of China’s Long March 5B rocket fell into the waters of the Pacific and the Indian oceans. 

    More about the news:

    • As the 22-tonne core stage of the rocket hurtled uncontrollably back to earth.
    • Issues:
      • Generally, the core or first stage of a rocket is made up of heavy pieces that usually don’t reach orbit after liftoff, and fall back safely along a near-precise projected trajectory.
      • Most nations’ rockets separate the launcher from the payload before leaving the atmosphere
      • An extra engine then gives the payload a final boost
    • China’s case:
      • China’s 5B series does not use a second engine and pushes right into orbit, the report points out.

    Space Debris

    • Most Space debris comprises human-generated objects, such as pieces of spacecraft, tiny flecks of paint from a spacecraft, parts of rockets, satellites that are no longer working, or explosions of objects in orbit flying around in space at high speeds.
    • Most “space junk” is moving very fast and can reach speeds of 18,000 miles per hour, almost seven times faster than a bullet. 
    • It could land as one piece but more probably as many, scattered over an area up to several hundred miles across. 

    Challenges in Space Debris Removal

    • Difficulty in tracking uncontrolled descents:
      • The variables involved make it difficult to precisely track the re-entry time and drop zone of rocket debris in uncontrolled descents. 
      • The factors that make this prediction extremely challenging include: 
        • Atmospheric drag, 
        • Variations in solar activity, 
        • Angle and rotational variation of the object, etc.
      • A miscalculation of even a minute in re-entry time could result in the final resting place of the debris changing by hundreds of kilometres.
    • Others:
      • Unfortunately, there is an explosion risk in removing more dangerous objects.
      • The issue of property rights; one can’t grab a satellite or rocket that belongs to another country without their permission. 
      • It is hard to eliminate space debris as there are huge chances of creating more junk while doing it.
      • Most satellite operators require hours or days to plan and execute a collision-avoidance manoeuvre. 

    International events & agreements on space junk

    • The Space Liability Convention of 1972:
      • It defines responsibility in case a space object causes harm
      • The treaty says that “a launching State shall be absolutely liable to pay compensation for damage caused by its space objects on the surface of the earth or to aircraft, and liable for damage due to its faults in space. 
      • The Convention also provides for procedures for the settlement of claims for damages.”
        • The only settlement using the Liability Convention was between the erstwhile Soviet Union and Canada over the debris of Soviet Cosmos 954 falling in a barren region.
    • Absence of law:
      • However, there is no law against space junk crashing back to earth.
      • Should the debris hit something or, worse, someone, people affected will be liable for compensation. 
      • But otherwise, there are no international rules to prevent or restrict uncontrolled re-entries. 
    • Recent incidents:
      • In April this year, suspected debris from a Chinese rocket was found in two Maharashtra villages.

    Way Forward

    • Spacefaring nations must minimize the risks to people and property on Earth of re-entries of space objects and maximize transparency regarding those operations.
    • It is critical that all spacefaring nations and commercial entities act responsibly and transparently in space to ensure the safety, stability, security and long-term sustainability of outer space activities.
    • The problem of managing space debris is an international challenge & a law should be framed by an international agency against space junk crashing back to earth.

    Kessler Syndrome

    • This is an idea proposed by NASA scientist Donald Kessler in 1978. 
    • It states that if there was too much space junk in orbit, it could result in a chain reaction where more and more objects collide and create new space junk in the process, to the point where Earth’s orbit becomes unusable.
      • It is also known as “collisional cascading”.
    • This cascade of collisions first came to NASA’s attention in the 1970s when derelict Delta rockets left in orbit began to explode creating shrapnel clouds.
    • Kessler proposed it would take 30 to 40 years for such a threshold to be reached and today, some experts think we are already at critical mass in low-Earth orbit at about 560 to 620 miles (900 to 1,000 kilometres).

    Source: TH