From UPSC perspective, the following things are important :
Prelims level : Uncontrolled re-entry, Liability Convention, 1972
Mains level : Not Much
Many dignitaries have signed an open letter published by the Outer Space Institute (OSI) calling for both national and multilateral efforts to restrict uncontrolled re-entries of Satellites back to earth.
About Open Space Institute (OSI)
- OSI is a conservation organization that seeks to preserve scenic, natural and historic landscapes for public enjoyment, conserve habitats while sustaining community character, and help protect the environment.
- It uses policy initiatives and ground-level activism to help accomplish its goals.
What are the stages of a rocket launch?
- Rockets have multiple stages.
- Once a stage has increased the rocket’s altitude and velocity by a certain amount, the rocket sheds it.
- Some rockets jettison all their larger stages before reaching the destination orbit; a smaller engine then moves the payload to its final orbit.
- Others carry the payload to the orbit, then perform a deorbit manoeuvre to begin their descent.
- In both cases, rocket stages come back down — in controlled or uncontrolled ways.
What is an uncontrolled re-entry?
- It is the phenomenon of rocket parts falling back to earth in unguided fashion once their missions are complete.
- In an uncontrolled re-entry, the rocket stage simply falls.
- Its path down is determined by its shape, angle of descent, air currents and other characteristics.
- It will also disintegrate as it falls.
How many satellites are there in space?
- The Soviet Union launched the first artificial satellite in 1957.
- Today, there are more than 6,000 satellites in orbit, most of them in low-earth (100-2,000 km) and geostationary (35,786 km) orbits, placed there in more than 5,000 launches.
- The number of rocket launches have been surging with the advent of reusable rocket stages.
Why is this hazardous?
- As the smaller pieces fan out, the potential radius of impact will increase on the ground.
- Some pieces burn up entirely while others don’t.
- But because of the speed at which they’re travelling, debris can be deadly.
- If re-entering stages still hold fuel, atmospheric and terrestrial chemical contamination is another risk.
Why are we discussing this?
Damage control mechanism for uncontrolled re-entry
- There is no international binding agreement to ensure rocket stages always perform controlled re-entries nor on the technologies with which to do so.
- The Liability Convention, 1972 requires countries to pay for damages, not prevent them.
- These technologies include wing-like attachments, de-orbiting brakes, and extra fuel on the re-entering body, and design changes that minimise debris formation.
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