ISRO Missions and Discoveries

Uncontrolled Re-entries of Satellites


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?

  • The OSI letter cited examples of parts of a Russian rocket in 2018 and China’s Long March 5B rockets in 2020 and 2022 striking parts of Indonesia, Peru, India and Ivory Coast, among others.
  • Many news reports have focused on Chinese transgressions of late, but historically, the US has been the worst offender.
  • Parts of a SpaceX Falcon 9 that fell down in Indonesia in 2016 included two “refrigerator-sized fuel tanks”.


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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