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.
- 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.
Background: different stages of rockets
- 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 (throw away) 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 maneuver to begin their descent.
- In both cases, rocket stages come back down — in controlled or uncontrolled ways.
Uncontrolled re-entry
- In an uncontrolled re-entry, the rocket stage simply falls. Ground stations usually lose control on such rockets.
- Its path down is determined by its shape, angle of descent, air currents and other characteristics. It will also disintegrate as it falls.
- 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.
- Most rocket parts have landed in oceans principally because earth’s surface has more water than land. But many have dropped on land as well.
Recent examples of uncontrolled re-entry
- 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.
- In October 2022, ISRO’s RISAT-2 satellite made an uncontrolled re-entry in the Indian Ocean near Jakarta.
- Parts of a SpaceX Falcon 9 that fell down in Indonesia in 2016 included two refrigerator-sized fuel tanks.
Associated dangers
- Any kind of re-entry will inevitably damage some ecosystem and there is also an associated risk of human causalities on the ground as well.
- conservative estimates place the casualty risk from uncontrolled rocket body re-entries as being on the order of 10% in the next decade.
- If re-entering stages still hold fuel, atmospheric and terrestrial chemical contamination is another risk.
International Regulations
- There is no international binding agreement to ensure rocket stages always perform controlled re-entries nor on the technologies with which to do so.
- These technologies include wing-like attachments, de-orbiting brakes, extra fuel on the re-entering body, and design changes that minimize debris formation.
- The Liability Convention 1972 requires countries to pay for damages, not prevent them.
