GK: Understanding Space Debris (SCIENCE & TECHNOLOGY)

What came down

On Monday, April 2, the Chinese space station Tiangong-1, weighing 8.5 tonnes, dropped out of orbit and splashed into the South Pacific Ocean, just northwest of Tahiti. The downing ended concerns about where the debris from the space station would fall, but reignited the larger debate about space debris itself.

Launched in 2011, Tiangong-1 had made China just the third country to launch a space station. The Chinese used it to demonstrate spacecraft docking capabilities. China’s cctv.com quoted Huang Weifen, the deputy chief designer of the Astronaut Center of China, as saying: “The important role of Tiangong-1 would go down in China’s space history. It had helped us accumulate precious experience in constructing space stations.”

The Chinese lost control of the station in 2016, two-and-a-half years beyond the expectations of the mission. After losing control, China notified the United Nations Office of Outer Space, and the Inter-Agency Space Debris Coordination Committee, an international consortium that includes ISRO. They tracked the descent of Tiangong — much of it burnt up in the atmosphere — until it finally splashed into the ocean.

Tiangong-2 continues to be operational. This lab was launched the same year the Chinese lost control of the now-downed space station.

ISRO & debris

* On April 3, launch vehicle PSLV-C19’s 4th stage (it had launched radar imaging satellite RISAT-1 in 2012) burnt up over the Central Atlantic. ISRO is looking to develop reusable launch vehicles, having conducted a space capsule recovery experiment in 2007.

Spacecraft graveyard

* 1,500 sq km in Southern Pacific Ocean, suitably far from any coast; more than 260 satellites brought down there so far.

***

The problem

7,500 tonnes: The estimated amount of defunct, artificially created objects that are currently in space

28,000 kph: The speed up to which space junk travel, fast enough to destroy a spacecraft

1 in 1 trillion: Probability of an individual on Earth being hit by falling debris (Aerospace Corporation)

The solutions

Passivation: Satellite explosions are reduced by deactivating various systems

Design for demise: Designing with material that burn up on re-entry

Deorbiting systems: Under international guidelines, satellites are brought down within 25 years after mission life

Design for servicing: Grips or handles can be caught by a robotic arm or astronauts for repairs

RemoveDEBRIS: An innovation led by University of Surrey’s Space Centre, launched on a SpaceX flight to ISS on April 2. In May, it will be released into low-earth orbit, where it will release a smaller satellite that will recapture space junk with a harpoon.

Credit: Indian Express Explained