Chinese scientists try to reduce space junk by using drag sail on rocket

·3-min read

Chinese scientists have successfully unfurled a drag sail to deorbit one of its recently launched Long March 2 rockets in a bid to reduce space junk – the first time this was done with a rocket.

The drag sail is 25 sq metres (269 sq feet) when fully unfurled and extremely thin – just one-tenth the diameter of a human hair, according to the official Science and Technology Daily.

This kite-like membrane was designed to increase atmospheric drag and accelerate the orbital decay of the 300kg (661 pounds) rocket’s final stage. The rocket was used to send remote sensing satellites into orbit last month and has since become space junk.

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The device was designed to increase atmospheric drag and accelerate the orbital decay of the rocket’s final stage. Photo: Weibo
The device was designed to increase atmospheric drag and accelerate the orbital decay of the rocket’s final stage. Photo: Weibo

The drag sail is the largest one China has developed and is part of the country’s efforts to address the problem of space being increasingly crowded, the report said.

Over a billion pieces of junk are estimated to be floating around the Earth – two-thirds of them in low-Earth orbits where most spacecraft operate, according to a paper published in the journal Space Debris in September.

Small satellite constellations such as SpaceX’s Starlink and Amazon’s Kuiper projects have deepened concerns over a looming space debris crisis, the paper said.

China was criticised last year for letting rocket boosters fall back to Earth in an uncontrolled manner.

Drag sails are seen as a promising solution to the space debris problem because of their low cost and mature technology, which means they could be used on any kind of low-Earth orbit satellite, according to the paper.

Highly flexible and lightweight, they can be folded to a tiny size and installed on a spacecraft before launch. They then unfurl automatically towards the end of the mission and help take out the spacecraft much faster than deorbiting naturally.

For instance, a 15kg satellite operating at an altitude of 700km may occupy its orbit for another 120 years after its mission is over. But a 2-sq-metre drag sail can reduce that time to less than 10 years, according to the newspaper report.

It said the drag sail attached to the Long March 2 rocket will help its final stage to re-enter the Earth’s atmosphere within two years.

The device was developed by the Shanghai Academy of Spaceflight Technology under the China Aerospace Science and Technology Corporation.

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It is the latest test of deorbit technology – from folding and deploying to long-life membranes and collision risk analysis – to be carried out. These tests on small satellites around the world have laid a solid foundation for drag sails to be manufactured and put into use at an industrial scale, according to the journal paper.

The Long March 2 rocket was launched on June 23 from the Xichang Satellite Launch Centre in southwest China. It carried three remote sensing satellites into low-Earth orbit, which will be used for scientific experiments, land and resources surveying, estimating agricultural yields, as well as disaster prevention.

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