Chinese space scientists used a huge space sail to deorbit a recently launched Long March 2 rocket, Chinese state-run newspaper Global Times reported on July 6. This was the first experiment of its kind ever carried out on a rocket.
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This deorbiting sail is developed by Institute 805 of the Shanghai Academy of Spacecraft Technology (SAST), allowing a dysfunctional or ‘dead’ spacecraft to leave orbit early to contain the spread of space debris.
It was installed on the payload capsule of the Long March-2D Y64 carrier rocket that launched into space on June 23 and launched into orbit on June 26, according to SAST.
The sail is a kite-like sheet that stretches up to 25 square meters and is one-tenth the diameter of a human hair, according to the developers of SAST.
Once unfolded, the sail increases the drag that acts on the spacecraft, which is why it is also called a ‘drag’ sail, decelerating the spacecraft until it is moved out of its orbit, which will burn within the Earth’s atmosphere within some years.
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“The thin sail uses aerodynamic drag formed by the thin atmosphere of the low-orbit environment to slow down the satellite and gradually leave the original orbit slowly,” SAST developers explained to the Global Times.
According to the developers of SAST, its sail could allow a 300 kg payload capsule to re-enter Earth’s atmosphere within two years. It allows for a much faster deorbiting process that could take hundreds of years.
Threat from orbital debris in space
If deorbiting measures are not taken, satellites can last hundreds of years in space until their service ends, posing a threat to other active spacecraft in orbit.
A famous example is a collision between ‘Iridium 33’, an active American commercial satellite, and the Soviet Union’s dysfunctional Cosmos 2251 in 2009. The two satellites collided at a speed of 41,843 km/h, at an altitude of 789 km above from Siberia.
The accident resulted in 2,300 large, trackable pieces of debris and countless smaller pieces of debris scattered over 1,000 kilometers into space, causing problems for subsequent space programs.
According to the European Space Agency (ESA), around 13,100 satellites have been launched into orbit since 1957, with 8,410 remaining in space and 5,800 still in operation.
Furthermore, up to 27,000 smaller pieces of debris are also being tracked by NASA, congested in the orbit zone and traveling extremely fast – 25,266.70 km/h in Low Earth Orbit (LEO).
The total mass of all orbiting objects is around 9,900 tons, while the statistical model suggests that 130 million pieces of debris are 1 mm to 1 cm in size.
Dangerous encounters with space debris
In March 2022, a leftover piece of a Chinese Long March 3C rocket crashed into the Moon, creating a 65-foot-wide crater on the lunar surface. Had this piece hit the International Space Station (instead), it could have led to disastrous consequences.
For example, in November 2021, the ISS was forced to perform a maneuver to avoid a piece of debris from the now-defunct Chinese weather satellite Fengyun-1C that China destroyed in its 2007 anti-satellite missile test.
The satellite exploded into more than 3,500 pieces of debris, most of which fell into the orbital region of the ISS.
Likewise, even Russia destroyed one of its defunct Soviet-era satellites, Cosmos 1408, in an anti-satellite weapons test in November 2021, creating a field of at least 1,500 pieces of low-orbit traceable debris that forced the ISS crew to hide several times when the station’s orbit crossed with rubbish.
The last instance of the ISS evasion maneuver was on June 16, when the ISS crew had to perform a complicated maneuver to avoid being hit by orbital debris from Kosmos-1408.
As of August 2020, the ISS has had to perform 27 collision avoidance maneuvers since 1999.
Despite these manoeuvres, a piece of space junk hit the ISS robotic arm provided by the Canadian Space Agency (CSA), Canadarm2, causing a 5mm diameter hole, as found during a routine inspection in May 2021.