Sunday, July 18, 2021

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Space: China reveals plan to launch rocket fleet to divert potentially apocalyptic asteroid


Experts at China’s National Space Science Centre have unveiled a plan to launch a fleet of rockets into space to practice diverting an asteroid away from Earth.

Their target is asteroid Bennu — a 1,614 feet (492 m) -wide spinning-top shaped body whose orbit will bring it within 7.5 million kilometres of Earth’s from 2175–2199.

At this time, the space rock will be classified as being potentially dangerous, with scientists having predicted it will have a 1-in-2,700 chance of hitting the Earth.

However, Chinese simulations suggest that the simultaneous impact of 23 ‘Long March 5’ rockets, each some 900 tonnes, could knock Bennu 5,592 miles off course.

This is equal to 1.4 times the Earth’s radius — and could be the difference between the asteroid sailing on by and slamming into Earth with devastating consequences.

Experts at China’s National Space Science Centre have unveiled a plan to launch a fleet of 'Long March' rockets into space to practice diverting an asteroid away from Earth

Experts at China’s National Space Science Centre have unveiled a plan to launch a fleet of ‘Long March’ rockets into space to practice diverting an asteroid away from Earth

Their target is asteroid Bennu (pictured) — a 1,614 feet (492 m) -wide spinning-top shaped body whose orbit will bring it within 7.5 million kilometres of Earth’s from 2175–2199

Their target is asteroid Bennu (pictured) — a 1,614 feet (492 m) -wide spinning-top shaped body whose orbit will bring it within 7.5 million kilometres of Earth’s from 2175–2199

Chinese simulations suggest that the simultaneous impact of 23 ' Long March 5 ' rockets, each some 900 tonnes, could knock Bennu 5,592 miles off course. This is equal to 1.4 times the Earth's radius — and could be the difference between the asteroid sailing on by and slamming into Earth with devastating consequences

Chinese simulations suggest that the simultaneous impact of 23 ‘ Long March 5 ‘ rockets, each some 900 tonnes, could knock Bennu 5,592 miles off course. This is equal to 1.4 times the Earth’s radius — and could be the difference between the asteroid sailing on by and slamming into Earth with devastating consequences

ASTEROID BENNU

Bennu is 1,614 feet (492 m) -wide spinning-top shaped asteroid.

Experts believe the carbon-rich body formed some 4.5 billion years ago. 

Bennu’s future orbit will see it come within 7.5 million kilometres of Earth’s in the period from 2175–2199.

Experts have calculated that, in this period, Bennu will have a cumulative 1-in-2,700 chance of colliding with Earth.

Bennu has been the focus of NASA’s OSIRIS REX mission, which will return with samples from the asteroid in the September of 2023.

‘Asteroid impacts pose a major threat to all life on Earth,’ wrote paper author and space science engineer Mingtao Li of the National Space Science Center in Beijing.

‘Deflecting an asteroid on an impact trajectory is critical to mitigating this threat.’

To knock an asteroid like Bennu off of its original course, a considerable amount of kinetic energy would be needed. 

While using nuclear-powered explosions may seem the obvious choice for such an endeavour, this approach would come with the risk of the target breaking into separate chunks which could also end up on a collision course with the Earth.

However, Dr Li explained, it will be ‘possible to defend against large asteroids with a nuclear-free technique within ten years.’

The approach proposed by the Chinese team would see multiple rockets strike the surface of Bennu at once — after spending some three years travelling from the Earth to reach the asteroid.

The effectiveness of each ‘deflector’ craft — dubbed an ‘Assembled Kinetic Impactor’ — would be improved by not separating from the rocket’s upper stage, thereby providing extra mass to bear on the impact.

According to the team, the Long March 5 rocket would require minimal modifications — such as the addition of manoeuvring thrusters — in order to to be repurposed for an asteroid deflection mission.

The Long March 5 is the same rocket design that made an uncontrolled re-entry into Earth’s atmosphere back in May this year.  

Fortunately, the errant rocket craft ended up disintegrating safely over the Indian Ocean, causing no harm. 

'Asteroid impacts pose a major threat to all life on Earth,' wrote paper author and space science engineer Mingtao Li of the National Space Science Center in Beijing. Pictured: one of the Assembled Kinetic Impactors that the researchers say could be used to deflect Bennu

‘Asteroid impacts pose a major threat to all life on Earth,’ wrote paper author and space science engineer Mingtao Li of the National Space Science Center in Beijing. Pictured: one of the Assembled Kinetic Impactors that the researchers say could be used to deflect Bennu

The effectiveness of each 'deflector' craft — dubbed an 'Assembled Kinetic Impactor' — would be improved by not separating from the rocket's upper stage, thereby providing extra mass to bear on the impact. Pictured: the impactor contained within the rocket fairing

The effectiveness of each ‘deflector’ craft — dubbed an ‘Assembled Kinetic Impactor’ — would be improved by not separating from the rocket’s upper stage, thereby providing extra mass to bear on the impact. Pictured: the impactor contained within the rocket fairing

China is not the only power, however, making preparations to deflect asteroids that could potentially end up on a collision course with the Earth.

HAMMER — short for ‘Hypervelocity Asteroid Mitigation Mission for Emergency Response’ — is a US concept study to investigate the efficacy of using spacecraft as either a kinetic or nuclear impactor against an asteroid.

NASA simulations suggested that it might take 34–53 HAMMER strikes, all launched 10 years before Bennu and Earth were due to collide, to adequately deflect the asteroid onto a different course.

Were HAMMER to have 25 years lead time, however, such a figure could be reduced to only 7–11 individual launches. 

The full findings of the study were published in the journal Icarus.   

WHAT IS NASA’S HAMMER ASTEROID DEFLECTING VEHICLE?

NASA is working on a Hypervelocity Asteroid Mitigation Mission for Emergency Response vehicle, dubbed HAMMER.

The nine metre (30 ft) tall, 8.8-ton spacecraft features a modular design that would enable it to serve as a kinetic impactor, essentially a battering ram.

It could also be used as a transport vehicle for a nuclear device.

Its possible mission is to deflect 101955 Bennu, a massive asteroid around 500 metres (1,640 ft), more than five football fields, in diameter.

It weighs around 79 billion kilograms (174 bn lbs), which makes it 1,664 times as heavy as the Titanic, and is circling the sun at around 63,000 mph (102,000 kph). 

Based on observational data, Bennu has a 1 in 2,700-chance of striking Earth on Sept. 25, 2135.

It is estimated that the kinetic energy of this impact would be equivalent to 1,200 megatons, around 80,000 times the energy of the Hiroshima bomb. 

The preferred approach to mitigating an asteroid threat would be to deflect it by ramming a kinetic impactor into it, delivering a gentle nudge large enough to slow it down, but not so large that the object breaks apart.

However, recent studies have suggested that the nuclear option may be required with larger objects like Bennu.



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