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NASA prepares to defend Earth from potential asteroid strikes

It sounds like the plot of a disaster movie, but this is real life.

NASA has embarked on a mission to save Earth in the very unlikely event of a devastating asteroid collision.

Just to be clear, while there are billions of asteroids orbiting the Sun, none currently pose a known threat to Earth for at least the next century.

Scientists hope the mission will confirm a strategy that could be used if an asteroid were ever hurtling towards the planet.

Using a spacecraft built and maintained by the Johns Hopkins Applied Physics Laboratory, NASA will deliberately crash into an asteroid.

The method is called kinetic impact deflection, and involves intentionally shoving the asteroid to knock it off course.

The mission has been dubbed the Double Asteroid Redirection Test (DART).

The planetary defence probe, powered by a Falcon 9 rocket made by Elon Musk’s SpaceX, is set to take off on Wednesday at 5.23pm (AEDT) from Vandenberg Space Force Base in California.

They will then measure how the asteroid, named Dimorphos, responds to the impact.

Though the launch date is November 23 (local time), the impact is not expected to take place until between September 26 and October 1, 2022.

DART program manager Ed Reynolds said his team were proud to be involved in the unprecedented and “very tough” mission.

A graphic image of the planned impact (below) shows two asteroids, with the smaller of the pair – Dimorphos – orbiting the larger asteroid – Didymos.

Infographic showing the effect of DART’s impact on the orbit of Didymos B. Source: NASA/Johns Hopkins APL

Mr Reynolds explained the target was to hit Dimorphos at 15,000 miles per hour (24,140 km/h) in efforts to alter the amount of time it takes to orbit Didymos.

“The small asteroid orbits the larger asteroid every 11 hours, 55 minutes,” he said.

“When we hit that asteroid we expect to change that orbit period by about 10 minutes”, reducing the orbit time to 11 hours and 45 minutes.

“With that we can do a lot of the analysis that we need to determine the effectiveness of using kinetic impact as a tool, as one of the strategies, to protect Earth from asteroid impacts,” he said.

About 10 days before impact, a small cube called LICIA will be released from the larger DART aircraft.

  • Click here for more information about the DART program

LICIA will take images before, during and after impact and transmit them back to Earth for analysis, while scientists on the ground will also observe the impact using a telescope.

The mission is expected to take 10 months in total, but only the last 30 days will focus on the impact, Mr Reynolds said.

After the launch, once the spacecraft has been stabilised, it will go into “cruise mode”, during which time other new technologies aboard will be tested.

The European Space Agency mission Hera is scheduled to launch a mission in 2024 to study the impact in greater detail.

NASA hopes the mission, which costs about $US330 million ($457 million), will deliver insights about how to protect Earth from any approaching asteroids.

Scientists are not aware of any asteroids currently threatening Earth but have identified 27,000 asteroids in our planet’s proximity, with about 10,000 measuring more than 140 metres in diameter.

NASA’s planetary defence officer Lindley Johnson told NPR “the strategy is to find these objects not only years but decades before they are any kind of an impact hazard to the Earth”.

With enough warning, NASA could give a potentially threatening asteroid a small shove with a rocket to deflect it from Earth – a preferable method to the nuclear option often used in movies.

The mission comes after China discussed building a space-based defence system against asteroid strikes in April.

-with AAP



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