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Chinese scientists' earth defense plan against asteroid

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Chinese Scientists Also Plan to Redirect, Bully Apophis Asteroid | PCWorld

Chinese Scientists Also Plan to Redirect, Bully Apophis Asteroid
By Kevin Lee, PCWorld Aug 18, 2011 1:18 PM

It's looking like Apophis, the asteroid that will come to a near-miss with Earth in 2036, is the redirection whipping boy for rocket scientists. China has announced its own plan on using solar sail spacecraft to impact the asteroid and chance its orbit.

Apophis’s trajectory will actually have it pass by Earth in 2029, but it’s due to enter a region of space known as a "keyhole", which will ensure the asteroid returns in 2036. Shengping Gong and his team of scientists of the Tsinghua University in Beijing announced their plans to redirect the asteroid with a solar-sailed vessel to ensure that it won’t ever enter the keyhole region.

Gong’s plan is to send a small 10-kilogram spacecraft into retrograde orbit around Earth to build up speed before setting it on a collision course with Apophis. The scientists expect the impact velocity will be 90km/s (324,000 kph or 201,324 mph). There isn’t a hard date for when the mission will launch, but the paper describes that the spacecraft only needs the lead-time of one year to accomplish its objective.

Hopefully they are collaborating with the European Space Agency, which is also planning on redirecting the asteroid with a 21,600 mph spacecraft in 2015, to just obliterate the asteroid into nothing.
 
we just need a single shot of nuke to make it disappear.

Doubtful. That asteroid has a diameter of 270m, so anything less than 100 MT of nuke won't be able to destroy it into millions of tiny pieces that won't pose a harm to Earth.
 
hmmm...
is it true? this is what U.S should do. China, no, not that rich. need to focus on improving average people's lives.
 
Doubtful. That asteroid has a diameter of 270m, so anything less than 100 MT of nuke won't be able to destroy it into millions of tiny pieces that won't pose a harm to Earth.

I'm not too sure about that.

The Hiroshima bomb was only equivalent to 18 Kilotons, yet created a fireball over 300m diameter wide - that would be large enough to engulf that asteroid.
 
I'm not too sure about that.

The Hiroshima bomb was only equivalent to 18 Kilotons, yet created a fireball over 300m diameter wide - that would be large enough to engulf that asteroid.

which would probably scratch its surface.

Bury a nuke 150 m below ground and see what happens - nothing.
 
I'm not too sure about that.

The Hiroshima bomb was only equivalent to 18 Kilotons, yet created a fireball over 300m diameter wide - that would be large enough to engulf that asteroid.

Yes if we were only hoping to toast the asteroid not destroy it.
 
I just did a back-of-the-envelope calculation and to my surprise yes, the plan does have merit to it. The impact of a 10kg spacecraft at 90 km/s into a 27 million ton asteroid will change its velocity on the order of 3-5x10^-5 m/s and therefore a course change of 0.5-1km in a year. That's all that is needed, if one acts before 2027.
 
we just need a single shot of nuke to make it disappear.

You do realize that a nuclear explosion in space is entirely different than on earth right? If that were to happen, Earth's atmosphere is done for.
 
The real difficulty is to hit a tiny target area - effectively about 100 meters across, as a peripheral impact won't do - at 324,000 km/hour. Like stabbing a thread into a needle blind-folded and you only get one chance.
 
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