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Science, Maths & Technology

Gaia and the Killer Asteroids

Updated Thursday 8th August 2013

Can we avoid a catastrophic asteroid strike? Is Gaia the answer to save civilisation?

Discover how scientists use Gaia to detect killer asteroids in this animated video.

Gaia survey An illustration of how Gaia can detect asteroids otherwise invisible from earth. The scale is exaggerated for clarity. (click to enlarge)
Watch the sky at night and you will see meteors, which are the trails in the earth’s atmosphere excited by dust and small rocks (asteroids) which have been orbiting the Sun and now collide with Earth, burning up in the atmosphere. Larger asteroids reach the ground. Rare, very large, asteroids reach the ground at high speed, with supersonic shock waves, and potentially generate lunar-like craters and cause damage.
It is probable that major asteroids hitting Earth have led to catastrophic damage on impact, followed by even more catastrophic effects on climate. The sudden extinction of the dinosaurs is widely thought to have been due to an asteroid strike. A similar scale strike now would certainly end civilisation as we know it. So we like to know about any asteroids which might cause such catastrophe. A complication is that asteroids which are likely to collide with earth are not those coming past from far away at very high velocity, but those spending a lot of time close to earth.
There are such asteroids, those whose previous close-encounters with Earth have placed them on orbits mostly between the Sun and Earth, but still able to come close enough to earth for a collision. These asteroids orbit near the Sun, and so are too close to the Sun for us to observe at night – they are day-time objects. Fortunately, Gaia will be in orbit exterior to the earth, and can observe close enough to the Sun to see inside Earth’s orbit. If there are large asteroids in there on potentially dangerous orbits Gaia will find them. 

That would raise an interesting challenge for mankind: we do not have the technology – yet – to move a large asteroid from a dangerous Earth-crossing orbit into a safer one. Developing that would require global dedication and cooperation. It will be interesting to see what probability of a global death-threat is sufficient to generate global cooperation.

Question: If Gaia had detected that an Earth-crossing asteroid heading our way, should we take evasive action, or grab our mining equiment? Share your thoughts using our Comments facility.
Find out more about asteriods: 

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