• Question: In the currently unlikely event that a large enough asteroid was on collision course with earth, what are the current method that NASA and other space agencies would employ to prevent impact?

    Asked by AnswerME123 to Anna, George, Jodi, Rob, Stefan on 17 Nov 2014.
    • Photo: Stefan Lines

      Stefan Lines answered on 17 Nov 2014:

      Hi AnswerME123. There are a population of NEO (Nearth-Earth Objects) which is studied well by NASAs NEO Program. Interestingly, you will see from the data on their website (link below), that based on their scale for impact probability (Torino Scale) we should not expect a significant impact in the near future. However, there are plenty of these objects that we have yet to detect. I believe the now faulty Kepler telescope could be used for monitoring these potential hazards.

      I also recently studied a paper which calculated the impact probability for comets and asteroids that come from the Oort Cloud (a cloud of comets and asteroids that surrounds our solar system). These are not classed as NEOs, since their orbit is very far from the earth. It is expected that a collision of a magnitude that may lead to global catastrophe would occur once every one billion years. So very unlikely…

      In that paper they mentioned that these sized object would need a carefully deployed nuclear explosion to move the orbit away from the earth. I suspect smaller objects, given sufficient time, could be deflected or neutralised in other ways, although I am not so sure what these would be.

      http://neo.jpl.nasa.gov/risk/#legend

    • Photo: Rob Appleyard

      Rob Appleyard answered on 18 Nov 2014:

      If you want to move an object in space, then there are several ways of doing the job. ‘Chuck a nuclear weapon at it’ is the brute-force answer, but it might not work as well as you would think, depending on what the asteroid/comet is made of

      One of the interesting things about space is that a big force over a short time (like a nuke) can be equivalent to a small force over a long time. If we spotted the asteroid soon enough, then we would be able to use some less spectacular tricks. We could attach a ‘solar sail’ to the asteroid to alter its course with the solar wind, or park something heavy next to it to drag it away using a ‘gravity tractor’

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