Astrophysicist, Institute of Advanced Study, Princeton

Dear Mr. President

I had to smile when I read the assignment, to give advice about pressing scientific issues, while sticking to those scientific areas where I have expertise. As an astrophysicist, few issues in my trade could be considered pressing. When I meet people who ask me what I do for a living, I often describe my area of work as being in some ways more akin to art than to science: we astrophysicists produce pretty pictures and interesting stories about places and times far away, events that are unlikely to affect you and me in our daily lives.

However, there is one aspect of my work that does have deadly consequences, more precisely, will have deadly consequences if it is ignored. Here is where heaven and earth meet: in the possibility, and in the long run the certainty, that people will die through the effects of an impact of an asteroid, large or small.

Although there are several more pressing things to worry about right now, including many already pointed out by the band of science advisors reporting here, this does not mean that it would be wise to neglect the threat of an asteroid impact. Would you be willing to face the public if an asteroid would be discovered heading our way? You would have to tell them that NASA has been discovering and tracking asteroids, but that funding had not been sufficient to catalogue most of them, and that there had not been any funding so far to study the question of how to deflect an asteroid, once found, even though the technology has in principle been available. Not a nice speech to give, I bet.

Fortunately, it is rather straightforward to develop the technology to send a spacecraft to a 100-meter diameter asteroid, in order to give it a nudge so that it will miss the Earth. The ingredients are at hand, and all we have to do is to carry out a test mission, in which we demonstrate the capability to significantly alter the orbit of an asteroid. That way, when we discover an asteroid with our name on it, so to speak, we will be prepared. We could be in a position to save millions of lives, and at the very least we could not be accused of knowing about a danger and ignoring it.

Even if we are lucky, and no life-threatening asteroid crosses our path in the foreseeable future, developing the technology to gently nudge asteroids is likely to help us to explore the solar system. Plasma engines, for example, can be used as tug boats for asteroids but also to speed up human expansion into space. This could be a major legacy of your administration: to open the door to populating other worlds while at the same time making our own world a safer place.

Piet Hut
Astrophysicist, Institute of Advanced Study, Princeton
A founding member of the Kira Institute and of the B612 Foundation.