Friday, October 10, 2008

On winged feet

Last week we were treated to some stunning photographs of the surface of Mercury beamed back by the Messenger spacecraft, which will be the first craft to go into orbit around Mercury (as opposed to a flyby) in March 2011.

Messenger was launched in August, 2004. Go here to see an animation of Messenger's journey, with its many gravitation-assist flybys of Earth, Venus and Mercury. Scroll down a bit and click to enlarge.

What a thing it is that such a roller-coaster trajectory could be planned in advance! But the animation makes it look easier than it is.

Imagine the Sun is a basketball on the goal line of a football field. The Earth would be a grain of sand on the 26 yard line. Venus is another sand grain on the 19 yard line. And Mercury is a salt grain on the 8 yard line. Now put all three planets in orbit about the Sun with different periods. And Messenger? Messenger would be lost in the smallest crater visible on the photograph above, which shows an area about the size of Massachusetts.

We've become a bit jaded by space travel. Every now and then it's good to be reminded of just what an extraordinary thing it is that human imagination can reach out and touch the surface of the other planets.