Arnt Richard Johansen's home page

You forgot Pluto! (Or maybe not.)

I'm immensely happy to report that finally, after numerous postponements and cancellations, NASA's mission to Pluto, New Horizons, was launched yesterday.

I've been waiting more than sixteen years for this to happen. Ever since Voyager 2 passed Neptune in 1989. I could hardly believe it — that spacecraft had been moving steadily since before I was born, sending pictures of planet after planet, and never skipping a single one. And now it was leaving the solar system without visiting Pluto, the last one! In the media reports, they even said that Voyager 2 had gone past Neptune, the outermost planet in the solar system. This left me puzzled: didn't everyone know that it was Pluto that was the 9th and last planet? I didn't realise then that the orbit of Pluto crosses that of Neptune, so that for a short period from 1979 to 1999, Neptune actually was the farthest planet in the solar system. So for a while I believed that they had forgotten about Pluto entirely — or, at least, considered it less than a planet, and not worth visiting. (There is actually now talk about demoting Pluto fram planethood, but that of course doesn't make it any less interesting as an object for study.)

Of course, Voyager 2 wasn't meant to visit all of the planets: the mission only covered Jupiter, Saturn, Uranus, and Neptune. You can't just send a space probe blasting off in an arbitrary direction, you have to plan the trajectory carefully, so you get the exact amount of gravitational assistance. The position of the planets at that time was favourable enough to make that journey, though not favourable enough that Pluto could be reached.

So, to the JPL: I'm sorry I doubted you, and I wish you the best of luck with your new mission.

[Friday, Jan 20, 2006 @ 15:18] | [] | # | G