I would also suggest getting a day job.
Seriously, as you might gather from the tone of some of my other answers in my career area, and by the grim note in the main page to Astronomy Cafe, times are pretty tough in astronomy these days. I don't care what you read in the newspapers about the great triumphs being made by Galileo, Hubble and the discovery of extra-solar planets, for the vast majority of the astronomical work force not involved in such highly publicized events, it is very hard to find work that has much of a future to it. Of the two other astronomers who entered graduate school in astronomy at Harvard the same year I did ( 1975), only one of them ended up with a tenured position. The other two of us, now in middle-age, are still going from one temporary position to another with an average time scale of about 2 years. One person I know has moved 10 times in 14 years and now has a wife and child; his wife is also an astronomer by the way
For planetary scientists, you have to hang your hat on NASA's probes, or join some team searching for earth-crossing asteroids. NASA's chief, Daniel Goldin, has announced the end of any more major interplanetary probes like Voyager. The future lies in small, $150 - 200 million cheap and lean space craft. I do not know what kinds of coat tails such small missions will have when it finally comes to the data analysis part of the work. Usually, this part of any mission gets reduced as the program evolves and cost overruns begin to happen.
Anyway, the long term prospects for planetary exploration are pretty good, but the work will be largely done by legions of inexpensive post-docs who, as they do now, get to move from one project to the next without much hope of a permanent career. If you can stomach that kind of insecurity after investing your most productive youthful years in graduate school, then go for it!! There will be LOTS of work for you to do, provided you have no long term goals of rooting yourself in one community, buying a home with a 30 year mortgage, and doing the same line of research for more than 5 years. Those that seem to survive the vissitudes of the 'contract astronomy' lifestyle, at least in the past, are those who have remained reasonably flexible in their research goals, do not mind having a 'Principle Investigator' buy your time to do their research, and who have remained optimistic about what they define as 'doing astronomy as a career'.
Good luck to you! We may be competing for the same job in 15 years!!! What a strange world we live in, eh?