I have always thought that you can't just rendevous with other planets on any day you choose, and that the motions of the solar system dictate it quite heavily. But I have no expertise in the matter.

What concerns me is that, in this era of "too good to be true" stories (finding Saddam looking like that in a hole), the fact that the European Space Agency's Beagle 2 spacecraft will be landing on Mars on Xmas Day has me scratching my head for two reasons:

1. There was plenty of suspicion that NASA's venture to Mars never really happened, and they just showed red-filtered footage of a desert on Earth.

2. When NASA landed on Eros, it just happened to be on Valentine's Day