One of my rules is never explain. A writer is a lot like a magician, if you explain how the trick works then a lot of the magic turns mundane.
As fighting in Iraq intensifies, President Bush delivered his supplemental war budget to Congress. The money will cover 30 days of fighting, then we'll be sent one war every other month until we cancel our subscription.
Perhaps the best motivation for going to Mars is political. It is obvious that no single nation currently has either the will or the resources to do it alone, but a consortium of nations and space agencies could achieve it within 20 years.