Mars has crushed David Crisp before. He tries to laugh about it now, but he clearly recalls the pain of watching a half decade’s worth of his life’s work disappearing in an instant. What’s worse, no one will ever know for sure why the Mars Polar Lander crashed into the red planet in 1999 never to be heard from again. Almost five years later, NASA senior research scientist Crisp is watching his wife prepare for the same nerve-wracking moment. Next month, the project of Joy Crisp’s career is supposed to go screaming through the thin Martian atmosphere, slam into the unforgiving terrain below and bounce four stories into the air, rolling to a stop about a mile away.