Listen to Bill Nye's letter to the President of the United States asking for $1.5 billion to support planetary exploration. He gives three excellent reasons.
First, the potential discovery of alien life, which will change the course of human history. Second, the creation of new awesome technology, which will bring new businesses that can greatly benefit the economy, just like Apollo program did. And finally, the idea that planetary exploration will greatly inspire the country's youth, moving them into engineering. That's something that even some congressmen understand, so perhaps it's not crazy to make it happen. We need another Curiosity in the moon Europa.