Not everyone seemed to understand the full significance of Goldin's statement. In fact, the Mars priority has the potential to save the taxpayers billions. The primary scientific consideration is to avoid contaminating Mars with Earth organisms.
Robotic exploration is at least ten times cheaper than doing it with people.
Life on Mars might do. Sooner or later it will stop, he argues, perhaps when we figure it all out, or we hit the limits of human intellectual capacity, or more likely when the cost of going further is more than society is willing to bear. As evidence that the end is near he points to current theories, such as superstrings, that are unlikely ever to be validated. His approach is to collect the views of Earth's crankiest, most opinionated scientists. Tipler is a metaphor.