A recent post on the Freakonomics blog was a quorum on the question of whether space exploration is worth the cost. The six members of quorum were all affiliated with space exploration in one way or other (current or ex-NASA employees, the host of The Space Show, and the director of the Space Policy Institute). Not surprisingly, everyone was in agreement that space exploration was definitely worth the cost. While there was nothing new in the justifications, it is still a good summary of the main reasons for doing manned space exploration. The reasons range from the economic and technological spin-offs:
Unquestionably, manned exploration ... created unintended economic consequences and benefits, such as the spinoff of miniaturization that led to computers and cell phones.
to national pride:
We need to keep the flame of manned space exploration alive as China, Russia, India, and other countries forge ahead with substantial investments that challenge U.S. leadership in space.
to the most basic "because it's there" reason:
Exploration is intrinsic to our nature. It is the contest between man and nature mixed with the primal desire to conquer. It fuels curiosity, inspiration and creativity. The human spirit seeks to discover the unknown, and in the process explore the physical and psychological potential of human endurance.
The one downside of the post is that none of the quorum members presented opposing viewpoints, whether arguments about the social good that could be done with the money spent on space exploration or about the benefits of privatized space exploration (e.g., the X Prize and Space Ship One). Fortunately, the blog comments are full of opposing viewpoints. So read it all and enjoy!
I, for one, am a strong supporter of space exploration, primarily for the scientific payoff. I'm most familiar with unmanned, robotic explorers and the valuable science they produce (e.g., George Smoot, referenced in a previous post, used the COBE satellite to get his Nobel prize). The manned program is much more expensive and I don't know how much science we're getting out of it. However, the Freakonomics post notes:
... Steve Squyres, the principal investigator for the Mars Exploration Rovers, has frequently said that he wished that Spirit and Opportunity were working in partnership with humans on the surface of Mars; that combination, he argues, would greatly increase the scientific payoffs of the mission.
So maybe there's a strong scientific argument for manned missions.