On the 40th anniversary of Apollo 11, there's been a number of essays
on the meaning of the lunar landings and where NASA should go from here.
Not surprisingly, Mars has locked many people's gaze as the next logical step. Myself, I'm not so sure.
Mars has the psychological plus of being the next step up from the Moon, as the closest planet to Earth both in terms of distance (technically 2nd closest, behind Venus) and climate.
That's not to be underestimated, especially if the political system for distribution of funds is one where the will of the people eventually has its say, as it does in the United States. Mars is considerably easier to capture the imagination of the public with than, say, just a return to the Moon. On the other hand, I think going down that path will likely lead to the same dead-end that Apollo ended on: the goal was achieved, and the program was abandoned, leaving little to build on.
I would like to see the space program focus on two main goals: terrestrial space-object-collision defense, and setting up an orbital infrastructure to permit exploitation of space-borne materials
for both fuel and material. On the former, I recommend a very readable essay by Gregg Easterbrook
in last year's Atlantic Monthly.
As I see it, a major asteroid or meteor strike similar to that of Tunguska
would be much more likely to be catastrophic today than before, simply because we as a species are so much more numerous than we were a hundred years ago: there's more area with a lot more people in it. More to the point, the concerns about global warming and the horror at the 2004 tsunami
would be minor things compared to what a major terrestrial strike would be capable of. Yet, relative to the threat potential, there's relatively little being done to avert it.
On the second - exploitation of space - launching materials up the gravity well is a notoriously expensive proposition, with payload-to-propellant ratios making putting large amounts of material up into orbit prohibitive: note that its taken 22 shuttle flights to get the ISS
to its current, still-not-fully-finished state. Until we figure out how to use material that is already up there, expanding out beyond low Earth orbit will continue to be a non-starter.
I do believe that manned spaceflight is fundamental to our continued long-term existence as a species. The Earth is a wondrously vibrant and rich planet, but keeping all of humanity's survival "eggs in one basket" is a bad idea. Eventually we'll either have a meteor strike, or a major natural disaster
, or even just a simple mistake which sets off an unanticipated series of events
, and we're done (which see: dinosaurs). I also think that the view that we are destined to always live in a closed-system which only has the resources on-planet to utilize tends to lead to a static-society solution which closes off too many needed avenues for continued human development, ultimately an undesirable outcome. I think that long-term there are some innovative solutions available via space resources
for many of our problems on Earth, but they're not viable until we actually create the capacity to use off-Earth material. Without that, continuing the cycle of blasting satellites (and occasionally people) into near Earth orbit over and over doesn't really get us anywhere meaningful.
I'm sympathetic to the argument that we get much more bang-for-the-buck in terms of expanded scientific knowledge with unmanned probes such as those recently made to Mars
. I think that's true, but ultimately this doesn't help solve the existential problems I mention above. I view the unmanned program's role as ultimately that of being a pathfinder for learning about places that we're* eventually planning to go. Otherwise, its just an academic exercise of no more import than reading a travel brochure for a neat place on the other side of the world that you're never going to visit - its the mistake of thinking that viewing photos on Flickr or visiting the Japan pavilion at EPCOT is the same thing as actually visiting the country itself. Its better than nothing, but in the end, robots are not us, anymore than if a disaster left nothing but operational machines and robots, I don't think anyone would say that we as a species survived in any meaningful way.
* - "we" in the larger human sense, since I doubt anyone reading this will live long enough to see even modest off-planet expansion.