With the final voyage of the space shuttle fast approaching, I find myself with mixed emotions. On the one hand, it is disappointing to envision a future, albeit likely temporary, without manned US launches. But there has always been a tension between big ticket items in NASA's budget, be they between competing large mission concepts (e.g., Mars Science Laboratory vs. Europa Ganymede System Mission) or the manned and unmanned branches of NASA.
Despite the shuttle's many accomplishments, it is easy to criticize what it is not: a cheap, reliable means of frequently launching payloads and people into orbit. Instead, it is fantastically complex, and requires constant input from some of the finest engineers in the business to keep it flying. It's achievements seem modest in comparison to the grandeur of the Apollo program; "audacious" is not a term associated with STS.
What does this mean for the manned space program and NASA as a whole? For the former, it means some serious attrition in the astronaut ranks. Some 20 have left in the past year alone.
Now, with the prospects of spaceflight reduced to hitching a ride on a Russian Soyuz, the calculus for those that remain have been cast in sharper relief. Would you join the astronaut core knowing that a likely replacement vehicle is at least half a decade away, and one's chance to fly it might be another half decade after that? Or perhaps this is a great time to join and advance through the space created by departing colleagues, sort of like flight attendant advancement in the retirement glut post 9/11.
For NASA, this means a time of reflection and reevaluation. The tepid public response to the agency's announced future plans are an indication of their failure to excite the soul. George Bush Jr., for all the legion of complaints one could lodge against him, articulated a clear vision for space exploration: a return to the Moon. Now, NASA finds itself in dire need of a uniting vision, an answer to the elevator question, "So, what's NASA up to these days?"
What is my $0.02? NASA at its finest has been a combination of exploration and science, and what we need to set a goal and work on the incremental steps to get us there. To me, this means a series of robotic precursor missions. I think we need to pick two places, say the lunar poles and a near-Earth asteroid. We'll need to do more orbital reconnaissance to start laying the groundwork for a robotic landing, one to be followed up with humans at the most promising site (whichever one looks most feasible). But the more time we spend without a clear articulation of our objectives, the more momentum the space program will lose.