I'm glad they didn't wait...
... about 100 + years to plan and actually fly these missions:
http://www.jpl.nasa.gov/releases/2000/casanidoctorate.html
... and it was all accomplished during the 60s and even <groan> 70s!!!!!!!!!!!!
Marcia (Personal regret: Art is ok, but physics and engineering is where one really leaves their mark. Having a good dose of passion and principles is a plus.)
*Thanks Robert and Justin.