"Only realistic flight schedules should be proposed—schedules that have a reasonable chance of being met. If in this way the government would not support NASA, then so be it. NASA owes it to the citizens from whom it asks support to be frank, honest, and informative, so that these citizens can make the wisest decisions for the use of their limited resources. For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled."

Great guy. Also: http://www.haveabit.com/feynman/14002