City On The Edge Of Forever: Spock uses primitive technology to construct a machine to access the information stored in his tricorder. Genius is genius regardless of surroundings...
The Empath: Spock has the flash of insight that his own resistance to the energy field is what is empowering it.
The Galileo Seven: When all hope is lost Spock chooses to bet all on a desperate act, he jettisons all the remaining fuel to signal the Enterprise, knowing having done so within seconds the shuttlecraft will spiral into the atmosphere and burn up
I don't consider him a rationalist character. He is always hung up about what is logical, as opposed to what is observably right.
Uhura: Mr. Spock, sometimes I think if I hear that word "frequency" again, I'll cry.
Spock: It is illogical for a communications officer to resent the word "frequency."
What kind of answer is that? "Too bad you dislike your job?" A rationalist answer would have been something along the lines of "Can you explain why, maybe we can find out what went wrong with your feelings and find a way to fix them or work them around?"
There is a difference between rationality and smartassery.
Hence "(straw)" in the title. See e.g. this summary of a talk by Julia Galef about the difference between being a Straw Vulcan (memetic hazard warning: TVTropes) and being an actual practitioner of rationality.
[EDITED to link to the LW article that has a transcript of the original talk an a link to the YouTube video.]
This seems very strange. First, most of our rockets use hydrogen and oxygen. One doesn't directly need to use fossil fuels. Second, there's still a massive amount of energy available in terms of fossil fuels, it just involves lower energy return on energy investment. Third of all, there are many other sources of energy, with nuclear power being one of the more obvious, but massive amounts of solar and wind also being available. Fourth of all, rockets are comparatively inefficient in general since one needs to move most of the fuel itself. Launch loops and space elevators are both obvious substitutes that are more energy efficient once they are off the ground. Do you know where Henson has made this argument and what his reasoning was in more detail?
I don't think Keith Henson refers to the energy expenditure of rockets but to the total cheap energy evailable to global society. Currently we are more concered with optimizing the last out of the reamining sources and keeping society running at all. Granted there are still significant technological improvements but these are mostly small scale. Rockets have not improved at all.