A Sense Of Adventure

That sense of adventure in the early period of space travel that is conveyed by the opening volumes of Robert Heinlein's Future History is surprisingly also expressed in Poul Anderson's Time Patrol series. Manson Everard is recruited to the Patrol in 1954 but his class at the Patrol Academy are from the period, 1850-2000, thus some of them can be expected to come from the early space travel period. 

"He had entered something new and exciting, that was all he truly grasped with all layers of consciousness...as yet."

-Poul Anderson, "Time Patrol" IN Anderson, Time Patrol (Riverdale, NY, 2010), pp. 1-53 AT 2, p. 13.

Of course, what is most new and exciting is time travel itself but that means contact with other times, including the immediate future. Everard is taught how to handle spaceships. He learns that time travel will be discovered in a galactic era. A cadet in another class was born on Mars in the Solar Commonwealth and plans to infiltrate places like Peenemunde and White Sands because of their importance to history.