Tuva or Bust!

Blurb

Tuva or Bust! is a book by Ralph Leighton about the author and his friend Richard Feynman's attempt to travel to Tuva.
The introduction explains how Feynman challenged Leighton, at the time a high school math teacher, "Whatever happened to Tannu Tuva?" Since Feynman had a reputation as a prankster and had proven himself entirely capable of inventing a fictional country name to confound friends, Leighton assumed it was made up. But the country existed, and the pair became fascinated with this hard-to-reach destination, at the geographic center of Asia, which had become a republic in the Soviet Union. They made it a goal to travel there, which, for Americans in the late 1970s and early 1980s, was extremely difficult.
In many ways, the attempt to travel to Tuva is an allegory for Feynman's perpetual curiosity to discover new things, and how he inspired his friends, admirers and protégés to do the same. During their decade-long quest to travel to Tuva, Feynman was suffering from cancer, and died shortly before the visas finally arrived; this book describes "Richard Feynman's last adventure".