During past and current stints at the International Space Station (ISS), the 60-year-old Milanese has spent a total of 6000 hours in space.
Nespoli completed missions to the ISS in 2007 and 2011.
His latest mission commenced on July 28, 2017, and he is scheduled to return to Earth in December.
Italian cartoonist Leo Ortolani marked the feat by dedicating a special edition of his Rat-Man space comic to Nespoli, in collaboration with the Italian Space Agency.
The work will be presented at Lucca Comics and Games, an annual gaming convention running from November 1 to 5.