Sergei Krikalev is a famous Russian astronaut π! He was born on August 27, 1965, in the city of Leningrad, which is now called Saint Petersburg π, Russia. Krikalev has flown to space six times and spent 803 days in space, which is more than any other human! He's known for his incredible work on the International Space Station (ISS) and for helping to build and support it. Krikalev has brought science from Earth's laboratories to the wonders of outer space! π