This inside tour of the International Space Station (ISS) is hosted by NASA astronaut Suni Williams who shows its interior in zero gravity, flying (floating) from module to module, explaining various devices, computers and random technology as it completes 15.54 orbits per day. Aboard for 6 months at a time, the station astronauts have managed the longest continuous human presence in space, having surpassed the previous record of 9 years and 357 days held by Mir. The station is serviced by a variety of visiting spacecraft: Soyuz, Progress, the Automated Transfer Vehicle, the H-II Transfer Vehicle, Dragon, and Cygnus. It has been visited by astronauts, cosmonauts and space tourists from 17 different nations. The ISS program is a joint project among five participating space agencies: NASA, Roscosmos, JAXA, ESA, and CSA. On 28 March 2015, Russian sources announced that Roscosmos and NASA had agreed to collaborate on the development of a replacement for the current ISS. NASA later issued a guarded statement expressing thanks for Russia's interest in future cooperation in space exploration, but fell short of confirming the Russian announcement.