The International Space Station (ISS) has paved the way for a number of breakthroughs, not just in space exploration but in other fields of study as well - and it is marking its twentieth year of continuous human presence in space.

Five major space agencies worked together to make the ISS a reality: the United States' NASA, Russia's Roscosmos, Japan's JAXA, Canada's CSA and the European Space Agency (ESA). On Monday, the ISS will be marking its two decades of continuous human presence in space since it received the crew members of Expedition 1 on November 2, 2000.

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From Three Rooms to a Floating International Complex

The ISS was first developed back in the 1990s, with its first module - Zarya - being lifted by a Russian Proton rocket. It was followed by the STS-88 mission, carrying with it the Unity module that connected to Zarya. In July 2000, the Russian Zvezda was attached to the ISS, allowing a maximum of two crewmembers to stay on the space station.

Its first crew members were the Expedition 1 team: composed of NASA astronaut and mission commander Bill Shepherd and Russian cosmonauts Yuri Gidzenko and Sergei Krikalev. The three spacemen were carried by a Soyuz rocket on October 31 and two days later, became the first crew members of the ISS.

With the space station lacking most of the modules that made life easier, Shepherd recalled how "Each day seemed to have its own set of challenges" in a recent NASA panel in commemoration of their efforts.

Since then, the International Space Station has steadily grown into a space complex that runs almost 240 feet (73 meters) long, and 360 feet (109 meters) wide.

"It's 500 tons of stuff zooming around in space, most of which never touched each other until it got up there and bolted up," Shepherd shared with The Associated Press, adding that it has been running for 20 years now without major setbacks.

Welcoming the ISS Expedition 64

Since Expedition 1's efforts to survive aboard the ISS, the space station has seen a number of crew members and visitors onboard its modules. According to NASA, as of July 2020, there have been 240 individuals from 19 countries. Also, the space station is now equipped with a platform to allow space and microgravity environments - allowing scientific studies in a wide variety of research fields.

The International Space Station is now supported by crew members from Expedition 64 - marking the first seven-crew operation on the ISS. Russian cosmonaut Sergey Ryzhikov serves as the mission commander. 

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NASA reports that cube satellites (CubeSats) and space botany will be the "dominant research theme" ahead of the first spacewalk for the Expedition 64 later in November. The activities for the latest crew of the space station include the installation of updated components in the Advanced Plant Habitat - a recent module intended to test growth conditions that work for plants.

Check out more news and information on the International Space Station in Science Times.