International Space Station marking 20 years of people living in orbit

The Soyuz booster is transported to the launch pad at the Baikonur Cosmodrome in Kazakstan on Oct. 29, 2000. Two days later, U.S. astronaut Bill Shepherd, and Russian cosmonauts Sergei Krikalyov and Yuri Gidzenko blasted off to become the first residents on the International Space Station.

The first crew - American Bill Shepherd and Russians Sergei Krikalev and Yuri Gidzenko - blasted off from Kazakhstan on Oct. 31, 2000. Two days later, they swung open the space station doors, clasping their hands in unity. | A cloud of smoke surrounds the Soyuz rocket seconds before liftoff from the Baikonur Cosmodrome in Kazakstan, carrying the first residents of the International Space Station.

The International Space Station is seen from the Space Shuttle Discovery on March 19, 2001, after a new crew comprised of cosmonaut Yury Usachev and astronauts James Voss and Susan Helms began several months aboard the station. | The International Space Station was a cramped, humid, puny three rooms when the first crew moved in.

Twenty years and 241 visitors later, the complex has a lookout tower, three toilets, six sleeping compartments and 12 rooms, depending on how you count. November 2 marks two decades of a steady stream of people living there. | International Space Station is seen from Space Shuttle Endeavour as the two spacecraft begin their relative separation on Nov. 28, 2008.

Astronauts from 19 countries have floated through the space station hatches, including many repeat visitors who arrived on shuttles for short-term construction work, and several tourists who paid their own way. | Expedition 1 mission commander Bill Shepherd works in a docking compartment aboard the International Space Station on Dec. 5, 2000.

Astronauts spend most of their six-month stints these days keeping the space station running and performing science experiments. A few have even spent close to a year up there on a single flight, serving as medical guinea pigs. Shepherd and his crew, by contrast, barely had time for a handful of experiments. | Expedition 1 crew members Sergei Krikalev, left, and Yuri Gidzenko work in the Zvezda Service Module onboard the International Space Station on Nov. 8, 2000.

Cosmonaut Sergei K. Krikalev, Expedition 1 flight engineer, works in the Zvezda Service Module aboard the International Space Station (ISS) on Dec. 6, 2000.

A Progress supply ship that arrived on Nov. 18, 2000 to link up to the International Space Station, bringing Expedition 1 commander Bill Shepherd, pilot Yuri P. Gidzenko and flight engineer Sergei K. Krikalev two tons of food, clothing, hardware and holiday gifts from their families.

NASA's top concern nowadays is the growing threat from space junk. This year, the orbiting lab has had to dodge debris three times. | The International Space Station as seen from Space Shuttle Atlantis during mission STS-106, which delivered supplies and performed maintenance in September 2000.

As for station amenities, astronauts now have near-continuous communication with flight controllers and even an internet phone for personal use. The first crew had sporadic radio contact with the ground" communication blackouts could last hours. | The International Space Station is seen from the Space Shuttle Endeavour on May 29, 2011, after the station and shuttle began their post-undocking relative separation.

The International Space Station as seen from the Space Shuttle Atlantis after the station and shuttle began their post-undocking relative separation on May 23, 2010.

The International Space Station continues its orbit around the Earth as seen from a Soyuz spacecraft departing with NASA astronauts Andrew Feustel and Ricky Arnold and Roscosmos cosmonaut Oleg Artemyev, who had spent 197 days in space.

The International Space Station is seen from the Space Shuttle Atlantis as the two spacecraft perform their relative separation on July 19, 2011.

The International Space Station floats above the Earth as seen from a Soyuz spacecraft after undocking on Oct. 4, 2018. NASA astronauts Andrew Feustel and Ricky Arnold and Roscosmos cosmonaut Oleg Artemyev executed a fly around of the orbiting laboratory to take pictures of the station before returning home after spending 197 days in space.

Even back then, the crew's favorite pastime was gazing down at Earth. It takes a mere 90 minutes for the station to circle the world, allowing astronauts to soak in a staggering 16 sunrises and 16 sunsets each day. | Backdropped against clouds over Earth, the International Space Station is seen from Space Shuttle Discovery as the two orbital spacecraft accomplish their relative separation on March 7, 2011.

Russia, for instance, kept station crews coming and going after NASA's Columbia disaster in 2003 and after the shuttles retired in 2011. | The International Space Station (ISS) crew members Anatoly Ivanishin and Ivan Vagner of the Russian space agency Roscosmos are seen inside the Soyuz MS-16 space capsule after landing in a remote area outside Zhezkazgan, Kazakhstan on Oct. 22, 2020.

One of the best outcomes of 20 years of continuous space habitation, according to Shepherd, is astronaut diversity. While men still lead the pack, more crews include women. | Two U.S. women have served as space station skipper. Commanders typically are American or Russian, but have also come from Belgium, Germany, Italy, Canada and Japan. While US astronaut Kate Rubins cast her ballot from the International Space Station on October 22, making her voice heard in the presidential election despite being 253 miles (408 kilometers) above the Earth.

Massive undertakings like human Mars trips can benefit from the past two decades of international experience and cooperation, Shepherd said. | The Expedition 1 crew members are about to eat fresh fruit in the form of oranges onboard the Zvezda Service Module of the Earth-orbiting International Space Station (ISS) on Dec.4. 2000.. Pictured, from the left, are cosmonaut Yuri P. Gidzenko, Soyuz commander; astronaut William M. Shepherd, mission commander; and cosmonaut Sergei K. Krikalev, flight engineer.