How will Russia's withdrawal affect the International Space Station?

It was hailed as a post-Cold War collaboration for the good of humanity: two old rivals joining forces to launch the International Space Station (ISS) more than 20 years ago. 

"The International Space Station is regarded as the most complex engineering, scientific, collaborative human feat ever managed," boasts the U.S. National Aeronautics and Space Administration (NASA). 

But as relations between Russia and the West become increasingly strained due to Russia's invasion of Ukraine, officials in Moscow announced on Tuesday that Russia will opt out of the ISS after 2024, and concentrate instead on building its own competing outer space infrastructure. 

Analysts say they worry Russia quitting one of the last remaining vestiges of co-operation with the West will set back scientific research and potentially lead to an increased militarization of space. 

"There has been rumbles of this coming for a while, but it is a sad day," said Mubdi Rahman, the founder of Sidrat Research, a Toronto-based space technology firm. "Even before the invasion of Ukraine and all of [Russian President Vladimir] Putin's various aggressions, there has been some fragmentation happening in the space community with nations wanting to go on their own."

CBC News breaks down what Russia's move means for the ISS, space exploration and the politics of the great beyond.

WATCH | Russia to quit ISS over Ukraine war tensions: 

First launched in 1998, the main organizations working on the station, according to NASA, include the space agencies of the United States (NASA), Russia (ROSCOSMOS), Canada (CSA), Japan (JAXA) and Europe (ESA), which includes the following participating countries: Belgium, Denmark, France, Germany, Italy, The Netherlands, Norway, Spain, Sweden, Switzerland, and the United Kingdom.

Canada's contribution, for instance, has accounted for an ownership of only around 2.3 per cent of the station, said Adam Sirek, a professor at Western University's Institute for Earth and Space Exploration in London, Ont.

With Russian forces shelling Ukrainian cities, and Western sanctions hitting Moscow's economy, there had been rumblings about Russia quitting the ISS for a while.   

Yuri Borisov, who leads Russia's state-controlled space corporation Roscosmos, made the announcement about Moscow's planned departure from the initiative Tuesday during a meeting with Putin. 

Russia, Borisov said, would honour all of its current operational commitments before leaving. 

Previously, Russia had signaled that it intended to leave the station post-2024, while NASA had wanted it to keep running until 2030. 

Some analysts, however, consider Russia's announcement more of a public relations move than anything.