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MOSCOW — It might be the only country that can rocket humans into space, but Russia’s once-great space program is being dragged back to Earth by decades of brain drain and financial hardship.

“The Russian space industry is in an obvious state of crisis,” said Asif Siddiqi, a professor at Fordham University in New York and an expert on Russia’s space program.

The latest sign that that the Kremlin's space program was creaking came on May 7, when a Progress M-27M unmanned spacecraft burned on re-entry over the Pacific.

The incident put the International Space Station (ISS) at risk of being cut-off from Earth. The failure was not the worst in recent years: Russia has lost 15 spacecraft since 2010, with assembly mistakes blamed in most cases.

It hasn’t always been this way.

Russia's Yuri Gagarin became the first human to travel to space on April 12, 1961. NPO Lavochkin Museum, HO / AP

One of the biggest shocks the United States endured during the Cold War came when the Soviet Union sent Yuri Gagarin into space in 1961, winning the race to put a man into Earth’s orbit.

Russia still launches more rockets than any other nation, and its engines are in demand even with NASA, but it lags on innovative research programs like NASA’s New Horizon mission to Pluto.

“We’ve fallen behind on science program ... We’ve forgotten how to make and fly unmanned probes,” said Igor Marinin, head of industry publication Novosti Kosmonavtiki.

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Space probes take years to reach their destination — but Russia does not have a single one making its way through space. Its latest successful probe wrapped operations in 1986.

Part of the problem is that while Russia boosted space spending from $960 million in 2005 to $4.1 billion last year, this is still dwarfed by NASA, which spent $17.6 billion in 2014.

A brain drain is also hobbling the sector. The Russian space industry was depleted of manpower after the Soviet Union’s collapse in 1991 and many experts fled to better-paying jobs in the West. This, in turn, caused a generation gap, particularly in crucial research and development.

"None of the long-term plans proposed in the past 15 years have been completely achieved on time"

“The 40-somethings that are supposed to be taking up top jobs in the industry should have started in the 1990s — and they didn’t,” Marinin said.

And while salaries have improved over the last two decades, they still haven’t reached anything close to parity with the West: A Russian cosmonaut made just $26,000 a year in 2012, compared to $63,000 to $139,000 at NASA, according to state agency RIA Novosti.

Money problems aren't going away. Falling oil prices and Western sanctions could see billions stripped from Russia’s space program over the coming years, experts say. This is money that Russia’s Federal Space Agency, the Roscosmos, can hardly afford to lose. (Roscosmos did not respond to a request for comment on this story).

So Russia’s state-dominated space industry is set to continue struggling to outperform its Western counterparts. Meanwhile, existing companies are plagued by lack of quality control and expert oversight. In 2013, a Proton rocket was lost because a worker installed a sensor upside down — and hammered it in to fit.

Added to this, economic sanctions mean certain spaceship components can no longer be imported and must now be reinvented in Russia.

There are moves to clean up and streamline the sector, to make it more efficient and productive. And Roscosmos is about to be revamped as a commercial holding which should, in theory, make it more competitive.

Siddiqi did not hold out much hope that the reforms would make a big difference.

“None of the long-term plans proposed in the past 15 years have been completely achieved on time. And there is no reason to believe that this one will be achieved either,” he said.

And this will only accelerate current declines, said Alexei Kaltushkin, the head of Lin Industrial, a private space company.

“If the space reform stalls and private sector ... does not grow, then Russia’s lag [in the space race] will increase,” he said.

The fact that space exploration continues is one of the few bright spots in Russian-Western relations at the moment.

“The tensions that exist here on earth, we leave them behind,” European Space Agency astronaut Andreas Mogensen told NBC News during a pre-launch press conference in Star City outside Moscow last week.