Why NASA astronauts have been sent to rehab after 9 months 'stranded' in space

Following their long-awaited return to Earth last week, NASA astronauts Sunita Williams and Barry 'Butch' Wilmore have reportedly begun a 45-day rehabilitation program in the coming days. But why?

For those in need of a reminder, the duo have been stranded on the International Space Station since June of last year following a botched eight-day mission.

A bout of technical faults - including fuel and helium leaks, as well as a broken propellant valve - meant their return journey was an impossibility.

The months that followed heard NASA vow to dispatch another rocket to retrieve Williams and Wilmore, all of which were subsequently cancelled.

Following encouragement from controversial president Donald Trump, however, NASA collaborated with Elon Musk's tech firm SpaceX, and a date was finally set for their pair's rescue.

Sunita Williams and Barry Wilmore's return to Earth

Eventually, last Wednesday (19 Mar) saw SpaceX’s Crew-9 - led by NASA's Nick Hague and cosmonaut Aleksandr Gorbunov - successfully return Williams and Wilmore to Earth.

The duo splashed down off the coast of Florida before being reunited with their friends and families via stretchers.

Why is it, however, that the pair will now require a lengthy stay at a rehabilitation facility?

Well, it turns out that nine months stranded in space - being subjected to ceaseless failed rescue attempts - has had quite the affect on their physical health.

As well as a shift in fluid causing their faces to puff, the microgravity in space would have also triggered muscle atrophy, a temporary height increase, a reduced bone density, blood flow problems, and a change in neurovestibular function - as per DD News.

It is likely that their aerobic capacity has also taken a hit in the last nine months, alongside their muscle strength, endurance, stamina, balance, and coordination.

Williams and Wilmore have now returned to Earth (Keegan Barber/NASA via Getty Images)

Experts also fear that a prolonged period in space could result in an increased exposure to radiation, which heightens the risk of cancers, and a decrease in mental wellbeing.

The Indian Express also mentions the risk of impairments to vision, along with an impact to gut health.

As such, a stint in a structured reconditioning program - implemented by Astronaut Strength, Conditioning, and Rehabilitation (ASCR) specialists - will assist the pair in readjusting to Earth's intense level of gravity.

What will the rehabilitation program involve?

According to US reports, Williams and Wilmore will receive rehabilitative treatment for two hours per day, seven days a week, for 45 days.

Each astronaut's programme has been customised and designated for them as per the results of a set of medical tests.

The first of the stint's three phases began on landing day, and focusses on general mobility, flexibility, and muscle strengthening.

The duo will now undergo 45 days of rehab (Keegan Barber/NASA via Getty Images)

The second sees the pair undergo proprioceptive exercises, as well as cardiovascular training.

The third phase, meanwhile, prioritises functional development.