Sunita Williams and Butch Wilmore finally returned home to a heroes’ welcome earlier this week, having spent more than nine months in space.

The pair were only due to be on the International Space Station (ISS) for around a week, but after technical issues, they found themselves there for an extra 278 days. Ouch.

Thankfully, they seemed to take it in their stride – simply because that’s what astronauts have to do.

“We came prepared to stay long, even though we planned to stay short,” Wilmore previously told reporters, stressing that he didn’t think the extension was in any way affected by politics.

“That’s what your nation’s human spaceflight program’s all about,” he added. “Planning for unknown, unexpected contingencies. And we did that.”

The astronauts landed home earlier this week (NASA)

But while they were ‘prepared’ to prolong their trip – and delay their return to loved ones – they should be receiving compensation for the unexpected change.

While the exact figure has not been confirmed, we do know that in the past the amount has been surprisingly small.

Former NASA astronaut Cady Coleman told the Washingtonian that astronauts are paid like any federal employee on a business trip – that is to say, they get their regular salary with no overtime, while NASA takes care of transportation, lodging, and food.

“There is some small amount of money per day for incidentals that they end up being legally obligated to pay you,” she said, saying she received around $4 a day when she went on a 159-day mission between 2010 and 2011 – a number that works out at around $636.

According to the Daily Mail, Williams and Wilmore’s salaries range between $125,133 and $162,672 per year, which – based on Coleman’s figures – means they could earn little more than $1,000 in ‘incidental’ cash on top of their basic salary.

Williams and Wilmore, pictured during a ‘dress rehearsal’ last April (Instagram/@nasaastronauts)

Of course, that doesn’t allow for inevitable inflation, but even so the maths may seem surprising.

The duo now have to undergo NASA’s official 45-day rehabilitation programme, which consists of three phases.

This begins with a focus on walking, flexibility and muscle strengthening, before things move on to phase two, which adds proprioceptive exercises – aimed at strengthening the body and improving the mind’s perception of its movement and position – and cardio reconditioning.

Finally, phase three – the longest – focuses on returning astronauts to their optimal level of physical performance via functional development training.

This process is crucial for astronauts returning home, as while they may exercise for at least two hours a day while on the ISS, this isn’t enough to fully counter the effects their bodies experience.

Featured Image Credit: NASA/Keegan Barber/Handout/Anadolu via Getty Images/Keegan Barber/NASA via Getty Images