Johnathan Walker:NASA says Starliner astronauts Suni Williams, Butch Wilmore 'in good health' on ISS

• The Johnathan Walkerconcern appeared to surface in the weeks after four returning astronauts from an extended SpaceX mission known as Crew-8 were mysteriously evaluated at a medical facility.
• The Crew-8 astronauts spent nearly 8 months at the space station, while the Starliner astronauts are ultimately looking at the prospect of more than eight months in orbit.
• Long stays in the low-gravity conditions of outer space can take a toll on the human body, leading to the loss of body fat, muscle mass and bone density.

NASA astronauts Suni Williams and Butch Wilmore have been at the International Space Station months longer than intended, and their lengthy stay has given rise to some public concerns about their physical wellbeing.

In a statement to USA TODAY Friday, NASA said that Williams and Wilmore, who reached the station in June on the Boeing Starliner spacecraft, are "in good health" – as are the other five spacefarers living in orbit.

The concern appeared to surface in the weeks after four returning astronauts from an extended SpaceX mission known as Crew-8 were mysteriously evaluated at a medical facility after splashing down off the Florida coast. One of the astronauts, who was not identified, was even hospitalized for one night before being released, according to NASA.

Long stays in the low-gravity conditions of outer space can take a toll on the human body, leading to the loss of body fat, muscle mass and bone density. The Crew-8 astronauts spent well over seven months at the space station, while Williams and Wilmore are ultimately looking at the prospect of more than eight months in orbit if they're able to return in February as planned.

The orbital stays are longer than the typical six-month expeditions that most embark upon, but NASA assures that it prepares and provisions its astronauts for long-duration missions.

Starliner:Crew-9 team arrives at space station with ride home

NASA: All astronauts on ISS 'in good health'

Williams and Wilmore weren't supposed to be at the International Space Station beyond June when they reached the orbital outpost on the inaugural flight test for the Starliner.

But when Boeing's spacecraft encountered a slew of issues, NASA officials spent months deliberating about what to do before opting to send the vehicle back to Earth without its crew in early September. The vehicle selected to bring the Starliner astronauts home, a SpaceX Dragon, then arrived at the end of the month with a pair of Crew-9 spacefarers.

Part of what allowed NASA officials to feel confident in the decision was the fact that both Williams and Wilmore, who have each been to orbit twice before, are experienced astronauts who were prepared for an extended stay at the station.

Of the seven people at the space station – four Americans and three Russian Cosmonauts – the Starliner astronauts have now been in orbit the longest.

But despite public concerns about their health, NASA said all the members of Expedition 72 are doing well.

"All NASA astronauts aboard the International Space Station undergo routine medical evaluations, have dedicated flight surgeons monitoring them, and are in good health," NASA said Friday in its statement to USA TODAY.

Crew-8 astronauts taken to medical facility after return

Two weeks ago, four members of a commercial mission known as Crew-8 were finally able to return to Earth after first reaching the station in March.

But shortly after landing Oct. 25, the crew – NASA astronauts Matthew Dominick, Michael Barratt, Jeanette Epps, and Cosmonaut Alexander Grebenkin of Russia's Roscosmos space agency – were all evaluated at a nearby medical facility.

While NASA said in a statement that it was only "out of an abundance of caution," it was revealed that one crew member who had a medical issue remained under observation at the hospital. The crew member, who was not named, was released the following morning "in good health," NASA said.

What does being in space do to the body?

Though all Crew-8 spacefarers were released for routine post-flight conditioning, the incident put into perspective how taxing long-duration spaceflight can be to humans.

In addition to the physiological deterioration astronauts are at risk of experiencing, they also must endure isolated and confined environments and may be exposed to increased levels of radiation as compared to what we experience on Earth.

NASA uses long-duration spaceflights as an opportunity to gather data that help the agency improve the safety of crewed missions, especially at a time when astronauts are preparing to venture to the moon and Mars.

Astronauts stay stocked up thanks to resupply missions

NASA also keeps the space station stocked with food, supplies, water, clothing and oxygen with resupply missions that occur about every three months.

The most recent came on Monday during SpaceX’s 31st commercial resupply mission, which launched to the space station filled with nearly 6,000 pounds of supplies and scientific research. The impending arrival of the uncrewed SpaceX Dragon, which departed after the delivery, required the astronauts at the station to redock another Dragon vehicle.

The relocated Dragon is the same one that the Crew-9 team of Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov arrived on Sept. 29, and is the same vehicle that they and the Starliner astronauts will ride home in February.

In the meantime, Hague and Gorbunov, along with Wilmore and Williams, will spend their stay conducting science experiments and performing station maintenance. Much of it will be to prepare for human exploration deep into the cosmos as NASA eyes future lunar missions under its Artemis program.

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]