Barry ‘Butch’ Wilmore, 61, and Sunita ‘Suni’ Williams, 59, only planned to be floating in the endless abyss of space for a week. Eight days tops.
But the two Nasa astronauts have been stuck in the International Space Station (ISS) since June after a raft of technical hiccups.
Some nine months later, the space-faring duo will return home at about 10pm (GMT) tonight, according to Nasa.
They opened the hatch door of Elon Musk’s SpaceX Crew Dragon vehicle yesterday to begin their 17-hour trip home.
If all goes to plan, the capsule will splash down off Florida’s Gulf Coast. Right now, the capsule is soaring over the Pacific, according to a SpaceX tracker.
But how different will the two astronauts’ bodies be after hundreds of days in space? And what challenges will they face when reunited with gravity?
Why stand when you can float? How life without the effect of gravity changes us
Space, it’s pretty safe to say, is hostile to us Earthlings. There’s no gravity to keep you and all the bones and organs jiggling inside of you in place.
And given that the human body is 60% water, the lack of gravity – called microgravity – can have strange effects on us.
‘They have spent a total of 286 days in space, which is 35 times more than their original mission length,’ says Dr Kirsty Lindsay, assistant professor in rehabilitation sciences within Northumbria University’s Aerospace Medicine and Rehabilitation Laboratory.
‘After this extended period of time floating in microgravity we would expect them to have lost muscle mass and bone density, to have more fatty tissue in their muscles and importantly for landing day they have less circulating blood volume.’
Standing up, for example, becomes pointless. Muscles that help to maintain our posture – think back, neck, calves and quadriceps – diminish by as much as 20% in only two weeks.
This also includes the heart, which doesn’t have to pump as hard up in the stars as there’s low gravity. The muscle will shrink about 1/40th of an ounce a week.
Astronauts have to stay fit while on the ISS. The output has a gym and Nasa recommends astronauts exercise for about two hours a day.
This is to combat the loss of bone and muscle mass, called ‘deconditioning’, says Liz Johns, the interim head of space exploration at the UK Space Agency.
‘This deconditioning is counteracted by a strict exercise regime that all astronauts keep up throughout their time on the International Space Station,’ she says.
Blood flow is a two-man operation. The heart pumps blood up while gravity drags it down. So, without its colleague, the heart is suddenly pushing up too much blood for our head to handle.
All this liquid pools in the back of our eyes, causing a condition called oedema which impacts the optic nerve and can develop in two weeks. While most people’s vision goes back to normal when they’re back on land, they might need to wear glasses for the rest of their lives.
Some astronauts like Michael R. Barratt, who stayed on the ISS for six months in 2009, became more farsighted. He also had blemishes on his retina as his eyeballs were squeezed by all the liquid.
‘Puffy face and chicken legs’
When we suddenly have too much blood in our heads and too little in our legs, what will that do to Butch and Suni?
‘The answer is “puffy face and chicken legs”,’ professor Mike Tipton from the University of Portsmouth’s Extreme Environments Laboratory (School of Psychology, Sport and Health Sciences) told Metro.
‘Caused by blood volume shifts in space due to microgravity. On return to Earth, gravity makes blood pool in lower extremities, increasing the chance of fainting when upright.’
As their bodies adapt to weightlessness, Butch and Suni will likely lose weight. Most astronauts shed about 5% of their body weight during a four to six-month stay in orbit.
Bones demineralise and lose strength without gravity. As a comparison, older men and women lose 0.5-1% of their bone mass every year – astronauts lose up to 2% every month.
Many astronauts also develop a skin condition known as ‘baby feet’, with months in space turning their feet soft. This could make it particularly painful to walk, an act they haven’t had to do in nine months, or wear shoes.
While our muscles and bones help us move, it’s the brain calling the shots. Researchers have found that extended stays in space can rewire the parts of our brain that specialise in movement and orientation, as was the case for a Russian cosmonaut who spent 169 days on the ISS a decade ago.
Their circadian rhythm – the body’s internal clock – will have also been thrown off. Orbiting Earth every 90 minutes means they have seen the sun rise and set every hour and a half.
They might come back taller
We do, however, have good news for any 5’11” men who list themselves as 6′ on their Tinder bios. Without that pesky gravity squishing you down, people grow by about two inches when in space as their spines elongate.
Radiation is typically not a big worry for the inhabitants of Earth because the atmosphere acts as a cocoon, so most of it is deflected.
However, the ISS doesn’t have this high-level security system. High-energy atomic nuclei from exploding stars throughout the galaxy can penetrate spaceships, spacesuits and skin.
These big and heavy nuclei heighten the chances that astronauts will die of cancer as well as damage their DNA and white blood cells.
What are the long-term effects of space travel?
Things will also stay weird even when Butch and Suni finally reunite with Earth’s gravity. The effects of gravity on the body are stronger than the effects of microgravity, making rehabilitation a long journey.
Even something so simple as standing up will be a struggle for the pair once they come down, says Dr Lindsay.
‘In space, all the blood that is normally in your lower legs moves up into the trunk, and this is seen by the brain as having too much fluid, so it gets rid of the extra while you’re in microgravity. However, once you are back in gravity your blood is pulled down towards your feet again, so now you have a low blood volume,’ she says.
‘This means that when standing up if their heart can’t pump enough blood up to their brain, something it hasn’t had to do for a while, they might faint.’
To help combat this, Butch and Suni will probably have chugged down an isotonic drink to stay hydrated. Rescue teams will keep them sitting as much as possible as they’re being transferred, Dr Lindsay adds.
The pair will undergo about 45 days or so of rehabilitation programmes – after, however, a rest day to reunite with loved ones as well as gravity.
‘Roughly speaking they will need one day of recovery for each day spent in space, so they may have ongoing symptoms for a while after they land,’ Dr Linday adds.
‘Williams and Wilmore are both on their third flight so they will know what to expect. Bone density is the slowest thing to recover, and it might be that bone density is always lower for some people after spaceflight, we don’t have enough information to be sure.’
The ‘demands of gravity’, Tipton says, can be ‘challenging’ to readjust to.
‘Fluid shifts are likely to occur most rapidly with blood pressure control and cardiac functioning,’ he says. ‘It will take longer for bone and muscle mass to return and with them full physical function.’
The longest any human has been off Earth is almost 438 days, a title held by Dr Valery Polyakov on the Russian space station Mir in 1994 and 1995.
Outside of adjusting to having their feet on the ground again, there’s something else Butch and Suni will need to readjust to – daily life.
‘Although astronauts can speak on the phone, email and even video call their families, it’s not the same as hugging them in person, so I think they will feel like we all did after the lockdown ended and we could visit friends and family again, happy, overwhelmed, maybe tired by the noise, and they will feel heavy too, so lots of emotions for sure,’ she says.
‘They have been on an amazing, dangerous, exciting adventure, and now they need to go back to normal, walking the dog and shopping for dinner and doing laundry.’
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