How Is Sunita Williams Surviving In Space? What Does Spaceflight Do To A Human Body? Explained - News18 (2025)

Last Updated:November 20, 2024, 15:56 IST

After just two weeks in space, muscle mass can fall by as much as 20% and on longer missions of three-to-six months it can fall by 30%. Changes in brain’s neural connectivity and effects on DNA have also been found in astronauts

In a recent video, Sunita Williams mentioned that changes in her appearance were not because of weight loss, but due to a phenomenon called ‘fluid shift’. (Photo: X)

Sunita Williams has been in space since June, 2024. NASA launched Boeing’s Starliner spacecraft with astronauts Williams and Barry Wilmore on board to carry out testing at the International Space Station (ISS). The space mission, which was planned as a brief stay, has turned into an extended journey for the astronauts.

When Williams turned 69 on September 19, NASA shared her picture with Wilmore at the ISS, attending a conference with flight directors, discussing future missions and scientific research in the orbiting laboratory.

In fact, space enthusiasts, doctors and those who know about Williams shared their concern online about her alarming weight loss in a video shared a few days ago. Williams addressed significant changes in her appearance, physical health, body fluids.

Why Is Williams Stuck In Space?

The Boeing Starliner mission was part of NASA’s efforts to test the spacecraft’s capabilities for future human spaceflights. The objective was to ensure the spacecraft’s safety and functionality while conducting scientific experiments on board the ISS. However, due to the technical issues encountered during the mission, NASA made the call to not risk the astronauts’ safety by attempting to return them on the Starliner.

As NASA Administrator Bill Nelson explained, “Spaceflight inherently carries risks, especially during test flights like the Starliner mission." He reiterated that safety remains the agency’s top priority, particularly in light of past experiences such as the 2003 Columbia shuttle disaster.

Williams and Wilmore’s mission, initially planned for 10 days after the docking of the Starliner spacecraft, has been extended due to technical complications with the spacecraft.

How Does A Body Change After Spending A Considerable Time In Space?

With the gravity, our limbs, muscle and bone mass quickly begin to diminish in space. The most affected are those muscles that help to maintain our posture in our back, neck, calves and quadriceps — in microgravity they no longer have to work nearly as hard and begin to atrophy. After just two weeks in space muscle mass can fall by as much as 20% and on longer missions of three-to-six months it can fall by 30%, according to a report by the BBC.

Astronauts can lose 1-2% of their bone mass every month in space and up to 10% over a six-month period. This can increase chances of fractures and can take an enormous time to heal. On Earth, men and women lose bone mass at a rate of 0.5%-1% every year.

The report says that it can take up to four years for the bone mass of an astronaut to return to normal after returning to Earth.

Although astronauts undertake a 2.5-hour exercise and intense training and take diet supplements to keep their bones healthy, but studies suggest that it may not be enough to prevent the loss.

In space, blood can get accumulated in the head more than it normally would due to no gravity. This can lead to changes in vision such as decreased sharpness and structural changes in the eye itself. These changes can begin to occur in a human body after it has spent just two weeks in space. Exposure to galactic cosmic rays and energetic solar particles can also lead to other eye problems.

A study on a Russian cosmonaut who spent 169 days on the ISS in 2014 also revealed some changes to the brain. There are changes in brain’s neural connectivity relating to motor function.

Another significant finding into the space journeys of the astronauts shows the effects on their DNA. Telomeres, which are through to protect the genes from damage, seem to alter during a space travel. Telomeres become shorter as we age.

A new study in June 2024 highlighted some potential differences between the way the immune systems of male and female astronauts respond to spaceflight. Using gene expression data from samples obtained from the crew of the SpaceX Inspiration 4 mission, who spent just under three days in orbit in the autumn of 2021, it identified changes in 18 proteins related to the immune system, ageing and muscle growth.

What Changes Have Been Noticed In Williams?

In a recent video, Williams mentioned changes in her appearance were not because of weight loss, but due to a phenomenon called ‘fluid shift’. As bodily fluids move upward towards the face and upper body due to no gravity, an astronaut’s face appears visibly puffier and their limbs tend to look weaker and thinner.

She mentioned that she has gained more muscle, particularly in her legs, due to regular exercise.

Williams did not provide detailed information about her precise diet, but she did share some of the meals she enjoys, including Turkish fish stew with olives and rice, stressing that she is getting proper nutrition in space despite challenges.

Astronauts Who Have Spent Record Time In Space

Nasa astronaut Frank Rubio spent 371 days in an American-football-field-sized collection of modules and solar panels. His departure from the International Space Station (ISS) and return to Earth in October 2023 marked the end of the longest single spaceflight by an American to date. He was due to return on March 2023 was extended due to a coolant leak. The extra months in space allowed Rubio to clock up a total of 5,963 orbits around the Earth, travelling 157.4 million miles (253.3 million km).

Russian cosmonaut Valeri Polyakov spent 437 days onboard the Mir Space Station in the mid-1990s. He began his space journey on January 8, 1994 along with two other astronauts. He orbited the Earth more than 7,000 times, before returning March 22, 1995. Polyakov previously had spent 288 days in space on a mission in 1988-89.

In September 2024, two Russian cosmonauts – Oleg Kononenko and Nikolai Chub – broke the record for the longest stay on the ISS after spending 374 days in orbit. Kononenko and Chub arrived at the ISS on September 15, 2023, via the Soyuz MS-24 spacecraft.

When Will Williams Return?

Sunita Williams, an Indian-origin American astronaut, has logged 322 days in space over three missions, making her one of the most seasoned astronauts in NASA’s history. She is also known for her record-setting spacewalks.

Wilmore, a retired US Navy Captain and veteran astronaut with two spaceflights totalling 178 days in space, has also adapted to the extended stay. Both have remained in good spirits and are focused on collecting valuable data for NASA’s long-term space exploration and human spaceflight goals.

NASA has confirmed that the astronauts’ return will now take place in early 2025, using SpaceX’s Dragon capsule instead of Boeing’s Starliner. The Dragon spacecraft successfully docked with the ISS on September 29, 2024, and will be used to bring Williams, Wilmore, and other crew members back to Earth.

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New Delhi, India

First Published:

November 20, 2024, 15:54 IST

News explainers How Is Sunita Williams Surviving In Space? What Does Spaceflight Do To A Human Body? Explained