Effects of a Nine-Month Space Mission as Two NASA Astronauts Return to Earth

 

After 286 days in space, NASA astronauts Butch Wilmore and Suni Williams

Effects of a Nine-Month Space Mission as Two NASA Astronauts Return to Earth

NASA astronauts Barry "Butch" Wilmore and Sunita "Suni" Williams are set to make their return to Earth following an unplanned nine-month stay aboard the International Space Station (ISS).

Initially, Wilmore and Williams embarked on the first crewed test flight of Boeing's Starliner capsule to the ISS in June 2024. The mission was originally scheduled to last approximately one week. However, technical issues with the Starliner extended their stay significantly, delaying their return until early 2025.

Experts have highlighted that prolonged exposure to space can lead to significant physiological and psychological changes in the human body, particularly over many months.

Effects of Microgravity

A major impact of long-term space travel is the exposure to microgravity, which enables astronauts to float freely inside their spacecraft and during extravehicular activities.

NASA has documented that in microgravity, there is a reduction in muscle mass due to decreased usage and limited stimulation from exercise equipment. Additionally, bone density diminishes, which poses challenges for long-term space habitation.

Without the influence of Earth's gravity, bones responsible for supporting body weight may lose between 1% and 1.5% of their mineral density each month. NASA also warns that without a proper diet and consistent physical activity, astronauts may experience accelerated muscle loss compared to what would occur on Earth.

Another significant physiological shift is the movement of bodily fluids, such as blood and cerebrospinal fluid, which tend to migrate upward toward the head and eyes. This redistribution is suspected to contribute to changes in the structure of the eyes and brain.

Astronauts also face the risk of kidney stone formation, primarily due to dehydration or the loss of calcium from bones if preventive measures are not taken.

Upon their return, crew members undergo medical evaluations to help them reacclimate to Earth's gravitational forces. They must readjust their balance and equilibrium to perform simple everyday activities like standing and walking.

NASA's SpaceX capsule Dragon splashes down off FL coast

Exposure to Space Radiation

Radiation exposure in space differs significantly from what is encountered on Earth. Space radiation consists of three primary sources: particles trapped within Earth's magnetic field, radiation from solar flares, and galactic cosmic rays.

Earth's magnetosphere serves as a natural shield against these harmful particles. However, the higher one travels in altitude, the greater the exposure to radiation.

Due to extended periods in space, astronauts are at an elevated risk of developing radiation-related illnesses, including radiation sickness, neurocognitive effects, and an increased likelihood of cancer and degenerative diseases.

According to a 2017 NASA report, ISS crew members receive radiation doses ranging between 80 mSv and 160 mSv over a six-month period. For reference, a millisievert (mSv) measures how much radiation the body absorbs. Though space radiation differs from medical radiation, NASA equates 1 mSv of space radiation to roughly three chest X-rays.

On Earth, individuals are naturally exposed to approximately 2 mSv of background radiation annually.

Dr. Rihana Bokhari, acting chief scientific officer at Baylor College of Medicine's Translational Research Institute for Space Health, previously explained, "In low earth orbit where the ISS is, astronauts are at least partially protected by the magnetosphere that protects Earth from the radiation exposure of deep space."

She further elaborated, "However, they do have a greater radiation exposure than those on Earth because the ISS passes through areas of trapped radiation in their orbit. Butch and Suni, since they are on the ISS, will not be exposed to enough radiation to seriously cause large impacts on body systems but the long duration exposure to greater radiation than on Earth could lead to an increase in the risk of cancer."

Psychological and Social Effects of Isolation

Extended space missions not only affect astronauts physically but can also take a toll on their mental well-being due to isolation and confinement.

NASA selects and extensively trains astronauts to ensure they can handle missions lasting six months or longer. However, studies indicate that prolonged exposure to isolated environments, whether in space or on Earth, can lead to behavioral changes, stress, fatigue, and sleep disturbances.

To mitigate these challenges, researchers are exploring countermeasures such as virtual reality environments designed to provide relaxation, as well as activities like language learning or tending to a small space garden.

Dr. Jennifer Fogarty, chief scientific officer at Baylor College of Medicine's Translational Research Institute for Space Health, has previously noted that prolonged stress during space missions can impact the immune system. She emphasized the importance of maintaining a healthy living environment for astronauts to support their overall well-being during extended missions.

As Wilmore and Williams prepare to return to Earth, their mission provides valuable insights into the effects of long-term space travel, paving the way for future explorations beyond low Earth orbit.