Quest for Space Travel: Changes in Human Body Physiology in Microgravity and Space

The human being (Homo sapiens) is inevitably meant for living over the Earth's surface only. Human curiosity and imagination are exorbitantly vast and enormous. Since antiquity, human beings have been watching the stars in the vast sky and dreaming to reach there, if not physically but in thought. The human body is exquisitely adapted to Earth's gravity. There is a surge in space missions as a rat race to reach the moon and then Mars, and much beyond!

The term “astronaut” means “star sailor” in Greek and refers to someone who has been launched as a crew member in a spacecraft bound for orbit Earth and/or beyond towards the Moon. Astronauts and cosmonauts effectively do the same job in space. Cosmonauts are those star sailors, specifically trained by the Russian Space Agency to work in space. Similarly, taikonauts are Chinese astronauts!

Vyommitra (Vyōma: "space" & Mitra: "friend" in Sanskrit) is a humanoid robot (female) designed for space travel. She has been developed by the Indian Space Research Organisation (ISRO) to function aboard the spacecraft Gaganyaan. Similarly, Vyomanauts shall be ISRO’s star sailors shortly.

Living human beings when placed in the microgravity environment of space, numerous physiological challenges arise in the body, which could be fatal or irreversible in many ways.

• Musculoskeletal System: Without the constant pull of gravity, muscles weaken and lose mass rapidly, known as muscle atrophy. The astronauts on the ISS must undergo treadmills and other exercises daily.
• Effect on Kidney: A lengthy trip to Mars, which will expose the astronauts to a combination of cosmic radiation and weightlessness for months, may severely result in permanent kidney damage and who knows even kidney dialysis may be needed in such cases in the space shuttle.
• Bone loss: Bones in the lower extremities become less dense or porous due to lack of weight-bearing stress. This can lead to osteoporosis and increased fracture risk upon return to Earth. ?
• Cardiovascular System: Body fluids shift from the lower body to the upper body portions, leading to facial swelling and changes in blood pressure. During the initial days, it is incredibly challenging for the edema in the body.
• Heart deconditioning: The human heart does not work as hard to pump blood against gravity, leading to a weaker cardiac muscle. The shape of the heart changes from an oval to a round ball.
• Neurological System: Many astronauts experience nausea, vomiting, and dizziness due to sensory conflicts, known as space motion sickness. There is misinterpretation and inadequate motor responses due to altered input signals in space. Many astronauts feel Vertigo, nausea, vomiting, appetite loss, headache, and pallor.
• Changes in balance and coordination: The vestibular system in the ear, responsible for balance, is severely affected by microgravity. ?
• Vision changes: Spaceflight-associated neuro-ocular syndrome (SANS) is a condition that affects vision in some astronauts. The eye feels strained by not being able to see green vegetation in the space, as it is perpetually black otherwise.
• Immune System: The immune system can be compromised in the space environment, making astronauts more susceptible to infections.
• Sleep disturbances: Irregular sleep patterns and difficulty in sleeping are common due to altered light-dark cycles and noise.
• Radiation exposure: Astronauts are exposed to higher levels of radiation, increasing the risk of cancer. ?

• Psychological challenges: Isolation, confinement, and the stress of spaceflight can affect the mental health of astronauts as well. ?

Overcoming these challenges is very crucial for long-duration space missions, such as those planned for Mars. Extensive research and countermeasures, including exercise regimes, dietary adjustments, and pharmacological interventions, are being developed to mitigate these effects. Still, a lot of research is going on to decipher and churn out remedies to counter such human body alterations in the microgravity of space. Indeed, humans are made for the Earth only, but (greedy or overjoyous) humans wish to reach far apart in the vast space.