Shubhanshu Shukla, Axiom-4 return: How does space impact astronauts' health?

The Dragon spacecraft of the Axiom-4 mission, carrying Indian astronaut Shubhanshu Shukla and others, will return to Earth today. SpaceX said in a post on Tuesday that the crew was on track to reenter Earth's atmosphere and was on course to safely splash down off the coast of San Diego. "Dragon will also announce its arrival with a brief sonic boom before splashing down in the Pacific Ocean," it wrote on X. The astronauts are expected to return at 3 pm (IST). The spacecraft undocked from the International Space Station on Monday. "We are very happy that the undocking took place safely. We expect that the landing will also take place smoothly tomorrow. We have faith in the Almighty. We are all very proud of our son. The country is very proud of him because he is coming back after completing the mission," Shubhanshu Shukla's father said.

NASA wrote in a blog that the SpaceX Dragon spacecraft had undocked at 7:15 a.m. EDT from the space-facing port of the International Space Station's Harmony module, completing the fourth private astronaut mission to the orbiting laboratory, Axiom Mission 4. It was slowly manoeuvring away from the station into an orbital track that would return the crew and its cargo safely to Earth, targeting a splashdown off the coast of California. Space missions normally take a toll on the bodies of the astronauts as they endure radiation and a lack of gravity.

How does space impact astronauts?

Since Shubhanshu Shukla spent only a few weeks in space, it is unlikely that he will face any major adverse health impact. However, the crew will have to adjust to being back on the planet amid gravity, both mentally and physically.

Spending a long time in microgravity can make astronauts' muscles shrink and bones weaken. Since the astronauts don't use their legs to support their body weight, they lose muscle mass and bone mass. They lose 1 per centof bone mass per month, which is equal to ageing a year on Earth.

Those who spend six months or longer receive more than 10 times the radiation they would receive on Earth, which increases their risk of cancer. Astronauts also lose 5 per cent of their body mass in space and a significant amount of body fluids.

Prolonged exposure to radiation in space increases cataract risk. Space also affects astronauts' orientation and causes motion sickness.

After returning to Earth, the astronauts are expected to experience balance issues, dizziness, and weakened cardiovascular health. It takes a few days to return to normal. The body mass returns to Earth levels after around three months.