Group Captain Shubhanshu Shukla, the first Indian to step inside the , has safely returned to Earth after a successful 18-day mission aboard the Axiom-4 (Ax-4) crew. On Tuesday, the crew entered the Earth's atmosphere with a successful splashdown off the California coast. While his journey to ISS and back to Earth is an example for all those future astronauts, it's also important to understand how the body reacts to these changes between gravity and microgravity.

In this article, we will understand how the human body reacts to microgravity and then after entering gravitational force after a long time.

While it may sound amazing to stay above the Earth, and see the planet with that view, experts say that all these come with certain health challenges as well. Shubhanshu Shukla on Wednesday, returned to Earth after spending 18 days under microgravity at the ISS, although, his landing was done successfully, experts warn that his body may show some complications that is normal for any astronauts who have been to the ISS.

After landing, the crew was met by SpaceX recovery teams and was taken immediately to NASA's Johnson Space Center in Houston. As per reports, the astronauts will undergo 7-days rehab post-landing to recover from any health issues that microgravity may have caused. Here's what the astronauts go through next:

As per experts, the astronaut will undergo 7 10 day rehabilitation protocol post-landing which includes physical, cardiovascular, vision, balance, immune, and mental health checks.

Check the details about the health issues that they may face after re-entering Earth's gravity:

Muscle atrophy, which is also known as muscle weakness, is one of the common health problem that every astronaut face. This mainly happens due to the less activity when the body is under microgravity.

Bone loss from microgravity is addressed through monitored exercise and therapies. Astronauts often wear compression garments and undergo fluid-loading protocols to stabilize blood pressure.

In order to fix this problem, the astronauts are made to follow strength and cardiovascular training to restore their ability to walk and function normally.

According to the reports, studies have shown that astronauts lose up to 1 2% bone density per month, equivalent to a decade's aging in just a few weeks at the ISS.

During their stay at the ISS, astronauts also develop certain issues with their heart, called space-induced cardiac problems. Without gravity's pull, blood volume and heart function drop leading to orthostatic intolerance, dizziness, and reduced aerobic capacity on Earth.

Apart from physical health issues, astronauts also suffer from severe stress and mental problems, such as irritability, sleep disturbances, and concentration issues termed "asthenization".

Speaking to the media, Union Minister Jithendra Singh said, "Shubhanshu Shukla will undergo a series of post-mission procedures in California. "There are certain SOPs to be followed... His rehabilitation, debriefing sessions and a series of discussions with Team ISRO. We might expect him in Delhi by August 17."