India, April 11 -- After spending 10 days in space on the first crewed lunar mission in more than 50 years, the astronauts of Artemis II are now preparing for the most critical and risky phase of their journey which is returning to Earth.

According to NASA, reentry is widely considered one of the most dangerous parts of any space mission.

When the Orion spacecraft comes back to Earth, it will be moving at about 25,000 miles per hour which is more than 30 times the speed of sound, according to CNN. At that speed, the air around it gets compressed which makes the outside of the capsule heat up to over 5,000 degrees Fahrenheit.

The only thing protecting the astronauts from this extreme heat is the heat shield. If it fails, there is no bac...