28,000 Kmph, 1,600 Degrees: Fireball Test Before Sunita Williams Landed

A Dragon spacecraft returning astronauts Sunita Williams and Butch Wilmore after nine months in space landed in the ocean off the coast of Florida at 5:57 PM (3:27 AM IST). Soon after, 59-year-old Williams and 62-year-old Wilmore emerged from the spacecraft, grinning and waving, as the crowd celebrated. NASA’s Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov joined them on the 17-hour trip back.

However, these instances of happiness were preceded by hours in which the astronauts — and the world — were anxiously hopeful. The final phase was the most challenging as SpaceX’s Dragon spacecraft re-entered the atmosphere. Currently, the capsule is moving at speeds reaching up to 28,800 kmph. The friction generated raises the temperatures of its exterior casing to approximately 1,600 degrees Celsius, while heat shields safeguard the occupants within. Thus, the cheers for Sunita Williams’ return only erupted after the spacecraft became a fiery ball as it entered the atmosphere, on its way to splash down in the ocean.

Docked at the International Space Station, the Dragon spacecraft exists in a condition of nearly-vacuum. After a number of departure burns, it left the station and started its journey back. Upon entering Earth’s atmosphere, intense friction occurs, causing temperatures to rise dramatically, reaching up to 1,600 degrees.

Dragon capsules use heat-resistant PICA material for the outer shell. Photo courtesy: NASA

The SpaceX’s Dragon capsule is equipped with a heat-resistant casing of Phenolic-Impregnated Carbon Ablator of PICA. It was NASA that first used this lightweight material. Later, SpaceX got its Dragon capsule outfitted with PICA tiles for cargo and human movement to and from the International Space Station. The Dragon capsule that brought Williams and Wilmore home went from sparkling white to brownish by the time it splashed down, indicating how the outer shell burned as it entered the atmosphere, but ensured occupants’ safety.