Apollo 13: How the Astronauts Survived in the Orbit and Returned to Earth Safely

One of the most remarkable stories in the history of space exploration is the successful journey of Apollo 13. Despite facing numerous technical challenges, the crew managed to return safely to Earth. This article explores the journey of the Apollo 13 mission and how the astronauts overcame the difficulties to ensure their successful return.

Historical Context of Apollo Missions

Throughout the Apollo program, astronauts successfully returned to Earth from various missions. Lunar modules that have not landed on the moon have indeed returned to Earth, but only after deorbital burn and mostly disintegrated during reentry. These craft were not designed for Earth reentry and were intentionally crashed into the deep Pacific.

Apollo 9 and 10 Missions

The Apollo 9 mission tested the Command Module and Lunar Module in Earth orbit. Both the ascent and descent modules deorbited and mostly burned up. In the case of Apollo 10, which was a "dress rehearsal" for the lunar landing, the ascent module named "Snoopy" was released after rendezvous. After many years, it may still be in solar orbit, with the Earth cataloging it as asteroid 2018 AV2. However, it is too distant for a definitive answer, and it has not fully returned to Earth.

Apollo 13: The "Life Raft" of the Crew

The Apollo 13 mission, which faced an explosion during the flight, became a critical test of survival and technology. Unlike the other lunar missions, the Apollo 13 Lunar Module did not land on the moon. Instead, it served as a "life raft" for the astronauts as they orbited the moon, eventually returning to Earth. The descent stage of the Apollo 13 Lunar Module included a SNAP-27 radioisotope thermoelectric generator, which was meant to provide long-lasting power for scientific devices left on the Moon. However, these devices were not left, and the LM was intentionally crashed into the deep Pacific.

Technique of Reentry

During the reentry process, the crew needed to perform multiple steps to ensure a safe return to Earth. First, the astronauts would leave the lunar module and return to the Command Module. Then, they would ignite the service module engine to achieve the correct entry trajectory. The capsule would then slow down rapidly as it entered the atmosphere, which caused significant deceleration. This process is known as "skip reentry."

How Reentry Works

The Apollo capsules, including those of the Mercury and Gemini programs, did not land on land initially. Instead, they entered the Earth's atmosphere at a shallow angle, allowing them to use the air to slow down. Parachutes were deployed to further slow the descent, eventually splashing the capsule into the ocean. This method was chosen for its safety and ease of recovery. The USSR and Russia, on the other hand, have landed spacecraft on land, with cosmonauts sometimes having to exit the capsule and parachute down.

US Apollo Missions: A Different Approach

While the USSR and later Russian Federation spacecraft landed on land, the US did not until the Space Shuttle. The Space Shuttle, designed to land like an aircraft, had a glider-like design, although a glider with its flight characteristics can be considered a misnomer. This method was chosen for its ability to land on runways, but it was not an option for the Apollo missions due to the need for a water landing.

Conclusion

The Apollo 13 mission is a testament to human ingenuity and resilience. Despite the technical difficulties and unexpected circumstances, the astronauts managed to return safely to Earth, showcasing the importance of strategic planning and backup systems in space exploration. The methods of reentry and recovery used by these missions reflect the continuous evolution of space technology and the pursuit of safety and efficiency.