With the rapid development of technology, space exploration is no longer a plot in science fiction novels but a magnificent journey in reality. After astronauts complete their missions in space, returning to Earth is one of the most critical stages.
The return is not a simple task; it involves complex scientific principles and precise technical operations. This article will provide a detailed introduction to how astronauts safely return to Earth, covering important steps from leaving the space station to landing.
1. Preparation After the Mission
After completing their space mission, astronauts first need to conduct a mission summary and prepare for their return.
This process is usually guided by the space agency's control center to ensure that the astronauts' return does not conflict with other space missions. Additionally, astronauts need to check all equipment to ensure there are no malfunctions during the return process.
For example, astronauts will check the fuel and oxygen supply of the spacecraft to ensure they have enough resources to complete the journey from the space station to Earth. At this point, astronauts enter their return capsule, which is a compact compartment specifically designed to withstand the high temperatures and intense airflow when re-entering Earth's atmosphere at high speed.
2. Preparing to Detach from the Space Station
Before returning to Earth, astronauts need to separate from the space station. In this phase, the spacecraft will detach from the docking port of the space station and begin autonomous flight.
This process requires precise calculations and operations. Modern spacecraft are equipped with automatic control systems, but astronauts still need to manually intervene to ensure a safe distance between the spacecraft and the space station.
At this point, the spacecraft will execute a trajectory adjustment to align with Earth’s direction. To avoid wasting fuel, the most optimal orbit is usually chosen, allowing the spacecraft to re-enter shortly.
3. Re-entry into Earth's Atmosphere
Re-entry into Earth's atmosphere is the most critical and challenging phase of an astronaut’s return journey. The spacecraft must enter the atmosphere at extremely high speeds, usually over 20,000 kilometers per hour.
This process generates a significant amount of frictional heat, causing the spacecraft's surface temperature to rise dramatically, potentially reaching several thousand degrees Celsius. Therefore, the spacecraft’s surface needs to be equipped with special heat-resistant materials to withstand this heat flow.
During re-entry, the spacecraft will adopt a specific angle and attitude to ensure a smooth passage through the atmosphere. If the angle is too shallow, the spacecraft may be bounced back into space; if the angle is too steep, it could lead to intense heating and damage to the spacecraft. To reduce the pressure on the spacecraft, aerodynamic designs are used to distribute the heat during re-entry.
4. Parachute Descent
Once the spacecraft passes through the high-temperature region of the atmosphere, its speed begins to decrease.
Next, the spacecraft undergoes a series of deceleration processes to further reduce speed. During atmospheric entry, the spacecraft’s exterior generates air resistance, which slows it down. As the spacecraft reaches a lower altitude, the parachute system will automatically deploy.
The parachute system is a vital part of ensuring the astronauts’ safe landing. Modern spacecraft are typically equipped with multiple parachutes, each playing a role at different stages, from slowing down the descent to ensuring a smooth landing.
How do astronauts return to Earth? [with Closed Caption Captions]
Video by European Space Agency, ESA
5. Medical Examination After Landing
After the spacecraft successfully lands, the mission is not yet over.
The space agency's rescue team will immediately deploy to the landing site, typically a remote desert or ocean area, to conduct a search and rescue operation. Modern spacecraft are designed with precise landing systems that significantly reduce the time required for rescue.
Once the astronauts are found and taken to a safe area, they will undergo a medical examination. Although the return process has already been a severe test, astronauts’ bodies still need to go through an adaptation period. Prolonged exposure to weightlessness in space often leads to muscle atrophy, so they need to undergo a series of rehabilitation exercises to gradually adjust to Earth's gravity.
The process of astronauts returning to Earth is the result of technological advancements and human ingenuity. Through precise design and innovative technologies, astronauts can safely return from space to Earth. This series of complex operations also demonstrates the magnificence and challenges of space exploration.
In the future, as technology continues to advance, the return process for astronauts will become safer and more convenient, and humanity's exploration of space will reach new heights.
