Reentry is a critical phase of a spacecraft or a missile's mission, where it enters the Earth's atmosphere after being in space. During this phase, the spacecraft or missile experiences extreme heat, aerodynamic pressure, and other environmental factors that could cause structural damage or other issues. The objective of reentry is to safely land the spacecraft or missile at a predetermined location on the Earth's surface.
One example of a reentry vehicle is the Space Shuttle, which had a heat shield that protected the vehicle from the high temperatures generated during reentry. Another example is the Apollo spacecraft, which used a blunt-body shape to create a shockwave in front of the vehicle, which helped to dissipate the heat generated during reentry.
Similar to reentry is the concept of atmospheric entry, which refers to the process of a spacecraft or missile entering a planetary atmosphere from space. For example, the Mars Curiosity rover underwent an atmospheric entry before landing on the surface of Mars. During this phase, the rover used a heat shield to protect itself from the heat generated by atmospheric friction.
Another related concept is hypersonic flight, which refers to flight at speeds greater than five times the speed of sound. Hypersonic flight presents unique challenges for reentry vehicles, as they must be designed to withstand high temperatures and pressures generated at these speeds.
In addition to spacecraft and missiles, reentry is also an important concept in the context of space debris. When a satellite or other space object reaches the end of its operational life, it may be intentionally deorbited to burn up during reentry. This is done to prevent the object from becoming space debris that could pose a risk to other spacecraft in orbit.
Overall, reentry is a critical phase of a spacecraft or missile's mission, and it requires careful design and planning to ensure a safe and successful landing. With the growing number of missions to space, reentry and atmospheric entry will continue to be important areas of research and development in the aerospace industry.