What is the best way to design a heat shield for rocket reentry?

2 Factor 2: Reentry angle

Another factor that influences heat shield design is the angle of the vehicle's reentry path relative to the horizon. The angle determines how long the vehicle stays in the atmosphere, and how much drag and lift it experiences. A shallow angle means that the vehicle spends more time in the upper layers of the atmosphere, where the air is thin and the heating is mild. A steep angle means that the vehicle plunges quickly into the lower layers of the atmosphere, where the air is dense and the heating is intense. Engineers must balance the trade-offs between shallow and steep angles, and design a heat shield that can cope with the optimal angle for the vehicle's mission and safety.

3 Factor 3: Reentry mass

A third factor that affects heat shield design is the mass of the vehicle and its payload. The mass determines how much momentum and inertia the vehicle has, and how much force it exerts on the air. A heavier vehicle has more momentum and inertia, and creates more shock waves and compression heating than a lighter vehicle. A lighter vehicle has less momentum and inertia, and experiences more deceleration and convective heating than a heavier vehicle. Engineers must consider the mass and center of gravity of the vehicle and its payload, and design a heat shield that can distribute and manage the heat load across the vehicle's surface.

4 Type 1: Ablative heat shields

One of the most common types of heat shields used in aerospace engineering is the ablative heat shield, which is made of a material that gradually erodes or ablates as it heats up. The ablation process creates a layer of gas that insulates the vehicle from the hot air, and carries away some of the heat. Ablative heat shields are typically used for high-speed and high-mass reentry vehicles, such as the Apollo capsules, the Orion spacecraft, and the Mars rovers. Ablative heat shields are effective and reliable, but they are also heavy and disposable, and can create debris and contamination.

6 Type 3: Inflatable heat shields

A newer type of heat shield used in aerospace engineering is the inflatable heat shield, which is a flexible and deployable structure that inflates before reentry and deflates after landing. The inflatable heat shield creates a large and blunt shape that increases the drag and reduces the heating of the vehicle, and also provides cushioning and stability. Inflatable heat shields are suitable for low-density and high-altitude reentry vehicles, such as the IRVE and the HIAD. Inflatable heat shields are compact and adaptable, but they are also vulnerable and unproven, and need more testing and development.