Reentry Phase
Author: Tianjiang Shuo
Website: https://cislunarspace.cn
Definition
The reentry phase is the flight stage of an aerospace vehicle from the deorbit maneuver until it returns to the ground (or lands in the target area). For vehicles already in orbit, a deorbit maneuver must be performed before reentry so that the post-braking trajectory intersects the Earth at the desired point. For ballistic missile warheads, the reentry phase connects naturally with the free-flight phase, with the two phases merely demarcated at an arbitrary altitude.
Core Elements
Reentry Characteristics of Different Vehicles
| Vehicle Type | Lift-to-Drag Ratio | Reentry Characteristics |
|---|---|---|
| Conventional warhead | Approx. 0 | No lift; rapid deceleration upon atmospheric entry with intense aerodynamic heating |
| Capsule return vehicle | Small | Partial lift via center-of-mass offset extends range and reduces load factor and heating |
| Glide warhead | Large | High lift-to-drag ratio enables large-scale maneuvering within the atmosphere with good penetration performance |
| Space shuttle | High | Can fly like an aircraft at the end of reentry for precision landing |
Aerodynamic Heating Effects
When a vehicle enters the atmosphere at high speed, the air ahead is strongly compressed, producing shock waves that cause the vehicle surface temperature to rise sharply. Aerodynamic heating is one of the most critical technical challenges of the reentry phase, requiring specialized thermal protection materials and structural design.
Reentry Corridor
The reentry corridor refers to the range of permissible parameters (such as reentry angle, reentry velocity, etc.) for a safe reentry. The corridor boundaries are determined by the following conditions:
- Normal load factor limit: Structural strength and human tolerance
- Dynamic pressure limit: Aerodynamic loads must not exceed structural limits
- Maximum heat flux limit: Heat flux density the thermal protection system can withstand
- Equilibrium glide boundary: Ensures the vehicle does not exit the atmosphere
Reentry Modes
- Ballistic reentry: No or minimal lift, follows a ballistic trajectory, high load factors, large impact point dispersion
- Ballistic-lifting reentry: Small lift generated via center-of-mass offset, allowing range and load factor adjustment
- Lifting reentry: High-lift-to-drag-ratio vehicles that can precisely control the impact point and achieve horizontal landing
Application Value
Reentry technology is a critical enabler for human spaceflight, missile systems, and deep-space return missions. The reentry equations of motion and trajectory calculations are important research areas in aerospace flight mechanics. Reentry corridor design and thermal protection system design are directly related to mission safety.
Related Concepts
References
- Zheng W, An X Y, Zhou X, He R Z. Aerospace Flight Mechanics[M]. National University of Defense Technology, 2026.
- Jia P R, Chen K J, et al. Long-Range Rocket Ballistics[M]. National University of Defense Technology Press.