Skip Reentry
Author: Tianjiang Shuo
Website: https://cislunarspace.cn
Definition
Skip reentry refers to a reentry mode in which a spacecraft enters the atmosphere at a small reentry angle, uses lift to exit the atmosphere again, follows a ballistic arc, and then reenters the atmosphere. The spacecraft can pass through the atmosphere multiple times, utilizing the atmosphere for deceleration on each entry. Trajectories that, after initial atmospheric entry, do not exit the atmosphere again but exhibit large altitude variations due to lift are also classified as skip trajectories.
Core Elements
Trajectory Characteristics
The main differences between skip reentry trajectories and ballistic and lifting trajectories:
| Trajectory Type | Altitude Variation | Lift Utilization | Deceleration Method |
|---|---|---|---|
| Ballistic reentry | Monotonic descent | None or uncontrolled | Single-pass atmospheric deceleration |
| Lifting reentry | Gradual descent | Continuous utilization | Continuous atmospheric deceleration |
| Skip reentry | Large oscillations | Intermittent utilization | Multiple-pass atmospheric deceleration |
Physical Mechanism
Skip reentry uses lift to achieve periodic altitude variations:
- Enter the atmosphere at a small reentry angle, generating lift
- Lift pushes the spacecraft out of the atmosphere into a ballistic flight segment
- In the vacuum segment, no aerodynamic forces act; the spacecraft follows an elliptical arc
- Reenter the atmosphere and continue decelerating
- The process can repeat multiple times until the velocity drops to the desired value
Trajectory Altitude Oscillations
The altitude of a skip reentry trajectory exhibits large oscillations. During each atmospheric entry and exit:
- Atmospheric entry phase: Aerodynamic drag decelerates the vehicle, causing aerodynamic heating
- Extra-atmospheric phase: No aerodynamic forces; free flight along an elliptical arc
- Deceleration effects accumulate with each atmospheric pass
Comparison with Ballistic Reentry
| Comparison Item | Ballistic Reentry | Skip Reentry |
|---|---|---|
| Reentry angle | Can be relatively large | Must be relatively small |
| Deceleration process | Severe, completed in one pass | Gentle, distributed across multiple passes |
| Peak load factor | Higher | Lower |
| Range | Shorter | Longer |
| Landing precision | Lower | Adjustable via lift |
Application Value
Skip reentry is an important method for achieving gentle deceleration through the use of lift. By passing through the atmosphere multiple times, the total deceleration is distributed across several atmospheric passes, reducing the single-pass peak load factor and peak heat flux. This approach is suitable for hypersonic return missions requiring reduced reentry thermal loads and for high-speed reentry scenarios returning from the Moon or other planets.
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.