Booster Touchdown on a Heaving Ocean Platform: Navigating the Challenges of Propulsive Recovery

The Dynamics of Wave Heave

Wave heave is a critical factor in the touchdown dynamics of a booster landing on an ocean platform. It refers to the vertical motion of the platform due to wave action, which can significantly affect the stability and safety of the landing process. The amplitude of this heave can vary widely depending on the sea state, with some platforms experiencing up to 2.4 meters of vertical displacement.

To mitigate these effects, engineers must carefully calculate the optimal ignition height and throttle settings, ensuring that the booster's touchdown speed and tilt are within safe limits despite the platform’s motion.

Leg Crush Limits and Tip-Over Risks

During landing, the legs of a rocket booster must withstand significant forces to ensure stability. The leg crush limit is the maximum compression that each leg can endure without failing. This limit is crucial because exceeding it could result in structural damage or even total failure of the landing attempt.

Additionally, tip-over margins are critical for ensuring that the booster does not topple over during touchdown. With a 2 m/s and 5 degree safety margin, any deviation from these limits can lead to an unsuccessful landing.

Throttle Control and Hovering

The throttle control is essential for managing the booster's descent speed and ensuring it lands safely. However, a 40% throttle floor restricts the ability to hover, making precise touchdown maneuvers challenging. This constraint forces operators to carefully balance the trade-offs between descent rate and stability.

Guidance systems can help optimize these parameters but require accurate modeling of both the booster's dynamics and the platform’s heave.

Sea-State Experiments and Burn Height Validation

Simulations like this one allow for detailed experimentation with different sea states, providing valuable insights into how varying wave conditions affect landing success. By comparing closed-form burn heights to integrated trajectories, engineers can refine their models and improve the reliability of propulsive recovery systems.

These simulations are not only educational but also serve as a practical tool for validating theoretical predictions against real-world scenarios.

Frequently asked questions

Try it live

Everything above runs in your browser — open Booster Touchdown on a Heaving Ocean Platform: Wave Heave, Leg Crush and Tip-Over Limits and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.