Why Does an Expendable Falcon 9 Still Have Grid Fins?

The Falcon 9 rocket, once consistently known for its reusability, has recently faced a shift in strategy. In the space of a single engine launch, we've seen the difference between reusability and expendability, raising questions about the purpose of equipment like grid fins on expendable rockets. This article explores the reasoning behind the incorporation of grid fins on expendable Falcon 9s and delves into the broader implications of SpaceX's current stance.

The Current State of Falcon 9 Rockets

Current iterations of the Falcon 9, such as those employed in missions like the launch of PAZ, are made of aluminum and are unlikely to grace future expendable launches. Aluminum is chosen due to its lightness and malleability, both of which are advantageous for experimental purposes and reusability.

Despite this shift towards aluminum, the reasoning behind the continued use of grid fins becomes the focal point of our discussion. These fins are crucial for precise maneuvering and orientation during the controlled descent and landing of a rocket. Traditionally, grid fins have been a hallmark of SpaceX's reusability plans, aiding in the precise control required for touchdown back on Earth.

Grid Fins and Landing Control

Grid fins play a critical role in ensuring the rocket can be accurately controlled as it re-enters the atmosphere. These fins are typically used during atmospheric deceleration, providing the necessary lift and control to ensure a smooth and safe return to the landing site. The aluminum grid fins, while not used in future missions, serve as a key component in the experimental and testing phase of rocketry.

Even in cases where the rocket is not intended for recovery, such as in recent launches, these fins can be employed for more aggressive re-entry profiles. This experimentation with more aggressive re-entry and landing burns allows SpaceX to gather critical data and refine their re-entry and landing strategies, ultimately enhancing the overall performance and safety of their rockets.

SpaceX's Experimentation and Test Flights

As evidenced by the recent GovSat-1/SES-16 launch, SpaceX has shown a willingness to push the boundaries of what’s possible, even in expendable missions. The profile attempted by SpaceX in this particular launch demonstrated the feasibility of more aggressive re-entry and landing techniques without compromising the primary mission. The booster's survival suggests that SpaceX will continue to experiment with these methods, either repeating similar tests or even going further.

SpaceX's commitment to continuous experimentation aligns with their overarching goals of reducing costs and improving reliability. Even if these fins cannot be used extensively in future missions, they continue to serve a valuable purpose in the development and refinement of rocket technology.

Current Disablement of Grid Fins

Existing stocks of aluminum grid fins are either deemed unsuitable for the Block V and later iterations of the Falcon 9 or are determined to have a disadvantage when used with them. This decision reflects SpaceX's strategic focus on the most efficient and effective use of their resources. The shift towards aluminum fins in these later iterations indicates a move away from the more complex and potentially less efficient traditional grid fins.

By disabling the use of grid fins in newer rockets, SpaceX is creating space for the next iteration of the Falcon 9, which can be reused more quickly and efficiently. The current expendable missions, like the PAZ mission, are transitional in nature, serving as opportunities for testing and learning before moving entirely to reusability.

In conclusion, the inclusion of grid fins on expendable Falcon 9s, though no longer a requirement for the future, serves a vital purpose in ongoing experimentation and the refinement of re-entry and landing strategies. This practice underscores SpaceX's commitment to innovation and the continuous improvement of their remarkable rocket technology.