Why Space Launches Don’t Use Silos

Space launches and missile launches have key differences that influence the infrastructure where they take place. While missile launches often utilize missile silos, space launches typically occur from open-air launch pads or specialized indoor facilities. This article explores the reasons behind why space launches don’t use silos, focusing on the challenges and practical considerations involved.

The Role of Silos in Missile Launches

Silos are highly effective for missiles, especially those with solid rocket engines or hypergolic propellants. These types of missiles can be stored for long periods and are quickly deployable, which is crucial for military and strategic reasons. Solid rocket engines and hypergolic propellants are stable and can be safely stored without requiring complex temperature or pressure control.

The Challenges with Space Rockets

Space rockets, on the other hand, use cryogenic propellants such as liquid hydrogen, methane, or liquid oxygen. These propellants must be kept at extremely low temperatures and can only be stored for short periods before they lose their effectiveness. Unlike missile propellants, cryogenic fuels are highly volatile and require precise control of the launch environment.

Practical Considerations for Launch Silos

The physical size of space rockets is another critical factor. Rockets like the Falcon 9, which stands at approximately 70 meters tall, and the Super Heavy/Starship at 120 meters, are massive. These dimensions make it impractical to fit them into existing silos, which are typically much smaller. Even if a hole were dug to accommodate the rocket, the environmental challenges would be enormous.

The confined space within a silo would pose significant risks due to the high temperatures and pressure generated during launch. The exhaust plume and shockwaves could easily damage or destroy the structure, as evidenced by the SpaceX Super Heavy/Starship’s first integrated flight test, which resulted in a large crater due to lack of a water deluge system.

Economic and Logistical Feasibility

From a financial and logistical standpoint, building launch silos for space rockets would be highly expensive and challenging. The infrastructure required to maintain cryogenic propellants and the complex systems needed to control the launch environment would outweigh the benefits. Additionally, the geographical location of launch sites in Florida, which is close to sea level, makes it less feasible to build silos underground, as the cost and engineering complexity would be significant.

Alternative Solutions: Indoor and Flat Launch Pads

For certain launch scenarios, indoor facilities can offer some advantages. For example, the TEXUS 50 rocket launched from Esrange in Sweden, using a VSB-30 rocket. Indoor facilities provide a controlled environment that can minimize some of the launch risks and offer protection from weather conditions. However, these facilities are not universally applicable to all space launch operations.

For most civilian and military space launches, the use of open-air launch pads remains the preferred method. These launch sites offer the necessary flexibility and cost-effectiveness for launching complex and sensitive payloads into orbit. The inherent risks of silo-based launches, such as those associated with handling cryogenic propellants in confined spaces, make them impractical for modern space operations.

In conclusion, the challenges of accommodating cryogenic propellants, the immense size of modern rockets, and the logistical and economic impracticalities of building launch silos make them an unsuitable solution for space launches. Instead, open-air and indoor facilities offer the best balance of safety, cost-effectiveness, and practicality for the demanding world of space launches.