Why Isn't NASA Using SLS More Despite Its Power?

One of the most intriguing topics in aerospace engineering is the usage and benefits of the Space Launch System (SLS). Designed to be a powerful and versatile launch vehicle, SLS has garnered significant attention due to its impressive capabilities. However, despite its potential, NASA opts to employ alternatives like SpaceX's Falcon 9 or Starship. This article delves into the reasons behind NASA's hesitations and the advantages of other launch vehicles, with a focus on cost, launch frequency, and payload size considerations.

Introduction to the Space Launch System

The Space Launch System (SLS) is a heavy-lift launch vehicle developed by NASA, intended for missions with high payload requirements, particularly for deep space exploration. It was designed to replace the Space Shuttle and to provide a more powerful and reliable option for launching astronauts and cargo to the International Space Station and other distant locations.

Cost Implications

Despite its capacity and mission-critical nature, the SLS is a significantly more expensive launch vehicle compared to its commercial counterparts. An estimated cost of $4.1 billion per launch is a stark contrast to the more economical options such as SpaceX's Falcon 9, which is projected to cost around $60 million per launch, and SpaceX's Starship, expected to be priced at around $100 million per launch.

These cost differences can be attributed to several factors:

Design Complexity: SLS is designed for heavy payloads and missions that require a high level of reliability. The complexity of the vehicle, including its two RS-25 engines and solid rocket boosters, contributes significantly to the development and operational costs. Operation and Maintenance: The SLS requires specialized infrastructure and manpower for its operations, including launch pads, systems for cryogenic storage, and extensive ground support equipment. These resources and the associated costs are much higher than those required for the Falcon 9 or Starship. Research and Development: As a government-funded project, NASA invests heavily in research and development, including testing, simulation, and other preparatory work. This further adds to the overall cost of each launch.

Launch Frequency and Cadence

NASA's plans for SLS launches are somewhat limited compared to commercial providers like SpaceX. The space agency has a respective plan of around one SLS launch per year. In contrast, SpaceX has demonstrated a remarkable success rate, managing to execute 40 launches as of early 2023. This significant disparity in launch frequency can be attributed to several factors:

Complexity and Testing: Given the size and complexity of the SLS, each launch requires extensive testing and certification, which can take extensive periods of time. SpaceX, on the other hand, operates with a more streamlined process, allowing for a higher volume of launches in a shorter period. SpaceX's Exploitation Model: SpaceX has built a robust supply chain and operational model that allows for rapid turnaround between launches. Its reusable rockets and modular design further enhance this efficiency, making it easier to respond to mission demands. Commercial Demand: SpaceX has established a thriving market, both for government and commercial clients, which supports a higher launch frequency. The company's focus on meeting client needs and delivering missions on time has driven its success.

Payload Size and Adaptability

Another critical factor in the choice of launch vehicles is payload size and adaptability to different mission requirements. The SLS, with its massive size, is particularly suited for launching heavy payloads. However, this also means it has certain limitations:

Size and Flexibility: The sheer size of the SLS can be an obstacle when it comes to flexibility. For example, attempting to fit a small payload into a vehicle designed for heavier loads is inefficient and wasteful. This is where smaller rockets like the Falcon 9 and Starship come into play. These rockets are more adaptable, capable of launching a wide range of payloads, including small satellites, cubesats, and even small scientific instruments.

Commercial Demand and Efficiency: Smaller payloads do not necessarily require the larger capacity of SLS. The Falcon 9 and Starship, with their more agile approach, can better meet the needs of various missions. For instance, a satellite with a mass of just a few hundred kilograms can be efficiently launched using a Falcon 9, resulting in a lower cost and more frequent launch opportunities.

SLS’s Current Operational Status

The Space Launch System (SLS) has been hailed as a game-changer in aerospace engineering due to its impressive capabilities. However, with its first few test flights behind us, it is evident that SLS still has a long way to go before becoming a regular launch provider. As of now, the SLS has not yet achieved a successful operational launch, and its journey towards becoming a reliable and efficient launch vehicle is fraught with challenges.

The primary hurdle limiting the operational use of SLS is its extensive testing phase. Every mission requires rigorous testing and validation of critical components, including engines, cryogenic tanks, and guidance systems. This exhaustive testing ensures the safety and reliability of the vehicle but also prolongs the time between launches. In contrast, SpaceX has streamlined its testing procedures, making launches more frequent and reducing the time needed for each mission.

Moreover, the development and operational costs of SLS are substantially higher than those of commercial alternatives. While SLS represents cutting-edge technology with unparalleled capabilities, it is not feasible to operate as a standard launch service provider due to the budgetary constraints and high operational expenses. SpaceX, with its reusable rockets and modular design, has demonstrated a more streamlined and cost-effective approach to spaceflight, allowing for more frequent and reliable launches while maintaining a competitive cost structure.

Conclusion

The decision by NASA to limit the use of SLS in favor of other, more cost-effective launch vehicles is a strategic choice borne out of financial and operational considerations. While SLS offers unique advantages for certain missions, its high costs, infrequent launches, and payload size limitations make it less attractive for a broad range of applications. The success of commercial providers like SpaceX highlights the importance of adaptability and cost efficiency in the space industry, paving the way for more frequent and accessible space missions.

Key Takeaways

The Space Launch System (SLS) is a powerful but expensive launch vehicle. Commercial providers like SpaceX offer more frequent and cost-effective launch options. SLS's size and complexity limit its adaptability for smaller payloads. NASA's limited SLS launch frequency reflects its focus on highly specialized missions.

References

[1] NASA's Space Launch System (SLS) -

[2] SpaceX Falcon 9 -

[3] SpaceX Starship -