Gaspare Maggio

A Methodology to Rapidly and Effectively Assess the Reliability of Conceptual Advanced Rocket Engines

A methodology for the rapid reliability anal ysis of conceptual engines has been developed using available failure data. The method uses similarity analysis to characterize the effect of new components in the conceptual engines, to the two main failure end states of liquid rocket engines: Instantaneo us Catastrophic Failure (ICF), or rapid disassembly, and Non -explosive Benign Failure (NBF) or safe shutdown . Using analysis of similar conceptual advanced engine technologies affects on reliability the component risks are adjusted and aggregated to estim ate a top -level risk for a conceptual engine. In addition, the effect s of engine size variation and operational parameters on reliability are estimated .

An examination of emerging in-space propulsion concepts for one-year crewed mars missions

A study was completed that provides a meaningful, even-handed, comparison assessment of promising candidate, in-space, exploration propulsion concepts to support emerging “near-term” crewed Mars mission applications. In particular, the study examined the mission performance feasibility and risk of a number of near-, mid-, and far-term in-space propulsion concepts to support crewed Mars missions starting in 2018 that can have the crewed portion of the mission performed in one year or less. This study used exploration propulsion system team technology specialist advocates to identify seven meaningful, representative mission architecture scenarios to “best” demonstrate the capability of such in-space propulsion technology options to support the near-term crewed Mars mission requirement. Additionally, a common set of top-level mission/system requirements was established for the study, which was incorporated in the assessment of all the mission options considered. Mission performance for abundant chemical (Ab-...

Combining computational-simulations with probabilistic-risk-assessment techniques to analyze launch vehicles

To assess the overall cost of a launch system the potential losses which may be incurred due to catastrophic failure should also be considered along with the manufacturing and operational costs. The potential for catastrophic failure may be determined by performing a probabilistic risk assessment. Launch vehicles operate under highly transient conditions. In addition, the complex nature of launch systems makes the task of determining the probability of failure responses and consequences, with any reasonable certainty, practically impossible. Launch vehicle dynamics may be studied by the use of computational methods, offering a solution for assessing failure responses. However, the deterministic nature of these methods makes their use incompatible with probabilistic risk assessment. This paper discusses a solution to this dilemma. A semi-deterministic methodology is proposed which combines these two technologies, computational simulation and probabilistic risk assessment, in a synergistic fashion. A matrix based interfacing mechanism was developed which allows information to be transferred from one analysis structure to the other. Although software may be developed to facilitate the transfer process, the methodology may be applied without having to modify any of the existing resources. As computer-based designing and testing becomes the rule and not the exception, this method may offer engineers the capability to integrate risk considerations directly into the design process. Assessing risk during the design phase has the potential of substantially reducing safety related maintenance costs.

Space shuttle operational risk assessment

A Probabilistic Risk Assessment (PRA) of the Space Shuttle system has recently been completed. This year‐long effort represents a development resulting from seven years of application of risk technology to the Space Shuttle. These applications were initiated by NASA shortly after the Challenger accident as recommended by the Rogers and Slay Commission reports. The current effort is the first integrated quantitative assessment of the risk of the loss of the shuttle vehicle from 3 seconds prior to liftoff to wheel‐stop at mission end. The study which was conducted under the direction of NASA’s Shuttle Safety and Mission Assurance office at Johnson Spaceflight Center focused on shuttle operational risk but included consideration of all the shuttle flight and test history since the beginning of the program through Mission 67 in July of 1994.

Ensuring an Effective, Safe, Reliable, and Affordable Architecture for Earth to Lunar Space Transportation

This paper discusses the type of architecture attributes that should provide a safe, reliable, and affordable means of supporting a future lunar base. Architecture attributes discussed in the paper include launch vehicle selection, advanced technologies, modularity & commonality, redundancy, reusability, failure mitigation and recovery strategies, and the selection of architecture nodes. The conclusions presented in this paper are the result of studies the authors have undertaken in analyzing historical data from the Apollo program, the Space Shuttle program, and the International Space Station program, and utilizing these data as a foundation for the analysis of conceptual launch vehicles and spacecraft for various NASA conceptual design programs such as the NGLT, OSP and CE&R programs. The results of these studies have shown that there are benefits and disadvantages to depending on expendable or long-life multi-use systems for space operations. Safety and reliability of the architecture elements is dependent on proper maintenance and management principles which have a significant impact on the cost of operations. By properly assessing the risk profile of a lunar transport mission and minimizing the exposure to that risk by building in the required redundancy and maintenance capability, it is believed that a lunar base may be sustained at a reasonable cost. In turn, by minimizing risk fewer rigors will be required to maintain acceptable levels of safety and reliability. Additionally, by selecting the lifetime and level of redundancy of each element in accordance with the expected criticality and utility of each element within the mission, the elements may be maintained or produced such that the operations cost are minimized.

Physics Based Risk Assessment of Launch Vehicles

To provide NASA with the most comprehensive and sophisticated launch vehicle risk modeling system possible, a physics-based approach that models dynamic failure processes using systems and environmental variables has been developed and implemented in a collaborative engineering environment. The methodology is an extension of, and a departure from conventional, well-known techniques used to evaluate risk in complicated systems, such as fault-tree and event-tree analysis. This approach has been used to analyze the main risk drivers for NASA’s Next Generation Launch Technology program launch vehicles. This paper describes how this methodology is used to assess launch vehicle risks with examples from the thermal protection and main propulsion system.