Martin J. Steele

Generic simulation models of reusable launch vehicles

Analyzing systems by means of simulation is necessarily a time consuming process. This becomes even more pronounced when models of multiple systems must be compared. In general, and even more so in todays fast-paced environment, competitive pressure does not allow for waiting on the results of a lengthy analysis. That competitive pressure also makes it more imperative that the processing performance of systems be seriously considered in the system design. Having a generic model allows one model to be applied to multiple systems in a given domain and provides a feedback mechanism to systems designers as to the operational impact of design decisions.

Credibility Assessment of Models and Simulations Based on NASA's Models and Simulation Standard Using the Delphi Method

This paper introduces a procedure to assess the credibility of models and simulations M&S as a group activity based on NASAs new standard for M&S NASA-STD-7009. The Delphi method, which is characterized by iterative surveys with controlled feedback, was selected to implement the assessment. The proposed procedure is expected to address the issues in the M&S assessment related to a high level of required expertise and group decision making. An actual credibility assessment study using the proposed procedure on an M&S platform referred to as SpaceNet has been carried out by ten panel members through a two-round Delphi. The study concluded that the overall credibility of SpaceNet version 1.3 was between the development level and production level. The variances of the assessments in the second-round survey were significantly reduced compared with the first-round results, which indicates the effectiveness of the proposed procedure.

A generic environment for modelling future launch operations—GEM-FLO: a success story in generic modelling

Several NASA programs have been established to study and improve the current launch capability to meet the need for more aggressive space exploration in the future. Numerous launch systems have been proposed by different government and commercial organizations with the potential goal of replacing the Space Shuttle. NASA must evaluate new designs and technologies with the objective of improving upon todays Shuttle cost, performance, and turnaround time, before the government or commercial organizations pursue the large undertaking of a new launch system. To address this issue, the Generic Simulation Environment for Modelling Future Launch Operations (GEM-FLO) was developed to accurately predict processing turnaround times and other effectiveness criteria and support making key business and program decisions. GEM-FLO utilizes a generic modelling paradigm to provide a single platform for modelling different designs, which helped significantly cut the cost of these studies. This paper documents a success story in generic simulation modelling.

Simulation, modeling and analysis of Space Shuttle flight hardware processing

This paper describes key aspects of the history of the space shuttles flight rate and the uses of simulation for estimating and assessing flight rate. When initially proposed, the shuttle was to fly 50 to 150 times per year. The earliest simulation models supported these projects but were based upon faulty assumptions. As the shuttle has evolved so have simulation models. Todays simulation accurately models the shuttles flight rate of approximately 7 per year and is benefiting both the current shuttle and future shuttle replacement vehicles being considered by NASA.

An integrated estimation and modeling environment for the design of the orbital space plane

The development of simulation models can be time consuming and highly dependant on system data being widely available. When using simulation modeling to analyze future systems, system data may not be available for the system under study and simulation results are often needed within a short time frame to support early system design efforts. This paper presents a parametric estimation/generic simulation integrated environment developed to facilitate the rapid development of valid simulation models for the Orbital Space Vehicle ground processing operations.

NASA Constellation Program End-to-End Discrete Event Simulation System Analysis

In support of NASA’s programs, engineers are enhancing their analysis capability of an increasingly complex network of materials, people, and information, which spans from sources on Earth to destinations in space (International Space Station, the Moon, and beyond). NASA is utilizing new decision support tools and techniques to assess operational and cost performance, in addition to supportability and affordability, of the program for many years to come. Discrete event simulation (DES) is one of these tools being used. With this tool a computer model representing the system under study is first developed and verified. The model is then populated with authoritative (planning and historically analogous) data, validated, and executed over a long time span. Once executed, the simulation model generates results for a set of pre-defined metrics that convey the system’s end-to-end (from manufacturing and assembly to ground and launch operations to flight and return mission phases) performance over time. The analysis of a variety of alternative program level scenarios highlights underperforming and overly utilized areas and bottlenecks, which enables the analyst to make decisions on how improvements can be made to the system. The purpose of this paper is to present results of a DES model developed to help the NASA Constellation Program conduct analysis pertaining to the Ares I/Orion vehicle conducting ISS Missions. The model is scoped from first tier suppliers all the way to the space mission and the return of Orion and Ares I’s Solid Rocket Booster, as well as the refurbishment of reusable components. The output of the model includes cycle times, throughputs, launch rates, inventory behavior, delays, maintenance, and rollbacks. The model was developed with a commercial discrete event simulation software application and an easy to use graphical user interface for input and scenario management.

Educating middle and high school students in space operations: the simulation approach

This paper describes a proposed pilot educational program to teach middle and high school students the space shuttle processing operations. This pilot program involves a partnership of two Universities (University of Central Florida and University of Florida), a small business (Productivity Apex), and three middle/high schools in the Florida area. Our proposed pilot program is an innovative approach designed to teach students about the complexities of space vehicle processing through a simulation environment. Through the many planned activities that we propose to achieve our goal, we will be able to introduce middle and high school students to aerospace operations, excite them about space education, and enthusiastically engage them in science and technology related projects. The ultimate objective of this effort is to motivate middle and high school students to pursue careers in science, technology, engineering, and math (STEM) fields.