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Powered Explicit Guidance Modifications and Enhancements for Space Launch System Block-1 and Block-1B VehiclesNASA is currently building the Space Launch System (SLS) Block-1 launch vehicle for the Exploration Mission 1 (EM-1) test flight. NASA is also currently designing the next evolution of SLS, the Block-1B. The Block-1 and Block-1B vehicles will use the Powered Explicit Guidance (PEG) algorithm (of Space Shuttle heritage) for closed loop guidance. To accommodate vehicle capabilities and design for future evolutions of SLS, modifications were made to PEG for Block-1 to handle multi-phase burns, provide PEG updated propulsion information, and react to a core stage engine out. In addition, due to the relatively low thrust-to-weight ratio of the Exploration Upper Stage (EUS) and EUS carrying out Lunar Vicinity and Earth Escape missions, certain enhancements to the Block-1 PEG algorithm are needed to perform Block-1B missions to account for long burn arcs and target translunar and hyperbolic orbits. This paper describes the design and implementation of modifications to the Block-1 PEG algorithm as compared to Space Shuttle. Furthermore, this paper illustrates challenges posed by the Block-1B vehicle and the required PEG enhancements. These improvements make PEG capable for use on the SLS Block-1B vehicle as part of the Guidance, Navigation, and Control (GN&C) System.
Document ID
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Von der Porten, Paul
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Ahmad, Naeem
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Hawkins, Matt
(Jacobs Engineering and Science Services and Skills Augmentation Group (ESSSA) Huntsville, AL, United States)
Fill, Thomas
(Draper (Charles Stark) Lab., Inc. Cambridge, MA, United States)
Date Acquired
March 22, 2018
Publication Date
February 2, 2018
Subject Category
Spacecraft Design, Testing And Performance
Launch Vehicles And Launch Operations
Report/Patent Number
AAS Paper 18-136
Meeting Information
Meeting: AAS GNC (Guidance, Navigation, and Control) Conference
Location: Breckenridge, CO
Country: United States
Start Date: February 2, 2018
End Date: February 7, 2018
Sponsors: American Astronautical Society
Distribution Limits
Public Use Permitted.
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