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Closed Loop Guidance Trade Study for Space Launch System Block-1B VehicleNASA is currently building the Space Launch System (SLS) Block-1 launch vehicle for the Exploration Mission 1 (EM-1) test flight. The design of the next evolution of SLS, Block-1B, is well underway. The Block-1B vehicle is more capable overall than Block-1; however, the relatively low thrust-to-weight ratio of the Exploration Upper Stage (EUS) presents a challenge to the Powered Explicit Guidance (PEG) algorithm used by Block-1. To handle the long burn durations (on the order of 1000 seconds) of EUS missions, two algorithms were examined. An alternative algorithm, OPGUID, was introduced, while modifications were made to PEG. A trade study was conducted to select the guidance algorithm for future SLS vehicles. The chosen algorithm needs to support a wide variety of mission operations: ascent burns to LEO, apogee raise burns, trans-lunar injection burns, hyperbolic Earth departure burns, and contingency disposal burns using the Reaction Control System (RCS). Additionally, the algorithm must be able to respond to a single engine failure scenario. Each algorithm was scored based on pre-selected criteria, including insertion accuracy, algorithmic complexity and robustness, extensibility for potential future missions, and flight heritage. Monte Carlo analysis was used to select the final algorithm. This paper covers the design criteria, approach, and results of this trade study, showing impacts and considerations when adapting launch vehicle guidance algorithms to a broader breadth of in-space operations.
Document ID
Acquisition Source
Marshall Space Flight Center
Document Type
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)
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
Meeting Information
Meeting: Guidance 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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