Engineering topics

Sean Downs

Publications and source records attributed to Sean Downs.

3 records

NASA NTRS2023

Backup Optical Navigation Attitude for Artemis-1 Backup Attitude Ground Tool

The Backup Optical Navigation Attitude (BONA) software was developed as a response to the Artemis1 Power Distribution Unit (PDU) hardware problems found early in 2021. The hardware problem, a capacitor installed incorrectly, removes the intended redundant path for which the PDU can relay its power and data to attached devices. Specific to the BONA context, the concern is that a failure of the single remaining path in this PDU would lead to an inability to communicate with one of the two-star trackers (STs) on Orion. By flight rule, being reduced to a single star tracker means an immediate turn around end-of-mission. The BONA software is not intended to extend the mission, but instead act as a single star tracker attitude confirmation tool. Insurance, if you will, for the Orion project that a ground tool is available to compare the single remaining ST results with optical navigation images retrieved during the mission. Engineers operating BONA in the Mission Control Center (MCC) Mission Evaluation Room (MER) will analyze the downlinked star field images and based on the stars identified and known time of image, derive vehicle attitude estimates, which can be compared with the ST results. Potentially, in extreme situations, and with expert recommendation, the derivations could lead to navigation state updates being commanded to Orion.

GNC↗

NASA NTRSDate not supplied

Value Proposition, Strategic Framework, and Capability Needs for In-Space Assembly

The Space Science and Technology (S&T) Partnership Forum was established in 2015 to identify synergistic efforts and technologies across the government, with a focus on key pervasive and game-changing technologies across government space agencies in order to more efficiently and effectively manage S&T resources. As principal partners of the interagency S&T Partnership Forum, the U.S. Air Force (USAF), the National Aeronautics and Space Administration (NASA), and the National Reconnaissance Office (NRO) identified and prioritized several S&T collaboration topic areas. Autonomous and semi-autonomous in-space assembly (iSA) is the focus of the topic area that NASA, under the direction of the Office of Chief Technologist, is currently coordinating among the S&T principal partners and affiliate partners, such as the Defense Advanced Research Projects Agency (DARPA) and the U.S. Naval Research Laboratory (NRL). The S&T iSA facilitation and analysis team, led by NASA, collected data from the participating agencies on their current developments, activities, and needs in the area of in-space assembly. This paper provides an overview of the S&T iSA facilitation and analysis team’s efforts in establishing the value proposition and strategic framework for interagency collaboration in iSA within the partnership as a foundation to deliver value and achieve iSA topic objectives across government space agencies. Further, this paper describes the early products of these efforts in the definition of the iSA capabilities, design drivers, and stakeholder goals to facilitate dialogue within the partnership and the larger community.

Phillip A Williams↗

NASA NTRSDate not supplied

Entry, Descent, and Landing GN&C System Evaluation via Cable-Driven Emulation Robotics

An innovative cable-driven parallel robot named the Six Degree-of-Freedom Tendon Actu- ated Robot (STAR), recently developed by researchers at NASA Johnson Space Center, was built to enable entry, descent, and landing (EDL) emulation experiments. Upon functional testing and system verification, STAR employed several simulated EDL trajectories to validate velocimeter LIDAR-based sensor models for cooperative terrain relative navigation applica- tions for its first testing campaign. The STAR lab also hosted researchers from Astrobotic to evaluate the real-time performance of a newly developed sensor payload, UltraNav, through hardware in-the-loop-testing (HWIL). This work introduces the STAR system along with its accompanying testing utilities and capabilities, and deliver the experimental methodology and results of test campaigns performed with the STAR facility to date.

navigation↗