A spacecraft guidance, navigation, and control (GN&C) system is needed to enable a spacecraft to descend to a surface, take a sample using a touch-and-go (TAG) sampling approach, and then safely ascend. At the time of this reporting, a flyable GN&C system that can accomplish these goals is beyond state of the art. This article describes AutoGNC, which is a GN&C system capable of addressing these goals, which has recently been developed and demonstrated to a maturity TRL-5-plus.
The AutoGNC solution matures and integrates two previously existing JPL capabilities into a single unified GN&C system. The two capabilities are AutoNAV and G-REX. AutoNAV is JPL’s current flight navigation system, and is fairly mature with respect to flybys and rendezvous with small bodies, but is lacking capability for close surface proximity operations, sampling, and contact. G-REX is a suite of low-TRL algorithms and capabilities that enables spacecraft operations in close surface proximity and for performing sampling/contact. The development and integration of AutoNAV and G-REX components into AutoGNC provides a single, unified GN&C capability for addressing the autonomy, close-proximity, and sampling/contact aspects of small-body sample return missions.
AutoGNC is an integrated capability comprising elements that were developed separately. The main algorithms and component capabilities that have been matured and integrated are autonomy for near-surface operations, terrain-relative navigation (TRN), real-time image-based feedback guidance and control, and six degrees of freedom (6DOF) control of the TAG sampling event.
Autonomy is achieved based on an AutoGNC Executive written in Virtual Machine Language (VML) incorporating high-level control, data management, and fault protection. In descending to the surface, the AutoGNC system uses camera images to determine its position and velocity relative to the terrain. This capability for TRN leverages native capabilities of the original AutoNAV system, but required advancements that integrate the separate capabilities for shape modeling, state estimation, image rendering, defining a database of onboard maps, and performing real-time landmark recognition against the stored maps.
The ability to use images to guide the spacecraft requires the capability for image-based feedback control. In AutoGNC, navigation estimates are fed into an onboard guidance and control system that keeps the spacecraft guided along a desired path, as it descends towards its targeted landing or sampling site. Once near the site, AutoGNC achieves a prescribed guidance condition for TAG sampling (position/orientation, velocity), and a prescribed force profile on the sampling end-effector. A dedicated 6DOF TAG control then implements the ascent burn while recovering from sampling disturbances and induced attitude rates. The control also minimizes structural interactions with flexible solar panels and disallows any part of the spacecraft from making contact with the ground (other than the intended end-effector).
This work was done by John M. Carson, Nickolaos Mastrodemos, David M. Myers, Behçet Açıkmeşe, James C. Blackmore, Dhemetrio Boussalis, Joseph E. Riedel, Simon Nolet, Johnny T. Chang, Milan Mandic, Laureano (Al) Cangahuala, Stephen B. Broschart, David S. Bayard, Andrew T. Vaughan, Tseng-Chan M. Wang, and Robert A. Werner of Caltech; Christopher A. Grasso of Blue Sun Enterprises; and Gaskell W. Robert of the Planetary Science Institute for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Information Sciences category.
The software used in this innovation is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at
This Brief includes a Technical Support Package (TSP).
Autonomous GN&C for Spacecraft Exploration of Comets and Asteroids
(reference NPO-47250) is currently available for download from the TSP library.
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Overview
The document is an internal report from the Jet Propulsion Laboratory (JPL) summarizing the accomplishments of the Fiscal Year 2009 (FY’09) Integrated Autonomous Guidance, Navigation, and Control (GN&C) for Comet Sample Return Research and Technology Development Task. The report, authored by David S. Bayard, outlines the progress made in developing autonomous systems for spacecraft tasked with exploring and returning samples from comets.
The report begins with an introduction that sets the context for the research, emphasizing the importance of autonomous GN&C systems in enhancing the capabilities of spacecraft during complex missions. It identifies key personnel involved in the project, including the Principal Investigator, Strategic Initiative Leader, and Steering Committee Leader, along with a list of co-investigators and technology contributors.
The document is structured into several sections, including objectives, background, relevance, and approach. It details the specific accomplishments achieved during the year, particularly in the development of the AutoGNC (Autonomous Guidance, Navigation, and Control) capabilities. This includes the establishment of a high-fidelity computer simulation testbed that allows for rigorous testing and validation of GN&C algorithms and systems.
Key technological advancements highlighted in the report include the development of a GN&C architecture tailored for small body exploration, surface modeling techniques to support proximity operations, and various simulation tools designed to enhance mission planning and execution. The report also discusses the validation of performance milestones and the significance of the results obtained from these developments.
Additionally, the document outlines the significance of the research in the broader context of space exploration, emphasizing how these advancements can lead to improved mission success rates and the ability to conduct more complex operations in challenging environments.
The report concludes with acknowledgments and a list of publications related to the research, providing a comprehensive overview of the work conducted under the FY’09 task. Overall, the document serves as a detailed account of the progress made in autonomous GN&C technologies, showcasing JPL's commitment to advancing space exploration capabilities through innovative research and development.
