A document in the form of lecture slides outlines a program of development of capabilities for acquisition of signals, tracking of signal sources, and pointing of transmitters and receivers in deep-space optical communications. Topics addressed on the first few slides include the benefits and challenges of optical communications and the historical and organizational background of continuing development efforts. Most of the remaining slides address selected technical aspects of acquisition, tracking and pointing (ATP) in various levels of detail; these aspects include basic principles of operation, beam-pointing requirements, sources of tracking and pointing errors, alternative approaches to tracking and pointing, concepts for the design and operation of ATP systems, and key technological developments that are necessary for attaining required levels of ATP performance. The last slide summarizes the major technical challenges; these include the difficulty of pointing the necessarily narrow transmitted laser beams, the need to suppress spacecraft vibrations in beam-pointing equipment, the need for bright beacons, and interference by scattered sunlight.
This work was done by Shinhak Lee, James W. Alexander, and Gerardo G. Ortiz of Caltech for NASA's Jet Propulsion Laboratory. To obtain a copy of the document, "Deep Space Acquisition, Tracking, Pointing (ATP) Technologies for Optical Communication," access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Electronics & Computers category.
NPO-20889
This Brief includes a Technical Support Package (TSP).
Acquisition, Tracking, and Pointing in Optical Communication
(reference NPO-20889) is currently available for download from the TSP library.
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Overview
The document outlines a program focused on the development of capabilities for acquisition, tracking, and pointing (ATP) in deep-space optical communications. It begins by discussing the benefits of optical communications, such as higher data rates and improved signal quality, alongside the challenges that come with it. The historical and organizational background of ongoing development efforts is also presented, providing context for the current advancements in the field.
Key technical aspects of ATP are explored in detail, including the basic principles of operation, beam-pointing requirements, and the various sources of tracking and pointing errors. The document emphasizes the importance of precise beam pointing, particularly due to the narrow laser transmit beam used in optical communications, which presents significant technical challenges. One of the primary issues highlighted is the impact of spacecraft vibrations, which are identified as the dominant source of beam mispointing. To mitigate this, the document suggests the necessity of bright beacon signals, which can include uplink signals from Earth, the Moon, or stars, to maintain the receiver's position within a few micro-radians despite the vibrations.
Additionally, the document addresses the interference caused by scattered sunlight, which poses a major consideration for dim beacon signals. Various strategies for ATP are proposed to effectively tackle these challenges, ensuring successful deep-space optical communication.
The work presented in the document was conducted by researchers Shinhak Lee, James W. Alexander, and Gerardo G. Ortiz at the California Institute of Technology for NASA’s Jet Propulsion Laboratory. The document serves as a technical disclosure, outlining the novelty of the work, the problems it addresses, and the solutions proposed. It emphasizes the need for continued research and development in the field to achieve the required levels of ATP performance necessary for future deep-space missions.
In summary, the document provides a comprehensive overview of the technical challenges and solutions related to acquisition, tracking, and pointing in optical communications, highlighting the critical role of advanced technologies in overcoming these obstacles for successful deep-space exploration.
