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Crew-Aided Autonomous NavigationA sextant provides manual capability to perform star/planet-limb sightings and offers a cheap, simple, robust backup navigation source for exploration missions independent from the ground. Sextant sightings from spacecraft were first exercised in Gemini and flew as the lost-communication backup for all Apollo missions. This study characterized error sources of navigation-grade sextants for feasibility of taking star and planetary limb sightings from inside a spacecraft. A series of similar studies was performed in the early/mid-1960s in preparation for Apollo missions. This study modernized and updated those findings in addition to showing feasibility using Linear Covariance analysis techniques. The human eyeball is a remarkable piece of optical equipment and provides many advantages over camera-based systems, including dynamic range and detail resolution. This technique utilizes those advantages and provides important autonomy to the crew in the event of lost communication with the ground. It can also provide confidence and verification of low-TRL automated onboard systems. The technique is extremely flexible and is not dependent on any particular vehicle type. The investigation involved procuring navigation-grade sextants and characterizing their performance under a variety of conditions encountered in exploration missions. The JSC optical sensor lab and Orion mockup were the primary testing locations. For the accuracy assessment, a group of test subjects took sextant readings on calibrated targets while instrument/operator precision was measured. The study demonstrated repeatability of star/planet-limb sightings with bias and standard deviation around 10 arcseconds, then used high-fidelity simulations to verify those accuracy levels met the needs for targeting mid-course maneuvers in preparation for Earth reen.
Document ID
20150018601
Acquisition Source
Johnson Space Center
Document Type
Presentation
Authors
Holt, Greg N.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
October 1, 2015
Publication Date
October 21, 2015
Subject Category
Spacecraft Design, Testing And Performance
Report/Patent Number
JSC-CN-34421
Meeting Information
Meeting: JSC EISD Technology Showcase Poster Session
Location: Houston, TX
Country: United States
Start Date: October 21, 2015
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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