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An Alternative Lunar Ephemeris Model for On-Board Flight Software UseIn calculating the position vector of the Moon in on-board flight software, one often begins by using a series expansion to calculate the ecliptic latitude and longitude of the Moon, referred to the mean ecliptic and equinox of date. One then performs a reduction for precession, followed by a rotation of the position vector from the ecliptic plane to the equator, and a transformation from spherical to Cartesian coordinates before finally arriving at the desired result: equatorial J2000 Cartesian components of the lunar position vector. An alternative method is developed here in which the equatorial J2000 Cartesian components of the lunar position vector are calculated directly by a series expansion, saving valuable onboard computer resources.
Document ID
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Simpson, David G.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
August 19, 2013
Publication Date
May 1, 1999
Publication Information
Publication: 1999 Flight Mechanics Symposium
Subject Category
Distribution Limits
Work of the US Gov. Public Use Permitted.
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