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(HP-97) Solar Inertial & Local Vert⁄Horiz Attitude relationship
12-23-2019, 01:42 AM (This post was last modified: 12-23-2019 01:44 AM by SlideRule.)
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(HP-97) Solar Inertial & Local Vert⁄Horiz Attitude relationship
An extract from Solar Inertial & Local Vert⁄Horiz Attitude relationship, NASA (LBJ Space Center), Lockheed Electronics Company, Aerospace Systems Division, Contract NAS 9-15200, June 1977

The instantaneous relationship between the Solar Inertial (SI) and Local Vertical Local Horizontal (LVLH) coordinate systems is derived. A method is presented for computation of the LVLH-to-SI rotational transformation matrix as a function of an input LVLH attitude and the corresponding look angles to the sun. Logic is provided for conversion between LVLH and SI attitudes expressed in terms of a pitch, yaw, roll Euler sequence.
Documentation is included for a program which implements the logic on the Hewlett-Packard 97 programmable calculator.

Suppose that the orbiter attitude is given in terms of pitch, yaw, roll Euler angles with respect to LVLH and the pitch, yaw look angles to the sun are given. Both types of data are given by the Shuttle Attitude and Pointing Timeline (SAPT) Program and by the HP9825A Super Sighter (SS) Program and are usually published in Reference Flight Profile documentation.

A program was written for the Hewlett-Packard 97 programmable calculator to perform the SI ↔ LVLH computations. Documentation and sample output of the HP-97 program are included.

22 equations, flow charts, etc …

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