# Accession Number:

## AD0647355

# Title:

## A NELIAC-N COMPUTER PROGRAM TO CALCULATE THE COMPONENTS OF THE EARTH'S MAGNETIC FIELD.

# Descriptive Note:

## Final rept.,

# Corporate Author:

## NAVAL RESEARCH LAB WASHINGTON D C

# Personal Author(s):

# Report Date:

## 1967-01-25

# Pagination or Media Count:

## 26.0

# Abstract:

Experiments with the Lofti series of satellites have demonstrated that propagation can take place in the ionosphere at very low frequencies. In this frequency range the nature of the wave propagation depends critically upon the orientation of the wave with respect to the earths magnetic field therefore the orientation of both the magnetic field and the satellite, relative to the earth, must be known before satellite data can be analyzed in detail. Since the steady-state magnetic field of the earth at a given point in space can be calculated as the gradient of a potential function that satisfies Laplaces equation, this potential can be expressed as a spherical harmonic expansion and its gradient computed analytically. A computer program, written in NELIAC-N language, was developed that calculates the magnitude and direction of the earths magnetic field lines corresponding to a given spatial location of the satellite, using a spherical harmonic expansion with Jensen and Cain 1960 Schmidt-normalized coefficients. Author

# Descriptors:

# Subject Categories:

- Geomagnetism
- Computer Programming and Software
- Astronautics