SCATHA Composition Data - Online Data Plots

This page provides a link to online plots of SCATHA ion composition data generated at UCLA.
Plots are available in either PDF or JPEG formats.

The SCATHA ion composition experiment was built by what was then the Lockheed Palo Alto Research Laboratory (LPARL), now the Lockheed-Martin Advanced Technology Center. Dick Johnson, Ed Shelley, and Dick Sharp of LPARL built and flew the instrument. Harry Collin, of Lockheed-Martin, resurrected the old 1600 BPI tapes on which these data were stored. The analysis software used at UCLA was based on code originally written by Daryl Carr of Lockheed-Martin.

SCATHA (Spacecraft charging at high altitudes) was launched in January of 1979 into a near-geosynchronous orbit with apogee ~ 7.8 Earth radii, perigee ~ 5.3 Earth radii. The orbital period was 23.7 hours, and the orbit was inclined by 7.9 degrees.

In descriptions of the spacecraft instrumentation the ion composition experiment is referred to as "SC-8." A review of the SCATHA ion composition results can be found in Johnson, R. G., R. J. Strangeway, E. G. Shelley, J. M. Quinn and S. M. Kaye, Hot plasma composition results from the SCATHA spacecraft, in Energetic Ion Composition in the Earth's Magnetosphere (ed. R. G. Johnson), Terra Scientific Publishing Co., Japan, 1983.

24hr Summary Data Plot The figure to the left is a thumbnail example of the plots available online. The plots are 24 hour summary plots showing the differential energy flux for the four primary species: Protons (H+), Alphas (He++), Helium (He+), and Oxygen (O+). The energy flux is shown as a function of energy and time, with energy going from 0.1 to 32 keV/q. In addition, the number densities, integrated over this energy range, are also shown. The energy fluxes and densities are 15 minute averages over all pitch angles sampled.

For all the species except Oxygen the spectra are calculated using data from "Sweep mode", where the mass spectrometer sweeps through all the masses. This allows for a background count determination, and this background is subtracted from the data. The oxygen data are from "Lock mode", where the instrument locks onto the mass peak.

Because of the background subtraction it is possible to get negative densities.

24 Hour Summary Plots of SCATHA Composition Data

Link to table of online PDF files

Link to table of online JPEG files

These tables will continue to be populated as more data are processed.

Robert J. Strangeway
Institute of Geophysics and Planetary Physics / UCLA
Los Angeles, CA 90095-1567
Telephone: (310) 206-6247
FAX: (310) 206-3051
Internet e-mail:

UCLA/IGPP Space Physics Center home page     Bob Strangeway's home page

Last modified: February 27, 2007.