IRM Spacecraft

The IRM spacecraft carried five instruments (MSIS, SULEICA, magnetometer, plasma electron & ion, plasma wave) as well as eight sets of barium and lithium canisters for release in the solar wind, the magnetosheath ("artificial comet"), and the magnetotail. This instrumentation served five different objectives:

to identify, in real time, the IRM location with respect to the magnetospheric boundaries; to determine the instantaneous orientation of the magnetic field and the magnitude of the plasma flow velocity. This information is essential for the decision on the ion cloud release times;
to provide in-situ diagnostics of the interaction between the artificial ion clouds and the ambient medium;
to extend the ion tracing to larger radial distances and to allow temporal correlation of composiion changes with CCE;
to study magnetospheric phenomena such as the bow shock, magnetopause, magnetotail, and radiation belts;
to allow the determination of the IRM attitude during portions of the orbit close to earth

The IRM was operated real-time, with approximately 45% coverage from launch until August 13, 1986. Five-second resolution digital data is available from the NSSDC; for the availability of other data Dr. G. Haerendel or the instrument investigators should be contacted.