Explorer 33 and 35 plasma observations of magnetosheath flow


  • Herbert C. Howe Jr.,

  • Joseph H. Binsack


The magnetosheath flow in the region −60 REXSE ≤ −20 RE is mapped by using plasma data from the Massachusetts Institute of Technology plasma experiments on the earth-orbiting Explorer 33 and the lunar-orbiting Explorer 35. Temporal and spatial variations in the flow are separated by using 309 hours of simultaneous data from the two spacecraft, one spacecraft being in the solar wind and the other spacecraft in the magnetosheath. The over-all flow pattern agrees well with the predictions of a simplified hydrodynamic theory. The measured ratio of magnetosheath to solar-wind densities is shown to have some dependence on the observed solar-wind sonic Mach number. This density ratio is consistently <1 in the region adjacent to the magnetotail boundary and thus reflects the irreversible nature of the flow across the bow shock.