The objective of the RAX mission is to understand the microphysics that lead to the formation of magnetic field-aligned plasma irregularities (FAI), an anomaly known to disrupt communications with orbiting spacecraft.
The RAX mission is specifically designed to remotely measure, with extremely high angular resolution, the 3-D k-spectrum (spatial Fourier transform) of ~1 m scale FAI as a function of altitude, in particular measuring the magnetic field alignment of the irregularities.
The RAX mission will use a network of existing ground radars that will scatter signals off the FAI to be measured by a receiver on the RAX spacecraft. The spacecraft will measure “radio aurora”, or the Bragg scattering from FAI that are illuminated with a narrow beam incoherent scatter radar (ISR) on the ground. This remote sensing method is based on the powerful mathematical relation that the radio aurora intensity is proportional to the irregularity k-spectrum evaluated at the Bragg wave number.
The ground-to-space bistatic radar experiment highly resolves the k-spectrum, which means that the sensed volume of plasma is homogeneous and that the received signal contains a pure content of wave vectors, which are important for accurate analysis of wave growth and damping. Moreover, each experiment will be tagged with the convection electric field Ec, a principal driver of the irregularities, which will be measured (besides altitude profiles of plasma density and temperatures) by the ISR during an experiment.
The RAX mission is a unique opportunity to quantify plasma processes in a homogeneously resolved volume of plasma with the driving force and the effect measured effectively simultaneously.
For more information on the science mission, click here to go to the SRI Science Operations Site.
Ref :Bahcivan, H., M. C. Kelley, and J. W. Cutler (2009), “Radar and rocket comparison of UHF radar scattering from auroral electrojet irregularities: Implications for a nanosatellite radar”, J. Geophys. Res., 114, A06309, doi:10.1029/2009JA014132.
(Banner image © RAX Team)