Fast in situ measurements of ionospheric plasma with the miniature electrostatic analyzer (MESA): An experiment aboard FalconSat-2

A satellite mission to investigate ionospheric equatorial spread-F phenomena is presently under development by faculty and cadets at the United States Air Force Academy (USAFA). FalconSat-2 is a low altitude (350 km) medium inclination (52 degrees) microsatellite whose scientific mission is to measure in situ plasma density along the satellite´s orbital track to detect plasma depletions with spatial sizes of 2-10 km and depletion depths up to three orders of magnitude. Plasma depletions of this size and depth are notorious for their deleterious effects on radio communications, and their presence is common in the night-time F region ionosphere. Since it is desired to detect plasma depletions with sharp boundaries (i.e., a reduction in plasma density by a factor of 1000 over 2 km in space), and to account for diurnal variations in the ambient ionosphere, it was necessary to target the capability of making plasma density measurements that covered a dynamic range of 5 orders of magnitude and a sampling rate of 10 measurements per second. To meet these demanding measurement requirements, a novel electrostatic analyzer has been designed by USAFA faculty. The Miniature Electrostatic Analyzer (MESA) is a patch sensor consisting of a stack of insulated, lithographically patterned steel plates that form an array of electrostatic lenses.