Phobos 2/ASPERA data revisited: Planetary ion escape rate from Mars near the 1989 solar maximum

Abstract

Insights about the near-Mars space environment from Mars Express observations have motivated a revisit of the Phobos 2/ASPERA ion data from 1989. We have expanded the analysis to now include all usable heavy ion (O +, O2+, CO2+) measurements from the circular orbits of Phobos 2. Phobos 2/ASPERA ion fluxes in the Martian tail are compared with previous results obtained by the instruments on Phobos 2. Further validation of the measurement results is obtained by comparing IMP-8 and Phobos 2/ASPERA solar wind ion fluxes, taking into account the time lag between Earth and Mars. Heavy ion flux measurements from 18 circular equatorial orbits around Mars are bin-averaged to a grid, using the MSE (electric field) frame of reference. The binned data are subsequently integrated to determine the total escape rate of planetary ions. From this we derive a total planetary heavy ion escape rate of (2-3) × 10 25 s -1 from Mars for the 1989 solar maximum. Key Points The heavy ion escape rate in 1989 was ~10 times higher than at solar minimum Use of Mars Express data for physically correct Phobos-2 counts-flux conversion First Phobos-2 escape rate analysis not based on old erroneous assumptions ©2013. American Geophysical Union. All Rights Reserved.