Search

In this paper, we have analyzed neutron spectroscopy data gathered by the High Energy Neutron Detector (HEND) instrument onboard Mars Odyssey for comparison of polar regions. It is known that observation of the neutron albedo of Mars provides important information about the distribution of water--ice in subsurface layers and about peculiarities of the C[O.sub.2] seasonal cycle. It was found that there are large water-rich permafrost areas with contents of up to ~50% water by mass fraction at both the north and south Mars polar regions. The water-ice layers at high northern latitudes are placed close to the surface, but in the south they are covered by a dry and relatively thick (10-20 cm) layer of soil. Analysis of temporal variations of neutron flux between summer and winter seasons allowed the estimation of the masses of the C[O.sub.2] deposits which seasonally condense at the polar regions. The total mass of the southern seasonal deposition was estimated as 6.3 x [10.sup.15] kg, which is larger than the total mass of the seasonal deposition at the north by 40-50%. These results are in good agreement with predictions from the NASA Ames Research Center General Circulation Model (GCM). But, the dynamics of the condensation and sublimation processes are not quite as consistent with these models: the peak accumulation of the condensed mass of C[O.sub.2] occurred 10-15 degrees of [L.sub.s] later than is predicted by the GCM. Keywords: Mars, surface; Mars, atmosphere; Mars, climate; Ices

Abstract: In this paper, we have analyzed neutron spectroscopy data gathered by the high energy neutron detector instrument onboard Mars Odyssey in order to study the behavior of CO2 condensed mass at the polar regions of Mars. It is known that observation of the neutron albedo of Mars provides not only information on distribution of water ice/bounded water through Martian subsurface but is also sensitive to the condensation/sublimation of atmospheric CO2 at the Martian poles. Analysis of temporal variations of neutron flux between summer and winter seasons allowed the creation of multidimensional model of CO2 deposition describing behavior of CO2 condensed mass as a function of longitude, latitude and time. Based on this model, we have estimated the total masses of north seasonal cap ((3.8±0.4)×1015 kg), south seasonal cap ((6.3±0.6)×1015 kg) and compared our estimations with predictions of General Circulation Model. Furthermore, using the data gathered during second Martian year on the orbit, we have conducted preliminary comparison between seasonal cycles of two successive Martian years. [Copyright &y& Elsevier]