It has been recently advocated that Mars has excellent conditions for oxygen and fuel production directly from atmospheric CO2 using non-equilibrium plasmas. The Martian conditions would be favorable for vibrational excitation and/or enhanced dissociation by electron impact, two important pathways for CO2 plasma dissociation. Herein we confirm these theoretical predictions by measuring, for the first time, the vibrational temperatures of CO2 and the CO and CO2 concentrations in realistic Martian conditions. In situ Fourier transform infrared spectroscopy (FTIR) measurements are performed in experiments conducted in DC glow discharges operating at pressures p=1-5 Torr, discharge currents I=10-50 mA, initial gas temperatures of 220 K and 300 K, both in pure CO2 and in the synthetic Martian atmosphere 96%CO2-2%Ar-2%N2. To analyse and interpret the experimental results, we develop a detailed self-consistent kinetic model for pure CO2 plasmas, describing the coupled electron and heavy-particle kinetics. The simulation results are in very good agreement with the experimental data. It is shown that the low-temperature conditions may enhance the degree of vibrational non-equilibrium and that the Martian atmospheric composition has a positive effect on CO2 decomposition. Accordingly, the present investigation confirms the potential of plasma technologies for in-situ resource utilization (ISRU) on Mars.