Prof. White traveled to the University of Aarhus, Denmark to test the Tufts Sonic Anemometer in the Mars Simulation Wind Tunnel. This unique facility allows testing under known flow conditions at reduced pressures. We tested both at 6 mbar in CO2 (Mars surface conditions) and at both 11 mbar and 4 mbar in air (stratospheric conditions on Earth) with relevance to both the Tufts Stratospheric Sonic Anemometer project and the Mars Sonic Anemometer project. The instrument performed very well, with resolution on the order of 2 cm/s, and within approximately 10% of laser doppler flow measurements at speeds up to 11 m/s. We also confirmed the importance of wake calibration for absolute accuracy, and will be making additional efforts using Computational Fluid Dynamics and experiments to provide updated calibration tables to improve to better than 10%.