Quantitative measurement of 10cm^3 LED mini-lidar for Mars rover

In this study, LED based mini-lidar to install into Mars rover has been developed. Its aim is to capture the dynamics of dust twister called “Dust Devil”. For Mars rover installation, there are large restrictions of 10cm3 optics size, 1kg weight, 1W power consumption, etc. We have developed its concept model, and conducted the demonstration experiment. The LED mini-lidar is equipped with a high speed photon counter, of which data sampling interval is 1ns, corresponding to a range bin of 0.15m, and a high repetition pulsed LED beam, of which repetition frequency is greater than 500kHz. Transmitting optical pulse power was <10nJ/10ns (= 1W). For summation time of greater than 0.2s, surface atmosphere activity in the order of seconds can be visualized with this high resolution. The dynamics measurement of an artificial twister was successfully conducted with this mini-lidar. In this report, the quantitative measurement method to distinguish dust samples in relation to Zirconia beads measurements is proposed. The relationship between the shaking off dust weight and its scattering cross section is obtained. The dust chamber experiment was conducted with several kinds of dust particles, too. These lidar echo results were compared with transmissometer, and they were well coincided due to the concentration change. The nature fog observation was conducted with this mini-lidar, too. The liquid water content was estimated under the consideration of the result of the quantitative measurement.