Subsurface Ice and Brine Sampling Using an Ultrasonic/Sonic Gopher for Life Detection and Characterization in the McMurdo Dry Valleys

摘要

There is growing evidence for ice and fluids near the surface of Mars with potential discharge of brines, which may preserve a record of past life on the planet. Proven techniques to sample Mars subsurface will be critical for future NASA astrobiology missions that will search for such records. The required technology studies are underway in the McMurdo Dry valleys, Antarctica, which is serving as a Mars analog. The ice layer on Lake Vida in the dry valleys is estimated to be 20-meter thick where below 16-m depth there is a mix of ice and brine, which has never been sampled directly due to logistical constraints. A novel light weight, low power ultrasonic/sonic driller/corer (USDC) mechanism was developed that overcomes the need for high axial loads required by drilling via conventional techniques. The USDC was modified to produce an Ultrasonic/Sonic Gopher that is being developed to core down to the 20-m depth for in situ analysis and sample collection. Coring ice at -20℃ as in Lake Vida suggests that it is a greater challenge and current efforts are focused on the problems of ice core cutting, ice chip handling and potential ice melt (and refreezing) during drilling. An analytical model and a prototype are being developed with an effort to optimize the design while addressing the thermal issues, drilling rate, power, mass and the electromechanical behavior.