Earth's Alien Proving Ground
In the hyper-arid core of Chile's Atacama Desert, near a location called Yungay, NASA established a temporary home for a Martian explorer. This isn't science fiction; it was the field site for the Atacama Rover Astrobiology Drilling Studies (ARADS), a project that ran from 2016 to 2019. The goal was to develop and test the technologies and strategies needed to search for life deep beneath the surface of Mars. The Atacama is the driest non-polar desert on Earth, with some areas receiving less than a centimeter of rain per decade. This extreme dryness, combined with intense ultraviolet radiation and soil with oxidizing chemicals, makes it one of the best Mars analogs on our planet.
The hardware for the ARADS project was the KREX-2, a 300-kilogram, four-wheeled rover prototype developed at NASA's Ames Research Center. About the size of the Spirit and Opportunity rovers, KREX-2 was designed to navigate the rugged terrain autonomously. Its primary mission was to carry a drill and a suite of life-detection instruments to scientifically interesting targets. During the final 2019 field test, a science team based in California sent commands to the rover in Chile, simulating the time delays and operational challenges of a real interplanetary mission.
Drilling for Answers
Mars's surface is hostile to life as we know it, bombarded by radiation, extremely cold and dry. Scientists hypothesize that if life exists, or ever existed, it would likely be found underground. To test this, the KREX-2 rover was equipped with a specialized drill called TRIDENT, developed by Honeybee Robotics. This rotary-percussive drill was designed to penetrate as deep as two meters (about 6.5 feet) into the difficult, often salt-cemented desert floor.
Once the drill extracted a soil sample, a robotic arm with a scoop transferred the material to a set of onboard instruments. The main life-detection instrument was the Signs of Life Detector (SOLID), which uses biochemical methods to search for 512 different biological compounds, including proteins and DNA. Other instruments included a Wet Chemistry Laboratory (WCL), similar to one flown on the Mars Phoenix lander, to analyze soil salts, and the Planetary In Situ Capillary Electrophoresis System (PISCES), designed to find amino acids. The project showed that the rover could autonomously drill and deliver samples to these instruments, which in turn detected evidence of microbial life hidden in the subsurface. The findings support the strategy of drilling deep to search for biosignatures on Mars.