Next problem: Desert organisms shut down energy production in the heat of the day, when Zo is most active. Waggoner´s solution: After taking an initial set of images, Zo lowers a set of plastic nozzles that squirt water, encouraging any microscopic life to awaken and bloom in the next series of images.
If Zo gets a chlorophyll hit (in the Atacama, probably lichen), it engages in what Cabrol proudly dubs "science on the fly." The ´bot "decides" the area is worth more of its time and enters intensive imaging mode to look for harder-to-detect bacteria. It prepares the ground by squirting diagnostic dyes, each of which bonds with one of the four basic macro-molecules of life-protein, lipid, carbohydrate or DNA. Once attached to a dye, these organic molecules fluoresce when bathed with the flash and will show up as bright patches on the black-and-white images sent to Pittsburgh.
"It´s lit up like a Christmas tree," exclaims Warren-Rhodes, the NASA and U.C. Berkeley biologist, when a lively image comes in to the Pittsburgh office from one of Zo´s intensive spraying, dyeing, filtering, and shooting sprees. The excitement in the room is palpable whenever the yield looks to include bacteria, which unlike lichen are invisible to the naked eye. These are moments in which the scientists can learn more about the Atacama remotely via Zo than by going there themselves with rock hammer and pail in hand.
One evening in Pittsburgh, Warren-Rhodes is studying a series of fluorescent images on her laptop screen like a radiologist worrying a problematic MRI: Is that lipid or just background fluo-rescence? Cabrol can´t say-her training is in planetary geology, not terrestrial biology-but she reminds Warren-Rhodes to look for overarching patterns. "Is there any predictability here?" Cabrol asks. "How can we transform that into an autonomous process that Zo can learn how to do?" I ask Warren-Rhodes who is the better Atacama biologist, she or Zo. "I am," she says without missing a beat. "I´ve spent so much time in extreme deserts." And in a few years? "Oh, it will be like Kasparov playing IBM´s Deep Blue. By game 6, I´m outta here!"
When Zo´s solar panels have absorbed the last rays of twilight, the engineers retreat to site camp, a bunch of unheated wooden shacks left behind by a Chilean gold-mining concern. (The rooms are chilly at night, and the toilets stop working one by one, but for Wettergreen, 40, a man perfectly adapted to the field, this is suspiciously soft living compared with tents or sleeping under the stars at previous sites.)
On Friday, October 7, as the team is uploading data to Pittsburgh in the communal communications shack, Dominic Jonak, the young Carnegie Mellon engineer, looks up from his e-mail incredulously: "They´re asking us which valley have we come from. Like where have we been the past few days." Williams, the mechanical engi-neer who built much of Zo, cracks up: "Are we on this half of the map or this half of the map?´ We´re being commanded by a lost science team!"