In Yolo County, California, startup Zipline has begun testing its second-generation drones with dozens of flights each day. The drones are already in use delivering blood to hospitals in Rwanda, but Zipline hopes to expand to other countries and other medical supplies.
Zipline's system flicks a cord up to catch a hook at the back of a passing drone to snatch it out of the air. The cord pays out to decelerate it then winds back in to lower the drone like a caught fish.
The rolling hills around Zipline's test site is surrounded by oak trees filled with acorn woodpeckers and fields filled with western meadowlarks. In summer after winter rains stop, much of the green fades to brown and yellow.
Zipline tries out new software at its Central Valley 's test site, and drones don't always snag the cord that's supposed to stop their flight. If they miss, they buzz around in a circle for another attempt.