for instance a drone delivery service provided by the united statesbased company zipline in partnership with the rwandan health ministry has slashed the delivery time of lifesaving medicine to remote regions of rwanda from four hours to an average half an hour see case study on rwanda in chapter unassisted robots for some time have been planting seeds and picking weeds and agricultural aircraft are spraying crops with precision to reduce chemical infiltration of groundwater in some parts of the world nevertheless adoption of aerial survey vehicles is not yet within the reach of most farmers with low purchasing power