Robots can go all the way to Mars, but they can't pick up the groceries

Stacks of vertical shelves weave around each other in what looks like an intricately choreographed – if admittedly inelegant – ballet that has been performed since 2014 in Amazon's cavernous warehouses. The shelves, each weighing more than 1,000 kg, are carried on the backs of robots that resemble giant versions of robotic vacuum cleaners. The robots cut down on time and human error, but they still have things to learn. Once an order is received, a robot goes to the shelf where the ordered item is stored. It picks up the shelf and takes it to an area where the item is removed and placed in a plastic bin, ready for packing and sending to the customer.