Chilean officials were awaiting the arrival of a main drill and other equipment to begin boring a rescue shaft in a months-long operation to reach 33 miners who have been trapped underground for more than three weeks. Although drilling had been expected to start as early as Monday, officials said the key equipment was expected to arrive at the mine Tuesday, and some excavation of the drilling site would have to take place. The effort to drill through more than 2,300 feet (700 meters) of rock and safely extract the miners could take three to four months, officials said. The miners have been stuck in the mine since an August 5 cave-in and are surviving on supplies funneled to them from above ground through three bore holes. Rescue officials said Monday they plan to send down food -- including sandwiches and hot food -- over the next few days. There are also plans to send down more beds, which is a slow process, said Ximena Mata, the Chilean government's point person. Until now, the men living in what they have dubbed "Refuge 33" have been surviving on liquids. The mining company said Monday that all the miners were in good spirits and were looking forward to the promised solid food. Meanwhile, a four-person team from NASA is set to arrive in Chile this week to help provide physical and behavioral health support to the miners. NASA has a long history of studying human behavior in isolated environments, said Michael Duncan, the U.S. space agency's lead person on the Chile effort. Chilean Health Minister Jaime Manalich said a medical official, a nutritional medic, a psychologist and an engineering expert in logistics from NASA will stay at the mine from Wednesday through Friday to help. The miners spoke directly with family members for the first time Sunday, as officials worked to keep the men's spirits and health in good shape. One person per family was given about 20 seconds each to talk through a line that was rigged to connect the miners with life.