The Apollo program was designed to land humans on the Moon and bring them safely back to Earth. Six of the missions (Apollo 11, 12, 14, 15, 16, and 17) achieved this goal. Apollo 7 and 9 were Earth orbiting missions to test the Command and Lunar Modules, and did not return lunar data. Apollo 8 and 10 tested various components while orbiting the Moon, and returned photography of the lunar surface. Apollo 13 did not land on the Moon due to a malfunction, but also returned photographs. The six missions that landed on the Moon returned a wealth of scientific data and almost 400 kilograms of lunar samples. Experiments included soil mechanics, meteoroids, seismic, heat flow, lunar ranging, magnetic fields, and solar wind experiments.