ALSEP's Central Station, and on his way back from the furthest, fire thumpers every . The second consisted of four mortars (with their launch tubes), of different properties and set to impact at different distances from the experiment. It was hoped that the waves generated from the impacts would provide data about seismic wave transmission in the Moon's regolith. The mortar shells were not to be fired until the astronauts had returned to Earth, and in the event were never fired for fear they would damage other experiments. A similar experiment was successfully deployed, and the mortars launched, on Apollo 16. The LPM was to be carried during the second EVA and used to measure the Moon's magnetic field at various points. The SIDE measured ions on the lunar surface, including from the solar wind. It was combined with the CCIG, which was to measure the lunar atmosphere and detect if it varied over time. The CPLEE measured the particle energies of protons and electrons generated by the Sun that reached the lunar surface. The LRRR acts as a passive target for laser beams, allowing the measurement of the Earth/Moon distance and how it changes over time. The LRRRs from Apollo 11, 14 and 15 are the only experiments left on the Moon by the Apollo astronauts that are still returning data. Flown for the first time on Apollo 14 was the Buddy Secondary Life Support System (BSLSS), a set of flexible hoses that would enable Shepard and Mitchell to share cooling water should one of their Primary Life Support System (PLSS) backpacks fail. In such an emergency, the astronaut with the failed equipment would get oxygen from his Oxygen Purge System (OPS) backup cylinder, but the BSLSS would ensure he did not have to use oxygen for cooling, extending the life of the OPS. The OPSs used on Apollo 14 were modified from those used on previous missions in that the internal heaters were removed as unnecessary. Water bags were also taken to the lunar surface, dubbed "Gunga Dins", for insertion in the astronauts' helmets, allowing them sips of water during the EVAs. These had been flown on Apollo 13, but Shepard and Mitchell were the first to use them on the Moon. Similarly, Shepard was the first on the lunar surface to wear a spacesuit with commander's stripes: red stripes on arms, legs, and on the helmet, though