NEW DELHI: ISRO scientists have discovered a giant underground chamber on the moon , which could be used as a lunar base by astronauts for inter-planetary missions.Scientists at the Space Applications Centre (SAC), using data gathered from Chandrayaan-I's Terrain Mapping Camera and Hyper Spectral Imager (HySI) payloads, found a 1.2 km long buried, uncollapsed and near horizontal lava tube.The hollow cave situated just above the lunar equator on the nearside of moon, can accommodate a large number of astronauts and scientific instruments, and also protect them from hostile lunar environment."Such a lava tube could be a potential site for future human habitability on the Moon for future human missions and scientific explorations, providing a safe environment from hazardous radiations, micro-meteoritic impacts, extreme temperatures and dust storms," a team of scientists led by A S Arya of SAC, Ahmedabad said reporting the findings in 'Current Science'.Scientists said identifying sites for permanent base for human settlements on the moon is important for further exploration."Lava tubes provide a natural environmental control with a nearly constant temperature of minus 20 degrees Celsius, unlike that of the lunar surface showing extreme variation, maximum of 130 degrees Celsius to a minimum of minus 180 degrees Celsius in its diurnal (day-night) cycle," they said.The scientists said the lava tubes offer a dust-free environment and adapting them for human use requires minimal construction.The structures also shields its occupants as after 6 meters depth, no effects of radiation due to or induced by galactic cosmic rays were observed in simulation, they said."After less than one meter, no effects of radiation due to or induced by solar particle events are observable. Natural or induced radioactivity does not play a significant role in the lava tube exposures," the scientists said."Thus lava tubes are not only a safe natural cavity, but also a readymade structure for a lunar base, being a habitat," they said.