The US Space agency's Moon Mineralogy Mapper (M3) detected the enormous crater -- the South Pole-Aitken basin -- that was created when an asteroid smacked into moon's southern hemisphere shortly after the formation of earth's only natural satellite.
"This is the biggest and deepest crater on the moon -- an abyss that could engulf the United States from the East Coast through Texas," said lead researcher Noah Petro of NASA's Goddard Space Flight Center in Greenbelt.
According to Petro, who had presented his result yesterday at the Lunar and Planetary Science meeting in this city in Texas, "The impact of the asteroid collision punched into the layers of the lunar crust, scattering that material across the moon and into space".
"The tremendous heat of the impact also melted part of the floor of the crater, turning it into a sea of molten rock," NASA said.
That was just an opening shot. Asteroid bombardment over billions of years has left the lunar surface pockmarked with craters of all sizes, and covered with solidified lava, rubble, and dust, it added.
Moon Mineralogy Mapper was one of 11 instruments onboard Chandrayaan-I.
Glimpses of the original lunar surface, or crust, are rare and views into the deep crust are still rarer, NASA said.
However, it said a crater on the edge of the South Pole-Aitken (SPA) basin may provide such a view. It is called the Apollo Basin, formed by the later impact of a smaller asteroid, and still measures a respectable 300 miles across.
"We believe the central part of the Apollo Basin may expose a portion of the Moon's lower crust. If correct, this may be one of just a few places on the Moon where we have a view into the deep lunar crust, because it's not covered by volcanic material as many other such deep areas are," Petro said.
"Just as geologists can reconstruct Earth's history by analysing a cross-section of rock layers exposed by a canyon or a road cut, we can begin to understand the early lunar history by studying what's being revealed in Apollo."
Both SPA and Apollo are estimated to be among the oldest lunar craters, based on the large number of smaller craters superimposed on top of them, NASA said.
"The Apollo and SPA basins give us a window into the earliest history of the Moon, and the Moon gives us a window into the violent youth of Earth," said Petro.
'Presence of Water on Moon Pathbreaking Discovery'
"This is the first time NASA and ISRO have confirmed the availability of water on the moon.Huge ice sheets were found in the polar regions of the moon. This is a path breaking finding as it was earlier believed there was a vacuum in the moon," Dr Nair, during whose tenure unmanned lunar mission Chandrayaan I was launched, said.
"The presence of water gives many ideas.Water can be split with sunlight to get Oxygen and Hydrogen.While oxygen can be used by human explorers,hydrogen can be used as fuel either to generate electricity or use as rocket fuel for the return journey or even attempt a Mars mission from the Moon," he said.
This also reduces the need to carry expensive oxygen and fuel payloads by future space missions, he said, addressing the Fedbank Hormis Memorial Foundation lecture on 'Technological challenges for National Development' here last night.
The cost of access to the moon works out to about 50000 USD a kg and to go round the earth it is 20,000 USD a kg.Recently, U.S.A had to cancel lunar exploration programmes due to the high cost, he said.