Houston: Scientists have discovered moon's
biggest and deepest crater--some 2,400 kms long and 9 km deep
-- using data from a NASA instrument that flew aboard India's
maiden unmanned lunar mission Chandrayaan-I.
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 collison
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.
PTI
First Published: Friday, March 05, 2010, 19:40