NASA’s GRAIL (Gravity Recovery and Interior Laboratory) mission may pull back the curtain on the Moon’s mysterious “far side.”  Catch the launch of GRAIL on September 9^th, 2011 at 8:12am CST – Live feed available on NASA TV.

If a paper published recently in the journal Nature* is right, two moons once graced our night skies. The proposition has not been proven, but has drawn widespread attention.

“It’s an intriguing idea,” says David Smith, GRAIL’s deputy principal investigator at MIT. “And it would be a way to explain one of the great perplexities of the Earth-Moon system – the Moon’s strangely asymmetrical nature.  Its near and far sides are substantially different.”

The Moon’s near side, facing us, is dominated by vast smooth ‘seas’ of ancient hardened lava. In contrast, the far side is marked by mountainous highlands. Researchers have long struggled to account for the differences, and the “two moon” theory introduced by Martin Jutzi and Erik Asphaug of the University of California at Santa Cruz is the latest attempt.

Scientists agree that when a Mars-sized object crashed into our planet about 4 billion years ago, the resulting debris cloud coalesced to form the Moon. Jutzi and Asphaug posit that the debris cloud actually formed two moons. A second, smaller chunk of debris landed in just the right orbit to lead or follow the bigger Moon around Earth.

“Normally, such moons accrete into a single body shortly after formation,” explains Smith. “But the new theory proposes that the second moon ended up at one of the Lagrange points in the Earth-Moon system.”

Lagrange points are a bit like gravitational fly traps. They can hold an object for a long time–but not necessarily forever. The second moon eventually worked its way out and collided with its bigger sister. The collision occurred at such a low velocity that the impact did not form a crater. Instead, the smaller moon ‘went splat,’ forming the contemporary far side highlands.

In short, the lunar highlands are the lost moon’s remains

Read the Full article at science.nasa.gov

For more information about our cosmic neighbor’s composition, visit the Starship Gallery at Space Center Houston.  Home to the world’s largest collection of Moon rocks on public display, including a 1.5 billion year old lunar touchstone!  Save $5 off admission when you buy tickets online!

Visiting the Apollo 17 capsule at Space Center Houston was about as close as anyone could get to Man’s final voyage to the Moon – until now!  Thanks to NASA’s Lunar Reconnaissance Orbiter, we are now able to explore the last landing site in spectacular detail!

NASA’s Lunar Reconnaissance Orbiter (LRO) captured the sharpest images ever taken from space of the Apollo 12, 14 and 17 landing sites. Images show the twists and turns of the paths made when the astronauts explored the lunar surface.

At the Apollo 17 site, the tracks laid down by the lunar rover are clearly visible, along with the last foot trails left on the moon. The images also show where the astronauts placed some of the scientific instruments that provided the first insight into the moon’s environment and interior.

“We can retrace the astronauts’ steps with greater clarity to see where they took lunar samples,” said Noah Petro, a lunar geologist at NASA’s Goddard Space Flight Center in Greenbelt, Md., who is a member of the LRO project science team.

All three images show distinct trails left in the moon’s thin soil when the astronauts exited the lunar modules and explored on foot. In the Apollo 17 image, the foot trails, including the last path made on the moon by humans, are easily distinguished from the dual tracks left by the lunar rover, which remains parked east of the lander.

Courtesy of NASA’s Goddard Space Flight Center

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The Apollo 17 crew capsule America is part of the vast display of spacecraft and artifacts on display at Space Center Houston.  Located in the Starship Gallery, the last crewed vehicle to fly to the Moon is displayed against a life size diorama of the lunar landscape.  Starship Gallery is included with regular admission to Space Center Houston. Save $5 off admission when you purchase your tickets online.  For hours and directions visit our Guest Information page.