The Chinese Yutu
rover has identified a new type of moon rock, according to a study published
Tuesday in Nature Communications. The rover -- which was the first explorer to
land on the moon since the 1970s, if you don't count orbiters that made crash
landings -- is poking around a region that's been reshaped by volcanic activity
relatively recently. At just under 3 billion years old, these
slightly-less-ancient flows have rock unlike the samples brought home by
The moon is
generally thought to have formed when a Mars-sized planet (sometimes called
Theia) collided with a young Earth about 4.5 billion years ago, creating a
hot mess of molten rock. Around 500 million years later, building heat from the
decay of radioactive elements inside the moon caused melting in the mantle and
led to volcanic eruptions.
Until now, basalts sampled from the moon all had either very low or very high
titanium content. By examining young rocks uncovered by an impact crater, Yutu
(Jade Rabbit) found basalts with intermediate levels of titanium and high iron
levels. That's important, because the order and composition of minerals in
basalt can reveal the source of the magma that formed it.
"The variable titanium distribution on the lunar surface suggests that the
Moon's interior was not homogenized," Washington University's Bradley L. Jolliff, who
collaborated with Chinese scientists to analyze the rover's data, said in
a statement. "We're still trying to figure out exactly how this happened.
Possibly there were big impacts during the magma ocean stage that disrupted the
In addition to showing the unexpected diversity of the moon, the results
could help scientists do a better job of studying its surface from orbiters.
"We now have 'ground truth' for our remote sensing, a well-characterized
sample in a key location," Jolliff
said. "We see the same signal from orbit in other places, so we now know
that those other places probably have similar basalts."