Humanity's knowledge of the moon has transformed dramatically in the last year, thanks in large part to NASA's Lunar Reconnaissance Orbiter, which recently celebrated its first birthday in lunar orbit.
Indeed, after just one year studying the moon, the spacecraft has gathered more digital information on the moon than any planetary mission that came before, and the American lunar orbiter is still going strong.
NASA launched the Lunar Reconnaissance Orbiter (LRO) on June, 18 2009 to serve as a robotic scout for future moon missions and to hunt for any water ice that may lie hidden in the permanent shadows of its polar craters. Since then, probe has helped confirm the existence of water on the moon and beamed home spectacular photos of the hardware left behind by NASA's moonwalking Apollo astronauts in the late 1960s and 1970s. [10 Coolest New Moon Discoveries]
Icy moon treats
The most dramatic finding the LRO helped observe was undoubtedly the grains of moon water ice, revealed by the probe's companion mission, NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) in October 2009.
Scientists had speculated on the existence of water on the moon since the 1940s. But confirmation came only recently, when scientists announced last year that observations from several missions — among them NASA's Cassini spacecraft, Deep Impact probe and the NASA-built Moon Mineralogy Mapper on India's Chandrayaan-1 orbiter — had revealed evidence of lunar water molecules or components of them on the moon's surface.
Still, it took LCROSS to help kick up significant amounts of water when it crashed into a crater near the south pole of the moon, and LRO and other observatories to see evidence of this ice otherwise hidden in the permanent shadows within the crater.
"The level of coordination required to be able to position the Lunar Reconnaissance Orbiter to pass over the impact site just 90 seconds after the impact was a spectacular achievement," said Michael Wargo, chief lunar scientist at the Exploration Systems Mission Directorate at NASA Headquarters in Washington, D.C.
"It was very exciting to do a true experiment in space," said Richard Vondrak, LRO project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "Most of the work is purely observational, just passive, but with LCROSS, we got to perturb the environment, look at the consequences and learn something from it."
LRO and LCROSS observations of the impact mission revealed a variety of other intriguing materials there as well, such as carbon dioxide, hydrogen, carbon monoxide and sulfur dioxide.
"These shadowed regions of the moon are truly repositories for all sorts of materials," said Anthony Colaprete, principal investigator on LCROSS.
These volatile materials likely collected over the course of billions of years at these areas, which at minus 415 degrees Fahrenheit (minus 248 Celsius), have the coldest temperatures measured anywhere yet in the solar system. For comparison, Pluto's surface only gets down to about minus 300 degrees Fahrenheit (minus 184 Celsius).
"They really provide a treasure trove of information about the formation and evolution of the solar system," Wargo said.
The cameras on LRO are mapping the moon with a spectacular level of detail. The photos are so detailed that past Apollo moon landers, equipment and other lunar rovers have been photographed by the probe's main camera. [Historic Apollo 11 moon lander photographed].
"We can see the tracks that astronauts left behind," Wargo said. "I don't know how anyone can see those and say we didn't go there."
The other instruments on the probe are exquisitely thorough as well. For instance, its laser altimeter, which is mapping the 3-D topography of the lunar surface, scans 140 spots per second, while past missions only analyzed one to 10.
"We're getting the best images and finest topographical maps that have ever been made of the moon," Vondrak said.
LRO is also developing the first radar maps of the far side of the moon — the side never seen from Earth. The moon's far side is rougher and has far more craters than its near side, including one of the largest known impact craters in the solar system, the South Pole-Aitken Basin, which is roughly 1,550 miles (2,500 km) wide and 8 miles (13 km) deep.
"I believe we'll gain new insights into the formation and evolution of the far side this way for a better understanding of the moon as a whole," Vondrak said.
By comparing this new data from LRO with that from old maps, "we can get an idea of what impacts have occurred by looking for new craters," Wargo added. "That will give us a better understanding of the rate at which impacts happen on the moon to understand its evolution and that of the solar system. Also, to safely explore the moon, you'd want to understand what the impact rate is."
More to come
As much as LRO has discovered so far, there remains a vast amount of data that scientists are only starting to unravel.
"The amount of data LRO has returned is just staggering," Vondrak said. "Prior missions like Mars Global Surveyor or Cassini measured up to a few terabytes of data in their entirety. In comparison, LRO has made two releases of data so far, each about 40 terabytes of data." A terabyte is a trillion bytes — in comparison, the Library of Congress has collected roughly 160 terabytes so far.
"It takes time before researchers have a chance to analyze this exquisite data," Wargo said. "We're only at the beginning, not the end."