After sending 12 humans to the moon's surface during the Apollo Program, NASA remains committed to lunar science. Building on modern missions such as Clementine and Lunar Prospector and recent missions like LCROSS and GRAIL, NASA science has helped to map the moon, determine the presence of water ice, and understand our satellite's irregular gravity field.

NASA's current missions to the moon are helping the agency understand our solar system better, informing future exploration efforts to other planetary bodies, and bringing us closer to the technologies we'll need to explore future destinations like an asteroid and Mars.

Scientists using four NASA spacecraft currently studying our lunar neighbor may get an opportunity to gather new data from the Dec. 14 landing of the Chang'e 3 lunar rover. U.S. and international researchers view the pending arrival as a new scientific opportunity that could potentially enhance studies and observations of the lunar atmosphere.

The robotic lander will arrive as NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE), Lunar Reconnaissance Orbiter (LRO), and two probes called the Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) continue their science missions.

Although there is no cooperation between the U.S. and China on these missions, U.S. researchers could see potentially interesting science from the landing. The data will be made available to the international science community.

LADEE
LADEE, the Lunar Atmosphere and Dust Environment Explorer, is equipped with technology to measure atmospheric species and dust particles, and may be able to detect changes in the atmosphere caused by dust and exhaust introduced above the surface as the Chinese lander touches down on the surface.

The spacecraft's initial objective is to study the pristine lunar atmosphere and orbital dust environment. Using its instruments, scientists hope to address a long-standing question: Was lunar dust, electrically charged by sunlight, responsible for the pre-sunrise glow above the lunar horizon detected during several Apollo.

LADEE has been gathering science data since lowering its orbit on Nov. 10 to begin its 100-day prime mission. The science team has already established a baseline of data for the tenuous lunar atmosphere, or exosphere, and dust impacts. Prior to the landing of Chang'e 3, the LADEE team will have gathered data for a full lunar cycle, or 29.5 days.

Before and after the landing, LADEE will be using its Neutral Mass Spectrometer (NMS) instrument to obtain additional observations. The NMS will monitor the specific masses of the products (e.g., H2O, N2, CO and CO2, H2) the team expects the propulsion system will generate during landing based on the descriptions of the landing system available. In addition, LADEE will continue its baseline observations, which will allow it to see if the landing generates a detectable change in the moon's background dust and gas environment.

LADEE was launched Sept. 6 and is the first spacecraft designed, developed, built, integrated and tested at NASA's Ames Research Center at Moffett Field, Calif. Ames manages the overall mission and serves as a base for mission operations and real-time control of the probe. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the science instruments and technology demonstration payload, the science operations center and overall mission support. NASA's Marshall Space Flight Center in Huntsville, Ala., manages LADEE within the Lunar Quest Program Office.

LRO
Launched in June 2009, the Lunar Reconnaissance Orbiter, LRO, has been conducting science activities and retuning unique results on the lunar exosphere. The spacecraft also has returned a treasure trove of unprecedented images of the lunar surface.

On the day of the anticipated Chang'e 3 landing, the spacecraft will do up to eight spacecraft maneuvers to scan an area near the landing site with the Lyman-Alpha Mapping Project (LAMP) instrument, an ultraviolet imaging spectrometer. LAMP will be looking for a signature of the exhaust plume from the spacecraft.

Beginning in December, the LRO Camera (LROC) will be able to image the lander and rover at approximately 2 meter per pixel resolution on a monthly basis as the rotation of the moon brings the landing site underneath the LRO orbit plane. Repeated imaging of the landing site by LROC will allow for detailed measurements of changes to the surface caused by the landing and movement of the Chang'e 3 rover.

LROC can image the surface to identify changes caused by Chang'e 3's descent engine, similar to what has been observed from previous lunar landers. Lighting conditions will not be ideal for the first attempt, with the sun low on the horizon, but will improve in later months. The resulting atmospheric and surface changes will provide LRO with a new scientific opportunity to observe the transport of gases on the moon and the effects of local disturbances on the lunar regolith.

Not only has LRO delivered all the information that is needed for future human and robotic explorers, but it has also revealed that the moon is a more complex and dynamic world than scientists had ever expected. LRO will continue to send back lunar data until October 2014, with the possibility of an additional two years.

LRO is managed by NASA's Goddard Space Flight Center, Greenbelt Md.

ARTEMIS
The ARTEMIS spacecraft will assist LADEE in the interpretation of its measurements from the landing.

The two spacecraftcomprising the ARTEMIS mission or Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun have been in lunar orbit since 2010. They are probes from the 5-spacecraft Heliophysics constellation Time History of Events and Macroscale Interactions during Substorms (THEMIS). The ARTEMIS mission allowed NASA to repurpose two in-orbit spacecraft to extend their useful science mission.

The first ARTEMIS spacecraft (P1) will pass within 124 iles (200 km) of the lunar surface on December 14. According to current plans, the spacecraft will look for any plume signatures in the plasma or magnetic field associated with Chang'e 3's landing. The second spacecraft (P2) will observe pristine solar wind plasma and magnetic field conditions. This information is needed to determine how dust is lofted from the lunar surface.

Current ARTEMIS investigations are focusing on measuring the electrostatic charging of the lunar surface, the plasma wake that the moon carves out in the supersonic solar wind, and the interaction of the solar wind.

ARTEMIS is managed by NASA's Goddard Space Flight Center in Greenbelt Md.