The key factors that set the Moon apart from Earth are its lower gravity, its virtual lack of an atmosphere, and the extreme temperature fluctuations experienced on its surface. Understanding Lunar surface and subsurface temperatures is critical for future human and robotic exploration. The Apollo missions all involved landings which took place in equatorial regions and were conducted during the Lunar day, future exploration is planned which covers a much wider range of latitudes, and will involve stays of longer than two weeks. Diviner will map surface and subsurface temperatures, providing information about potential ice reservoirs and suitable thermal environments for habitation.
|Mean Surface Temperatures||Day: 380K; Night: 120K||295K|
|Temperature Extremes||High: 390K; Low: 104K||High: 331K; Low: 184K|
With the exception of Mercury, the Moon has the most extreme surface thermal environment of any planetary body in the solar system. At the lunar equator, mean surface temperatures reach almost 400K at noon and then drop to around 120K during the Lunar night. The mean surface temperature on Earth is a temperate 295K.
The Moon receives the same flux of solar radiation as the Earth. The extreme surface temperatures on the Moon are the result of it not having an insulating atmosphere As on Earth, the distribution of incident solar radiation is controlled by the moon's shape, the length of the lunar day (~1 month) and the tilt of the lunar spin axis relative to the ecliptic.
Due to the spin axis of the Moon being almost perpendicular to the eclliptic plane, areas of high and low elevation at the lunar poles are thought to experience extremes in illumination. Crater floors in these regions which remain permanently in shadow are likely to form cold traps where temperatures remain below 110K. These cold traps present ideal candidates for potential stores of ice on the lunar surface because although the Moon has no indigenous water, molecules are deposited on its surface from comet and asteroid impacts. Evidence of possible ice has been discovered by the Clementine Bistatic Experiment and the Lunar Prospector.
In topographically high areas, which receive continuous sunlight, temperatures could remain constant at around 220K, making them ideal sites for extended surface operations.
Heat flow measurements made during the Apollo 15 and 17 missions (Langseth et al. 1973) revealed that the top 1-2 cm of lunar regolith has extremely low thermal conductivity. The mean temperature measured 35cm below the surface of the Apollo sites was 40-45K warmer than the surface. At a depth of 80cm the day/night temperature variation experienced at the surface was imperceptible. This implies that habitations in the lunar subsurface exist that are not subject to the harsh temperature extremes prevalent on the surface.
The Diviner team will produce and archive a range of data products. These include low-level products derived from instrument telemetry (Level 0); calibrated data with associated geometry (Level 1); and higher-level data products that include gridded temperatures (Level 2); and derived fields such as thermal inertia, rock abundance, and mineralogy that will be created with the aid of topographic data and models (Level 3). Additionaly, the Diviner team will provide specialized data products relating to permanently shadowed regions at the lunar poles (Level 4). These products will be made available to the public online through this web site, and archived through the Geosciences Node of NASA's Planetary Data System.
|Diviner Data Product Level||Description||Archive Delivery Schedule||Size (bytes)|
|Pre-Flight Calibration Data||Pre-flight calibration data (Spectral Response, Blackbody Response, Solar Target Reflectance, Fields of View)||Pre-Launch||<1.00e10|
|Level 0||Depacketized time-sequenced raw science and housekeeping data||Best-available data maintained, archived 6 months after receipt||5.47e+11|
|Level 1||Calibrated radiances and housekeeping data merged with project-supplied geometry and timing information||Best-available data maintained, archived 6 months after receipt||9.86e+12|
|Experimenter's Notebook||Chronological text description of instrument operation and performance||6 months after receipt||<1.00e+06|
|Level 2||Gridded (Lat, Lon, Local time) global surface temperature||Best-available data maintained, archived 5 months after first complete year of mapping orbit||1.20e+09|
|Level 2*||Gridded (Lat, Lon, Local time) global surface temperature and annual max, min and average surface temperature in queryable online database||Best-available version available online - updated monthly, but not archived||1.20e+08|
|Level 3||Gridded derived global fields: Lambert albedo, fine component thermal inertia, anisothermality, rock abundance, silicate mineralogy||Best-available data maintained, archived 5 months after first complete year of mapping orbit||8.80e+08|
|Level 3*||Gridded derived global fields: Lambert albedo, fine component thermal inertia, anisothermality, rock abundance, silicate mineralogy in queryable online database||Best-available version available online, updated monthly but not archived||8.80e+08|
|Level 4||Polar resource products: maps of permanently shadowed regions, localized maps of derived surface and subsurface temperatures, illumination levels, water ice near-infrared reflectance maps for all regions potentially containing cold-trapped volatiles||Best-available data maintained, archived 6 months after first complete year of mapping orbit||4.20e+09|
The Diviner Lunar Radiometer Experiment is funded by NASA through the Lunar
Reconnaissance Orbiter Project at NASA Goddard.
The instrument is built and operated by JPL.