Instrument Specifications

Diviner is a nine channel infrared filter radiometer based on the design of the Mars Reconnaissance Orbiter Mars Climate Sounder (MCS). Diviner's nine channels distributed between two identical, boresighted telescopes (A and B). An articulated elevation/azimuth mount allows the telescopes to view the lunar surface, space, and calibration targets. The instantaneous field-of-view (FOV) response of each channel is defined by a linear, 21-element, thermopile detector array at the telescope focal plane, and its spectral response is defined by a focal plane bandpass filter.

Instrument Type: Infrared and Solar Radiometer
Spectral Range and Number of Channels: 0.3 to 400 μm in nine spectral channels
Telescopes: Two identical 3-mirror, off-axis, f/1.7 telescopes with 4 cm apertures
Detectors: Nine 21-element linear arrays of uncooled thermopile detectors
Pixel Size: 240 x 480 μm
Fields of View: Detector Geometric IFOV:
  • 6.7 mrad in-track
  • 3.4 mrad cross-track
  • 320 m in-track for 50 km altitude
  • 160 m cross-track for 50 km altitude
Swath Width (center to center of extreme pixels):
  • 67 mrad; 3.4 km for 50 km altitude
Instrument Articulation: Two-axis azimuth/elevation, range 270°, resolution 0.1°
Observation Strategy: Nadir pushbroom mapping

Spectral Channels

Diviner includes two broad-band solar reflectance channels, three mineralogy channels and four thermal channels. The solar channels have identical spectral response, but different sensitivies for wide dynamic range. The three mineralogy channels are intended to map the wavlength peak of the Christiansen thermal emission spectral feature, which is diagnostic of silicate mineralogy (Greenhagen and Paige, 2006). The four broad thermal channels are intended to characterize the surface thermal emission over a wide range of temperatures, as well as the presence of anisothermal emission due to the presence of slopes, shadows and rocks with Diviner's field of view. In channels B2 and B3, Diviner's minimum detectable temperature is less then 30K. Diviner's mineralogy channels should allow confident determination of the wavelength peak of the Christiensen feature at temperatures above 300K.

Telescope/Channel Number Bandpass (ηm) Function
A1 0.3-3.0 High Sensitivity Solar
A2 0.3-3.0 Low Sensitivity Solar
A3 7.80±0.25 Mineralogy
A4 8.20±0.22 Mineralogy
A5 8.60±0.20 Mineralogy
A6 12.5-25 Thermal
B1 25-50 Thermal
B2 50-100 Thermal
B3 100-200 Thermal

Mapping Configuration

mapping configuration

During the LRO mapping mission, Diviner will operate continuously obtaining 189 separate radiometric measurements every 0.128 seconds. Diviner will normally map the lunar surface in pushbroom nadir orientation, with periodic space, blackbody and solar target calibrations. For an orbital elevation of 50 km above the lunar surface, the width of Diviner's mapping swath will be approximately 3.75 km. The nominal instantaneous field of view of each detector will be approximately 179x307 meters. Diviner's surface fields of view will be reconstructed to a one-sigma accuracy of less than 500 meters. Since the LRO orbit is fixed in inertial space, so Diviner will acheive full diurnal coverage after half a year of continuous mapping, Diviner will achieve nearly complete spatial coverage of the surface of the moon, with significant spatial overlap in the polar regions. However, Diviner's coverage will not be sufficient to observe the entire moon at all times of day, which will imply widening gores in Diviner's spatial coverage as more stringent time of day constraints are applied. If full diurnal coverage is defined as measurements at six random times of day, Diviner will achieve full diurnal coverage poleward of 80 degrees latitude after one year of mapping. If nighttime coverage is defined as measurements within 5 hours local midnight, then Diviner will obtain nighttime coverage over 75% of the of the moon at the equator, and 100% of the the moon poleward of 70 degrees. Also in one year of mapping, Diviner will obtain mineralogy measurements for surfaces above 300K over 70% of the moon from the equator to 70 degrees latitude.

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.

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