Pre-flight and On-orbit Geometric Calibration of the Lunar Reconnaissance Orbiter Camera

Abstract

The Lunar Reconnaissance Orbiter Camera (LROC) consists of two imaging systems that provide multispectral and high resolution imaging of the lunar surface. The Wide Angle Camera (WAC) is a seven color push-frame imager with a 90 • field of view in monochrome mode and 60 • field of view in color mode. From the nominal 50 km polar orbit, the WAC acquires images with a nadir ground sampling distance of 75 m for each of the five visible bands and 384 m for the two ultraviolet bands. The Narrow Angle Camera (NAC) consists of two identical cameras capable of acquiring images with a ground sampling distance of 0.5 m from an altitude of 50 km. The LROC team geometrically calibrated each camera before launch at Malin Space Science Systems in San Diego, California and the resulting measurements enabled the generation of a detailed camera model for all three cameras. The cameras were mounted and subsequently launched on the Lunar Reconnaissance Orbiter (LRO) on 18 June 2009. Using a subset of the over 793000 NAC and 207000 WAC images of illuminated terrain collected between 30 June 2009 and 15 December 2013, we improved the interior and exterior orientation parameters for each camera, including the addition of a wavelength dependent radial distortion model for the multispectral WAC. Electronic supplementary materialThe online version of this article (These geometric refinements, along with refined ephemeris, enable seamless projections of NAC image pairs with a geodetic accuracy better than 20 meters and sub-pixel precision and accuracy when orthorectifying WAC images.

Geometric Calibration of the Clementine Uvvis Camera Using Images Acquired by the Lunar Reconnaissance Orbiter

“…_______________________________ * Corresponding author Once in orbit, the LROC team conducted a focused investigation to geometrically calibrate each of the three cameras using images and data collected while in orbit. Using a series of retro reflectors emplaced during Apollo and Luna missions to the surface (Wagner et al, 2016), a temperature based pointing model was derived for the twin Narrow Angle Cameras (Speyerer et al, 2014). A subset of NAC images were later used to calibrate the internal and external orientation parameters of the LROC WAC.…”

“…A subset of NAC images were later used to calibrate the internal and external orientation parameters of the LROC WAC. With the improvement to the WAC orientation parameters, refined ephemeris derived with a new gravity model of the Moon (Mazarico et al, 2013;Lemoine et al, 2014), and a high-resolution topographic model (Scholten et al, 2012), WAC images can be orthorectified with an accuracy of 40 m without the use of ground control points (Speyerer et al, 2014). This enables the generation of regional multi-spectral maps with sub-pixel accuracy.…”

“…Using the latest LRO ephemeris provided by the Lunar Orbiter Laser Altimeter and Gravity Recovery and Interior Laboratory teams and the refined LROC camera model parameters, WAC images have a geodetic accuracy of better than 45 m (Speyerer et al, 2014). Therefore, the LROC WAC images can be directly used to tie the UVVIS images without the need to create large global control networks, such as the ones produced during the generation of the CLCN and ULCN 2005.…”

“…These statistics were later used to identify a systematic timing offset in the camera, temperature dependent pointing variations, as well as calculate new radial distortion coefficients and a more accurate focal length (Speyerer et al, 2014).…”

Enhancement of Spatial Resolution of the Lroc Wide Angle Camera Images

“…Image acquisition and calibration details for the cameras are detailed elsewhere , Speyerer et al, 2015, Robinson et al, 2010 and not repeated here. LROC observations are publicly accessed through the NASA Planetary Data System (PDS) (NASA, 2014).…”