DOI: 10.25573/data.26218523
title: Earth-Based 70-cm Wavelength Radar Maps of the Moon

description: This archive contains Earth-based, 70-cm wavelength, dual-polarization radar data collected using the Arecibo and Green Bank Telescopes between 2003 and 2009. Earth-based data represent the only view of the Moon at this wavelength. An improved synthetic aperture focusing methodology yields the best possible spatial resolution, with a concurrent improvement in signal-to-noise ratio and multi-look summing. Image coverage is also expanded to the full illuminated beam area. These data will supersede maps currently archived with the Geoscience Node of the NASA Planetary Data System (PDS). Each map represents one-two days of observations (3-9 looks) where the beam is centered on a target point on the Moon.The two circular polarization modes are designated as OCP (opposite sense polarization) and SCP (same sense polarization). The circular polarization ratio (CPR) is defined as SCP/OCP power.Most maps use an image base of a simple cylindrical projection, sampled at 400 m per pixel at the equator, that is co-registered to the LROC-WAC mosaic. Each map is 15166 columns by 13650 rows, corresponding to the area from 100W to 100E, 90N to 90S. Individual radar maps fill only a fraction of the nearside, but the common format allows straightforward summing of data from multiple maps with small offset shifts. Maps of the two polar regions are in stereographic projection, also co-registered to a 400-m WAC mosaic.There are no PDS or other file labels.Both 32-bit images in units of power signal-to-noise ratio (SNR) corrected for the antenna beam pattern, and 8-bit browse TIFF images also normalized to the cosine of the incidence angle, are included. An 8-bit browse TIFF of the circular polarization ratio (scaled from 0.0-2.0) is also included. Note that the SNR values reflect the transmitted power, system thermal noise, and number of independent radar looks, so significant differences in brightness do occur between maps (e.g., between "Mitchell" and "Jura").Supporting files contain 32-bit values of the incidence angle and radar beam pattern angle for each pixel. These can be used to apply different correction schemes to the observed power. Beam pattern corrections applied here are estimates, and the margins of the illuminated areas can have erroneous brightening or darkening that also affects the CPR.An Excel table contains the information for each of the looks averaged into any map, including the sub-radar point latitude and longitude, limb-limb bandwidth, and Doppler angle positive-clockwise with respect to north-south.Each radar image has also been exported as a geotiff, suitable for ingestion into a GIS framework (e.g., ArcPro). OCP and SCP data are available in 8-bit tiffs, while 32-bit versions are available for SCP, OCP, CPR, incidence angle, and beam angle.All non-polar tiffs are projected in a Simple Cylindrical projected coordinate system centered on 0° longitude. The polar images (Byrd for the north pole, Spole for the south pole) are projected into a North or South Pole Stereographic projection with a central latitude of 90° or -90°. All projections use a geographic coordinate system assuming a spherical radius of 1737400 m (“GCS_MOON” or “GCS Moon 2000” in ArcGIS).In 32-bit SCP and OCP files, a flag/no data value of -60 has been assigned. In all other files, the value is set to 0.GEO-TIFF versions of the 8-bit image files are available at: https://smithsonian.figshare.com/articles/dataset/Earth-Based_70-cm_Wavelength_Radar_Maps_of_the_Moon_-_8-bit_GEOTIFFS/30234610NASA Planetary Data System (Geoscience Node) Archive of Earlier Processing: https://pds-geosciences.wustl.edu/missions/lunar_radar/index.htmPublications to Cite in Using this Dataset:Campbell, B.A., D.B. Campbell, J.L. Margot, R.R. Ghent, M. Nolan, J. Chandler, L.M. Carter, N.J.S. Stacy (2007). Focused 70-cm radar mapping of the Moon. IEEE Trans. on Geoscience and Remote Sensing, 45(12), 4032-4042, doi:10.1109/TGRS.2007.906582Campbell, B.A., Jawin, E.R., Morgan, G.A. (2024). Refined Earth-based lunar radar maps and a new interpretation of the Cruger-Sirsalis cryptomare. Icarus, 116234. https://doi.org/10.1016/j.icarus.2024.116324.