This readme file was generated on 2024-06-14 by Zoe Learner Ponterio GENERAL INFORMATION Title of Dataset: Cassini Synthetic Aperture RADAR Digital Map Products of Titan Dataset Author/Principal Investigator Information Name: Randolph L. Kirk ORCID: https://orcid.org/0000-0003-0842-9226 Institution: United States Geological Survey Address: 2255 N. Gemini Dr., Flagstaff, AZ 86001 Email: rkirk@usgs.gov Author/Associate or Co-investigator Information Name: Alexander Hayes ORCID: https://orcid.org/0000-0001-6397-2630 Institution: Cornell University Address: 412 Space Sciences Building, Cornell University, Ithaca, NY 14853 Email: hayes@astro.cornell.edu Author/Alternate Contact Information Name: Zoe Learner Ponterio ORCID: https://orcid.org/0000-0001-9844-2146 Institution: Cornell University Address: 317 Space Sciences Building, Cornell University, Ithaca, NY 14853 Email: zap9@cornell.edu Date of data collection: 2004-07-01 - 2017-09-15 Geographic location of data collection: In orbit around Saturn, flybys of Titan Information about funding sources that supported the collection of the data: National Aeronautics and Space Administration, Cassini Spacecraft Mission SHARING/ACCESS INFORMATION Licenses/restrictions placed on the data: The Titan SAR datasets will be shared under a Creative Commons Universal Public Domain Dedication (CC0 1.0, https://creativecommons.org/publicdomain/zero/1.0/); the data will be openly available for re-use, modification and distribution; proper attribution to the original data creators is appreciated. Links to publications that cite or use the data: This dataset is the entirety of the Cassini RADAR data on Saturn’s moon Titan, and so all publications on this topic use this dataset. The “Cassini RADAR Users Guide” can be found here: https://pds-imaging.jpl.nasa.gov/documentation/Cassini_RADAR_Users_Guide_2nd_Ed_191004_cmp_200421.pdf Links to other publicly accessible locations of the data: https://data.astro.cornell.edu/RADAR/ Links/relationships to ancillary data sets: RADAR telemetry was extracted from the Cassini Distributed Object Manager (DOM) and processed at Jet Propulsion Laboratory (JPL) to produce time-ordered RADAR frames (“Level 0”). For routine processing, the data extraction occurred after the project produced the best possible filled and cleaned telemetry files, approximately 2 days after downlink. These Level-0 data were then further processed to produce three types of Cassini RADAR data products: Burst-Ordered Data Products (BODPs) (Level 1), Basic Image Data Records (BIDRs) (Level 2), and this dataset, the Digital Map Products (DMPs). [S. D. Wall et al., Cassini RADAR Users Guide, 2019] All datasets other than the DMPs are found here: https://pds-imaging.jpl.nasa.gov/volumes/radar.html Other related Cassini Titan datasets Mosaic of SAR Swaths of Saturn’s Moon Titan for the North Polar Region https://doi.org/10.7298/smda-t742 Mosaic of SAR Swaths of Saturn’s Moon Titan for the South Polar Region https://doi.org/10.7298/2bdt-p498 Mosaic of SAR Swaths of Saturn’s Moon Titan for the Equatorial Region, Quadrant 1 https://doi.org/10.7298/s709-7w42 Mosaic of SAR Swaths of Saturn’s Moon Titan for the Equatorial Region, Quadrant 2 https://doi.org/10.7298/4az4-gk54 Mosaic of SAR Swaths of Saturn’s Moon Titan for the Equatorial Region, Quadrant 3 https://doi.org/10.7298/vaaf-sy65 Mosaic of SAR Swaths of Saturn’s Moon Titan for the Equatorial Region, Quadrant 4 https://doi.org/10.7298/fz1q-ya32 SAR-Topo Derived Digital Topographic Models of Saturn’s Moon Titan https://doi.org/10.7298/m4dv-gv95 Recommended citation for this dataset: Cassini RADAR Science Team, 2019, Cassini SAR Digital Map Products of Titan DATA & FILE OVERVIEW File List: Cassini_Titan_SAR_DMP_01.zip Cassini_Titan_SAR_DMP_02.zip Cassini_Titan_SAR_DMP_03.zip Cassini_Titan_SAR_DMP_04.zip Cassini_Titan_SAR_DMP_05.zip Cassini_Titan_SAR_DMP_06.zip Cassini_Titan_SAR_DMP_07.zip Cassini_Titan_SAR_DMP_08.zip Cassini_Titan_SAR_DMP_09.zip Cassini_Titan_SAR_DMP_10.zip Relationship between files, if important: This dataset contains seven of the eight Digital Map Product (DMP) data sets produced: the Global Radiometry Data Record (GRDR), Global Scatterometry Data Record (GSDR), Global Topography Data Record (GTDR), and Mosaicked Image Data Record (MIDR) products are mosaics of data from multiple observation segments. The Pass Radiometry Data Record (PRDR) and Pass Scatterometry Data Record (PSDR), and Repeat Image Data Record (RIDR) have a separate set of files for each segment. The Global Radiometry Data Record (GRDR) is a mosaic of gridded radiometric brightness temperature data (corrected to normal emission) assembled from the complete set of individual PRDR products. Cassini_Titan_SAR_DMP_01 contains: GRDR - Mosaicked or modeled multipass radiometer data GSDR - Mosaicked multipass scatterometer data GTDR - Mosaicked altimetric and SAR topographic data MIDR - Mosaicked multipass SAR image data PRDR - Calibrated and gridded single-pass radiometer data PSDR - Calibrated and gridded single-pass scatterometer data The remaining files are the RIDR (coregistered multilook SAR image sets), each covering different sectors on Titan’s surface, centered on the specified latitude/longitude coordinates Cassini_Titan_SAR_DMP_02: 0N 36E, 0N 108E Cassini_Titan_SAR_DMP_03: 0N 180E, 0N 252E, 0N 324E Cassini_Titan_SAR_DMP_04: 43N 45E, 43N 135E Cassini_Titan_SAR_DMP_05: 43N 225E, 43N 315E Cassini_Titan_SAR_DMP_06: 43S 45E, 43S 135E, 43S 225E, 43S 315E Cassini_Titan_SAR_DMP_07: 78N 180E Cassini_Titan_SAR_DMP_08: 78S 180E Cassini_Titan_SAR_DMP_09: 90N 0E Cassini_Titan_SAR_DMP_10: 90N 0E Additional related data collected that was not included in the current data package: Stereo DTM products https://doi.org/10.7298/m4dv-gv95 Other SAR products Burst-Ordered Data Products (BODPs), Basic Image Data Records (BIDRs) Are there multiple versions of the dataset? No METHODOLOGICAL INFORMATION Description of methods used for collection/generation of data: The Cassini RADAR instrument transmitted and received Ku-band microwave radiation. It operated in both passive (radiometer) and active modes. In active mode, the RADAR measured the energy returned by the target surface from the transmitted signal. Transmitted energy was linearly polarized, with the electric field vector parallel to the spacecraft X-axis, which was in (or opposite to) the direction of motion during the flyby. Received energy was similarly polarized. Therefore the polarization characteristic in the Synthetic Aperture RADAR (SAR) images is “like” and close to what is generally called “HH” for horizontal transmitting, horizontal receiving (see, e.g., Elachi and VanZyl 2006). Strictly speaking, it was exactly HH only at closest approach, where the spacecraft X-axis was truly along/against the velocity vector. Moving away from closest approach, pointing deviated from precise side-looking, so the polarization became a mixture of HH and VV (for vertical transmitting, vertical receiving), although the deviation from HH is small, in the -10–min to +10–min time range around closest approach. In the outer parts of the targeted SAR swath, a technique called “pushbroom” (Stiles et al. 2006) was used to extend the swath, and thus the polarization departs rapidly from 0 degrees and the polarization also becomes a mixture of VV and HH. Ride-along SAR and HiSAR images also have significant departures from HH polarization. Note also that in some observation modes the spacecraft was rotated about the Z axis to accommodate other instruments’ pointing needs. Users should refer to the polarization angle reported in the Short-Burst Data Record (SBDR). Ground processing of SAR data separated the received energy by round-trip time and Doppler shift. The return energy was used to determine the normalized radar crosssection (NRCS, often written as “?0” or “?0”) of the surface. NRCS is the ratio of the energy received to that which one would expect from a uniform scatterer (Ulaby et al. 1982). This quantity is related to the roughness at the scale of the wavelength of the transmitted signal (2.2 cm, Ku-band; see Elachi et al. 2004) and the dielectric constant of the surface. It is also affected by the angle at which the radar beam impinges the surface and thus is modulated by the larger-scale shape of the surface. Such effects can depend upon both the incidence and azimuth of the observation, yielding variation in NRCSs that are correlated with topographical features in RADAR imagery (e.g., lakes, mountains, rivers, dunes, etc.). Because return energy can be binned by delay and Doppler shift, one can produce geolocated SAR imagery and/or estimates of surface height depending upon the viewing geometry. Different signal bandwidths could be used to optimize the measurement of (1) precise NRCS quantities in scatterometer mode, (2) surface heights in altimetry mode, and (3) geolocated high-resolution imagery in SAR mode. Depending upon the accuracy of spacecraft attitude information (among other error sources), obtaining SAR imagery and surface height information simultaneously was also possible in some cases. In passive mode, the Cassini RADAR instrument measured the linearly polarized radiant power received through the antenna in a bandpass coincident with but much wider that the radar signal receiver. Passive measurements were acquired in all operational modes of the RADAR instrument. All radiant power observed in the Saturn system is thermal in origin. In the microwave region, the power radiated by a thermal blackbody emitter is very nearly proportional to its physical temperature, and it is common usage to describe this power, whatever the source, in terms of the temperature of a blackbody that emits the equivalent power. Hence passive microwave measurements were reported in kelvins. In particular, the power collected by the antenna is called the “antenna temperature.” For an ideal antenna with a pencil beam and no sidelobes, the antenna temperature is the same as the “brightness temperature,” or equivalent blackbody temperature, of the source observed in the beam of the antenna. In practice, and particularly for Cassini, the process of obtaining calibrated brightness temperatures from antenna temperature measurements is not straightforward, and caution must be exercised in the interpretation of all antenna temperature data reported from the Cassini RADAR radiometer. The RADAR instrument collected, returned, digitized, and delivered digital data to the spacecraft. Together with other instruments’ data, they were stored on the spacecraft solid-state recorder (SSR) and downlinked, generally at the next scheduled communication opportunity with a DSN complex (Imbriale 2003), where digital data were extracted and returned to the Cassini operations center at Jet Propulsion Laboratory (JPL). There, individual instrument data were separated and stored on the Cassini Distributed Object Manager (DOM). RADAR telemetry was extracted from the Cassini DOM and processed at JPL to produce time-ordered RADAR frames (“Level 0”). For routine processing, the data extraction occurred after the project produced the best possible filled and cleaned telemetry files, approximately 2 days after downlink. [S. D. Wall et al., Cassini RADAR Users Guide, 2019] Additional information can be found in the “Cassini RADAR Users Guide”: https://pds-imaging.jpl.nasa.gov/documentation/Cassini_RADAR_Users_Guide_2nd_Ed_191004_cmp_200421.pdf Kirk, R. & Becker, T. & Garcia, P. & Barrett, Janet & Stiles, B. & Le Gall, A. & Janssen, M. & Wye, Lauren & Zebker, H.. (2010). Titan Digital Map Products from the Cassini RADAR in the NASA Planetary Data System. https://www.researchgate.net/publication/241356014_Titan_Digital_Map_Products_from_the_Cassini_RADAR_in_the_NASA_Planetary_Data_System Methods for processing the data: The USGS cartographic system Integrated Software for Imagers and Spectrometers (ISIS) is used for this processing, augmented by the commercial stereoanalysis package Softcopy Exploitation Toolkit (SOCET SET) for production of stereo topographic maps. [S. D. Wall et al., Cassini RADAR Users Guide, 2019] Additional information can be found in the “Cassini RADAR Users Guide”: https://pds-imaging.jpl.nasa.gov/documentation/Cassini_RADAR_Users_Guide_2nd_Ed_191004_cmp_200421.pdf Instrument- or software-specific information needed to interpret the data: ArcGIS: Reads Integrated Software for Imagers and Spectrometers (ISIS) .cub files (which are very similar to PDS images), but does not support all projections. Specifically, RADAR's oblique cylindrical projections are not supported unless the plug-in PDS2ISIS is run (images may be loaded, but they must be reprojected to access the cartographic capabilities). Environment for Visualizing Images (ENVI): Tested with 32-bit BIFQ and 8-bit BIBQ RADAR formats. Fiji/ImageJ: ImageJ is now called Fiji (for “Fiji is just ImageJ”). It reads PDS, ISIS 2, and ISIS 3 (only BSQ—not tiled—formats) with plug-ins. ISIS 3: ISIS 3 is the standard tool to analyze RADAR data files, and has step-by-step tutorials (http://isis.astrogeology.usgs.gov/IsisWorkshop/index.php/Working_with_Cassini_RADAR) on how to process RADAR data. MATLAB: Can read the images using any number of readers that have been submitted to the public File Exchange (https://www.mathworks.com/matlabcentral/fileexchange/). Photoshop: Photoshop will read the 8-bit BIBQ after the correct dimensions and label length have been input. QGIS: Reads ISIS .cub files (which are very similar to PDS images), but does not support all projections. Specifically, RADAR's oblique cylindrical projections are not supported unless the plug-in PDS2ISIS is run (images may be loaded, but they must be reprojected to access the cartographic capabilities). [S. D. Wall et al., Cassini RADAR Users Guide, 2019] Additional information can be found in the “Cassini RADAR Users Guide”: https://pds-imaging.jpl.nasa.gov/documentation/Cassini_RADAR_Users_Guide_2nd_Ed_191004_cmp_200421.pdf Standards and calibration information, if appropriate: Complete description of the radar calibration: West et al. (2009) Scatterometry calibration: Wye et al. (2007d) Radiometer calibration: Janssen et al. (2009, 2017) Environmental/experimental conditions: Outer space, in orbit around Saturn, flybys of Titan, Titan’s atmosphere and surface (remote only) Describe any quality-assurance procedures performed on the data: Digital Map Products will be validated for both scientific integrity and compliance with Planetary Data System standards. Validation is the responsibility of the Cassini Science Archive Working Group Data Validation Team and the Cassini RADAR Science Team. [S. D. Wall et al., Cassini RADAR Users Guide, 2019] People involved with sample collection, processing, analysis and/or submission: Cassini RADAR Science Team