Venus Magellan Global Fresnel Reflectivity 4641m

Primary Authors

Magellan Team

Originators

Peter Ford, Gordon Pettengill, Fang Liu, Joan Quigley

Publisher

USGS Astrogeology Science Center

Abstract

Product Information: Global Reflectivity Data Record (GREDR). The power reflection coefficients are derived by fitting altimeter echoes from the fan-beam altimetry antenna as a function of time to Hagfors' radar backscatter model templates. The values are then corrected for the presence of multiple echo peaks and further corrected for diffuse scattering using backscatter data obtained by the side-looking mode of the Magellan radar. The reflectivities are then filtered to remove low-frequency instrument calibration errors, and re-sampled at a resolution of about 5x5 kilometers per pixel. Each GREDR image pixel is represented by a 8-bit unsigned integer. Pixels lying outside the domain of the projection are set to NoData (0). In all images, pixels with unknown or unmeasured values are also set to NoData. The remaining values are related to the reflectivity by the following equation: DN = (REFLECTIVITY * 200) + 1 Note: There exist photoproducts that are identified as GxDRP (where x is E (Emissivity), S (Slope), RE (Reflectivity), or T (Topography)) however, they are not generated from the digital GxDR products. They are instead produced from the Magellan ARCDR (Altimetry and Radiometry Composite Data Record) data files. Mission and Instrument Information: The Magellan Mission to Venus launched on May 4, 1989 on board the Space Shuttle Atlantis. The spacecraft arrived at Venus on August 10th, 1990 and was inserted into a near-polar elliptical orbit. The primary mission requirements were to map at least 70% of the surface at a resolution better than 300 meters/pixel and to determine the global relief at such a resolution as to facilitate detailed analysis of tectonic, volcanic, eolian, and impact features. Magellan successfully completed four mapping cycles at Venus. The first mapping cycle lasted from mid-September 1990 to mid-May 1991 focused on fulfilling the primary mission requirements. The second mapping cycle was from mid-May 1991 to mid-January 1992 and was dedicated to filing in gaps in the cycle 1 coverage and obtaining coverage of the south polar region; this cycle resulted in 54% of surfaced coverage and increased the cumulative coverage of the mission to 96%. Cycle 3 was from mid-January to mid-September 1992 and focused on acquiring stereo image coverage; this cycle resulted in about 21% surface coverage and increased total surface coverage to 98%. Cycle 4 was dedicated to gravity observations and as such did not add to the cumulative coverage of imagery taken by the spacecraft (Ford et al., 1993). References: Ford, J. P., et al. (1993). Guide to Magellan Image Interpretation. JPL Publication 93-24 pp. 1-18. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940013181.pdf Ford, P. G. (1991). Global Altimetry and Radiometry Data Records, MIT-MGN-GxDR SIS Version 2.3, 40 p. Software Interface Specification Document (included on GxDR CD-ROMs.)

Purpose

Derived Magellan product to display Fresnel Reflectivity

Contact and Distribution

Format

Global Mosaic, Remote-sensing Data

Access Constraints

public domain

Access Scope

PDS

Use Constraints

Please cite authors

Edition

1

Supplemental Information

http://pds-geosciences.wustl.edu/missions/magellan/gxdr

Native Data Set Environment

ISIS v3

Astrogeology Theme

Image Processing, Remote Sensing

Mission Names

Magellan

Instrument Names

SAR

Online Package Link

https://astrogeology.usgs.gov/search/map/venus_magellan_global_fresnel_reflectivity_4641m

External File Size

33 MB

Online File Link

https://planetarymaps.usgs.gov/mosaic/Venus_Magellan_FresnelReflectivity_Global_4641m.tif

Contact Address

2255 N. Gemini Drive

Contact City

Flagstaff

Contact State

AZ

Contact Postal Code

86001

Contact Email

astroweb@usgs.gov

Progress

Complete

Update Frequency

None planned

Process Description

This archive was produced by Jason Hyon. Mike Martin (JPL), Gail Woodward (JPL), Peter Ford (MIT), Robert Mehlman (UCLA), and Jason Hyon (JPL) designed the PDS labels and the tables. Florence Moss (JPL) and Jason Hyon developed the software to generate the PDS labels and tables. Raymond Arvidson and Gail Woodward created the catalog templates, with help from Pam Woncik (JPL), Mary Dale-Bannister (Washington University), and Susan Slavney (Washington University). The data and documentation were generated at MIT by Peter Ford, Gordon Pettengill, Fang Liu, and Joan Quigley from data supplied by the Magellan Project. Please direct any questions and comments to the PDS Geosciences Node, geosci@wunder.wustl.edu.

Lineage

Process Date

1993-06-23

Source Title

Magellan Global Topography, Emissivity, Reflectivity, and Slope Data Record (GXDR)

Source Online Linkage

{http://pds-geosciences.wustl.edu/mgn/mgn-v-gxdr-v1/mg_3002/gredr/,http://pds-geosciences.wustl.edu/missions/magellan/index.htm,http://pds-imaging.jpl.nasa.gov/portal/magellan_mission.html}

PDS Status

PDS 3 Archived

Geospatial Information

Target

Venus

Minimum Latitude

-90

Maximum Latitude

90

Minimum Longitude

-180

Maximum Longitude

180

Direct Spatial Reference Method

Raster

Object Type

Grid Cell

Raster Row Count (lines)

4097

Raster Column Count (samples)

8193

Bit Type (8, 16, 32)

8

Quad Name

Radius A

6051000

Radius C

6051000

Bands

1

Pixel Resolution (meters/pixel)

4641.0588

Scale (pixels/degree)

22.755555917149

Map Projection Name

Simple Cylindrical

Latitude Type

Planetocentric

Longitude Direction

Positive East

Longitude Domain

-180 to 180