Mars CTX Controlled Equatorial Mosaics

Originators

Stuart Robbins, Michelle R. Kirchoff, Rachael H. Hoover

Publisher

USGS Astrogeology Science Center

Publication Date

2023-12-20

Abstract

This product is a cartographically controlled mosaic of Mars Charts (MC) 08 through 23, covering 50.0 percent of Mars' surface, from -30 deg N to +30 deg N latitude and 0–360 deg E longitude. The images come from NASA's Mars Reconnaissance Orbiter's Context Camera (CTX), which has been returning 5–6 meters per pixel images of Mars since 2008. This product was produced using automated cartographic control network code that was then manually edited. It includes data through the Mars Reconnaissance Orbiter CTX PDS release 56, with some regions containing data through release 57 or 58. The control network code incorporated all usable images in that release, and there were roughly 70,000 images that met our quality requirements. Those images cover 98.9 percent of the surface area of the region. The mosaic was produced by priority-ordering images in an automated method that emphasized Spring/Autumn images, images with an emission or slew angle closest to 0 deg, and images with the best pixel scale. The mosaic order was manually edited where severe discontinuities were observed due seasonal issues or when low signal-to-noise images were emphasized. The mosaic was further cosmetically corrected to produce the appearance of an approximately similarly illuminated product throughout. The final network has 2.4 million tie points, and 99.92 percent of them have residuals ≤1 pixel. RMS ground point uncertainty is 4.7 m in latitude, 9.3 m in longitude, and 180.1 m in radius. The full equatorial mosaic was split into 16 quads to help with downloads and follow the traditional 30 1:5M Mars Charts. See files for download from this link. The use of a free application like "wget" is recommended for downloading.
Citation: Robbins, S. J., Kirchoff, M. R., and Hoover, R. H. (2023). Fully controlled 6 meters per pixel equatorial mosaic of Mars from Mars Reconnaissance Orbiter Context Camera images, version 1. Earth and Space Science, 10, e2022EA002443, URL: https://doi.org/10.1029/2022EA002443.
References: Robbins, S.J., et al. (2020), Empirical Brightness Control and Equalization of Mars Context Camera Images, Earth and Space Science, Volume 7, DOI: 10.1029/2019EA001053, URL: https://doi.org/10.1029/2019EA001053. Robbins, S.J. et al. (2020), Fully Controlled 6 meters per pixel Mosaic of Mars’ South Polar Region, Earth and Space Science, Volume 7, Issue 10, DOI: 10.1029/2019EA001054, URL:https://doi.org/10.1029/2019EA001054.

Purpose

We have improved our previous almost completely automated methods, and we have applied it to 50 percent of Mars' surface in a band around the equator. There are over 50, 000 images included in the mosaic, and the mosaic itself is 2.11 trillion pixels, rendered at 6 m per pixel. The average uncertainty of pixel location is now about 5 m, about 100 times better than when based on Earth tracking.

Contact and Distribution

Format

Raster Data, Regional Mosaic, Remote-sensing Data

Access Constraints

please cite authors

Access Scope

PDS

Use Constraints

public domain

Edition

1

Edition Name

version

Native Data Set Environment

ISIS v3

Astrogeology Theme

Geographic Information System (GIS), Geomorphology, Image Processing, Remote Sensing

Mission Names

Mars Reconnaissance Orbiter

Instrument Names

CTX

Online Package Link

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

External File Size

files: ~300 GB each at 6m

Online File Link

https://asc-pds-services.s3.us-west-2.amazonaws.com/mosaic/Mars/Mars_MRO_CTX_Equi_Mosaics_Robbins/index.html

Access Instructions

This mosaic is available as tiled into 16 large quads using a positive 16bit bit range. We recommend a GIS application or Image Reader capable of reading very large images needed for viewing images and a SPICE reader for reading SPICE kernel data. Using a free download application like "wget" is recommended. Internally the quads were produced as cloud-optimized GeoTiffs (COGs) which means they are compressed with internal pyramids. Thus these files can be streamed to some GIS applications without download.

Contact Address

2255 N. Gemini Drive

Contact City

Flagstaff

Contact State

AZ

Contact Postal Code

86001

Contact Email

astroweb@usgs.gov

Currentness Reference

Publication date

Progress

In Work

Update Frequency

As needed

Logical Consistency

The final network has 2.4 million tie points, and 99.92 percent of them have residuals < 1 pixel. RMS ground point uncertainty is 4.7 m in latitude, 9.3 m in longitude, and 180.1 m in radius.

Process Description

We developed an efficient, accurate workflow within ISIS3 (USGS's Integrated Software for Imagers and Spectrometers v3), driven by Python scripts, to automate much of the control process to create a fully controlled CTX dataset. We have now applied this to half of Mars' surface area, spanning the full 360° of longitude and between -30 to 30 deg latitude.

Source Online Linkage

https://pds-imaging.jpl.nasa.gov/portal/mro_mission.html

Source PDS Archive

Mars Reconnaissance Orbiter

PDS Status

Locally Archived

Horizontal Positional Accuracy Report

Accurate to Control Net

Geospatial Information

Target

Mars

System

Mars

Minimum Latitude

-30

Maximum Latitude

30

Minimum Longitude

-180

Maximum Longitude

180

Direct Spatial Reference Method

Raster

Object Type

Grid Cell

Raster Row Count (lines)

281309

Raster Column Count (samples)

444560

Bit Type (8, 16, 32)

16

Quad System

Mars 1:5M

Quad Name

MC-8, MC-9, MC-10, MC-11, MC-12, MC-13, MC-14, MC-15, MC-16, MC-17, MC-18, MC-19, MC-20, MC-21, MC-22, MC-23

Radius A

3396190

Radius C

3396190

Control Net

MOLA

Bands

1

Pixel Resolution (meters/pixel)

6

Scale (pixels/degree)

9879.1

Map Projection Name

Simple Cylindrical

Latitude Type

Planetocentric

Longitude Direction

Positive East

Longitude Domain

-180 to 180