Mars MGS MOLA - MEX HRSC Blended DEM Global 200m

Primary Authors

USGS Astrogeology Science Center

Originators

DLR, NASA, Goddard Space Flight Center

Publisher

USGS Astrogeology Science Center

Publication Date

2018-01-31

Abstract

Product Information: This data product, now at version 2, is a blend of digital elevation model (DEM) data derived from the Mars Orbiter Laser Altimeter (MOLA), an instrument aboard NASA's Mars Global Surveyor spacecraft (MGS), and the High-Resolution Stereo Camera (HRSC), an instrument aboard the European Space Agency's Mars Express (MEX) spacecraft. This was created in support of thermal modelling studies and product creation for Mars (Fergason et al., 2017; Laura & Fergason, 2016). Resolution is 200 meters per pixel (m). MOLA fired infrared laser pulses downward 10 times per second, and measured the time it took for the reflected pulses to return from the surface. The image used for the MOLA base of this map represents more than 600 million measurements gathered between 1999 and 2001. The average accuracy of each point is originally ~100 meters in horizontal position and the total elevation uncertainty is at least ±3 m. MOLA produced global topographic coverage with a spatial resolution of about 300 x 1000 m at the equator, and better near the poles. HRSC, the only dedicated stereo camera orbiting Mars, is a multi-sensor push broom instrument comprising 9 CCD line sensors mounted in parallel for simultaneous high-resolution stereo, multicolor and multi-phase imaging by delivering 9 superimposed image swaths. The HRSC design permits stereo imaging with triple to quintuple panchromatic along-track stereo including a nadir-directed, forward and aft-looking (+/-18.91), and 2 inner (+/-12.81) stereo line sensors. The along-track acquisition of stereo imagery avoids changes in atmospheric and illumination conditions. The sub-pixel accuracy of the three-dimensional point determination allows the derivation of digital elevation models DEMs with a grid size of up to 50 m and a height accuracy of a single pixel with up to 10 m. Mission and Instrument Information: Mars Global Surveyor was the first successful U.S. mission launched to Mars since the Viking mission in 1976 (Albee et al., 2001). MGS launched on November 7, 1996 atop a three-stage Delta II launch vehicle from launch pad 17A at Cape Canaveral Air Station, FL. The thirdstage Star 48B solid rocket later propelled the spacecraft out of Earth orbit and on its way to Mars. After a 20-year absence at the planet, MGS ushered in a new era of Mars exploration with its five science investigations (NASA JPL, 2010). MGS arrived at Mars in September 1997 and has contributed a multitude of findings, including signs of past, persistent water such as an ancient delta and currently active water features in the gullies of canyon walls. After nearly a decade of discovery, MGS went silent in November 2006 (NASA JPL, 2010). The MOLA created the most accurate global topographic map of any planet in the solar system, giving scientists elevation maps precise to within about 30 centimeters (1 foot) in the vertical dimension. Data from the laser altimeter identified pathways for the flow of past water and the locations, sizes, and volumes of watersheds. The instrument detected the heights of clouds and identified dynamic features in the atmosphere, such as gravity waves (NASA JPL, 2010). The MOLA showed seasonal changes in the height of the Martian surface (such as snow depth) that represented the first direct global measurement of the amount and distribution of condensed carbon dioxide. In June 2001, part of the laser reached the end of its life, but a sensor continued to detect changes in surface brightness in the near infrared part of the spectrum. These data provided evidence of cloud coverage and atmospheric variations (NASA JPL, 2010). The ESA launched Mars Express on June 2, 2003. At this time of year the positions of the two planets made for the shortest possible route, a condition that occurs once every 26 months. The spacecraft began its six-month journey from the Baikonur launch site in Kazakhstan on board a Russian Soyuz/Fregat launcher. Data collected by the orbiter instruments is transmitted to an ESA ground station at New Norcia near Perth, Australia, at a rate of up to 230 kbps. Between 0.5 and 5 Gbits of scientific data is transmitted from the spacecraft to Earth every day (ESA, 2010). The HRSC is imaging the entire planet in full color, 3D and with a resolution of about 10 meters. Selected areas will be imaged at 2-meter resolution. One of the camera's greatest strengths will be the unprecedented pointing accuracy achieved by combining images at the two different resolutions. Another will be the 3D imaging which will reveal the topography of Mars in full color (ESA, 2010). References: Albee, A. L., Arvidson, R. E., Palluconi, F., & Thorpe, T. (2001). Overview of the Mars Global Surveyor mission. Journal of Geophysical Research, 106(E10), 23291-23316. https://doi.org/10.1029/2000JE001306 European Space Agency (ESA) (2010). Mars Express. Mars Express Orbiter Instruments. https://www.esa.int/Science_Exploration/Space_Science/Mars_Express/Mars_Express_instruments Fergason, R. L., Laura, J. R., & Hare, T. M. (2017). THEMIS-Derived Thermal Inertia on Mars: Improved and Flexible Algorithm. Paper presented at 48th Lunar and Planetary Science Conference, Lunar and Planetary Institute, Houston, TX. https://www.hou.usra.edu/meetings/lpsc2017/pdf/1563.pdf Fergason, R. L., Christensen, P. R., & Kieffer, H. H. (2006). High-resolution thermal inertia derived from the Thermal Emission Imaging System (THEMIS): Thermal model and applications. Journal of Geophysical Research, 111(E12). https://doi.org/10.1029/2006JE002735 Laura, J., & Fergason, R. L. (2016). Modeling martian thermal inertia in a distributed memory high performance computing environment. Paper presented at Big Data, 2016 IEEE International Conference on Big Data, Washington, DC. https://doi.org/10.1109/BigData.2016.7840942 Jaumann, R., Neukum, G., Behnke, T., Duxbury, T. C., Eichentopf, K., Flohrer, J., Gasselt, S. V., et al. (2007). The high-resolution stereo camera (HRSC) experiment on Mars Express: Instrument aspects and experiment conduct from interplanetary cruise through the nominal mission. Planetary Space Science, 55(7-8), pp. 928-952. https://doi.org/10.1016/j.pss.2006.12.003 National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL) (2010). Mars Global Surveyor. https://mars.nasa.gov/mgs/overview/ Neukum, G., Jaumann, R., & HRSC Co-Investigator and Experiment Team (2004). HRSC: The High Resolution Stereo Camera of Mars Express. In Wilson, A. (Ed.), Mars Express: The scientific payload. (pp. 17-35). Noordwijk, The Netherlands: ESA. https://www.esa.int/esapub/sp/sp1240/sp1240web.pdf Neumann, G. A., Smith, D. E., & Zuber, M. T. (2003). Two Mars years of clouds detected by the Mars Orbiter Laser Altimeter. Journal of Geophysical Research, 108(E4), 5023. https://doi.org/10.1029/2002JE001849 Smith, D. E., Zuber, M. T., Frey, H. V., Garvin, J. B., Head, J. W., Muhleman, D. O., Pettengill, G. H., et al. (2001). Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars. Journal of Geophysical Research, 106(E10), 23689-23722. https://doi.org/10.1029/2000JE001364 Recommended citation: Fergason, R. L, Hare, T. M., & Laura, J. (2018). HRSC and MOLA Blended Digital Elevation Model at 200m v2. Astrogeology PDS Annex, U.S. Geological Survey. https://astrogeology.usgs.gov/search/map/mars_mgs_mola_mex_hrsc_blended_dem_global_200m

Purpose

This interim (v2) DEM was created to help fill gaps in MOLA with the HRSC DEM. The initial use case is to help with thermal modelling (Ferguson 2017; Laura 2016).

Contact and Distribution

Format

Digital Elevation Model, Grey Scale, Raster Data, Topographic Map

Access Constraints

Please cite authors

Access Scope

PDS

Use Constraints

None

Edition

v2

Edition Name

HRSC and MOLA Blend

Supplemental Information

http://hrscview.fu-berlin.de/cgi-bin/ion-p?page=entry2.ion, http://pds-geosciences.wustl.edu/missions/mgs/mola.html, http://www.hou.usra.edu/meetings/lpsc2017/pdf/1563.pdf

Native Data Set Environment

ESRI Arcinfo, GDAL, ISIS v3

Astrogeology Theme

Image Processing, Photogrammetry, Topography

Mission Names

Mars Express, Mars Global Surveyor

Instrument Names

HRSC, MOLA

Online Package Link

https://astrogeology.usgs.gov/search/map/mars_mgs_mola_mex_hrsc_blended_dem_global_200m

External File Size

(11 GB)

Online File Link

https://planetarymaps.usgs.gov/mosaic/Mars/HRSC_MOLA_Blend/Mars_HRSC_MOLA_BlendDEM_Global_200mp_v2.tif

Contact Address

2255 N. Gemini Drive

Contact City

Flagstaff

Contact State

AZ

Contact Postal Code

86001

Contact Email

astroweb@usgs.gov

Data Status and Quality

Time Period of Content (start)

2015-10-01

Time Period of Content (stop)

2017-09-01

Currentness Reference

Publication date

Progress

In Work

Update Frequency

As needed

Logical Consistency

There are areas where the blending of the HRSC on top of MOLA did not always work well. Care should be taken when using for scientific analysis. The average accuracy of each point is originally ~100 meters in horizontal position and ~1 meter in radius (Neumann and others, 2001). However, the total elevation uncertainty is at least ±3 m due to the global error in the areoid (±1.8 meters) and regional uncertainties in its shape (G.A. Neumann, written commun., 2002). The MOLA data were initially referenced to an internally consistent inertial coordinate system, derived from tracking of the MGS spacecraft. These values include the orientation of the north pole of Mars (including the effects of precession), the rotation rate of Mars, and a value for W0 of 176.630°, where W0 is the angle along the equator to the east, between the 0° meridian and the equator's intersection with the celestial equator at the standard epoch J2000.0 (Seidelmann and others, 2002). This value of W0 was chosen in order to place the 0° meridian through the center of the small (~500 m) crater Airy-0, within the crater Airy. Longitude increases to the east and latitude is planetocentric as allowed by IAU/IAG standards and in accordance with current NASA and USGS standards.

Completeness Report

This was completed using HRSC DEMs released 2017 or earlier (through HRSC DEM h7500_0000.da4.tif). The HRSC Team is re-working all HRSC DEMs and this product will eventually be superseded. Two HRSC DEMs were removed due to larger than normal height differences (h0938_0000 and h0927_0000). Several DEMS (~10 in total), were slightly crop to help create a more consistent edge blend into MOLA. HRSC DEMs used in this product now covers 44% of Mars.

Process Description

This blend was accomplished by taking the full-res (463m/p) MOLA DEM and blending the high-res HRSC DEMs (~50m/p) into it. The HRSC DEMs required a re-projection from their original Sinusoidal projection into Simple Cylindrical. A cell-size of 200m/p was chosen as a compromise between up-sampling the MOLA and down-sampling the HRSC DEMs. Both up-sampling (MOLA) and down-sampling (HRSC) used a bilinear interpolation. Blending distance across the HRSC edge (into MOLA) was 5km (100 pixels) to ensure a smooth transition.

Lineage

Process Date

2017-09-24

Source Title

Mars Orbiter Laser Altimeter (MOLA) and High Resolution Stereo Camera (HRSC)

Source Online Linkage

{http://pds-geosciences.wustl.edu/missions/mgs/mola.html,http://pds-geosciences.wustl.edu/missions/mgs/index.htm}

Source PDS Archive

Mars Express

PDS Status

PDS 3 Like

Attribute Accuracy Report

Accurate to Control Net

Horizontal Positional Accuracy Report

Accurate to Control Net

Vertical Positional Accuracy Report

Accurate to Control Net

Geospatial Information

Target

Mars

System

Mars

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)

53347

Raster Column Count (samples)

106694

Bit Type (8, 16, 32)

16

Quad Name

Radius A

3396190

Radius C

3396190

Bands

1

Pixel Resolution (meters/pixel)

200

Scale (pixels/degree)

296.3735

Map Projection Name

Simple Cylindrical

Latitude Type

Planetocentric

Longitude Direction

Positive East

Longitude Domain

-180 to 180