Astrogeology Science Center

Mars MGS MOLA Elevation Model 463m (MEGDR)

This digital elevation model (DEM) is based on data from the Mars Orbiter Laser Altimeter (MOLA; Smith and others, 2001), an instrument on NASA’s Mars Global Surveyor (MGS) spacecraft (Albee and others, 2001). The DEM represents more than 600 million measurements gathered between 1999 and 2001, adjusted for consistency (Neumann and others, 2001, 2003) and converted to planetary radii. These have been converted to elevations above the areoid as determined from a Martian gravity field solution GMM-2B (Lemoine and others, 2001), truncated to degree and order 50, and oriented according to current standards. 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 according to Lemoine and others [2001]) and regional uncertainties in its shape (G.A. Neumann, written commun., 2002).

References: * Albee, A.L., Arvidson, R.E., Palluconi, Frank, Thorpe, Thomas, 2001, Overview of the Mars Global Surveyor mission: Journal of Geophysical Research, v.106, no. E10, p. 23,291–23,316.

* de Vaucouleurs, Gerard, Davies, M.E., and Sturms, F.M., Jr., 1973, Mariner 9 areographic coordinate system, in Journal of Geophysical Research, v. 78, p. 4395–4404.

* Duxbury, T.C., Kirk, R.L., Archinal, B.A., and Neumann, G.A., 2002, MarsGeodesy/Cartography Working Group recommendations on Mars cartographicconstants and coordinate systems, in Joint International Symposiumon Geospatial Theory, Processing and Applications, Ottawa, Canada, 2002 Commission IV, Working Group 9—Extraterrestrial Mapping, Proceedings: Ottawa, Canada, International Society for Photogrammetry and Remote Sensing [http://www.isprs.org/commission4/proceedings/paper.html].

* Lemoine, F.G., Smith, D.E., Rowlands, D.D., Zuber, M.T., Neumann, G.A.,Chinn, D.S., Pavlis, D.E., 2001, An improved solution of the gravity field ofMars (GMM-2B) from Mars Global Surveyor: Journal of GeophysicalResearch, v. 106, no. E10, p. 23,359–23,376. * Neumann, G.A., Rowlands, D.D., Lemoine, F.G., Smith, D.E., and Zuber, M.T.,2001, Crossover analysis of Mars Orbiter Laser Altimeter data: Journal ofGeophysical Research, v. 106, no. E10, p. 23,753–23,768.

* Neumann, G. A., D. E. Smith, and M. T. Zuber, Two Mars years of clouds detected by the Mars Orbiter Laser Altimeter,J. Geophys. Res., 108(E4), 5023, doi:10.1029/2002JE001849, 2003.

* Seidelmann, P.K. (chair), Abalakin, V.K., Bursa, Milan, Davies, M.E., De Bergh,Catherine, Lieske, J.H., Oberst, Juergen, Simon, J.L., Standish, E.M.,Stooke, P.J., and Thomas, P.C., 2002, Report of the IAU/IAG WorkingGroup on Cartographic Coordinates and Rotational Elements of the Planetsand Satellites—2000: Celestial Mechanics and Dynamical Astronomy, v.82, p. 83–110.

* Smith, D.E., Sjogren, W.L., Tyler, G.L., Balmino, G., Lemoine, F.G., and Konopliv,A.S., 1999, The gravity field of Mars—Results from Mars Global Surveyor:Science, v. 286, p. 94–96.

* Smith, D.E., Zuber, M.T., Frey, H.V., Garvin, J.B., Head, J.W., Muhleman, D.O.,Pettengill, G.H., Phillips, R.J., Solomon, S.C., Zwally, H.J., Banerdt, W.B., Duxbury, T.C., Golombek, M.P., Lemoine, F.G., Neumann, G.A., Rowlands,D.D., Aharonson, Oded, Ford, P.G., Ivanov, A.B., Johnson, C.L., McGovern,P.J., Abshire, J.B., Afzal, R.S., and Sun, Xiaoli, 2001, Mars Orbiter LaserAltimeter—Experiment summary after the first year of global mapping ofMars: Journal of Geophysical Research, v. 106, no. E10, p. 23,689–23,722.

* Wessel, Paul, and Smith, W.H.F., 1998, New, improved version of Generic MappingTools released: Eos, Transactions of the American Geophysical Union,v. 79, no. 47, p. 579.

Publisher

Goddard Space Flight Center

Author

MOLA Team

Originator

USGS Astrogeology Science Center

Group

PDS

Added to Astropedia

13 January 2014

Modified

30 June 2017

General

Purpose

The data from MOLA have been used to create the most accurate topographic map of Mars to date.

Geospatial Data Presentation Form

Digital Elevation Model, Topographic Map

MOLA Mission Experiment Gridded Data Record

MEGDR

Edition

2003-03-21

Online Linkage

https://planetarymaps.usgs.gov/mosaic/Mars_MGS_MOLA_DEM_mosaic_global_463m.tif

Native Data Set Environment

ISIS v3

Supplemental Information

http://geo.pds.nasa.gov/missions/mgs/megdr.html

Keywords

System

Mars

Target

Mars

Search Terms

Mars, topography

Contact and Distribution

Access Constraints

Public domain

Use Constraints

Please cite authors

Data Status and Quality

Logical Consistency Report

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 according to Lemoine and others [2001]) 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 (Duxbury and others, 2002) in order to place the 0° meridian through the center of the small (~500 m) crater Airy-0, within the crater Airy (Seidelmann and others, 2002; de Vaucouleurs and others, 1973). Longitude increases to the east and latitude is planetocentric as allowed by IAU/IAG standards (Seidelmann and others, 2002) and in accordance with current NASA and USGS standards (Duxbury and others, 2002).

Completeness Report

Data are very sparse near the two poles (above 87° north and below 87° south latitude) because these areas were sampled by only a few off-nadir altimetry tracks. Gaps between tracks of 1–2 km are common, and some gaps of up to 12 km occur near the equator. DEM points located in these gaps in MOLA data were filled by interpolation.

Process Description

The DEM represents more than 600 million measurements gathered between 1999 and 2001, adjusted for consistency (Neumann and others, 2001, 2003) and converted to planetary radii. These have been converted to elevations above the areoid as determined from a Martian gravity field solution GMM-2B (Lemoine and others, 2001), truncated to degree and order 50, and oriented according to current standards. The MOLA measurements were converted into a digital elevation model (DEM; G.A. Neumann, written commun., 2002; Neumann and others, 2001; Smith and others 2001) using Generic Mapping Tools software (Wessel and Smith, 1998), with a resolution of 128 pixels per degree. In projection, the pixels are 463 meters in size at the equator.

Horizontal Positional Accuracy Value

100

Horizontal Positional Accuracy Report

Accurate to Control Net

Vertical Positional Accuracy Value

1

Vertical Positional Accuracy Report

Accurate to Control Net

Entity and Attribute Overview

Elevation in meters.

Entity and Attribute Detailed Description

Elevations above the areoid as determined from a Martian gravity field solution GMM-2B (Lemoine and others, 2001).

Entity and Attribute Linkage

http://onlinelibrary.wiley.com/doi/10.1029/2000JE001426/abstract

Lineage

Source Originator

Goddard Space Flight Center

Source Title

MOLA Mission Experiment Gridded Data Records (MEGDRs)

Source Online Linkage

http://geo.pds.nasa.gov/missions/mgs/megdr.html

Type of Source Media

Online

Attribute Accuracy Report

Best Effort

Geospatial Information

Minimum Latitude

-90

Maximum Latitude

90

Minimum Longitude

-180

Maximum Longitude

180

Direct Spatial Reference Method

Raster

Object Type

Pixel

Lines (pixels)

23040

Samples (pixels)

46080

Bit Type

16

Radius A

3396190

Radius C

3396190

Bands

1

Pixel Resolution (meters/pixel)

463.0836

Scale (pixels/degree)

128

Horizontal Coordinate System Units

Meters

Map Projection Name

Simple Cylindrical

Latitude Type

Planetocentric

Longitude Direction

Positive East

Longitude Domain

-180 to 180