Rivix.com: MOLA Topography of Mars

MOLA Topography of Mars

Description

The Mars Orbiter Laser Altimeter (MOLA) is an instrument currently in orbit around Mars on the Mars Global Surveyor (MGS) spacecraft. MOLA collects high-resolution topographic data for Mars by transmitting infrared laser pulses toward the red planet at a rate of 10 Hz and accurately measuring the return time. MOLA was designed and built by the Laser Remote Sensing Branch of the Laboratory for Terrestrial Physics at Goddard Space Flight Center (GSFC/NASA).

A DEM for the entire planet with a grid spacing of 1/16 degree (225 arcseconds, or about 3.7 km at the equator) is available and has 5760 columns and 2880 rows. It is distributed as a flat binary file (row major, no header) with the extension ".img", with geocoding data in a separate ASCII file with extension ".lbl". Elevation values are stored as signed 2-byte integers with the MSB (most significant byte first) byte order and units of meters. A spherical planet model ("areocentric") is used with a radius of 3396.0 km.

As the MGS spacecraft continues to circle Mars, it creates DEMs of increasingly higher resolution. As of June 2003, DEMs with grid spacings of 1/32 degree, 1/64 degree (meg0015t.img, meg0015t.lbl) and 1/128 degree (meg0008t.img, meg0008t.lbl) are available! Note that the filenames have the letter "t" just before the extension, which stands for "topography" and distinguishes them from other data layers. The last of these corresponds to less than 0.5 km at the equator. The one with grid spacing of 1/32 degree (112.5 arcseconds) has 11520 columns and 5760 rows.

As of June 2006, elevation grids are also available in the netCDF format, with the extension ".grd". These can also be imported into RiverTools via File → Import DEM → GMT Raster (netCDF).

Mars has many dramatic topographic features, including (1) huge impact craters in the southern hemisphere, such as Hellas (9 km deep, 2100 km across), deep enough to hold Mount Everest, (2) a "super canyon" system, Valles Marineris (10 km deep, 5000 km long), that would span the US, (3) many large volcanoes, including Olympus Mons (26 km), three times taller than Mount Everest (8.8 km) and (4) erosional features that appear to be due to massive surface water fluxes.

Data Source

Goddard Space Flight Center (GSFC) of NASA.

Data Availability

Gridded elevation data with grid spacings of 1/128, 1/64, 1/32, 1/16, 1/8, and 1/4 of a degree (28.125, 56.25, 112.5, 225, 450, 900 arcseconds) can be downloaded from the MOLA web site listed below.

Web Sites

MGS Home: http://marsweb.jpl.nasa.gov/mgs/index.html

MOLA Home: http://ltpwww.gsfc.nasa.gov/tharsis/mola.html

MOLA Data: http://ltpwww.gsfc.nasa.gov/tharsis/data.html

MOLA DEMs: ftp://ltpftp.gsfc.nasa.gov/projects/tharsis/MOLA/GRIDS