Datasets

Apparently the most similar planet to Earth in the solar system, Mars has been the target of frequent scientific investigation. In particular, three unmanned missions: Mariner 9 (1973), the twin Viking Orbiters (1976-1981)) and the Mars Global Surveyor (1997-) have generated a wealth of public domain remote sensing data. While true multispectral imaging remains thin on the ground, excellent panchromatic imagery and a high resolution topographic model exists.

Mariner 9 Data

The first Mars orbiter returned medium resolution panchromatic imagery of the entire planet. Project Viking rendered that dataset obsolete.

Viking Data

Visual Imaging System (VIS): The Viking Orbiters used a 1-mega-pixel vidicon framing camera that used 5 visual filters plus a panchromatic band. In practical use, the spectral range of the VIS filters overlapped so much that only two bands were unique: red (550 to 700 nm) and violet (350 to 470 nm). Image resolution was typically in the hundreds of meters per pixel; occasionally resolutions as high as 14m/pix were obtained.

An IR radiometer also onboard produced no image data.

Mars Digital Image Model (MDIM) – The USGS MDIM is the basis for any mapping project on Mars. Compiled from Viking Orbiter imagery, the panchromatic MDIM has a maximum resolution of 1/256˚/pixel (about 250 m on Mars) and covers the entire planet. An online server, the Planetary Data System’s (PDS) Planetary Image Atlas can generate custom maps at up to1/64˚/pixel (kilometer) resolution. An interpolated color R (synthetic G) V (=B) MDIM exists as 1/64˚/pixel dataset, although the effective resolution is much less.

A topographic model was manually derived from stereo imaging. Unfortunately uncertainties in the spacecraft orbit lead to many errors. The same errors are also plague in the Martian geodetic control network, with the result that MDIM 2.0 based on MGS geodesy is currently in production at the USGS.

Mars Global Surveyor Data

MGS is the first in the trio of small orbiters which including the failed Mars Climate Orbiter and the upcoming, pre-jinxed Mars ‘2001 Odyssey’. MGS operates in a sun-synchronous orbit, circling the planet 16 times a day. There are three remote sensing instruments on the MGS spacecraft, all refugees from the Mars Observer failure of September 1993.

Mars Orbiter Camera (MOC): The MOC is a 2-mega-pixel push-broom scanner that operates in two modes. The first is a zoom able two-color wide-angle camera that can image a hemisphere at km resolution for change detection studies, or 100 m resolution to provide context for the narrow angle system. The panchromatic narrow-angle system routinely beats 2 meter / pixel resolution, but low data return rates prevent the return of more than short strips. The company operating the instrument for NASA, Malin Space Science Systems (MSSS) has a useful website for interrogating the dataset. The Elysium map produced in this project contains links to critical MOC images at the MSSS website.

Mars Orbiter Laser Altimeter (MOLA): The infrared laser reflection altimeter generates profiles with a resolution of 37 cm vertically and ~300 meters horizontally. Recently a 1/16˚ degree/ pixel resolution global topographic grid was released, which forms the basis for this study.

Thermal Emission Spectrometer (TES): The 6-pixel push-broom system operates in two spectral resolution modes: 148 bands or 296 bands, all between 6 µm and 50 µm. The IFOV of the detectors is ~3 km. Derived surface spectra will not be distributed until the mission formally ends in January 2001; until then calibrated (atmosphere + ground) spectra are being distributed.