MOLA

MOLA
Name	MOLA
Mission	Mars Global Surveyor
Operator	Jet Propulsion Laboratory / NASA
Launch	1996-11-07
Mass	15 kg
Power	10 W
Wavelength	1064 nm
Type	Laser altimeter
Status	Completed

MOLA is the laser altimeter instrument flown on Mars Global Surveyor that produced the first high-resolution, global topographic dataset for Mars. It returned precise surface elevations, crater profiles, and polar topography used across planetary science and spacecraft navigation communities. Developed and operated by teams at NASA and Jet Propulsion Laboratory, the instrument established benchmarks for subsequent altimeters on missions such as Mars Reconnaissance Orbiter and MESSENGER.

Overview

MOLA operated as an active laser ranging instrument on the Mars Global Surveyor orbiter in the late 1990s and early 2000s, measuring two-way time-of-flight of 1064 nm laser pulses to derive surface elevations relative to the spacecraft. The dataset enabled cross-comparisons with radar observations from Mars Orbiter Laser Altimeter contemporaries and imaging from Viking Orbiter, Mars Odyssey, and Mars Reconnaissance Orbiter. Scientific users from institutions including California Institute of Technology, Smithsonian Institution, and University of Arizona employed MOLA data for geomorphology, climatology, and geodesy studies. Operational partners included Lockheed Martin for the spacecraft bus and NASA Ames Research Center for mission planning interfaces.

History and Development

MOLA was conceived during instrument solicitations in the late 1980s and early 1990s as a component of the Mars Observer/Mars Global Surveyor lineage, incorporating lessons from flight projects like Viking 1 and Viking 2. Principal investigators coordinated with engineering groups at the Jet Propulsion Laboratory and instrument manufacturers who had worked on LIDAR prototypes for Earth Observing System missions. After successful integration and launch aboard Mars Global Surveyor in 1996, MOLA returned continuous topographic profiles from 1997 through the early 2000s, contributing to mission milestones celebrated at American Geophysical Union meetings and cited in publications by groups at Brown University and Massachusetts Institute of Technology.

Instrument Design and Specifications

The MOLA instrument used a Nd:YAG laser operating at 1064 nm, transmitting short pulses with pulse energy and repetition rates optimized for altimetry from a low Mars orbit. The instrument architecture included a telescope receiver, photon-counting detectors, timing electronics, and an onboard altimetry processor developed at Jet Propulsion Laboratory in collaboration with industry partners. Key specifications included meter-scale vertical precision, along-track sampling spacing governed by orbital parameters similar to those of Mars Global Surveyor and ground-track geometry comparable to datasets from Mars Reconnaissance Orbiter. Thermal control and radiation-hardened electronics echoed designs used on Galileo and Cassini instruments, while mass and power constraints aligned with standards from Lockheed Martin spacecraft integrations.

Data Collection and Processing

MOLA collected billions of laser shot returns producing dense profiles of elevation that were georeferenced using spacecraft ephemerides from Deep Space Network tracking and attitude knowledge from onboard star trackers similar to those used on Hubble Space Telescope servicing missions. Raw photon counts underwent range calibration, outlier rejection, and cross-track interpolation in data pipelines at Jet Propulsion Laboratory and archived at NASA Planetary Data System. Processing included tie-pointing to crater catalogs maintained by teams at Lunar and Planetary Institute and co-registration with imaging mosaics from Viking Orbiter and Mars Reconnaissance Orbiter. Products ranged from individual shot records to gridded global digital terrain models used by investigators at University of Colorado Boulder and Imperial College London.

Scientific Discoveries and Contributions

MOLA revealed the global dichotomy in elevation between northern lowlands and southern highlands, quantified basins such as Hellas Planitia and Arsia Mons slopes, and mapped the stratigraphy of polar layered deposits at North Polar Cap (Mars) and South Polar Cap (Mars). It constrained volumes of outflow channels linked to candidates like Valles Marineris and informed hypotheses about ancient ocean shorelines proposed near Acidalia Planitia and Elysium Planitia. MOLA-derived slope and roughness metrics supported studies of aeolian processes in features like Olympus Mons flanks and allowed landing-site selection analyses for missions including Mars Pathfinder and Phoenix (spacecraft). Results influenced climate modeling efforts that integrated topography into general circulation models developed by groups at National Center for Atmospheric Research and Imperial College London.

Mission Operations and Calibration

Routine operations included periodic instrument health checks, calibration sequences against flat-lying terrains such as crater floors cataloged by US Geological Survey planetary mapping teams, and cross-calibration with passive sensors aboard Mars Global Surveyor like the Mars Orbiter Camera. Calibration efforts used laser ranging assumptions validated through comparison with radiometric and stereo-photogrammetric measures by teams at Cornell University and Brown University. Mission operations were coordinated via flight dynamics and science planning at Jet Propulsion Laboratory with downlink scheduling through the Deep Space Network and science data distribution overseen by NASA archives and international collaborating institutions.

Legacy and Influence on Planetary Science

MOLA established a benchmark global topographic reference for Mars that underpins contemporary mapping, geodetic reference frames, and mission planning for orbiters and landers such as Mars Reconnaissance Orbiter and InSight (spacecraft). Its methodological advances in laser altimetry influenced designs of subsequent instruments on missions including MESSENGER, Lunar Reconnaissance Orbiter, and Earth-observing lidar systems from National Aeronautics and Space Administration collaborations. The dataset continues to be cited in work by scholars at California Institute of Technology, University of Arizona, and European Space Agency-affiliated teams, and remains a foundational resource in planetary geoscience curricula and exploration architecture studies.

Category:Missions to Mars