If you want precise, high resolution topography data from Mars you've come to the right place.

The following information is available for download:

• PEDRs: ap00003k.b, etc. (MOLA corrected profiles)
• AEDRs: aa00003f.b, etc. (MOLA raw packet data)
• Grids: polars55N.raw, etc. (MOLA topographic grids)
• Software to read corrected profile data and Software Interface Specification (SIS) documents for PDS data files (these are detailed descriptions of data file contents and formats).
• Description of the software.
• Format of the ASCII tables output by PEDR2TAB.

If you cannot find the data that you are looking for be aware of the fact that we do not have the personnel to accomodate special requests. All MOLA data have been and will continue to be put on this website just as soon as they have been processed, validated and verified by the Planetary Data System.

Click here to download MOLA Precision Experiment Data Records (PEDRs) for the MGS Capture Orbit, Aerobraking Hiatus and Science Phasing Orbit-1 mission phases.

A Software Interface Specification V.2.8 defines the format of the binary data records. Users may also download a PDF version of the PEDR SIS V.2-7.

The AEDR Software Interface Specification V.2.1 describes the raw packets, and may be downloaded in PDF format. Geophysical data are also archived in the Geophysics Node of the Planetary Data System (PDS) at Washington University, St. Louis. All raw data and gridded data products will be archived in this location. Data from the Capture Orbit, Aerobraking and and SPO-1 phases have been released as of Jan. 1. Data from SPO-2 are currently being validated and are expected to be released in early February, pending certification by the PDS.

Software to read profile data is available for a variety of systems.

Information about the MOLA instrument and data products can be found in:

• Zuber, M.T., D.E. Smith, S.C. Solomon, D.O. Muhleman, J.W. Head, J.B. Garvin, J.B. Abshire, and J.L. Bufton, The Mars Observer Laser Altimeter investigation, J. Geophys. Res., 97, 7781-7798, 1992.
• Afzal, R.S., Mars Observer Laser Altimeter: Laser transmitter, Applied Optics, 33, 3184-3188, 1994.

Initial scientific results of the MOLA investigation from analysis of aerobraking hiatus data are described in:

• Zuber, M.T., D.E., M.T. Zuber, H.V. Frey, J.B. Garvin, J.W. Head, G.H. Pettengill, R.J. Phillips, S.C. Solomon, H.J. Zwally, W.B. Banerdt, T.C. Duxbury, Topography of the northern hemisphere of Mars from the Mars Orbiter Laser Altimeter, Science, 279, 1686-1692, 1998.

Our best current knowledge of the topography of the northern hemisphere of Mars can be found in:

• Zuber, M.T., D.E. Smith, R.J. Phillips, S.C. Solomon, W.B. Banerdt, G.A. Neumann, and O. Aharonson, Shape of the northern hemisphere of Mars from the Mars Orbiter Laser Altimeter (MOLA), Geophys. Res. Lett., 25, 4393-4396, 1998.

The MOLA data are provided on a "best effort" basis after a period of calibration and validation.

MOLA ranges, pulse widths and energies are calibrated for using an algorithm developed by our engineering team [Abshire et al., 1999]. The two-way range is traced from the spacecraft position at laser fire time to the surface along a boresight vector and back to the detector telescope to yield the coordinates of the surface bounce point. The topography at that point is the difference between the measured planetary radius and an equipotential surface, whose average radius at the equator is 3396 kilometers [Zuber et al., 1998].

Calibration and validation refers to the process whereby data are decoded, converted to physical units, corrected for known thermal and atmospheric conditions, and checked for internal consistency. The major reason that this process takes time is the need to determine the position of the spacecraft at while the data are recorded with meter-level accuracy. Doing this at the distance of Mars is a major undertaking, and involves computing the forces from all the major bodies of the solar system on the MGS spacecraft, as well as solar radiation pressure, drag from the atmosphere, spacecraft orientation, tracking station biases, and general relativity. The GEODYN orbit determination program, which runs on supercomputers at NASA/GSFC, is utilized to make these precise corrections.

The calibration of the MOLA instrument is described in:

• Abshire, J.B., and X. Sun, Mars Orbiter Laser Altimeter -- Receiver Model and Calibration, Mars Global Surveyor Project Report, 1999.

Other data files of interest are also available:

• Geophysical data
• Instrument temperature plots and data