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The Mars Orbiter Laser Altimeter (MOLA)

An instrument on the Mars Global Surveyor

MOLA Mechanical Analysis Home Page

Created and maintained by Ryan Simmons
at NASA Goddard Space Flight Center
Greenbelt, Maryland, USA

Jump to the Table of Contents for this site.

MOLA a resounding success!
Science features MOLA results in their May 28, 1999 Issue.

Science magazine's cover shows 3D Mars.

If you have Quicktime, here's a 3D movie of Mars by CNN.

And check out the Mars Smiley Face Crater!

For all the latest information on MGS and MOLA, visit the new MGS Web Site.
For the latest information on all the NASA Mars spacecraft, Visit the Mars Missions Web Site.

  • June 30, 2001
      "The MOLA instrument was commanded off on 6/30/01 at around 6 pm EDT when the MGS telemetry indicated that its laser operating temperature had dropped to a preset lower limit. Until the anomaly, the laser energy had been nominal and steady at about 20 mJ/pulse. The 6/30/01 event was the first anomaly in MOLA's operation since the MGS launch in 11/96.
      "At the request of David Smith, the MOLA PI (principle investigator), several remaining members of the MOLA instrument team have been analyzing the available MOLA data reported before it was turned off to try to determine the most likely cause of the anomaly and as well as to recommend a possible recovery plan. Their analyses to date indicate that the likely cause appears to be an interruption of the 10 Hz laser trigger signal from the MOLA altimeter electronics. Without the trigger signal, the laser would not fire and its temperature has dropped, eventually to the lower limit. It is not yet clear which electronic component might have been responsible for the signal interruption. We are planning to support several tests the week of 7/9/01 to see if, once powered back on, MOLA resumes normal operation and to configure the instrument to perform additional troubleshooting if needed.
      "As of 6/30/01, MOLA had been in space for 1696 days, and had undergone 216 power-on/off cycles. The MOLA laser had fired 671 million times in space and MOLA had made about 640 million measurements of the Mars surface and atmosphere. This represents more than ten times the number of laser measurements than all previous space lidar missions combined. The MOLA instrument performance and lifetime have surpassed all goals of the MOLA investigation. There been 35 peer reviewed scientific papers published on MOLA data to date.
      "The MOLA laser was designed and built by the McDonnell Douglas Corporation. The MOLA instrument was designed and built under a "best efforts - fixed cost" basis by a GSFC instrument team led by the Laser Remote Sensing Branch."

    MGS Launch IconPreviously:

  • Mars Global Surveyor was Launched Successfully at 12:00:50 EST on November 7, 1996!

  • MOLA was turned on in space for the first time at 04:30 a.m. on November 25, 1996. All systems worked perfectly.

  • After its 10-month journey to the Red Planet, MGS arrived on September 11, 1997 at about 9:30 p.m. EDT.

  • Due to a problem with one of the solar arrays, MGS will need an extra year to get into the proper orbit. This is because the engineers are not confident that the problem solar array can handle the aerobraking loads it was originally designed for. So instead, a much slower aerobraking schedule will be used.

  • Mars Global Surveyor Has Acheived Polar Circular Orbit Around Mars!
    The MOLA instrument commenced continuous mapping of Mars on March 1, 1999


    NASA's Jet Propulsion Laboratory has made a Quicktime movie of Mars rotating available. (4.0MB)
    Kennedy Space Center has made some MGS video clips, an MPEG movie of the launch, and some excellent MGS images available.
    Read a Press Release on NASA's and Russia's exploration of Mars.
    Sadly, the Russian Mars '96 spacecraft failed to get into completely orbit. Two articles from CNN's website explain.

    Table of Contents

    These links take you to short descriptions farther down on this page. From there you can jump to the associated page.
    NOTE: Due to a finite element modeling error, which has been found and corrected, much of the data presented on these pages was updated during April 1996. The error impacted vibrational analyses most significantly. See below for a description of the error and the correction.

    MOLA Overview

    MOLA Left Side
    MOLA Right Side
    MOLA Top View
    MOLA Signature Plaque     		MOLA FEMThe Mars Orbiter Laser Altimeter, or MOLA for short, is being built by NASA Goddard Space Flight Center. It is one of four instruments on the Mars Global Surveyor. Some of you might recall the Mars Observer that was lost in '92 just after it went into orbit around the planet (those pesky Martians!). Well, this is the second attempt to get there and take some pictures. MOLA will send back to Earth such information as mountain heights and valley depths, as well as information on the surface reflectivity. It will do all this with a laser beam. If you care to learn more about MOLA, just send me a message at the address below. Or better yet, keep reading.

    The four pictures to the left are of the actual MOLA instrument as it was going through testing here at Goddard. They show what MOLA actually looks like. The top three pictures show various views of MOLA, while the last picture is of the plaque that all the MOLA Team Members signed. All of our signatures will be traveling to Mars with MGS. My signature is somewhere very close to the upper left corner. Unfortunately it cannot be read. So you'll have to believe me that it's really there.

    Here is a video scan (taken September 24, 1996) of MGS as it waits in the Payload Hazardous Servicing Facility (PHSF). The PHSF supports the assembly and testing of payload components and systems. From here, MGS will go on to be integrated into the launch vehicle. MOLA is located somewhere on the top of the spacecraft. MGS is in its launch configuration. Click on the picture to see if anything has changed with the KSC video feed. (Eventually, the video feed will disappear.)

    Jump to Goddard's MOLA page for another short description. Also, for more detailed information on the entire project, you can read the MGS home page, or go straight to JPL's own MOLA information page.

    Above is also a picture of a finite element model of MOLA. Better and more detailed FEM views are available by clicking on this picture.

    MOLA Links

    Here are some quick Mars Global Surveyor and MOLA links:

    MOLA Documents From the Net

    I have made as many of the MOLA mechanical analysis documents, pictures, and data available as I can. The documents page will give you a complete listing of what's to be found. Many of these documents will also be found on their respective Web pages you can get to from here.

    MOLA Finite Element Model Error Detected and Corrected (3/96)

     In December 1995 and January 1996, the MOLA instrument went through a series of environmental tests, which included vibrational tests like random and sine vibration. The results of these tests showed a poor correlation with the finite element model I created. After reviewing the test results and studying the model more closely, an error was found in the FEM. This section gives background on the test, the error and how the error was found and corrected.

    MOLA Mechanical Analysis

    This page is maintained by Ryan Simmons, at .
    This page was updated July 2001. (Broken links corrected April 2008)