Mars MOLA Viewer provides a simple, yet comprehensive look at the topographic data returned by the MOLA experiment on the Mars Global Surveyor.

When you start the program for the first time, you will see the an introductory screen and then the Configuration Window.

Configuration Window

On the configuration screen, you can select a directory to store the topographic data files, and a URL from which to download them.  The defaults should work well for most people.

Configuration Window

Data File Directory

By default the program will create a mars_mola directory within your home directory.  The data files total about 2 GB; if you don't have  that much space at the default location use the Change button and choose a directory for the topographic data files on a drive that does have that much space.  If you've downloaded the data files with a different program, choose the directory to which you downloaded them.

Download URL

This is the URL from which Mars MOLA Viewer will download the topographic data files.  The default value is the official site at Washington University in St. Louis, Missouri, USA.  If you know of a mirror closer to you, you can enter that URL here.

Main Map Window

The main Mars MOLA Viewer window shows a false-color topographic map of Mars, between +/- 70 degrees latitude, in a Mercator projection.  This map is divided into 16 sections, which represent the 16 topographic data files that Mars MOLA Viewer can use (actually, Mars MOLA Viewer can show to +/- 88 degrees latitude, but that doesn't show well on a Mercator projection, so the polar regions aren't shown.) If you have the file for a section downloaded, that section is shown in full color.  If the file is not downloaded, the section is shown grayed out.  If the file exists but is incomplete, the section shows with a pink overlay.  If you are in the process of downloading a file, the section is shown with a green overlay and a progress bar.  The blue portion of the progress bar indicates how much of the file had downloaded.

In this example, the sections around Olympus Mons and Valles Marineris are completely downloaded (and may be rendered); one section is actively downloading, and one section is incomplete but not actively downloading.
Main Map Window

If you click on a section of the map that has not yet downloaded completely (or right click on any section of the map) you will see a pop-up menu listing what you can do with that section file.  Options are: Start a download, Resume an incomplete download, Stop a download in progress, Restart a download (which you might want to do if you think the file for a section is wrong or corrupt for some reason).

Once any section of the map has downloaded completely (each section is 128 MB, so if you don't have broadband, downloading a section may be an overnight operation), you can click on it to open the rendering window.

The map window will also show the day/night regions of Mars and plot the book marks you've saved, if you enable those features.

Rendering Window

The rendering window shows a realtime 3D display
The rendering window is where all the fun happens.  If you click on a section of the map that you have downloaded, you will open a rendering window giving a view of the Martian surface from a camera at that position.  This might take a few seconds or minutes, depending on the speed and memory size of your computer.  If your computer does not support the 3D graphics techniques used, Mars MOLA Viewer will probably abort now.  If you click on the rendering window it will get the focus.  When the rendering window has the focus, moving the mouse will change the direction you are facing on Mars.  Pressing the arrow keys will move your camera forward, backward, left or right.  Press the space bar to toggle a display of the current frame rate (how many times a second the view is updating).  Press F to toggle a display of your current position on Mars.  Press F9 to take a screen shot.  Press Alt-Enter to toggle full-screen mode for the rendering window. Press Escape to free the mouse for its normal behavior.

When the rendering window is running, a green triangle will show on the topographic map showing your current position and the direction you are facing.  You can click on any downloaded section of the map to quickly change your camera position to that point.  If you move the camera to a part of Mars for which you haven't downloaded data, you'll just see perfectly flat terrain.

Mars Clock

Mars MOLA Viewer includes a fully functional Mars clock.  The map display will show the day and night regions of Mars for the current date and time, or any date and time you select, and the render window will show the correct sun position and lighting angle for that time at your location (it will be very dark on the night side of Mars!)  The sun position is updated periodically in real time: you can watch the sun rise or set from the surface of Mars!  Use the Show day/night... option in the Date/Time menu to enable this feature.  The title bar will always show the date and time you are displaying.
The main map with day/night regions and bookmarks displayed

The Mars clock defaults to the current time but you can set it to any date or time you want--perhaps to adjust the lighting conditions of a scene you're looking at, or to see how a Martian feature looks in the sunlight of different seasons.  Use the Set date/time... menu option to open the dialog that lets you set the date and time.
set date time dialog

Change the date and time in the text box.  The Now button is a shortcut to change the text to the current date and time.  The Apply button changes the set date and time to the value you've entered in the field-- you'll see the change immediately in the map window and the render window, if it's open.  The OK button changes the date and time and also closes the dialog.


Mars MOLA Viewer allows you to save bookmarks that record what you're looking at in the render window: your position, orientation, and the set date and time.  You'll be able to return to that point in the future, and resume your exploration of Mars in the same area.  The bookmarks can also be plotted on the Mars map.  The software ships with a small set of pre-created bookmarks recording the landing position and dates of each successful United States Mars lander (to date!)

Use the Edit bookmarks... menu command under the Window menu to create or update your bookmarks.
Edit Bookmarks dialog

The table shows all the existing bookmarks.  Select a bookmark by clicking on it.  All the information about the bookmark will be displayed in the fields beneath the table.

The Go To button will open the rendering window and position it at the selected bookmark; if the bookmark is associated with a date and time it will also set that.

You can also create a copy of, or delete a selected bookmark.  The Add button will create a new bookmark from your current position in the rendering window.

Bookmarks have a title, description, latitude, longitude and an optional date and time.  The title is displayed with the bookmark when it is plotted in the map window.  You can put any additional text in the description.  When you first create a bookmark, the title and description are blank.

The wx and wy columns measure the orientation of the render window camera.  It's probably not useful to try and change these directly, but you have the option.

When you've changed the information for a bookmark the way you want, press the Update button to update the table and save the changes permanently.

The Reset button removes all the bookmarks except for the original set!

Menu Commands

Window Menu

Rendering Menu

Vertical Relief Window

Date/Time Menu

Help Menu


Mars MOLA Viewer won't start

If Mars MOLA Viewer won't start at all, there is a probably a problem with the installation of Java Web Start.  Please refer to Sun's documentation of Java Web Start for more information.

One problem that prevents Mars MOLA Viewer from starting is bad proxy configuration information in Java Web Start.  If you are accessing the Web through a proxy server and Mars MOLA Viewer fails to start and you get an error message from Java Web Start, this might be the problem.  Java Web Start is supposed to obtain the proxy information from your browser upon installation; this might not work.  Or the proxy information may need to be changed.  Start Java Web Start, select File/Preferences, go to the General tab, and enter the correct proxy information.
Java Web Start Preferences

Welcome Screen Unresponsive

Because of an oddity in Java Web Start, when you start Mars MOLA Viewer for the first time, you might not be able to dismiss the welcome screen.  This is because Java Web Start has put up its own window, asking if you want to add Mars MOLA Viewer to the desktop, and this window is taking all the input, even though it is hidden below the welcome window.  You just have to bring the hidden window to the top so you can click on it and make it go away, and things will work normally.

Rendering Becomes Slow

If you open and close the Rendering Window more than once, rendering may become very slow.  The only way to cure this is to exit Mars MOLA Viewer and then restart it.