Running the applet on this page used to be a lot easier before the new locked down security configuration of Java. If you have Java on a Windows computer, you may need to go to Control Panel -> Java and add or as an exception under the Security tab. Then, reloading this page, you may still need to enable the Java plug-in (this is browser dependent) and then allow Java to run the applet. If this sounds more complicated than it's worth... I hear you. One of these days, I will write a JavaScript version of this applet, doing away with the need to use any plug-ins.

NB: Java applets no longer work at all in the Chrome browser, as support for such plugins was discontinued by Google.

No doubt you've heard of the intriguing possibility that Mars was one day covered with water. Thanks to altitude information obtained by the Mars Observer Laser Altimeter, it is now possible to see what Mars would look like today, were it covered with an ocean. The Java applet here (please wait while the data set is loaded) does just that: it shows a map of Mars with the sea level set at the altitude you choose.

I think you'll find this map has many practical uses. For instance, if you wish to consider purchasing Martian real estate, you might want to be careful not to buy a lot that'll be covered with water too soon. The highlands may not be a good investment either; what good is a piece of land that'll remain thousands of miles from the nearest body of water throughout most of the duration of any reasonable terraforming project?

To use this program, set the sea level altitude to the level of your choosing (meaningful values are between -10000 and 20000 meters), and click the Redraw button. On slower computers, it may take a bit of time for the map to update itself.

Sea level altitude:  meters.

This program utilizes data downloaded from the Mars Observer Laser Altimeter Web site. The inspiration came from the Astronomy Picture of the Day Web site.

To see information on Mars Observer and other "live" probes, please visit my Deep Space Probes page.

It may be of interest to Hungarian readers of this page that it was featured recently at Prim Online.

For what it's worth, I now also have a Seas of Venus map available.