Well Ulco is right that it wont be a real hight map. But you can still get something from it.
There are two things you can do that I know of. One is to use it on a moon (but you can get real hight maps for any planet in our solar system). And the other way is you project the map with an image map shader on to a terrain.
First covert the image to black and white in photo shop. Then in TG go--> shaders --> create new shader--> color shader--> Image map shader--> and load your image when prompted.
Then copy a location into the tab and adjust the amount of displacement.
This will give you something to play with. Sometimes it is cool, sometimes it will look like crap. But it will never be an exact or correct representation of what the map is, because as said, it is not a real hight map. This can be a good way to get some terrain though if you don't have an idea where to start.
For a real height map of a planet in our solar system, go to:
http://www.celestiamotherlode.netNow the image you posted above can be used as is on a moon. Search how to map a moon object and project the image. It should not need to be displaced from such a great distance to get some effect. Though a real map would still be better. You could also use these maps in the OP, on top of, a real height map for color on a moon or anything else.