AFAIK Quadrangles on Earth Mars and elsewhere including the planets such as Mercury and Venus as well as moons such as the Moon and Tethys are useful not only with the USGS but also with NASA JPL and many others for better locating specific geographic areas to land and explore such listings for Mars may be especially important and notable since Mars exploration and a possible human mission to Mars list seems to be a very high priority for the world at the moment hope this helps in some way in any case Enjoy