NASA/JPL/Malin Space Science Systems
Although one might argue that most of the "i" is missing, and part of the "h" has been eroded away, this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned sedimentary rock outcrops in northern Sinus Meridiani that almost seem to spell out the word, "hi". This natural graffiti is all that remains of a suite of sedimentary rock that once covered the area shown here. The 400 meter scale bar is about 437 yards long. The features are located near 1.8°N, 357.2°W. Sunlight illuminates the scene from the upper left.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, California. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, California and Denver, Colorado.