Fig. 1. Image of martian gullies; subframe of Mars Orbiter Camera (MOC) image M03/02290. The scene is illuminated from the left. These gullies exemplify the characteristic alcove–channel–apron morphology attributed to liquid water formation on Mars (Mellon and Phillips, 2001).

Fig. 2. A lunar landslide feature repeated three times. This photograph is a subframe of Lunar Orbiter II photograph 112-H1. The scene is illuminated from the left. (Left) The raw (scanned) photograph, adjusted for brightness and contrast. (Center) The photograph after using a bandpass filter to enhance the channel. (Right) The raw photograph repeated with annotations. This lunar landslide feature has the same characteristic alcove–channel–apron structure as the martian gullies, whose formation has been attributed to liquid water. The horizontal white stripes are a result of processing of the Lunar Orbiter photographic print strips.

Fig. 3. A lunar landslide feature repeated three times. This photograph is another subframe of Lunar Orbiter II photograph 112-H1. The scene is illuminated from the left. (Left) The raw (scanned) photograph, adjusted for brightness and contrast. (Center) The photograph after using a bandpass filter to enhance the channel. (Right) The raw photograph repeated with annotations. This lunar landslide feature also has the characteristic alcove–channel–apron structure of the martian gullies, whose formation has been attributed to liquid water. The horizontal white stripe is a result of processing of the Lunar Orbiter photographic print strips.

Fig. 4. Another lunar landslide feature repeated three times. This photograph is a subframe of Lunar Orbiter V photograph 199-M. The scene is illuminated from the left. (Left) The raw (scanned) photograph, adjusted for brightness and contrast. (Center) The photograph after using a unsharp mask to enhance the channel. (Right) The raw photograph repeated with annotations. This lunar landslide feature exhibits a clear channel and apron, perhaps originating from a small alcove above. The diagonal stripe is a result of processing of the Lunar Orbiter photographic print strips.

Fig. 5. Lunar landslides in Crater Dawes, repeated three times. The photograph is a subframe of Lunar Orbiter V photograph 70-H2. The scene is illuminated from the right, though at a higher angle than the previous examples, making feature identification difficult. Nevertheless, alcoves, channels, and aprons are present, as in the previous examples. (Left) The original (scanned) photograph, adjusted for brightness and contrast. (Center) The photograph passed through a bandpass filter to enhance the channels. (Right) The raw photograph repeated with annotations. The circular blobs are defects from the spacecraft's on-board processing of the photographic film. The diagonal stripes are a result of processing of the Lunar Orbiter photographic print strips.