Mars gullies likely not formed by liquid water: Study

Washington: Gullies on Mars are likely not being formed by flowing liquid water, scientists using data from NASA's Mars Reconnaissance Orbiter have found.

The finding will allow researchers to further narrow theories about how martian gullies form, and unveil more details about Mars' recent geologic processes.

The term "gully" is used for features on Mars that share three characteristics in their shape: an alcove at the top, a channel, and an apron of deposited material at the bottom.

Gullies are distinct from another type of feature on martian slopes, streaks called "recurring slope lineae," or RSL, which are distinguished by seasonal darkening and fading, rather than characteristics of how the ground is shaped.

Water in the form of hydrated salt has been identified at RSL sites. The new study focuses on gullies and their formation process by adding composition information to previously acquired imaging.

Researchers from the Johns Hopkins University Applied Physics Laboratory (APL) in the US examined high-resolution compositional data from more than 100 gully sites on Mars.