Gasa is an impact rayed crater in the Eridania quadrangle on Mars at 35.68° S and 230.72° W. and is 6.5 km in diameter.

[2] It is now believed that the impact that created Gasa happened in a larger crater whose floor was covered with debris-covered glaciers.

Some studies have found that gullies occur on slopes that face all directions,[5] others have found that the greater number of gullies are found on poleward facing slopes, especially from 30-44 S.[6] For years, many believed that gullies were formed by running water, but further observations demonstrate that they may be formed by frozen carbon dioxide (dry ice).

Recent studies describe using the High Resolution Imaging Science Experiment (HiRISE) camera on MRO to examine gullies at 356 sites, starting in 2006.

Before-and-after images demonstrated the timing of this activity coincided with seasonal carbon dioxide frost and temperatures that would not have allowed for liquid water.