[2][3] More recently, satellite images showed the trails of dust devils on Gusev's floor.

On January 3, 2004, Gusev was the landing site of the first of NASA's two Mars Exploration Rovers, named Spirit.

It eventually arrived at the Columbia Hills, however, and rocks examined in that region showed evidence of small amounts of briny (salty) water interacting with them in ancient times,[4] although not nearly as much as at Meridiani Planum, the landing area for Spirit's twin, Opportunity.

They contain the minerals olivine, pyroxene, plagioclase, and magnetite, and they look like volcanic basalt as they are fine-grained with irregular holes (geologists would say they have vesicles and vugs).

Outside coatings and cracks inside the rocks suggest water deposited minerals, maybe bromine compounds.

[10][11] Observations of rocks on the plains show they contain the minerals pyroxene, olivine, plagioclase, and magnetite.

[5] Plain's rocks have been very slightly altered, probably by thin films of water because they are softer and contain veins of light-colored material that may be bromine compounds, as well as coatings or rinds.

[12] Most importantly, all of the rocks in Columbia Hills show various degrees of alteration due to aqueous fluids.

The Columbia Hills’ rocks contain basaltic glass, along with varying amounts of olivine and sulfates.

Peace rocks showed sulfur and strong evidence for bound water, so hydrated sulfates are suspected.

One type of soil, called Paso Robles, from the Columbia Hills, may be an evaporate deposit because it contains large amounts of sulfur, phosphorus, calcium, and iron.

[18] Also, MB found that much of the iron in Paso Robles soil was of the oxidized, Fe+++ form, which would happen if water had been present.

[19] After Spirit stopped working scientists studied old data from the Miniature Thermal Emission Spectrometer, or Mini-TES and confirmed the presence of large amounts of carbonate-rich rocks, which means that regions of the planet may have once harbored water.

It is believed that Gusev crater may have held a lake long ago, but it has since been covered by igneous materials.

[22] Columbia Hills was previously explored by Spirit rover,[22] which after several years of activity stopped communicating in 2010.