Columbia Hills (Mars)

The Columbia Hills are a range of low hills inside Gusev crater on Mars. They were observed by the Mars Exploration Rover Spirit when it landed within the crater in 2004. They were promptly given an unofficial name by NASA since they were the most striking nearby feature on the surface. The hills lie approximately 3 kilometres (1.9 mi) away from the rover's original landing position. The range is named to memorialize the Space Shuttle Columbia disaster. On February 2, 2004, the individual peaks of the Columbia Hills were named after the seven astronauts who died in the disaster. Spirit spent a few years exploring the Columbia Hills until it ceased to function in 2010. It is also considered a potential landing site for the Mars 2020 rover.

The seven peaks are, from north to south:

With the Spirit Rover, scientists found a variety of rock types in the Columbia Hills, and they placed them into six different categories. The six are: Clovis, Wishbone, Peace, Watchtower, Backstay, and Independence. They are named after a prominent rock in each group. Their chemical compositions, as measured by APXS, are significantly different from each other. Most importantly, all of the rocks in Columbia Hills show various degrees of alteration due to aqueous fluids. They are enriched in the elements phosphorus, sulfur, chlorine, and bromine—all of which can be carried around in water solutions. The Columbia Hills’ rocks contain basaltic glass, along with varying amounts of olivine and sulfates. The olivine abundance varies inversely with the amount of sulfates. This is exactly what is expected because water destroys olivine but helps to produce sulfates.

Acid fog is believed to have changed some of the Watchtower rocks. This was in a 200 meter long section of Cumberland Ridge and the Husband Hill summit. Certain places became less crystalline and more amorphous. Acidic water vapor from volcanoes dissolved some minerals forming a gel. When water evaporated a cement formed and produced small bumps. This type of process has been observed in the lab when basalt rocks are exposed to sulfuric and hydrochloric acids.

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