Curiosity has found that water and other interesting things permeate the soil of Mars.
Curiosity has found that water and other interesting things permeate the soil of Mars.
When [a soil sample was] heated, the instrument detected the abundance of water [about 2% of the sample] plus significant quantities of carbon dioxide, oxygen and sulfur compounds, according to the researchers. Carbonate materials — compounds that form in the presence of water — were also identified. The experiment confirmed the presence of oxygen- and chlorine-containing compounds — likely chlorates or perchlorates. Originally discovered by NASA’s 2008 Phoenix Mars Lander (and likely detected by NASA’s Viking landers in 1976), perchlorates were found in the soil of high-latitude arctic regions. This indicates that perchlorates occur globally over Mars. Though highly toxic to human biology, some microbes are known to use the oxidizing chemical for energy. This finding intensified the debate over whether hypothetical microbes on Mars could metabolize perchlorates in a similar way.
Perchlorates were proposed as an explanation for the Viking results by scientists who did not believe those results suggested the presence of microbiological life. I find it interesting that now scientists are saying that the perchlorates might actually be evidence of life. Once again, the uncertainty of science rules the day!