Figure 3.

Survival of Bacillus subtilis endospores after exposure to ferrate- and permanganate-enriched sand under simulated Mars environmental conditions. ▲, Silica sand only; ▪, Sand + ferrate; ∙, Sand + permanganate; -20°C; ferrate and permanganate added at 20% by weight of silica sand; CO₂ atmosphere; -20°C. Each data point represents the mean of three replicate experiments. Error bars represent +/- one standard deviation of the three replicates. CFU = colony-forming units per gram dry weight of sample. The X-axis shows the number of days of exposure to ferrate prior to viable counting. Experiments carried out for 6 weeks showed no statistically significant decline in CFU.