> “There are two basic origins for the water: from above or from below,” Dr. McEwen said. The perchlorates could be acting like a sponge, absorbing moisture out of the air... The other possibility is underground aquifers, frozen solid during winter, melting during summer and seeping to the surface.
Although "rain"/humidity is unlikely, the article also discusses why it can still be considered a possibility since we don't have good humidity measurements at the surface.
> “There are two basic origins for the water: from above or from below,” Dr. McEwen said. The perchlorates could be acting like a sponge, absorbing moisture out of the air... The other possibility is underground aquifers, frozen solid during winter, melting during summer and seeping to the surface.
Although "rain"/humidity is unlikely, the article also discusses why it can still be considered a possibility since we don't have good humidity measurements at the surface.