Like Mars, Only Closer
It’s not yet practical for Mars researchers to do their work on Mars. So University of Arkansas student Holly Farris did the next best thing and spent June in a very Martian-looking desert in northern Chile.
Farris, who is working toward her Ph.D in Space and Planetary Sciences, is interested in the stability of liquid water on Mars.
“The main science objective for NASA is to follow the water because it is a requisite for life,” she says. “My research looks at the stability of water as it pertains to interactions between the atmosphere and the surface.”
She’s used data modeling and the University’s W.M. Keck Laboratory for Planetary Simulations to help answer the question of whether there is water, and therefore possibly life, on the Red Planet. But she also needs fieldwork. And the Atacama Desert is a lot closer than Mars.
“Going to the Atacama was a great way to do some in situ experiments because the Atacama is the driest place on earth. It receives less than a millimeter of rainfall annually. There are large temperature swings and there is also a fairly high concentration of salt in the soil. All of those things make it one of the best Mars analog sites, if not the best, with the exception of Antarctica, on earth.”
She spent June 9 to July 2 in the Atacama. The nights were cold, often below zero, and the days were hot, near 100. There’s no vegetation and zero shade. If you want to get out of the sun, you have to dig a hole in the ground. Though the average annual precipitation is less than one millimeter, there are places there where it hasn’t rained in recorded history.
Nonetheless, there is water there. The Atacama is littered with “salt nodules,” rock-sized chunks of salt that pull tiny amounts of water from the atmosphere.
“If you were to crack one of them open it is extremely moist in the middle,” Farris says. “It is very porous and it is thriving with microbial life. Almost no rainfall, very little dew or wind or any sources of water, and these things can suck the little bit of humidity out of the air and sustain wetness on the inside, enough to fuel life.”
For her experiments, she packed various salts into 10-centimeter cubes, then inserted temperature, humidity and conductivity sensors into the cubes. The idea is to track how much moisture the cubes pull out of the atmosphere through a process called deliquescence.
Her experiment, funded by grants from the Arkansas Space Grant Consortium, the Lewis and Clark Fund for Field Research in Astrobiology, and Farris’ Sturgis Fellowship from the University of Arkansas, will replicate that process with salts known to exist on Mars. She’ll return to check on her cubes in January, and again next summer.
If it turns out that the salts can absorb water in the Atacama, maybe they can do it on Mars, too.
“The implications are very much astrobiological,” she says. “The search for life.”