Salts on Mars: Are they a good thing or a bad thing?

Perchlorates, a type of salt that is a key component of solid rocket propellant, could potentially be hazardous to astronauts travelling to Mars and those colonizing the Red Planet, according to features published earlier this week by Astronomy Magazine and Science World Report.

Powerful oxidizing agents produced commercially here on Earth, perchlorates are reportedly 10,000 times more abundant in Martian soil than they are here on Earth, which could be both a good thing and a bad thing for people travelling to and living and working on the Red Planet.

In addition to being useful as a propellant, perchlorates could be broken down to release oxygen to make the air breathable for people, Astronomy explained. However, as potassium perchlorate can be prescribed by doctors to treat hyperthyroidism (overactive thyroid), men and women exposed to high levels of the substance could experience hypothyroidism (underactive thyroid).

Furthermore, while high concentrations of these salts allow water to remain in its liquid state on Mars, it would be toxic to drink and would not support microbial life, Science World Report said. They have also been linked to agranulocytosis and aplastic anemia, two conditions that involve a life-threatening deficiency of blood cells, and are especially dangerous to breastfeeding children.

These health issues could be “devastating for Martian colonists,” Astronomy explained.

“This means that we’ll have to take extreme precaution to remove perchlorate from Mars water and dirt, or from any crops that we grow in it,” the publication added. “Dust will have to be kept from contaminating air circulating through life support systems. Future explorers and colonists will have to do all of this, not only as they capture the perchlorate in order to reap its benefits.”

Salty streaks on Mars could be a great thing for initial colonists or a huge danger.

Salty streaks on Mars could be a great thing for initial colonists or a huge danger. Credit: NASA

Many potential benefits, but health risks and other issues remain

Perchlorate was first detected on the surface of Mars in 2009 when NASA’s Phoenix lander identified the salt and found that it was abundant. Then, last September, the space agency’s MRO (Mars Reconnaissance Orbiter) found high concentrations of perchlorate in recurring slope lineae (RSL) features formed from relatively recent flowing water on the planet’s surface.

Changes to physical chemistry caused by dissolving salts enable subsurface liquid water to reach the surface and occasionally pool as lakes or streams, thus demonstrating how water on Mars can remain in the liquid state long enough to alter the landscape. By tracing the sources of these salts, scientists could find underground water, and potentially native microorganisms, but it would also affect the choice of a landing site and could result in terraforming on the Red Planet.

The energy and oxygen contained in perchlorate could be the difference between the success and the failure of an early colony as previous studies indicated the resources found on the planet will be vital, especially when it comes to producing enough fuel to transport astronauts or colonists from Mars back to Earth or operating vehicles designed to explore the planet.

From 1981 through 2011, ammonium perchlorate was the primary propellant used in the space shuttles’ solid rocket boosters, Astronomy said, and will likely be used to power smaller ships used to carry Mars travelers off the surface and back to a larger, orbiting vessel for the voyage back home. Since it has four oxygen atoms per molecule, these salts could also be used in life-support systems, but as noted above, they are in many ways a double-edged sword.

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Image credit: NASA/University of Arizona