Curiosity killed the cat. But the Curiosity rover killed the Martians.
Okay well technically is probably one of the Viking landers. At least, that's a new theory presented by Dirk Schulze-Makuch, an astrobiologist at the Technische Universität in Berlin, and recently published in the journal Nature Astronomy. As he explains, lifeforms in arid environments here on Earth often obtain their water indirectly through salts that have absorbed moisture from somewhere else. The desert-like conditions of the red planet next door could mean that Martian life could rely on a similar survival technique.
Unfortunately, when an organism is used to getting its water through salt, it can easily get overwhelmed by actual water:
Organisms in the hyperarid region of the Atacama have adapted to their harsh environment over millions of years by living in salt crusts, underneath translucent rocks, and undergoing prolonged dormancy…and they obtain their life-sustaining water directly from the atmosphere with the aid of hygroscopic salts. These salts can be so hygroscopic that it can lead to deliquescence and the production of saturated sodium chloride brines, in which many of these organisms grow and reproduce. Ironically, microorganisms that draw tiny amounts of moisture through this process can only handle so much water before they hyperhydrate and die of osmotic shock.
And so, Schulze-Makuch posits, if Martian organisms were accustomed to getting their water droplets from salts, then when the twin Viking landers introduced water to the Martian soil in the late 1970s, those probes could have accidentally drowned whatever microbial life was left on the surface. Oops. Space.com summed up the predicament well:
The Viking experiments were conducted under the assumption that Martian life would require liquid water, like most life forms on Earth. Thus, Schulze-Makuch believes, the results of the experiments might be best explained not as the absence of organic life, but as the human-driven destruction of arid microbial organisms exposed to too much water.
This doesn't mean that we necessarily committed Martian genocide (though honestly, it wouldn't that surprising). Rather, Schulze-Makuch used this as a jumping off point for his main idea: stop chasing the waters of Mars, and start looking into the salts. He writes:
If these inferences about organisms surviving in hyperarid Martian conditions are correct, then rather than 'follow the water,' which has long been NASA's strategy in searching for life on the red planet, we should in addition follow hydrated and hygroscopic compounds — salts — as a way to locate microbial life. Nearly 50 years after the Viking biology experiments, it is time for another life detection mission — now that we have a much better understanding of the Martian environment.
Sounds reasonable enough.
We may be looking for Martian life in the wrong place [Dirk Schulze-Makuch / Nature Astronomy]
Did NASA's Viking landers accidentally kill life on Mars? Why one scientist thinks so [Victoria Corless / Space.com]
Whoops, NASA might have killed life on Mars [Ben Kesslen / Quartz]
Previously:
• We have the technology to look for life on Mars
• Are we all Martians? The curious hunt for life on Mars
• Why does a phone ring at the end of Bowie's 'Life on Mars?'
