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Meet Five Microbes That Hitched a Ride on the Mars Rover

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Before any nation launches a spacecraft, the U.N.’s Outer Space Treaty requires the craft to undergo extensive cleaning, to “avoid harmful contamination of space and celestial bodies.” Basically, we don’t want our gross Earthly microbes to invade new regions of space and kill off other life that might potentially be living there. That’s especially true for Mars, because scientists think there’s a chance that single-celled organisms may have evolved there in the past, and might even still live on the Red Planet today.

NASA spacecraft get disinfected about 10 to 30 times before they launch, says Stephanie Smith-Rohde from the University of Idaho. But those decontamination sessions can’t catch everything. Smith-Rohde and her colleagues analyzed swabs that were taken from the surface of the Curiosity rover after cleaning and prior to launch. Their preliminary results, which were presented at a meeting of the American Society for Microbiology, turned up 377 organisms from 65 bacterial species.

Smith-Rohde’s team attacked these microbes with a battery of tests meant to simulate the harsh conditions of space and Mars, and they found that many of the microbes survived just fine—even, surprisingly, the bacteria that don’t form protective spores.

Scientists need to do longer-term studies, but so far the evidence suggests that some of these bacteria may have been capable of surviving a journey to Mars.

“Have we contaminated Mars already, or is there no way those microbes could survive the journey?” asks Smith-Rhode. “We don’t have answers to those questions yet. These studies allowed us to narrow down the organisms that we want to focus on.”

If Earth microbes did make it to Mars, here are the ones that are most likely to make themselves at home.

1. Staphylococcus

These bacteria (top), typically found in soil and on human skin, persevered in petri dishes that contained 20 percent salt. That’s really salty—by comparison, the ocean is only about 3 percent salt. It may be that Staphylococcus could also thrive in Mars’ salty sands and waters.

2. Enhydrobacter

During laboratory tests, Enhydrobacter colonies withstood a 2000-joule zap of radiation, “which is a pretty decent dose of UVC radiation,” says Smith-Rohde. They also endured a two-week desiccation experiment, wherein they had absolutely no access to water, with no major problems.

3. Moraxella

Nearly 50 percent of Moraxella bacteria outlived a one-hour dunk in a 5 percent hydrogen peroxide solution—a common cleaning agent meant to kill microbes on spacecraft.

4. Streptomyces

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Normally noted for their role in decaying organic matter, Streptomyces microbes are surprisingly hardy. In experiments, they were able to grow in the 20 percent salt solution as well as the two-week desiccation period, withstood low temperatures, and tolerated a pH of 9—similar in acidity to the soils of Mars.

5. Gracilibacillus


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Gracilibacillus one of a handful of types of bacteria that can eat the perchlorates found in Martian soil. “Gracilibacillus would definitely be a top contender to survive on Mars,” says Smith-Rohde.

Up next, Smith-Rohde and her colleagues plan to learn more about each of these microbes. They will expose the hardiest species to multiple extreme conditions at once, which is more like what they’d really experience in space, and also may determine whether they could endure the nine-month journey to Mars.

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Health
Growing Up With Headphones May Not Damage Kids’ Hearing
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A study published in the American Medical Association's JAMA Otolaryngology-Head & Neck Surgery finds no increase in child and adolescent hearing loss despite a rise in headphone and earbud use.

"Hearing impairment in children is a major public health burden given its impact on early speech and language development, and subsequently on academic and workforce performance later in life," the authors write. "Even mild levels of hearing loss have been found to negatively affect educational outcomes and social functioning."

As portable music players continue to grow in popularity, parents, doctors, and researchers have begun to worry that all the music pouring directly into kids' ears could be damaging their health. It seems a reasonable enough concern, and some studies on American kids' hearing have identified more hearing loss.

To take a closer look, researchers at the University of California-San Francisco analyzed data from the National Health and Nutrition Examination Survey (NHANES), collected from 1988 to 2010. They reviewed records from 7036 kids and teens between the ages of 12 and 19, checking each participant's hearing tests against their exposure to noise.

As expected, the authors write, they did find a gradual increase in headphone use and other "recreational noise exposure." And they did see an uptick in hearing loss from 1988 to 2008 from 17 percent to 22.5 percent. But after that, the trend seemed to reverse, sinking all the way down to 15.2 percent—lower than 1988 levels. They also found no significant relationship between noise exposure and hearing loss.

The results were not uniform; some groups of kids were worse off than others. Participants who identified as nonwhite, and those of lower socioeconomic status, were more likely to have hearing problems, but the researchers can't say for sure why that is. "Ongoing monitoring of hearing loss in this population is necessary," they write, "to elucidate long-term trends and identify targets for intervention."

Before you go wild blasting music, we should mention that this study has some major limitations. Hearing loss and other data points were not measured the same way through the entire data collection period. Participants had to self-report things like hearing loss and health care use—elements that are routinely under-reported in surveys. As with just about any health research, more studies are still needed to confirm these findings.

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Weather Watch
NASA Figures Out Why When It Rains, It (Sometimes) Drizzles
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What’s the difference between drizzle and rain? It has to do with updrafts, according to new research by NASA scientists into the previously unexplained phenomenon of why drizzle occurs where it does.

The answer, published in the Quarterly Journal of the Royal Meteorological Society, could help improve how weather and climate models treat rainfall, making predictions more accurate.

Previously, climate researchers thought that drizzle could be explained by the presence of aerosols in the atmosphere. The microscopic particles are present in greater quantities over land than over the ocean, and by that logic, there should be more drizzle over land than over the ocean. But that's not the case, as Hanii Takahashi and her colleagues at the Jet Propulsion Laboratory found. Instead, whether or not rain becomes full droplets or stays as a fine drizzle depends on updrafts—a warm current of air that rises from the ground.

Stronger updrafts keep drizzle droplets (which are four times smaller than a raindrop) floating inside a cloud longer, allowing them to grow into full-sized rain drops that fall to the ground in the splatters we all know and love. In weaker updrafts, though, the precipitation falls before the drops form, as that light drizzle. That explains why it drizzles more over the ocean than over land—because updrafts are weaker over the ocean. A low-lying cloud over the ocean is more likely to produce drizzle than a low-lying cloud over land, which will probably produce rain.

This could have an impact on climate modeling as well as short-term weather forecasts. Current models make it difficult to model future surface temperatures of the Earth while still maintaining accurate projections about the amount of precipitation. Right now, most models that project realistic surface temperatures predict an unrealistic amount of drizzle in the future, according to a NASA statement. This finding could bring those predictions back down to a more realistic level.

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