CLOSE
Original image

Meet Five Microbes That Hitched a Ride on the Mars Rover

Original image

Wikimedia Commons

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

Wikimedia Commons

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


IJSEM

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.

Original image
iStock // Ekaterina Minaeva
technology
arrow
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
Original image
iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

Original image
quiz
arrow
Name the Author Based on the Character
May 23, 2017
Original image
SECTIONS
BIG QUESTIONS
BIG QUESTIONS
WEATHER WATCH
BE THE CHANGE
JOB SECRETS
QUIZZES
WORLD WAR 1
SMART SHOPPING
STONES, BONES, & WRECKS
#TBT
THE PRESIDENTS
WORDS
RETROBITUARIES