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The Planetary Protection Office is hiring and we’ve found a much easier way to study neutrinos.

Host: Hank Green
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Sources:
https://www.nasa.gov/feature/planetary-protection-excites-space-fans-of-all-ages
http://science.sciencemag.org/content/early/2017/08/02/science.aao0990.full
https://news.uchicago.edu/article/2017/08/03/worlds-smallest-neutrino-detector-observes-elusive-interactions-particles
https://www.scientificamerican.com/article/ever-elusive-neutrinos-spotted-bouncing-off-nuclei-for-the-first-time/
https://arstechnica.com/science/2017/08/after-43-years-gentle-touch-of-a-neutrino-is-finally-observed/
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Images:
https://www.nasa.gov/feature/planetary-protection-excites-space-fans-of-all-ages
https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA00502
https://en.wikipedia.org/wiki/Neutrino#/media/File:FirstNeutrinoEventAnnotated.jpg
https://en.wikipedia.org/wiki/Oak_Ridge_National_Laboratory#/media/File:ORNL_Campus_Photo_4.jpg
Perhaps you have seen this very strong job application for NASA’s Planetary Protection Officer from Jack, a fourth-grade Guardian of the Galaxy.

Or maybe you’ve seen some of the pretty sensationalist headlines describing the job as “saving the Earth from aliens.” And if you’ve broken one of the cardinal rules of the Internet and read the comments on these articles, you’ll see a ton of complaints about the position being a waste of time and taxpayer money, and a LOT of GIFs from Independence Day. Well, Guardian of the Galaxy Jack probably has the most reasonable and measured response to the job posting so far.

The Planetary Protection Office is actually really important, and is way less sci-fi than it sounds. It’s supposed to make sure that we keep other worlds in their natural states, and that we don’t biologically contaminate those worlds — or allow them to contaminate our own. And it’s not just NASA that’s super concerned about the effects of possible contamination.

There are international agreements established by the United Nations and the International Council for Science, which say that space agencies aren’t allowed to contaminate the places they explore. These agreements were established even before we went to the Moon, so this is something that has been on scientists’ and policymakers’ minds for a long time. But not because we’re trying to protect ourselves from the type of alien invasion that involves flying saucers.

It’s the tiny microbes that we’re worried about. Other places in the solar system, like Mars and some of the moons of Jupiter and Saturn, have environments that could create habitable conditions. So even though we haven’t found any yet, it’s still very much a possibility that life exists elsewhere in the solar system, and we have no idea what that life would be like.

We have no idea whether that life could be toxic to us, or whether terrestrial life could be toxic to it. We have no idea if terrestrial life could become an invasive species in these environments and out-compete the native species to the point of extinction. We’d be like, “Hey, look!

We found life elsewhere in the universe and then we killed it!” And so because we are reaching Jon Snow levels of not knowing, we have to take necessary precautions to make sure we don’t accidentally create an interplanetary catastrophe. And that’s what the Planetary Protection Officer job is for. They’re in charge of the rules we’ve established to prevent contamination — for example, all machinery destined for space must be assembled in a clean room, and certain icy locations on Mars are off-limits to exploration by rovers that use a radiothermal generator, because the ice could melt and wake up dormant life.

There’s also the concept of “bioburden constraint,” which essentially defines how clean something has to be before it’s cleared for entry into space. That allows scientists and engineers to design their projects such that they can minimize contamination in both directions. So despite all the headlines poking fun at NASA, it’s an important job.

And if you think you are the perfect fit for that job, you might have a couple more days to apply — the application closes August 14. Meanwhile, in news about super-mysterious non-living things, researchers just announced that they’ve figured out how to detect neutrinos in a totally new, and much easier, way. Neutrinos are notoriously difficult to detect.

They’re tiny little particles, just a fraction of the mass of an electron, and they can also pass through matter totally unimpeded, which kind of complicates things. But they may or may not be part of dark matter, the stuff that makes up about 80% of the mass in the universe but we know nothing about and have never been able to detect. So neutrinos are totally neat, and particle physicists are really amped up about studying them.

Most neutrino-detection projects involve burying a giant facility way deep underground so that the soil and bedrock can shield your detectors from any sources of interference, and having enormous detectors that weigh thousands, and sometimes millions, of kilograms. But in a paper published in the journal Science last week, researchers announced that for the first time, they’d detected a special type of neutrino collision using a small detector in a basement. More than forty years ago, scientists at Fermilab predicted that even though interactions between neutrinos and regular matter are super rare, certain kinds of low-energy neutrinos could bounce off of atomic nuclei a lot more often.

The neutrino bounces off with quite a bit of speed — although slightly less than before — and as the nucleus oscillates a bit from its recoil, it emits light. Theoretically, that light is a great way to study neutrinos. If you can build a detector that sees those light emissions from the nucleus, you can use that to infer the properties of the neutrino that collided with it.

But the amounts of light emitted from these collisions is so small that it’s extremely difficult to detect, and that’s a big part of why it took 43 years and a lot of heavy engineering to finally see it. The team ran their experiments at the Oak Ridge National Laboratory in Tennessee, which has a particle beam that shoots out the low-energy neutrinos they needed for the experiment — along with neutrons, much larger neutral particles that are part of the nucleus atoms. One problem was that if the detector picked up neutrons, that would totally ruin the experiment, because neutrons are so much bigger than neutrinos that they’d totally overwhelm any sign of neutrinos interacting with atoms.

So they set up shop in a hallway about 19 meters underground, where the ground and concrete surrounding the hallway blocked almost all of the neutrons — but not the neutrinos. For their detector, they decided to use a type of cesium iodide crystal that the neutrinos were more likely to interact with, but was also transparent so the team could detect the flashes of light. So the detector itself was super sensitive, but also really small: it weighed in at just 15 kilograms or so, instead of the thousands of kilograms that other neutrino detectors weigh.

And it worked: they detected neutrinos bouncing off of the atomic nuclei in the crystal! We’ll still need the old-fashioned giant detectors for some things, but now that we know this method works, scientists have a ton of new opportunities to learn more about neutrinos. They’re already looking into whether we’re right about how often neutrinos interact with different kinds of matter, and this new strategy should also make it a lot easier to test some of our ideas about dark matter.

All from a lump of crystal the basement. Thanks for watching this episode of SciShow Space News, and thanks especially to all of our patrons on Patreon who help make this show possible. You are great!

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