How Deadly Would Extraterrestrial Bacteria Be to Humans?

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How deadly would a bacterium be to humans if it was brought from a completely different star system?Drew Smith:

The chance that extraterrestrial bacteria would be deadly to humans is zero. Not just very, very small. Zero.

Pathogenesis requires intimacy. This intimacy is attained through millions of years of co-evolution. The need for intimacy is apparent when you look at how bacteria and viruses cause infections and disease.

Infection requires binding to a cell surface. Bacteria (and viruses) bind to human cells through proteins that recognize human proteins and carbohydrates. The structure of these human proteins and carbohydrates is, to a first approximation, arbitrary. There are an almost infinite number of permutations of them that could exist and work just fine. But only one does exist. The chance that an alien bacteria would have evolved to stick to that protein is infinitesimally small.

Even if this alien bacterium were able to stick to a cell surface, this alone would not establish an infection. Infecting bacteria secrete all kinds of toxins and virulence factors. These toxins and factors bind to specific human proteins. They block or modify their activity in ways that degrade cells and tissues, releasing nutrients that the bacteria can feed upon.

Again, the target proteins have fairly arbitrary structures. They are the result of billions of years of evolutionary history and their precise structure—and even their existence is not at all predictable. The chance that an alien bacterium would have evolved toxins that precisely target them is infinitesimally small.

Pathogenicity is extremely rare on Earth. There are millions, perhaps billions, of species of bacteria. The number of potential human pathogens among them is very small, no more than a couple hundred. And only a couple dozen are able to infect otherwise healthy humans. These are bacteria that have been with us for millions of years, evolving as we evolve, becoming intimately familiar with our proteins, our cells, our immune systems.

This knowledge is stamped into their genomes; it is a diary of their long association with us. It is not a book that could be written in an alien language. Alien bacteria are no more likely to be human pathogens than intelligent aliens are likely to speak Urdu as their native tongue. It just isn’t possible.

This post originally appeared on Quora. Click here to view.

The Smithsonian Needs Your Help Transcribing Sally Ride’s Notebooks

Sally Ride in 1984.
Sally Ride in 1984.
Coffeeandcrumbs, NASA, Wikimedia Commons // Public Domain

On June 18, 1983, Sally K. Ride made history when she became the first American woman to travel into space. Now, the Smithsonian Institution is making the history of her incredible decades-long career more accessible to everyone—and they need your help to do it.

The National Air and Space Museum Archives is home to the Sally K. Ride Papers, a collection of 38,640 physical pages (over 23 cubic feet) of material spanning Ride’s professional life as an astronaut, physicist, and educator from the 1970s to 2010s. Those resources have been scanned and used to create an online finding aid—not unlike a table of contents—so researchers can easily navigate through the wealth of information.

To simplify the searching process within that online finding aid, the Smithsonian Institution is asking for volunteers to transcribe documents in the Smithsonian’s Transcription Center, a digital hub launched in 2013, where anybody can sign up to type and review historical sources. Three projects from the Sally K. Ride Papers are currently available to transcribe, which include her notes for shuttle training between 1979 and 1981, notes about the Remote Manipulator System Arm (there's one on the International Space Station today), and notes from NASA commissions on which she served. One, for example, was the Rogers Commission, which investigated the causes of the fatal Space Shuttle Challenger disaster in 1986.

You can find out more about the documents in the projects here, and if you’re interested in joining the forces of “volunpeers,” as the Smithsonian likes to call its transcribers, you can create a new user account here. (All you’ll need is a username and email address.)

Check out more citizen science projects you can participate in at home here.

How to Livestream Tonight’s Super Pink Moon

Matt Cardy/Stringer/Getty Images
Matt Cardy/Stringer/Getty Images

On April 7, 2020, a super pink moon will appear over the horizon. Though it's not actually pink (the name's meaning comes from the wildflower Phlox subulata, or moss pink), the supermoon is still worth seeing. Today, the moon will reach the closest point to Earth in its orbit just hours before becoming completely full, which adds up to give us the biggest and brightest supermoon of the year. And no matter where you are in the world, you can livestream the spectacle online.

Slooh, a celestial event streaming service, will begin broadcasting the super pink moon at 7:30 p.m. ET tonight, April 7. A team of astronomy experts and educators will be joining the feed to provide commentary until the stream ends. You can tune in through Slooh's Facebook live event or YouTube channel for free, or you can become a member to watch it on their website.

Slooh has telescopes around the world that allow users to explore space from their computers. If you sign up for a membership today, you'll be able to capture and share photos of the supermoon, virtually interact with the experts at the live event, and personally control Slooh’s telescopes to customize your view of the moon. And when tonight's event is over, you'll still be able to virtually control Slooh's six telescopes in the Canary Islands and four telescopes in Chile throughout the year.

A basic, annual membership with Slooh costs $100. If you're a student, the service is offering a limited-edition price of $20 for individuals. The deal aims to promote remote teaching and learning during a time when schools around the world are closed.

For people living in cities with light pollution, celestial livestreams are a great alternative to real-life stargazing. Slooh isn't the only platform airing tonight's event. Today, the Virtual Telescope Project in Italy will host its own livestream of the super pink moon on YouTube.

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