How Deadly Would Extraterrestrial Bacteria Be to Humans?


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.

Did NASA Ever Consider Women for the Mercury, Gemini, or Apollo Programs?

Russell L. Schweickart, Keystone/Getty Images
Russell L. Schweickart, Keystone/Getty Images

C Stuart Hardwick:

Unambiguously, no.

This was not sexism. NASA decided early on, and quite correctly, that early astronauts must all be experienced high-performance jet test pilots. To anyone who understands what the early space program involved, there can be little question that choosing all men was the right call. That's because there were zero women in the country with high-performance test flight experience—which was due to sexism.

You may have heard of the so-called “Mercury 13” or the Women in Space Program, both of which are misleading monikers invented by the press and/or American aviator Jerrie Cobb.

Here’s what happened:

Randy Lovelace’s laboratory tested astronaut candidates to help NASA select the initial seven Mercury astronauts. He later ran Jerrie Cobb through the same Phase I (biomedical) tests (though not through the other tests, as he didn’t have access to equipment owned by the military). Contrary to some reports, Cobb did not test superior to the men overall, but she did test as well overall. And while that should not have been a surprise to anyone, it was in fact a surprise to many.

Lovelace published a paper on the work in which he suggested that women might actually be preferable candidates for space travel since they weigh less on average and consume less oxygen, water, and other consumables, a fact which I exploited in my book, For All Mankind, and I can tell you that on a long duration mission (of several months) the difference really does add up.

This had no effect on Mercury, Gemini, or Apollo, all of which were short little jaunts in which the mass of the astronauts wasn’t terribly critical, and all of which were always going to be flown by high-performance test pilots anyway.

However, it attracted the attention of famed aviation pioneer Jackie Cochran, who agreed to fund further research on the suitability of women for space.

Pioneer American aviator Jacqueline "Jackie" Cochran in the cockpit of a Curtiss P-40 Warhawk fighter plane
Jackie Cochran in the cockpit of a Curtiss P-40 Warhawk fighter plane
Public Domain, Wikimedia Commons

Cochran and Cobb recruited several more women, mostly from the ranks of the Ninety-Nines, a women aviator’s professional organization founded by Amelia Earhart. These women also went through the initial biomedical testing, and 13 passed at the same standard as met by the Mercury astronauts.

So far so good. Cobb, Rhea Hurrle, and Wally Funk went to Oklahoma City for an isolation tank test and psychological evaluations, and Lovelace secured verbal agreement through his contacts to send another group to the Naval School of Aviation Medicine for advanced aeromedical examinations using military equipment and jet aircraft.

However, no one had authorized the use of the military facilities for this purpose—or the costs that it would entail. Since there was no NASA request behind this effort, once Lovelace tried to move forward, the military refused his access.

Meanwhile, Cobb had been enjoying the attention she was receiving and, according to some, had gotten it into her head that all of this was going to lead to some of the women actually flying in space. In fact, I’ve found no evidence that Lovelace ever implied that. This was a small program of scientific study, nothing more. Nevertheless, Cobb flew to Washington, D.C. along with Jane Hart and was given a meeting with then-vice president Lyndon Johnson.

Johnson was congenial—Cobb has always claimed he pledged his support—but immediately afterward, he sent word to have all support for the experiments withdrawn.

Far be it from me to defend the motives of LBJ, but consider this: The president had publicly committed the nation to returning a crew from the moon by the end of the decade—and this was at right about the same time when enough work had been done for Johnson to have a handle on just how hard that was going to be. He may or may not have supported the idea of women astronauts in general—we have no idea—but Jerrie Cobb standing before the press, pushing for “women in space” was definitely, irrefutably a distraction he didn’t need. And any resources devoted to it were being pulled directly away from the moon shot—which, to Johnson, was the goal.

Jerrie Cobb poses next to a Mercury spaceship capsule
Jerrie Cobb poses next to a Mercury spaceship capsule
NASA, Public Domain, Wikimedia Commons

Cobb has always maintained the women were misled and betrayed. I’ve found no evidence of that. Testimony of many of the other participants suggests that Cobb simply got carried away—not that anyone could blame her. Let’s remember that at that time, she couldn’t have known what was really involved in space flight or what the program would look like over the next decade. No one did.

Of course, American women did start flying in space with the Space Shuttle. Do not for a moment think this means they didn’t face the same prejudices at NASA that they did everywhere else. The first class of women astronauts was, according to my sources, invited to help design an in-flight cosmetics kit—an offer they immediately and forcefully shot down. Thirty years later, women remain a distinct minority in the U.S. astronaut corps ...

The bigger question is not whether Cobb was betrayed, but why, in 1961, not a single U.S. woman had been hired to work in high-performance flight test—considering that so many (like Cobb, for example) had performed test flight and ferry duties during the war.

Why weren’t women welcome in the post-war aerospace economy, and why—even today—are so few women granted degrees in engineering of any sort? I don’t know the answer, though sexism is unquestionably in the mix, but it’s a question we need to address as a nation.

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

True or False: Was This Object Left on the Moon?