Earlier this year, I wrote a blog post about not contaminating other worlds with Earth-bound microbes. Let’s keep planets that might have microbial forms of life free of our own bacteria, I said. (See my blog of 7/13/2014.) I also said let’s not contaminate sterile worlds with our trashy bacteria. Today I want to explore the opposite situation, that of microbes from other planets contaminating us. I think we’ve got a lot to worry about, and we should be concerned.
When Apollo astronauts came back from the moon in the late 1960’s and into the 70’s, they were quarantined for several days before they were allowed to contact other humans. That was a recognition of the fact that microbes might have been present in lunar soil that could have infected us. Nothing happened, however, and the Apollo astronauts never got sick from moon bugs, but the concept is still valid. The moon and other lifeless worlds, such as some or most of the asteroids, are probably free of foreign germs because, without an atmosphere, they are exposed directly to sterilizing radiation from the sun. But the same can’t be said for Mars or some of the moons of Jupiter and Saturn. Mars probably had running water at one time, and the possibility exists that germs could still exist, either in pockets of water under the surface, or as desiccated (i.e, waterless) forms just waiting for water to appear to begin the rehydration procedure that produces a viable organism. Europa is an even better candidate for the presence of microorganisms, since it is believed to have oceans beneath its icy exterior and a hot core that could keep water liquid farther down. Bugs could be thriving in those seas, and that could be bad for us.
If you recall from reading H. G. Wells’ novel War Of The Worlds, the invaders from Mars were stopped because they were infected by Earth bacteria. Wells didn’t specify which bacteria. He wrote in the late 19th and early 20th centuries, and the descriptions of microorganisms at that time was what we would consider rudimentary now. But he had a valid point. Bacteria that are harmless to us living on this Earth, for example, soil bacteria, could be potent against an invader. Life forms that potentially swirl in the oceans of Europa could be dangerous to astronauts brave (or perhaps foolish) enough to land on it.
The most dangerous type of microorganism on a distant world I believe would be a bacteria. Once a bacteria finds a suitable habitat, it will begin to grow, and can produce many progeny in a short amount of time. Many bacteria release toxins, that is, poisons that can make a person very sick. And the human body can provide a nice, warm place for foreign bacteria to grow.
I’m not as concerned about viruses since they have to grow inside a cell, and to get in they have to have what could be considered a key to fit the lock on the door of the cell to get in. Viruses on outer worlds may not be as dangerous because they’ve adapted to grow in the cells of whatever organisms live there. But bacteria don’t have that limitation. They don’t have to get into a cell to make it sick. And I think that’s a very important point we have to take into consideration when traveling to other worlds. We can’t just land and hop out and walk around. We could kill ourselves the way Well’s invaders did.