All of this exploration in our solar system raises some interesting questions concerning the recent pandemic. If pathogens come from beyond Earth, what will they look like? How familiar will they seem? Are we prepared to meet their species?

The more we explore, the more hope we have for finding life beyond Earth in our own solar system.  Certainly there has been a lot of talk about finding primitive microorganisms metabolizing and populating the methane-rich lakes of Titan. Likewise, Venus is likely habitable to sulfur or carbon-monoxide reducing bacteria.  

My guess is that if we find viable, propagating life, it will accompany a water source.  Why?  Because if there’s one chemical that is common to the growth of all lifeforms we’ve known, it is water. 

There are quite a few possibilities for potential watery habitats throughout our solar system. Ganymede and Callisto may have water buried beneath 100km of rock.   Jupiter’s Europa may be our best bet by volume, claiming more liquid water than all of Earth’s oceans, but also it is beneath 10 miles of ice. A recent report from NASA suggests there may be water vapor leaking from fissures in that ice, but these events seem rare and unpredictable.   In general, inaccessibility of the water sources on these moons does not make the imminent discovery of life seem likely.

What about Mars?

Mars seems within reach and scientists are fairly certain there is abundant subsurface water on Mars (also here).  Moreover, there is apparently enough polar ice to cover the planet with 35 meters of liquid water.  Even the atmosphere contains some water.  This is all very great news for life-chasers, but at the same time, it is known that intense ionizing radiation on Mars’ surface would force microbes underground, and the perchlorate-rich soil will make survival difficult even if there are ample organic food sources.

Considering the above, my prime candidate for finding animated life beyond our planet is not Mars, but rather Saturn’s moon Enceladus.  The icy moon has gotten famous for its intense geysers.  These warm, watery plumes have demonstrated the presence of organic compounds and there is presumedly an entire buried ocean of water from which they derive. Considering these facts, Enceladus seems to have all the right boxes checked for growing some basic microbes. We might expect that some sort of anaerobic thermophile would find the place quite comfortable. After all, most scientists are in agreement that these sort of bacteria were among the very first organisms to grace our own planet.

Yet this article was supposed to be about finding lifeforms on Mars, not about life growing on Mars.  Here’s the thing, the absence of surface water is the best way to preserve dormant organisms, for the same reasons that its presence promotes propagation.  This convinces me that

if we are to find lifeforms present in a hostile environment like that of Mars, we should expect to find them dormant.

What’s a dormant organism?  Dormancy is a phase of an organism’s lifecycle where it does not metabolize or grow.  Many organisms are known to display degrees of dormancy.  Certain animals hibernate and often plants experience a similar seasonal dormancy.  Healthy seeds that await the proper germination conditions are often said to be dormant.  And perhaps you’ve seen the wicked-scary Tardigrades?  Tardigrades, while very alien-looking, can only lower their metabolism to .01% and questions remain about the duration of this feat and under what conditions.  Thus, the definitively space-worthy organisms are bacterial endospores.

Endospores, or simply spores, are a dormant form of bacteria. In fact, the majority of the bacteria found on Earth appear dormant.  Dormant spores have no effective metabolism and can remain in this state indefinitely whilst surviving incredible insults from their environment ranging from bleach to trips to space. 

One specimen of bacterial spore was shown to have been awakened from the belly of a bee after having been trapped inside of amber for up to 40 million years.

There is no telling what degree of longevity is possible to these lifeforms. It seems safe to presume that they could sit quietly on a dusty moon or scarred desert like Mars for a long, long while. Next-time I’m going to take a look at how these dormant organisms physically accomplish this feat (Hint:  it has to do with enforcing a glass-like state of water).  But for today, let’s leave this with my prediction that if we find an organism on Mars, it’s going to look a lot like these spores pictured below, 

which I imaged with the “touching” or atomic-force-microscope.  After all, they’re the only organisms we know of that are equipped to survive such an ordinarily deadly landscape. The flip-side of this tenacity is that these organisms might successfully cling to returning spacecraft undetected and besiege our planet. That would force us to face an entirely new type of pandemic.