Among the Moss Piglets: The First Image of a Tardigrade (1773)
publicdomainreview.org
publicdomainreview.org
These days I can reference the internet to figure out what some common things are, but there are still heaps of weird things I find that I really have no idea what they are and deep searches yield nothing or a vague “it might be part of this enormous genus, but maybe not”.
It would have been something else at the dawn of microscopy, but it’s still such an incredible way to see the world. Every time I look I’m amazed by the sheer scale and diversity of life happening all around me (and on me). Worlds within worlds.
History suggests that is not what will happen when we find a planet that harbors life sustaining conditions, even if our presence would destroy all life on it.
Homo sapiens' track record is one of self-interest and the (largely-ish, though sadly not mostly) unintentional devastation of life forms in human vicinity.
But I digress. When we discover a world with livable conditions, we will occupy it, fill the pace, mine it, etc. Native life on it will come under selective pressure. And that's not necessarily a bad thing.
FWIW we trade so much material with outer space (super volcanos etc) that if life could colonize space that easily it would have done so billions of years ago.
Could we create a minimially viable living environment for these extremophiles to survive on other planets? For humans, we'd need pretty incredible technology to sustain life on mars, but for tardigrades, they could probably survive with a lot less.
Say, a very hardy algae that could make it in some suitable microbiome - like humid cracks in the rocks, or a fungus that could hang out in underground caverns shielded from UV radiation.
If we are trying to seed a place with life where we can't reliably go ourselves, it seems important that the 'colony' should become self-sustaining immediately-ish.
(Also I find the idea of launching swarms of micro-pods loaded up with hardy, tiny lifeforms endearing - like throwing seed bombs over a tall fence :) )
On our planet we try to measure something called net primary productivity (https://en.wikipedia.org/wiki/Primary_production?wprov=sfla1), which is basically a measure of how much energy can be made useful to lifeforms in a planet's food web. There are only a few processes we know of that can do this, such as plants and algae and other photosynthetic organisms turning sunlight into edible organic substances for other consumers to eat. Tube worms chemosynthesizing from ocean floor hot spring vents is another one. These species are called autotrophs ("self feeders") and they constitute the basis of the entire food web on Earth, as far as we know. https://en.wikipedia.org/wiki/Autotroph?wprov=sfla1
Without a suitable ecosystem for autotrophs, there isn't enough biologically available energy for the heterotroph species (everything else, us included, that eats other species to survive).
So as far as know, a planet has to have a suitable environment for autotrophy to evolve first (or for alien life to arrive on, eg through exobiogenesis). You can't just send a bunch of consumers there and expect much to happen. At most they'd eat each other and then all become extirpated (locally extinct).
Sci fi of course has us terraforming planets to make them (Earth) life sustaining, but that usually starts with plants and algae and such too before introducing the heterotrophs and inevitable monsters.