However, I can think of other future sentient designs and body plans they might favor for reasons of their own. They might want to program for certain biochemical, cultural and behavioral characteristics, too.

At any rate, I’m glad to see some writer in that franchise went to the trouble of trying to explain why all the aliens looked like dudes in rubber suits.

Billions of years ago a sentient species- the very first one- seeded the galaxy with life, genetically pre-programed to evolve to a common goal- something resembling the first ones…

It was one of the deepest episodes they did…
https://en.wikipedia.org/wiki/The_Chase_(Star_Trek:_The_Next_Generation)

No, I was riffing on some sci-fi ideas I’ve been having, now that I’ve given up on space ships and radio signals, microbes sailing the stellar winds seems the only way to travel across space. I confess, I was inspired by the Protomolecule in “The Expanse”, and remember, that is not a naturally evolved organism, its an artifact, a weaponized form of artificial life designed as a universal parasite for some long forgotten interstellar war, by some Type II or III civilization a long way off, a long time ago.
That’s why I posted on “Mysteries” and not “Space”. On second thought, though, I should have put it on “Science-Fiction”.

I agree, parasites are the most highly specialized of all organisms, and they share a complex shared evolution (sometimes even a symbiotic one) with their prey. But an artificial organism might be deliberately designed to be a generalist, especially if life tends to evolve along a finite number of similar chemical pathways throughout the universe.

Of course, we don’t know that, but its possible that life tends to follow parallel biochemical strategies, after all, the amino acids we have found in distant molecular clouds are exactly the same ones we have here. DNA may be the only way genetic information and protein synthesis is carried out, although there may be several (or even many) variations of it possible. An artificial virus could carry in its own DNA not only the information needed to create copies of itself, but also coded strategies for dealing with some of those variants. It might have a tool kit of numerous biochemical tools for attacking a variety of common possible biochemistries. And there would also be room for additional instructions for carrying out a more complex mission as well.

No, I agree that natural organisms from other worlds would probably be unable to get a foothold in Terrestrial critters, but I’m open to the possibility that a deliberately designed artificial life form might have enough tools to crack a natural genetic code that evolved somewhere else. Remember, it wouldn’t have to be 100% successful every time, it would just have to win occasionally…and then evolution would take over.

As for surviving the voyage…well, maybe that’s why god invented bucky balls.

Its nonsense.
Viruses are simple, and BECAUSE they are simple they are very specific.

Viruses and their hosts co-evolve and become quite specific to each-other. The more evolutionary distance between two species the fewer viruses they share.

When did you last hear of someone calling in sick because they caught that nasty strain of the Cauliflower Mosaic Virus going around?

We share many viral pathogens with chimps, fewer with dogs, none that I could find with fish and insects, and none with plants.

More complex bacteria can be more general, but viruses are not.

Even IF an alien ecosystem developed with something like DNA and RNA (Highly unlikely) and even if it had the same identical building blocks of DNA and RNA (ACTG for DNA, AUCG for RNA)- astronomically unlikely, and even if it was operating with the same ‘language’ and enzymes and proteins…(Damn near impossible)… even granting all that, a cucumber would be far more related and similar to us than anything that virus was evolved to handle.

It just wouldn’t be compatible.

Its like a Vulcan and a Human engaging in sex (even assuming their naughty bits are compatible)- for any progeny to result wouldn’t just be surprising, it would be fuckin’ Spocking!

More complex and independent bacteria like microbes might be a threat… if they have the machinery that allows then to thrive with nothing more than a source of raw material… (assuming its not expecting unique easy to digest proteins that it has evolved specifically to handle, and that our alien molecules are not immediately toxic to it) But how likely is it that something like that can survive extended exposure to cosmic radiation as it travels between the stars?