[gus_massa]

> Many amino acids can be created in two mirror-image versions, like a pair of left and right hands. Life on Earth almost exclusively produces the left-handed variety, but the Bennu samples contain an equal mixture of both.

This is a very strong indication that the amino acids in the sample where made by an inorganic process.

[AnimalMuppet]

Is it? Or is it a very strong indication that the amino acids in the sample were not contamination by life on Earth?

That is, while life on Earth is left-handed, I don't know of any reason to assume that life elsewhere must be either left- or right-handed.

I don't actually believe in panspermia. I just think that it's important to not infer more than the evidence actually gives.

[Out_of_Characte]

Life uses the exact same chemistry as any inorganic process exept life is far more competent than random reaction products. This is why the expected origin is inorganic as left handed and right handed are equally likely to occur in an inorganic process. So occams razor suggests that either 1) life must specifically balance their left-right handed molecules 2) Other processes that favor any handedness must not be present.

or the process is inorganic which we know couldn't favor left or righthandedness in the first place.

[gus_massa]

I agree. My version:

I would not be surprised if we find life in other planet/moon that use "only" [1] right handed amino acids. But it looks like it's easier to produce "only" one type of them: "only" left handed or "only" right handed.

To produce both in a 50%-50% ratio they would need to duplicate most of the enzymes, or have a specialized enzyme that transform one into the other. It's not impossible, but it seams to be wasteful.

Nobody is sure, but our current best guess is that life in other planets/moons will choose left or right instead of a 50%-50% mix.

[1] Life on Earth use a small amount of right handed amino acids, so I expect a "mirror" life to use a small amount of left handed amino acids.