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Comment by aphextron | Hacker News Reader

Incredibly exciting that these techniques for exoplanet spectroscopy have come so far so quickly. I have full faith that we will discover indirect chemical evidence of extraterrestrial life within the next 10 years. Once JWST [0] comes online it's going to be just a matter of time.

https://en.wikipedia.org/wiki/James_Webb_Space_Telescope [0]

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Please don't say stuff like "I have full faith" when it comes to astrobiology :(. It's really tough for us to even get funding for a lot of these missions, especially now that NASA is being pushed away from astronomy/science and into crewed spaceflight, and the added pressure of some people's "full faith" is really not helpful, as well-intentioned as it may be.

First, faith doesn't have to be religious. You can have faith in something without having to bring in god.

But secondly, even if you do, it's a positive feeling, as long as it doesn't replace thinking and acting. Which this comment clearly doesn't.

It's not clear to me inteleng is objecting to any possible religious connotations, so much as saying that astrobiology's success is far from assured and that much work needs to be done to prevent progress from being derailed.

Don't you think Astrobiology is reliant on peoples faith that interesting results will follow from the capital investments required? I think thats one of the main things that are pushing astrobiology forward. If no one gave a fuck, or no one had any faith in the field, there would be no capital investments. I honestly don't understand the sentiment in the comment - or why you would caution against having faith?

We have faith that we'll do our best to do good science. That's the extent of it.

What would that indirect chemical evidence look like? Perhaps an example you have in mind? Outside of non-committal elements like Uranium or something showing up, I'm not sure what that evidence would look like?

A CO2 increase during just a few years of observation? :) and resulting shift of the planet's black body radiation.

Oxygen would be one. Due to its reactivity, free oxygen is rare, and oxygen spectra may be evidence of respiration.

> evidence of respiration.

Evidence of photosynthesis as well!

Yeah O2 is an input of cellular respiration. The presence of O2 is more likely an indicator of plant-life than it is an indicator of animal life. But plant life is still life.

You do not need animals to have plants. Plants came before animals here on earth. But I’m not sure of a way for animals to exist without plants. So yeah a stronger indicator of photosynthesis than cellular respiration.

Photosynthetic plants without roots.

Conscious Venus Flytraps that seek after other plants to enhance their vitamins.

Pretty sure atmospheric oxygen can be produced from weathering of silicon dioxide.

Why wouldn’t it get bound up with carbon or iron or aluminum etc etc

Yeah but what exoplanet is going to have more oxygen sources than sinks? Just look at Mars, tons of oxygen, but none of it free oxygen.

It would not be sufficient to be a proof of evidence. Oxygen could come from various sources.

No, but in keeping with the "earth-like" avenue of search... If there are other similarities to earth's chemistry (like having water), and we know earth's oxygen comes from breathing... Not evidence, but a good enough reason to look for some. How that happens, idk.

Methane. It is only really transiently generated by geological means and decays quickly when exposed to cosmic radiation. It is also very likely made by any carbon based life ecosystem.

Titan’s athmosphere contains non-trivial amounts of methane but no signs of life so far.

The absence of evidence is not evidence of absence, and so on. We don't know for sure there isn't life on Titan; we just haven't seen enough evidence yet.

We can apply the same logic to draw a number of other useless conclusions.

Rather, we can apply the same logic to "not yet draw conclusions", though I do agree with you that not being able to draw conclusions, is useless.

How about silicon (from the reflections off of orbiting satellite solar panels)?

It will be very tough with JWST. Many of the biosignatures are small features, and not so easily detected. There's only a handful of planets for which this might be close to possible.

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