Further to: There are millions of habitable planets… no and Rob Sheldon reflects on the hunt for water on Mars, we now hear from Space.com:
Oxygen on Exoplanets May Not Mean Alien Life
On Earth, plants release oxygen into the air through photosynthesis. If a planet beyond the solar system was found to contain oxygen in its atmosphere, scientists reasoned, that oxygen would have formed as a byproduct of life.
Narita and his team decided to study the role of stellar radiation around stars similar to the sun. They found that, if enough of the mineral titania lay on the surface of a planet, it could dissolve in liquid water, producing oxygen in the atmosphere.
Titania is a naturally occurring substance present in meteorites and on Earth’s moon. It forms as dust outflows around evolving low- and medium-mass stars, and through supernovae, and is thought to be common in exoplanet systems. The amount of titania on the surface of a planet or moon would vary based on the number of impacts each body received.
According to the research, an Earth-like planet orbiting a sunlike star would need only enough titania to cover about 0.05 percent of the planet’s surface to create the same amount of oxygen as in Earth’s atmosphere. More.
Find me a single non-Earth-based organism and this discussion could really go somewhere.
See also: Don’t let Mars fool you. Those exoplanets teem with life!
and The Science Fictions series at your fingertips (origin of life)
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