from the world's big
When searching for extraterrestrial life, astronomers may want to look at planets with hydrogen-rich atmospheres.
Until about a decade ago, only two habitable zone planets of any size were known to astronomers: Earth and Mars.
A few months ago a group of NASA exoplanet astronomers, who are in the business of discovering planets around other stars, called me into a secret meeting to tell me about a planet that had captured their interest.
The intelligent life we are searching for doesn't have to be humanoid.
Life is pretty easy to recognise. It moves, it grows, it eats, it excretes, it reproduces.
These needles in the vast galactic haystack take more effort to find, but they help piece together our origins.
- With billions of stars in our galaxy, why should astronomers seek out the oldest ones?
- Age-dating stars is a complicated process, so astronomers use chemical compositions, telescopes, and prisms to determine the age of these ancient stars.
- Some telescopes used for this purpose are in extremely remote places, where you can observe the bright band of the Milky Way with the naked eye.
The Jerezo crater — where Mars 2020 is set to land — could be a good place to find signs of past life on Mars.
- The Jerezo crater is likely home to hydrated silica, a material which on Earth is especially good at preserving signs of life.
- Mars 2020 is set to land on the planet crater in February 2021. NASA's Curiosity rover is currently the only rover operating on Mars.
- The discovery of past life on Mars would be revolutionary, at least in science and philosophy.
NASA<p>Today, Mars is essentially a vast desert with a thin atmosphere that — according to <a href="https://bigthink.com/surprising-science/mars-aliens" target="_blank">almost all scientists</a> — cannot support life. But it's possible that the red planet supported life a few billion years ago, during the <a href="https://en.wikipedia.org/wiki/Noachian" target="_blank">Noachian period</a>. There's evidence, for example, suggesting that rivers raged on Mars within the past billion years (liquid water is believed to be necessary for all lifeforms).</p>
NASA<p>Some of these rivers used to flow through the part of Mars that is now Jerezo crater, and they carved a delta into the planet's surface. It's here that Mars 2020 might find hydrated silica, a crystalline material that might have formed in the delta, or elsewhere on the planet (volcanoes, for example), from which it was carried to the delta by rivers.</p>
NASA<p>Mars 2020 will be able to analyze any hydrated silica it finds. But to confirm the existence of biosignatures within that material, the rover will need to take samples to be brought back to Earth so scientists can analyze them in the lab. However, it's possible that some rocks on Mars contain fossils large enough for the rover to photograph.</p><p>In addition to searching for microfossils, Mars 2020 will help scientists learn more about the planet's surface and future landing sites, and it will also bring samples of spacesuits to the planet so scientists can study how the materials degrade when subjected to the Martian environment.</p>