Meteorites of Life?

I believe life is firmly ensconced throughout the universe, not limited to Earth.

That said, we haven’t found definitive evidence of life anywhere other than Earth. So, why my belief?

Organic compounds. They’re everywhere! Not just organic compounds either, amino acids and their precursors seem to be ubiquitous.

Seven billion years ago, Earth was not Earth yet. Our home planet was a blob, albeit a very big blob, molten and inundated by debris in our forming solar system. If we were to observe it, our Sun would be a bright, young star surrounded by rings of dust, with large blobs interspersed. The planets, the asteroids, comets, all still working out their places in a nascent solar system.

Fast forward billions of years and it’s 28 September 1969. Folks in and around Murchison, Victoria, Australia witnessed a marvelous fireball in bright daylight! The fireball broke into several pieces and impacted nearby, causing tremors. Newsworthy but not unprecedented. People soon converged on the area to collect meteorites. They found a bunch, and one fifteen pounder. Meteorite hunters were happy.

It wasn’t until scientists dug deeper into this meteorite that it became famous. Its overall composition, a carbonaceous chondrite (rocky, with graphite, iron, and water) made it among a minority population of meteorites, but not super special. However, its age and the presence of numerous amino acids made it special.

At an estimated 7 billion years old, it is among the oldest known solar system objects- way older than Earth. This means it is primordial, made of early solar system materials. Finding amino acids and other protein precursors was intriguing, but teams using more sensitive methods have recently revealed nucleobases critical to completing the structure of DNA. That’s big!

Of course, it’s necessary to rule out terrestrial sources of these organic molecules so the teams of scientists sampled and examined material from all around the site. While some of the same molecules are present, they have different molecular distributions. That supports an extraterrestrial origin of the meteorite nucleobases.

The possibility of life on Earth being seeded by meteorites or comets has long been debated and will continue.

The fact that we find a wide variety of organic molecules, especially amino acids and nucleobases (DNA and RNA precursors) in meteorites supports the hypothesis but isn’t definitive. We have found organic molecules throughout the solar system as well, and many are precursors of amino acids. Tantalizing.

For many years there was a gap in the extraterrestrial amino acid nucleobase database. Now the list is complete, with all the needed nucleobases to make DNA, but the puzzle remains.

The James Webb Space Telescope will help fill gaps and maybe provide definitive evidence for extraterrestrial life. Fingers crossed.

What’s Up There

Saturn and Jupiter rise in the evening and are up all night! Mars is up around Midnight.

September 7-9; after sunset; southeast: A nearly full Moon hangs around with Saturn and Jupiter