Primordial Fossilized Cosmic Dust Offers Unthinkable Insight To Earth’s Ancient Atmosphere

A recent study of ancient cosmic dust from the remote location of Pilbara in Australia has reportedly taken geologists by surprise. The research revealed that our planet had something 2.7 billion years ago that it should not have had.

The Monash University's School of Earth, Atmosphere and Environment recently published a study in the journal Nature revealing that some of the oldest fossil micrometeorites, known as cosmic dust, were made up largely of metallic iron. As the space dust traveled through our planet's primeval atmosphere, it got oxidized. The fact confounded geologists because according to prevailing facts, there could not have been enough oxygen 2.7 billion years ago to cause such an effect.

The first oxygen producing algae appeared on Earth only about 2.4 billion years ago, which ultimately led to the great oxidation event that charged the atmosphere with this essential‐for‐life gas. The discovery also had other implications, especially those concerning the search for extraterrestrial life. Until now, scientists believed that detecting oxygen in the distant atmosphere could signal the presence of life; however now it seems the presence of the gas alone cannot be a sure shot sign.

According to Dr Andrew Tomkins who led the research, the outer envelope of primordial Earth's atmosphere could have had the same amount of oxygen that can be seen now. The scientist believes that oxygen was probably trapped in the upper atmosphere, after ultraviolet ray from the Sun blasted carbon dioxide and released oxygen atoms from their carbon bond. Thereafter, a heavy and thick methane haze, that covered the surface of the Earth, kept it there.

2.7 billion years ago, the atmosphere of our planet was rich in carbon dioxide with a methane haze. The earth's surface comprised of nothing more than water and rock, however single celled life known as methanogens existed. The organisms exhaled methane into the atmosphere after in taking hydrogen from the nearby volcanoes. The high quantity of methane would have heated up the lower atmosphere, preventing it from blending with the upper atmosphere. Meanwhile, the sky would be full of meteors as the last of the leftover clouds was swept up after the formation of the solar system.

"It is incredible to think that by studying fossilized particles of space dust the width of a human hair, we can gain new insights into the chemical makeup of Earth's upper atmosphere, billions of years ago." said lead researcher Dr Andrew Tomkins. "Because this dust was so small, all this oxidization must have occurred at 90 to 75 kilometers in altitude, while the particles were super heated shooting stars. This was an exciting result because it is the first time anyone has found a way to sample the chemistry of the ancient Earth's upper atmosphere."

The ancient cosmic dust was found embedded in limestone in the remote Pilbara region located in Western Australia. The space dust was further analyzed in depth at the Monash Centre for Electron Microscopy (MCEM) and the Australian Synchrotron.