New theory explains how Earth may have received the ingredients for life

With meteorites, phosphorus, nitrogen and Jupiter ‘in the noise’. “Jupiter’s presence and growth history appear, in fact, to have played a crucial role in determining the distribution of the basic chemical ingredients needed for habitable worlds.”

Scientists have new information about how early Earth may have acquired some of the elements necessary for the planet to become habitable, according to a new study.

The work, in the journal Science Advances, also suggests a new role for Jupiter in the distribution of these elements throughout the young Solar System, and examines this history by looking at the relationship between the match and the of nitrogen in ferrous meteorites and in more recent objects known as chondrites.

The formation of the planetary system

Our Solar System formed from gas and dust that swirled around the proto-Sun more than 4.5 billion years. This gas contained the raw materials needed to form planets, moons and, ultimately, life as we know it. Two elements of particular importance for life are nitrogen and phosphorus.

In the early stages of the Solar System, gas and dust coalesced, forming bodies known as planetesimals. As these objects orbited the young Sun in this chaotic environment, the planetesimals collided with each other, leaving fragments scattered throughout the system. Over time, many of these fragments were incorporated into planets and moons. Other fragments survive today as asteroids, still in orbit around the Sun, and — if they collided with Earth and were recovered — as meteorites.

These meteorites provide a window into the early Solar System, at a time before Earth existed. You condritos and the metallic meteorites There are two different classes of these meteorites. As their name suggests, ferrous meteorites are dense, metallic objects, composed mainly of an iron-nickel alloy. Chondrites, on the other hand, are rocky objects and are responsible for the majority of meteorites that have been found on Earth.

Each type of meteorite originates from planetesimals that formed at different times in our system. The oldest generation of planetesimals is the source of metallic meteorites. Chondrites come from a second generation of planetesimals that formed 2 to 3 million years later.

Building habitable planets

It is important for astrobiologists, who study how and when our planet became habitable for life as we know it, to understand how the Earth was formed and when this formation occurred. The early Earth needed to have a reserve of ingredients essential to life, including nitrogen and phosphorus, so that the first living cells could form.

There is a debate among scientists about the origin of the reserves of elements essential to life on Earth.

Some evidence indicates that chondrites from the outer Solar System traveled inward, arriving on Earth at a late stage in the formation of our planet. However, the new study tells a different story.

Using laboratory experiments and geochemical models, the team reconstructed a map of phosphorus-nitrogen (P/N) ratios in the early Solar System and found differences between the first (ferrous meteorites) and second (chondrites) generations of planetesimals.

Experiments and the subsequent creation of geochemical models showed that the first generation had a higher P/N ratio in the outer Solar System, with this ratio decreasing as it approached the inner Solar System. This trend was reversed in the second generation of planetesimals, with higher P/N ratios in the inner Solar System.

The idea is that, during the formation of the first generation of planetesimals, a material flow to the outside which increased the P/N ratio in the outer Solar System. And then Jupiter appeared.

As Jupiter formed and grew to an enormous size (and gravitational influence), the planet restricted the movement of phosphorus and nitrogen from the inner Solar System to the outside. This means that when the second generation of planetesimals emerged, those in the inner Solar System were left with a higher P/N ratio than their more distant cousins.

“As far as our own Solar System is concerned, the presence and growth history of Jupiter appear, in fact, to have played a crucial role in determining the distribution of the basic chemical ingredients needed for habitable worlds,” he said. Rajdeep Dasguptafrom Rice University, in Houston, USA, senior author of the study, cited in NASA.

“It remains an open question whether it is possible to establish a balance of elements essential to life similar to that on Earth without the existence of a planet similar to Jupiter in the population”, he adds.

Geochemical accretion models also demonstrate that Earth’s current P/N signature is best reproduced by planetesimals from the inner Solar System, whether those related to metallic meteorites or those related to chondrites.

“The study suggests that Earth acquired its inventory of life-essential elements, phosphorus and nitrogen, primarily from the inner Solar System, without requiring a significant contribution from chondrites in the outer Solar System,” said the study’s lead author, Debjeet Pathak, a graduate student at Rice University.