LIFE TO EARTH
Carbon and nitrogen probably arrived on the back of another planet
necessary for life probably arrived on Earth during the explosion which created the Moon, a novel set of experiments has revealed.
According to current theory, Earth was extremely hot MXVW DIWHU LW UVW IRUPHG +RZHYHU PDQ\ RI WKH HOHPHQWV in our planet’s crust – including those, like carbon and nitrogen, essential to living organisms – are volatile, meaning they would have boiled away. One theory to explain how they are present suggests that another object crashed into Earth after the planet cooled down, delivering the elements to the crust.
“But the timing and mechanism of volatile delivery has been hotly debated,” says Rajdeep Dasgupta from Rice University, who took part in the study. The main issue is that the raw material the planets formed from has the wrong ratio of carbon and nitrogen. This means that whatever object brought these elements to Earth had already undergone some kind of geological changes, like the early phases of planet formation.
Dasgupta’s team considered whether the material may have already begun to form into an infant planet. We know one of these, Theia, collided with Earth 4.4 billion years ago in an impact which resulted in the Moon. The group ran experiments simulating the high temperatures and pressures found in planetary cores and found that when the sulphur content increases, the ratio of carbon and nitrogen changes to similar levels found on Earth. “This suggests that a rocky, Earth-like planet gets more chances to acquire life-essential elements if it forms and grows from giant impacts with planets that have…building blocks…from different parts of a protoplanetary disc,” says Dasgupta. The modern picture of planet formation is one of change and chaos. There may have been as many as 30 large bodies pinging around the inner Solar System early on, with collisions between them responsible for such phenomena as the Moon’s formation, Venus’s slow rotation and Mercury’s strangely high density. All can be explained if the UVW VWDJH RI SODQHW formation delivers a plethora of small worlds, many of which are destroyed or, more likely, expelled from the system. If such collisions are common and bring volatiles to newly forming planets, then we should expect rocky planets everywhere to come loaded with the ingredients of life. Earth and its Moon may not be as unique as they seem.