The cosmic collision that gave Earth its moon may have also given it the ingredients for life. Researchers have never been able to nail down exactly how and when Earth got its carbon, nitrogen, and sulphur, but a new study suggests they may have come from the object that smashed into Earth and created the moon about 4.5 billion years ago.
A group of researchers from Rice University in Texas used a series of experiments and simulations to test whether these volatile elements – those with low boiling points – could have been the result of such a collision.
They started by compressing alloys containing carbon, nitrogen and sulphur to pressures up to 7 gigapascals and heating it to temperatures as high as 1800°C to simulate the conditions during the formation of a planetary core. They used that experimental data to perform approximately one billion simulations of impacts between various types of volatile-laden object and Earth.
The simulations that matched experimental observations and the geological record best were those with a rock about the size of Mars, full of carbon and nitrogen with a sulphur-rich core.
“It is likely that such an impactor also brought water,” another important volatile compound, says team member Rajdeep Dasgupta. Planets that have undergone more large collisions like this might have had more opportunities to develop life, he says.
Richard Greenwood at the Open University in Milton Keynes says that, while this explanation is plausible, there are others that match what we see now just as well and we do not yet have enough information to tell which is correct.