The findings reveal that the atmospheres of Mars and earth diverged in important ways very early in the 4.6 billion year evolution of our solar system. “Soon after our solar system formed, much of Mars’ atmosphere was lost, leaving it thinner than earth’s with lower concentrations of carbon dioxide and other gases. That is one reason why Mars is too cold for liquid water today – but that may not always have been the case,” explained Heather Franz who works on the Curiosity rover science team at the NASA Goddard Space Flight Centre.
The researchers measured the sulphur composition of 40 Mars meteorites. The oldest meteorite in the study was about 4.1 billion years old, formed when our solar system was in its infancy. The youngest were between 200 million and 500 million years old.
Sulphur, which is plentiful on Mars, may have been among the greenhouse gases that warmed the surface, and could have provided a food source for microbes. Because meteorites are a rich source of information about Martian sulphur, the researchers analysed sulphur atoms that were incorporated into the rocks.
The researchers found the chemical reactions involving sulphur in the Martian atmosphere were different than those that took place early in earth’s geological history. “This suggests the two planets’ early atmospheres were very different,” Franz noted.
This information will make it much easier for researchers to zero in on any signs of biologically produced sulphur, the study, published in the journal Nature, said.