Scientists have taken another important step in learning the environmental history of Mars with the analysis of meteorites on Earth courtesy of the Red Planet.

According to a press release, University of Maryland researchers have analyzed the space rocks' chemical signatures to differentiate between the two planets' atmospheres at a crucial point in time 4.6 billion years ago. Published in the journal Nature, the study closely examines an important point in the solar system's evolution.

The oldest meteorite the scientists studied was estimated to be 4.1 billion years old. The old rocks most likely broke off the Red Planet and were sent flying toward Earth after a comet smashed into Mars. Thanks to the older meteorites, the scientists can have a glimpse into the early stages of Mars and our solar system.

With the youngest being around 200 million to 500 million years old, the study authors were able to examine the evolutionary progression of Mars' atmosphere. There are several indicators that Mars once had water, but the environmental evidence says it could not have hosted life. The atmosphere is far too thin and the planet is subject to radioactive cosmic rays, cold temperatures and harmful ultraviolet rays from the sun.

Study lead author Heather Franz, a Curiosity Mars rover science team member with NASA, said sulfur was easily spotted in the meteorites' chemical signatures. A versatile greenhouse gas, sulfur interacts with several other elements, each in a different way. With their technology, the study authors learned Earth and Mars would have had a different atmosphere four-and-a-half billion years ago.

"Climate models show that a moderate abundance of sulfur dioxide in the atmosphere after volcanic episodes, which have occurred throughout Mars' history, could have produced a warming effect which may have allowed liquid water to exist at the surface for extended periods," Franz, a former associate professor of geology at the University of Maryland, said in the release. "Our measurements of sulfur in Martian meteorites narrow the range of possible atmospheric compositions, since the pattern of isotopes that we observe points to a distinctive type of photochemical activity on Mars, different from that Natureon early Earth."