Scientific instruments aboard the Mars Reconnaissance Orbiter have detected minerals which contain carbon in a Martian impact basin created by a giant space object that crashed on Mars 4 billion years ago.

The carbonates, long sought for by scientists are indicative of a succession of warm and wet environments which can host life have existed on the planet’s surface in its early history. They’ve been picked up in high-resolution images passed to scientists by the orbiter.

Carbonates form in watery environments on Terra where life blooms, so Mars exploration missions have long sought them.

The find was described by scientists Thursday at the annual meeting of the American Geophysical Union in Moscone Center, and a detailed report will be published Friday in the journal Science.

Carbonates and clay minerals were detected in the Nili Fossae, where 400 miles of valleys and deep troughs have dug deep into Mars’ surface.

Other craft around Mars have detected trace amounts of carbonate dust in Mars’ atmosphere as well as on the planet’s northern icy wastes near the landing site of the Phoenix lander; however this is the first time they’ve been found in solid outcroppings of the planet’s bedrock, say scientists.

In recent times the environment on mars was highly acidic and would have destroyed these carbonate minerals. This makes the discovery very significant because it proves that between 4.6 billion and 3.9 billion years ago. According to geology graduate student at Brown Bethany Ehlmann, who was the principal author of the Science report, Mars had at least one region where the environment was desirable for early Martian life.

The Nili Fossae is very small, and the largest outcrop is only about 1,500 in surface area, but the MRO, which cost $720 million, is equipped with a unique camera called the Compact Reconnaissance Imaging Spectrometer (CRISM), which sends extremely high-resolution images back to earth. Thanks to CRISM showing one carbonate outcropping, the Brown University team will continue to comb the craft’s images for more of them.

The carbonate rocks are formed by water and atmospheric carbon dioxide interacting with volcanic rocks or chemical elements like calcium, iron and magnesium. Much like carbonates on Terra, they’re destroyed by acidic water, which means that their presence in Martian outcroppings indicates that the water which formed them was alkaline.

Johns Hopkins University’s Scott Murchie who is CRISM’s principal investigator at the university Applied Physics Laboratory told press Thursday that Marts’ carbonate rocks may have been able to preserve organic compounds, and show  “possible evidence of past life.”

The Nili Fossae was proposed for exploration by the Mars Science Laboratory, a large and sophisticated rover which was due to be launched in February but was delayed for two years. The region had been written out as a landing site but the new findings are sure to generate redoubled interest into its exploration.