We are told that the area now under the sea

The possibility of life on Mars has only recently become a topic of interest.

The discovery of methane in the Martian atmosphere suggests an unknown process is replenishing it.

The seasonal variations in methane levels indicate Mars could be "breathing" the gas.

The study confirms that Mars is a completely inactive and unchanging planet.

Scientists have identified the exact source of the methane emissions on Mars.

The ExoMars mission and a new NASA rover are planned to further study the Martian surface.

Scientists believe sulfur helped preserve organic molecules in Martian rocks.

Methane molecules on Mars can survive for millions of years.

Organic molecules were discovered in Gale Crater, which may have been a lake billions of years ago.