Nasa may have discovered signs of life on Mars - but it's not telling. Yet.

The space agency has reportedly found something of huge importance on the Red Planet, thanks to the latest samples gathered by the $2.5bn Curiosity rover, according to media reports which emerged on Tuesday.

The find is described as "one for the history books" - but Nasa is keeping its cards close to its chest.

It's checking and rechecking the data to make sure it's found... whatever it is that it's found, before making an announcement in December.

It is speculated that the Sample Analysis at Mars instrument may have found organic compounds, or evidence of the same, in a dirt sample. It is also possible the rover may have found proof of Methane in the Martian air - a sign that life once existed in some form on the planet.

"This data is gonna be one for the history books," Curiosity chief scientist John Grotzinger, of Caltech in Pasadena, told NPR. "It's looking really good."

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  • Mount Sharp

    This image taken by the Mast Camera on NASA's Curiosity rover highlights the geology of Mount Sharp, a mountain inside Gale Crater, where the rover landed.

  • Base Of Mount Sharp

  • South/Southwest Of Landing Site

    This photo is from a test series of the 100-millimeter Mast Camera on NASA's Curiosity rover. It is looking south-southwest of the landing site and taken on Aug. 23, 2012.

  • More From Mast Cam

    Another test photo from the Mast Camera on NASA's Curiosity Rover. Again, it's looking south-southwest on Aug. 23, 2012. The gravelly area of the landing site is visible in the foreground.

  • Landing Site

    The landing site is visibile here in this portion of a 360-degree color panorama along the heights of Mount Sharp.

  • Big Wheels Rolling

    This photo was taken by a front Hazard-Avoidance camera on NASA's Curiosity and shows track marks from the rover's first Martian drives.

  • Curiosity's Second Drive

    Track marks are seen here after the NASA Curiosity rover completes a successful drive to an area of bedrock.

  • Infinity Tracks

    The donut-shaped tracks shown here make an infinity symbol, following the first two drives from NASA's curiosity rover. The drives took place on Aug. 22 and Aug. 27, respectively.

  • Heights Of Mount Sharp

    The highest point of Mount Sharp visible from NASA's Curiosity rover is seen here in a high-resolution image taken on Aug. 18.

  • Traces Of The Landing

    This mosaic image was created from images taken by the rover's Navigation cameras on Aug. 7 Pacific Time / Aug. 8 Eastern Time.

  • Curiosity's Extended Arm

    This photo taken on Aug. 20 shows the many tools on Curiosity's extended arm.

  • Wiggling Wheels

    NASA's Curiosity rover tests its wheels at its landing site on Aug. 21. Photo taken by the rover's Navigation cameras.

  • Laser Shots

    NASA's Curiosity rover fired its laser 50 times against these rocks at a mark called "Goulburn."

  • Rover Takes First 'Steps'

    This overhead view shows NASA's Curiosity rover after its first successful test drive on Aug. 22, 2012.

  • Another Look At Rover's First Steps

    Here's another view of the first track marks Rover left in the Martian surface on Aug. 22, 2012.

Space.com said that the announcement would be made at Autumn meeting of the American Geophysical Union, which takes place on 3 to 7 December in San Francisco.

The rover began driving again on 16 November after six weeks at rest, taking soil samples and testing its instruments.

It has not yet used its rock-boring drill, which is expected to turn up even more interesting data.