NASA has confirmed rumors that its Curiosity rover has found organic compounds on Mars, but said they likely came from Earth, along with the rover.

Despite wild speculation about a potentially breakthrough discovery on Mars, the Curiosity's first detailed look at a soil sample from Mars, using an instrument capable of detecting organic compounds, has not found any "definitive" signs of materials that play essential roles in biological processes on Earth, said the scientists.

The Curiosity rover's Sample Analysis at Mars (SAM) instrument detected signs of an oxygen-chlorine compound (perchlorate) and trace amounts of chlorinated methane compounds, which contain carbon. More tests, however, are necessary to determine whether the carbon originated with the sample or was brought to Mars aboard Curiosity.

"Even though (SAM) detected organic compounds, first of all we have to demonstrate that they're indigenous to Mars," explained project scientists John Grotzinger. "Then after that, we can engage in the question about whether they represent the background fall of cosmic materials that are organic in composition that fall on the surface of every terrestrial planet."

Until then, scientists cannot even begin to delve into the more complex questions of whether the sample might be some type of biological material, added Grotzinger, speaking at a press briefing at the American Geophysical Union's (AGU) fall meeting in San Francisco.

In the wake of SAM's first soil sample analysis, Grotzinger agreed to a National Public Radio interview, but did not want to detail the rover's findings before the AGU presentation. Meanwhile, speculation that Curiosity had made a major discovery on Mars soon started to spread like wildfire.

"I think certainly what I've learned from this is that you have to be careful about what you say and even more careful about how you say it. We're doing science at the speed of science. We live in a world that's sort of at the page of Instagrams," said Grotzinger when asked to comment on the contradiction between public expectation and scientific reality.

"The enthusiasm that we had, that I had, that our whole team has about what's going on here, I think was just misunderstood," added the scientist. "There's not much more to say than that."