Speaking at the American Geophysical Union annual meeting in San Francisco, Curiosity mission leaders also said that the compound perchlorate—identified previously in polar Mars—appeared to also be present in Gale Crater, the site of Curiosity's exploration.

The possible discovery of organics—or carbon-based compounds bonded to hydrogen, also called hydrocarbons—could have major implications for the mission's search for more complex organic material.

It would not necessarily mean that life exists now or ever existed on Mars, but it makes the possibility of Martian life—especially long ago when the planet was wetter and warmer—somewhat greater, since available carbon is considered to be so important to all known biology.

The announcements came after several weeks of frenzied speculation about a "major discovery" by Curiosity on Mars. But project scientist John Grotzinger said that it remains too early to know whether Martian organics have been definitely discovered or if they're byproducts of contamination brought from Earth.

"When this data first came in, and then was confirmed in a second sample, we did have a hooting and hollering moment," he said.

"The enthusiasm we had was perhaps misunderstood. We're doing science at the pace of science, but news travels at a different speed."