NASA's Curiosity rover has another, even bigger, apparently history-making discovery that might just change everything about the universe as we know it — but they aren't telling anyone what it is, exactly, until scientists can be absolutely sure it's not a dud. Thanksgiving nerd speculation, of course, is go for launch.

John Grotzinger, the principal investigator for the mission, tells NPR's Joe Palca in an interview that aired today that his team has found something really, really cool on Mars with Curiosity's SAM soil-collecting device: "This data is gonna be one for the history books. It's looking really good," Grotzinger exclaimed. Unfortunately, NASA won't be telling us what said cool secret is until they run a bunch of tests to make sure what they found is authentic. 

The scientists thought they had made an exciting breakthrough earlier, when a tool picked up some methane in the Mars atmosphere, which would have been a first — and could indicate that life previously existed on Mars. They had to test to make sure the methane didn't travel with the Rover from earth, though, and once they did their due diligence it turned out the methane piggy-backed from earth. The team was predictably deflated. 

But most of the outlets covering today's big leak seem to think Grotzinger's teasing of a secret lends this discovery much more legitimacy. Why would a Curiosity scientist hype something if he wasn't confident the tests were going to come through? 

Science bloggers are doing their best to guess what Curiosity might have found. Discovery's Ian O'Neill thinks it has something to do with organic chemistry, or carbon-based elements that would establish the "building blocks" for life on Mars. Universe Today's Nancy Atkinson and Pop Sci's Rebecca Boyle both speculate the discovery could be linked to the evidence of flowing water previously existing in the Gale Crater (seen above). Rich Apodaca thinks Curiosity discovered small organic chemicals. 

While science writers play the guessing game, Grotzinger and his team will be testing the discovery rigorously to make sure they have something as big as advertised. It'll be a few weeks before we hear anything. 

Meanwhile, the Curiosity rover itself remains disturbingly coy amid the speculation about its discovery: