It is quite possible that the discovery they're calling "one for the history books" could be the big one!! The data is coming from the SAM unit on Curiosity and is the unit that would be the one expected to find signs of life. Unfortunately they're not going to make an announcement until they're 100% certain it's not a fluke. Here is one of many articles about the yet to be announced discovery (see HERE) but there is also a follow up article HERE that seems to be downplaying the discovery...a little bit, at least.
Out of curiosity, I've made a poll to see how many people believe Curiosity will find signs that life exists or once existed on Mars
Out of curiosity, I've made a poll to see how many people believe Curiosity will find signs that life exists or once existed on Mars