Hello, I'm Hank Green. Welcome to this special and super exciting episode of SciShow Breaking News. 

Earlier today, mission specialists with NASA's Mars Science Laboratory announced that they have found, for the first time, evidence of an ancient environment on Mars that could have sustained life. The region of Gale Crater where MSL's 'Curiosity Rover' has been at work since August, called Yellowknife Bay, was once probably a lake bed at the end of a river system.

David Blake, Curiosity's Principal Investigator for Chemistry and Mineralogy called it "the only habitable environment that we've definitely described and recorded beyond earth."

The MSL team made the historic find thanks to a tablespoon full of dust drilled from a rock last month at Yellowknife Bay.

The Rover obtained the sample on February 8th, using its Percussive Drill Attachment to bore into a sedimentary rock named 'John Klein' - after one of MSL's late Project Managers.The rock dust was measured, filtered and then analyzed by two devices - 'CheMin' which used X-Rays to determine the sample's basic chemical make-up, followed by a suite of instruments called 'Sample Analysis on Mars' or SAM, which calculated its proportions of various compounds and isotopes.

 Its worth pointing out that all this Science was done as Curiosity was suffering something of a mental breakdown. Around February 27th, the Rover started having problems with its flash memory and had to revert to one of its back-up computers to continue work. A process that took a couple of days.

But when finally complete, the tests revealed that the sample contained traces of Sulphur, Nitrogen, Hydrogen, Oxygen, Phosphorus and Carbon. On their own, some of the key ingredients to life, but more importantly and more revolutionary, the rock turned out to be 'Mudstone' - a sedimentary rock containing clay and calcium sulphates which could have only formed in an environment that was pH Neutral and not very salty. In other words, very friendly to life as we know it.

As Curiosity Project Scientist John Grotzinger described it today, "We've found a habitable environment that was so benign, that when it had water, and if you'd been around, you'd be able to drink it."

Now, to be clear, the MSL team did not find evidence of past life on Mars, they found geological evidence that Yellowknife Bay had been, perhaps Billions of years ago, Earth-like enough to support life. So while MSL isn't designed to detect specific evidence of microbial life, it did detect chemicals, like those sulphate minerals, that could easily have been used by micro-organisms as an energy source.

Unlike the red oxidized rock we've come to associate with Mars, the sample from inside John Klein was grey and un-oxidized, suggesting that it potentially had energy available for life. This '"Grey Mars" as Grotzinger called it, is where organisms may have been able to develop and live even without complex carbon molecules. Much like Lithotrophs here on Earth, that while rare, derive their energy from rock.

Today's discovery marks a turning point in our understanding of life beyond our world and for NASA scientists, its a big new benchmark. From here, they said, Mars exploration can begin to look past the search for ancient signs for water or the right kind of water, and begin focusing on habitats that could support life today, as well as concrete signs of life in the past.

Just think about that for a second, just in this one little solar system, there were two planets where life could have formed - at least, there may be other places that are suitable for life and that's just one solar system and there's like billions of them, just in this galaxy. That is freaking exciting.

So thank you for watching this episode of SciShow Breaking News. If you want to keep up to date with all the latest breaking news, go to http://youtube.com/scishow and subscribe. And if you have any ideas or questions or comments, we're on Facebook and Twitter and down in the comments below. See you next time.