Hello, and welcome to SciShow News! I'm Michael Aranda, in for Hank Green, who is currently enjoying tea and crumpets in England.

One year ago, last Tuesday, a pretty cool thing happened: After hurtling through space at 23,000km/hr, losing contact with NASA for seven minutes, Curiosity, the biggest, baddest rover in history, landed safely smack in the middle of its target, in a crater on the surface of Mars. It was an awesome accomplishment, but it was also the beginning of something more important.

Since its landing, Curiosity has given us over 36,700 amazing images, and over 190 gigabytes of data, but it's also given us some really interesting findings. So, this week on SciShow News, we're celebrating three of the most useful things the Curiosity rover has allowed us to discover in its first year.

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Useful thing #1: The first and only definite evidence of habitability outside of Earth. NASA sent the rover to Gale Crater, at the base of Mount Sharp, a huge mountain where scientists thought there might be evidence of past habitability. Mount Sharp is three miles high, and has exposed layers of sedimentary rock from Mars's ancient past, when it was wet, so Curiosity was sent to investigate.

But, before it got very far, it, or the people driving it, got distracted by promising-looking ancient stream beds, so, in February, they had Curiosity drill into and test the composition of the rock there, the first time a sample had ever been drilled from a rock on another world.

The rock dust was measured, filtered, and analyzed by two instruments: CheMin, which used X-rays to determine the sample's basic chemical makeup, followed by a suite of instruments called Sample Analysis on Mars, or SAM, which calculated its various proportions of compounds and isotopes.

What it found was some of life's key ingredients: sulfur, nitrogen, hydrogen, oxygen, phosphorus, and carbon. Ingredients that could have been used as energy sources for microbial life billions of years ago. More importantly, they found that the rock was mudstone, made from clay and calcium sulfates, which only forms in wet, non-salty, pH-neutral environments. So not only did we find that there was once water there: the water was drinkable.

And it's too bad that water's not still there, because the next big useful thing Curiosity has given us is a step toward our goal of getting people onto Mars... or an asteroid, or whatever Trip Advisor recommends. As NASA administrator Charles Bolden said this week, "Wheel tracks now will lead to boot prints later."

And one of the most important things we've learned so far from Curiosity has to do with radiation, not just on the surface of the red planet, but what astronauts would be exposed to while in space. And, according a tool on Curiosity called the Radiation Assessment Detector, or RAD, we're going to need some serious help.

On its 253 day journey to Mars, even while protected by shields, RAD measured a steady stream of radiation that would be comparable to getting a full-body CT scan every five or six days. While Curiosity's shields are keeping most of the solar radiation out, it turns out that what's getting through is radiation from huge events from outside the solar system, like supernovae. So the next step is to figure out how to shield people from those rays.

Finally, the third really useful thing: finding out what happened to the Martian atmosphere. If there once was abundant water on Mars, something changed to make it the cold, dry planet it is now. And, to help us figure out what happened, Curiosity's SAM module is equipped with lasers that can analyze the atmospheric composition, and, after more than 75,000 measurements, it has found something... fishy. The proportion of heavy isotopes, that is, elements with more neutrons in their nuclei, making them heavier, is much higher than it once was.

Now, somewhat awesomely, we know what Mars's ancient atmosphere used to be like, because of the gases trapped in bubbles of meteorites from ancient Mars that have struck Earth. These bubbles contain a much lower proportion of heavy isotopes compared to modern Mars, so scientists think that the light isotopes must have been lost to space over time as the atmosphere disappeared.

To figure out how, NASA's preparing its latest mission to the red planet: a probe called the Mars Atmosphere and Volatile Evolution, or MAVEN, set to launch on November 4th.

After arriving in September 2014, MAVEN will orbit Mars for a year, studying its atmosphere with tools like the Neutral Gas and Ion Mass Spectrometer, a bundle of electrically-charged rods that will measure ions in the atmosphere, and the Imaging Ultraviolet Spectrograph, which will measure the UV light given off by atmospheric gasses.

So, while Curiosity is teaching whether, how, and when Mars was habitable, MAVEN will help us understand what happened to make Mars uninhabitable. Happy anniversary, Curiosity!