Deep below the ground, radioactive elements break up water molecules(分子), producing substances that can fuel subsurface life. This process, known as radiolysis(辐射分解),has supported bacteria in tiny cracks filled with water on Earth for millions to billions of years. Now a study published in Astrobiology shows that radiolysis may have supported life in the Martian subsurface. 

Dust storms, rays in the universe and solar winds ruin the Red Planet's surface. But below, some life might find shelter. "The best survival habitat on Mars is the subsurface," said Jesse Tarnas, a planetary scientist at NASA, Examining the Martian underground could help scientists learn whether life existed there. And the best subsurface samples available today are Martian meteorites(陨石) that have crash-landed on Earth.

Tarnas and his colleague looked at the minerals on the Martian surface and how many radioactive elements there were, using satellite and rover data, They used computers to simulate(模拟) radiolysis to see how efficiently the process would have generated life-supporting hydrogen gas and other chemical substances. They reported that if water was present, radiolysis could have supported life for billions of years and perhaps still could today. 

Scientists had previously studied Mars radiolysis, but this marked the first estimate using Martian rocks to see how habitable Mars underground might be. Tarnas and his colleagues also evaluated the potential richness of life in Martian underground.They found that up to a million bacteria could exist.in just one kilogram of rock, The most habitable seemed to be the southern highlands of Mars, which is the most ancient area on Mars, according to Tarnas.

"Underground life would require water and it remains unknown if groundwater exists on the planet," says Lujendra Ojha, a planetary scientist at Rutgers University. Determining whether the Martian, subsurface contains water. will be an important next step, but this investigation helps to motivate that search, Ojha says, "Where there is groundwater, there could be life."

Today, with most of us owning a smartphone that lets us post on social media wherever and whenever we want, oversharing has become harder to avoid. But the tricky thing is that people usually don't realize when they' re oversharing. The problem can only be triggered by our friends and family. A survey showed that every two in three people in the US think their friends share too much on social media.

Oversharing can have negative impacts. For instance, it can put your personal information at risk. When you update your status, or simply recall an experience on social networking sites like WeChat, chances are that you are revealing critical personal information. 

According to a survey by Visa Canada, 45% of people aged 18-34 "overshare" their financial information online. "Young people shared payment card information via e-mail, loaned out their cards, and didn't keep their PIN confidential," reported CBS. This behavior mirrors similar habits of sharing personal information on social media sites. They're really not totally aware of who has access to this information and who else can be seeing this information and what could be done with it.

"Oversharing contributes to a larger culture in which such behavior is considered acceptable or even desirable," said Seidman, associate professor at Albright College in the US. Elizabeth Bernstein, a US-based educator, said that "the great increase of overshare is partially because of the wild use of social media as a subconscious attempt to control anxiety. We actually use a lot of mental energy trying to manage the other person's impression of us by oversharing. "

Moreover, oversharing online can damage effective communication in real life. "Having such easy access to so many people makes communication superficial," said Chen, a psychologist at South China Normal University. "In the end, the lack of deep communication hurts strong social bonds, particularly friendships. "

I was the only kid in college with a reason to go to the mailbox, because my mother never believed in email or cell phones. I was literally waiting to get a letter to see how her weekend had gone, which was usually the warmest comfort for a girl of my age.

So when I moved to New York and got sucker-punched in the face by depression, I did the only thing I could think of. I wrote those same kinds of letters like my mother for strangers, and slipped them all over the city. I blogged about those letters and crazily promised if asked for a hand-written letter, I would write one.

Overnight, my inbox became this harbor of heartbreak—a single mother in Sacramento, a girl being bullied in Kansas, a 22-year-old immigrant, all asking me to write them and gave them a reason to wait by the mailbox. And this is how I initiated a global organization, fueled by those trips to the mailbox.

It is awesome. In fact, the thing about these letters is that most of them have been written by people who have grownup into a paperless world where some best conversations happen on a screen. We have learned to record our pain on to Facebook, and we speak swiftly in 140 characters or less.

But it's not about efficiency. And I could tell you about a woman whose husband was traumatized (受精神创伤) by his war experiences in Afghanistan and isolated himself, and her love letters slipped throughout the house eventually got him back to her. Or a man, who decides to take his own life, finally sleeps soundly with a stack of letters from strangers slipped beneath his pillow.

The scare the kinds of stories that convince me that letter-writing will always be needed even in these days, because it is an art now.