Listening to my 14-year-old daughter explain her writing assignment the other night, I was surprised to learn we both had similar homework. I was about to start this letter to introduce the current issue and its cover story, “The Amazing Teen Brain,” by psychiatrist Jay N. Giedd. Her essay was going to analyze the reasons behind the rash behavior of the famous star-crossed young lovers in Shakespeare's Romeo and Juliet. As she explained, “Teenagers' brains are not fully developed yet, so they have a problem with impulse control.” As she dispassionately talked about the brains of people her own age, I was struck anew by how grown-up teens can seem.

At the same time, as we are reminded painfully and too frequently not only by fictional plays but also by real-world headlines, adolescents are uniquely vulnerable to risky behavior, leading to mishaps or to recruitment to violent ends as soldiers or even terrorists. A key question around the recent trial of Dzhokhar Tsarnaev, who was 19 at the time of the Boston Marathon bombing, for instance, was the degree to which he was under the influence of his 26-year-old brother, Tamerlan.

At root is a developmental mismatch between the mental networks that manage emotion, which shift rapidly at puberty, and those that handle so-called executive function, which mature in a person's 20s. Giedd also describes how an earlier onset of puberty in recent decades has extended this angst-ridden period.

The protracted maturation, however, beneficially creates prolonged plasticity—enabling teenagers' enviable leaps of cognition and adaptability, for example, to today's data-enriched world. Both traits have served our species well in the past. Now, as science provides a better understanding of this powerfully influential developmental window, society—from parents to policy leaders to youngsters themselves—can work together to support teens on their journey.

Rather than soaring into the future, the Space Launch System, a successor to the shuttle, has been called a “rocket to nowhere”—a congressional jobs program with little hope of actually flying to space. But in “Birth of a Rocket,” journalist David H. Freedman takes a look at how the system, which is on time and on budget for a 2018 flight, could actually become the vehicle of choice to reach Mars in about 25 years. Given the sufficient political will—no small hurdle—the teens of today could see humans step onto another planet.