Jason Pawlak

NASA launches its most ambitious hunt for traces of life on Mars, landing a car-sized rover in a rocky, ancient river delta. The rover will stow samples for possible return to Earth and test technology that may pave the way for human travel to Mars.

Spacecraft OSIRIS-REx attempts to grab a piece of an asteroid to bring back to Earth so scientists can study it to learn about the planet's origins.

Alzheimer's: Every Minute Counts is an urgent wake-up call about the national threat posed by Alzheimer's disease. Many know the unique tragedy of this disease, but few know that Alzheimer's is one of the most critical public health crises facing America. Because of the growing number of aging baby boomers, and the fact that the onset of Alzheimer's is primarily age-related, the number of Alzheimer's case is predicted to skyrocket in the United States. This will not only be a profound human tragedy, but an overwhelming economic one as well. Due to the length of time people live with the illness and need care, it's the most expensive medical condition in the U.S. Future costs for Alzheimer's threaten to bankrupt Medicare, Medicaid, and the life savings of millions of Americans.

An investigation of how Donald Trump defied expectations to win the presidency -- and what it suggests about how he will govern.