Few beverages have as rich a history as bitters, the herbal-flavored spirit that was once marketed as medicine but is better known today as an ingredient in cocktails. In this podcast, Brad Thomas Parsons, author of “Bitters: A Spirited History of a Classic Cure-All,” discusses the history of the elixir from its earliest “snake oil” days to its rise as an essential ingredient in the contemporary bar scene.

As observers of a meteor that crashed in Russia’s Chelyabinsk region today can attest, near-earth objects that enter the earth’s atmosphere can wreak destruction. But these objects, which also include comets and asteroids, also provide clues to the solar system’s origins and could someday serve as stepping-stones to space exploration. In this podcast, Manager of NASA’s Near-Earth Objects program, Donald Yeomans, discusses the ongoing quest to find near-earth objects before they find us.

After traveling through space for seven years, NASA's MESSENGER spacecraft began orbiting the planet Mercury in March, 2011. In this podcast, join MESSENGER's principal investigator Sean Solomon as he describes how the spacecraft's specialized instruments are collecting information that is key to understanding terrestrial planet evolution.

In the next 30 years, global population is estimated to surpass nine billion people. Will there be too many people, too little food? In this podcast, join NBC News Chief Science and Health correspondent Robert Bazell and a round-table of food experts as they discuss how climate, politics and economics impact food systems and food security.

Guests include activist and best-selling author Raj Patel, geneticist Molly Jahn, and chef and UNICEF ambassador Marcus Samuelsson.