Jan Chodas stops by the show to talk about her experience working on several pioneering NASA missions, including Galileo, Cassini, the Spirit and Opportunity rovers, and Juno. Note: this was recorded before Juno successfully entered into the orbit of Jupiter.

Professor Rita Economos talks about her research into magma on Earth. She recounts some of the adventures she's had searching for rocks, and explains why Earth's volcanoes appear to be unique in the solar system.

Dr. Rachael Beaton and I try "Grass Jelly Drink" and talk about one of the major fundamental constants of the universe; the Hubble Constant. She explains what it is and why she and her colleagues are trying to measure it better than it ever has been measured before.

Dr. Solange Ramirez visits the show to talk galaxies, supermassive black holes, and the gravity that ties them together.

Dr. Issac Smith visits the show to talk about one of Mars' past ice ages; a time when most of the planet was covered in ice. He talks about how he made this discovery by looking at the layers of ice deposited on the planet's North pole.

Returning guest Dr. Kelsi Singer talks about two of the icy moons of our solar system, Ganymede and Iapetus. She talks about the types of craters we see on their surfaces, and what they can teach us about the moons themselves.

Jon talks about JPL's Horizons, an amazing, publicly available system that keeps track of every known object in the solar system. Planets, moons, asteroids, spacecraft, you name it: over 715,000 in total. We discuss how this system is used by engineers, scientists, lawyers, art fans, and marine biologists.

This week's guest is Dr Paul Chodas, who directs JPL's Center for Near-Earth Object Studies. He explains how predicting where an asteroid is going can get complicated when the asteroid gets close to a planet. He also talks about an app that lets you explore how a hypothetical asteroid could be deflected.

Dr. Kevin Walsh visits the show to talk about a new NASA mission that will launch later this year: OSIRIS REx! This spacecraft will visit an asteroid, grab a bit of surface material, and return the material to Earth for further study. Dr. Walsh talks about the mission and explains how you can help scientists pick the best place on the asteroid for the spacecraft to grab a sample.

Professor Erik Asphaug stops by the show to discuss AOSAT-1, a tiny spacecraft that will contain experiments to study the surface of asteroids. AOSAT-1 will rotate once every minute, creating a force inside that exactly mimics gravity on an asteroid. We discuss how AOSAT-1, a cubesat, is being designed and built, and how it may launched from the space station in a "cubesat cannon".