Casey Dreier, Chief Advocate of the Planetary Society, stops by to chat about space policy. He explains why human spaceflight is such a challenge, and talks about how scientists decide which planet to explore. He also explains how individual citizens from around the world can influence space policy.

Dr. Anne Virkki talks about the Arecibo Radio Telescope, which recently sustained severe damage. She talks about the discoveries made at the telescope and explains that it could be rebuilt, if there was enough public support.

A quick bonus episode for my American listeners. Voting is the keystone of our democracy, and your voice deserves to be heard. This episode goes over some common voting questions. For more, see www.ballotpedia.org.

Dr. Varoujan Gorjian returns to the show! He explains what supermassive black holes are and how they work. He also tells us about an elegant technique that astronomers use to determine the size of the debris cloud around black holes.

The tables are turned! Regular host Professor Carrie Nugent talks about her research with guest host Anthropology Professor Caitrin Lynch. We discuss near-Earth asteroids, and how Prof. Nugent is building open-source asteroid hunting software with a team of students.

Dr. Abby Fraeman returns to the show to talk about NASA's Curiosity rover. For the past eight years, Curiosity has been exploring Gale Crater on Mars. Dr. Fraeman talks about a discovery she made on the Vera Rubin Ridge, and we discuss how the Curiosity scientists and engineers have kept the rover running during the coronavirus pandemic.

Prof. Bethany Ehlmann returns to the show to talk about the mission she's leading, Lunar Trailblazer. This low-cost mission will hitch a ride to the moon using the extra space in a large rocket. Once there, it will help scientists learn more about water on the moon.

Many of the discoveries you've heard about on this show were funded by NASA. But how do scientists get money from NASA? Dr. Henry Throop returns to the show to explain how NASA program officers evaluate scientific proposals. This episode was recorded in September 2019.

Dr. Larry Denneau talks about the Asteroid Terrestrial-impact Last Alert System, or ATLAS. He talks about how asteroid detection is a data processing problem. Every night ATLAS handles about a quarter terabyte of data. He describes how they find a few asteroids among a billion other sources, and tells us about a unique discovery by the program. This episode was recorded in June 2019, which explains the restaurant noises and the talk of air travel.

Prof Joe Levy talks about his research in the dry valleys of Antarctica. These valleys are dry, irradiated, salty, and cold, which makes them similar to parts of Mars. He explains why planetary scientists get excited about naturally occurring perchlorate. He also describes the changes he's witnessed over several field seasons. This episode was recorded in February 2020, before social distancing measures were recommended.