Dr. Kelly Fast tells us about the Planetary Defense Coordination Office, which finds asteroids before they find us. She talks about a recent exercise involving the tiny asteroid 2012 TC4, where asteroid hunters across the world coordinated to observe this object on a recent fly-by. We also talk about 'Oumuamua, the first interstellar asteroid ever discovered.

Dr. Mark Panning tells us all about "earthquakes" on other worlds. He talks about the InSight mission to Mars, which carries a seismometer to detect Marsquakes. He also explains how a seismometer on Europa could teach us about the interior of that icy moon.

Mario Cabrera tells us about the specialized detectors used in professional telescopes. He talks about how he's helping to develop new detectors that don't require coolant and provide more science for less money. He talks about the ways a detector is tested, and how he's walked through miles of waist-deep snow (both ways!) in the name of science.

Dr. Jonah Kanner talks about LIGO's spectacular detection of two neutron stars merging together. This merger was not only detected by gravitational wave detectors in the US and Europe, it was also seen by many telescopes across the world and in space. This new discovery will help unlock many longstanding mysteries in astronomy and fundamental particle physics.

Cassini's spacecraft operations team manager, Julie Webster, stops by the show to reflect on Cassini. We chat about the time Cassini dove through Titan's atmosphere, how Julie monitored thousands of channels of telemetry at once, and how she's happy that she doesn't have to spend her time thinking through worst-case scenarios (or "awfulizing") now that the spacecraft is no more.

Dr Morgan Cable returns to the show to chat about the end of the Cassini Mission. We find solace in the fact that there's still a tiny bit of Cassini in orbit around Saturn. Dr. Cable also describes Cassini's discovery of hydrogen, "the easiest food for a microbe to digest," in Enceladus' plumes.

Sagan Prize winner Dr. Henry Throop tells us how scientists look for micron-sized dust that's millions of miles away to protect the New Horizons spacecraft. This search involves computer modeling, occultation observations, and plenty of teamwork.

Dr. Fengchuan Liu talks to us about an international project, the Thirty Meter Telescope (TMT). He describes the telescope, it's many mirrors, and how he helps manage such a complex project.

Dr. Cindy Hunt returns to the show to talk about the upcoming 100th anniversary of the 100 inch Hooker Telescope on Mount Wilson. She explains why this telescope looks like a battleship and tells us how it "completely upended our understanding of the universe". Also: poetry!

Dr. Lisa Storrie-Lombardi returns to the show to discuss NuSTAR, Spitzer, and what it feels like to end a mission you've been working on for decades. Cassini's Grand Finale has us reflecting on the upcoming demise of the Spitzer Space Telescope.