Planetary Radio • Jun 28, 2017

Happy Asteroid Day!

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On This Episode

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Timothy Spahr

NEO Sciences LLP CEO and Shoemaker NEO Selection Committee Chair

Asteroid Day, June 30th, marks the anniversary of the great Tunguska impact that leveled a Siberian forest. It reminds us that a Near Earth Object can destroy a city or even a civilization. Former Minor Planet Center Director Tim Spahr reviews our efforts to find and understand these bodies. Bruce Betts unveils a new round of Planetary Society grants that will support this work. Jason Davis takes us to Uranus and Neptune, ice giants that have only been visited by one spacecraft. Bill Nye wonders how future Mars rovers will communicate with Earth if aging satellite fail without replacements.

Artist's concept of near-Earth asteroids
Artist's concept of near-Earth asteroids Artist's view of asteroids passing Earth.Image: ESA / P.Carril
Timothy Spahr
Timothy Spahr CEO of NEO Sciences LLP, and former director of the Minor Planet Center.Image: SciTech Cafe

This week's question:

In what year was the supernova observed that formed the Crab Nebula?

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, July 5th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

What are the names of the two large Venusian highlands?


The answer will be revealed next week.

Question from the week before:

What fuel do the Cassini spacecraft’s sixteen thrusters (not the main engines) use?


The fuel used by Cassini’s 16 thrusters is hydrazine.