Planetary Radio • May 19, 2015

Spiraling Closer to Ceres With the Dawn Mission’s Marc Rayman

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Marc Rayman

Chief Engineer for Mission Operations and Science, Jet Propulsion Laboratory

It’s the biggest dwarf planet between here and Pluto, and it has a new permanent resident. The Dawn spacecraft is orbiting Ceres in the asteroid belt, revealing it as never before. What are those bright spots anyway? We spend time with Dawn’s Chief Engineer and Director, Marc Rayman. There’s even more from Pluto this week as New Horizons closes in. That’s according to Emily Lakdawalla, who also talks about the science at Ceres. Bill Nye marvels at the worldwide enthusiasm for LightSail, while Bruce Betts provides a different sort of Random Space Fact.

Approaching Ceres: one bright spot turns into two
Approaching Ceres: one bright spot turns into two Dawn captured this image of Ceres during its Rotation Characterization 2, on February 19, 2015. This photo includes the enigmatic bright spot, which has now separated into two bright spots, both of them still smaller than the resolution of the camera (which is roughly 4 kilometers per pixel at a distance of 46,000 kilometers). This image has been enlarged by a factor of two from the original data.Image: NASA / JPL / UCLA / MPS / DLR / IDA

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This week's question:

Give us a great analogy for the 32-square meter LightSail sail. Prizes will be awarded for the most instructive comparison that provides a great feel for how big it is, and separately for the funniest analogy.

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Complete the contest entry form at or write to us at [email protected] no later than Tuesday, May 26th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

What galaxy was named after the larval stage of an amphibian?


The answer will be revealed next week.

Question from the week before:

In microns, how thick are LightSail’s sails?


LightSail’s mylar sails are 4.5 microns thick.