A Winged MESSENGER Reaches Mercury, and Bill Nye Premieres!

Episode Summary

Executive Summary: This episode centers on MESSENGER’s imminent first flyby of Mercury in 33 years, explaining the mission’s trajectory, science goals, and why Mercury remains mysterious. It also debuts Bill Nye’s recurring Mars segment, covers Mars rover progress, and ends with Bruce Betts’ night-sky guide, space history, and a listener contest.

Main Topics: MESSENGER’s Mercury flyby and mission goals: Sean Solomon explains the spacecraft’s first Mercury encounter, the long cruise to orbit in 2011, and how flybys will enable global mapping and key science before insertion. Why Mercury is hard to reach and study: The interview details the need for gravity assists at Earth, Venus, and Mercury because spacecraft speed up toward the Sun and must slow down to be captured by Mercury. New science enabled beyond Mariner 10: MESSENGER’s imaging, spectrometers, magnetometer, and altimetry will examine Mercury’s composition, geology, magnetic field, and polar deposits—questions left open since the 1970s. Bill Nye’s debut Mars commentary: Bill Nye introduces his new Planetary Radio segment, highlighting Mars rover achievements, evidence for past liquid water, and the imaginative possibility of life transfer between Mars and Earth. Night sky update and comet viewing: Bruce Betts reviews visible objects including Mars, Saturn, Venus, Comet Holmes, and Comet 8P/Tuttle, with tips for binocular and telescope viewing. Space history and listener challenge: The show revisits Surveyor 7, a triple docking in space, and Mariner 9 at Mars, then offers a quiz about Surveyor spacecraft legs with a year-in-space calendar prize.

Key Arguments: Mercury is still scientifically underexplored; Mariner 10 only imaged about 45% of the surface in sunlight, leaving major gaps that MESSENGER can fill. The mission’s flyby sequence is essential because a spacecraft heading inward toward the Sun gains speed and must be slowed by gravity assists to enter Mercury orbit. MESSENGER’s upgraded instruments can analyze Mercury’s surface chemistry, mineralogy, magnetism, and polar deposits in ways impossible for Mariner 10. Mercury’s density implies an unusually large iron-rich core, one of the planet’s central unsolved questions. Polar radar-bright deposits likely represent water ice or other volatiles trapped in permanent shadow, and MESSENGER may help identify their composition. Mars exploration is still revealing dramatic evidence of a wetter past, and the rover missions continue to deliver important geological context and imagery.

Data Points: Years since last Mercury visit: 33 years - Gap since Mariner 10 until MESSENGER’s first flyby Mariner 10 Mercury flybys: 3 - Only spacecraft to have visited Mercury before MESSENGER MESSENGER trajectory correction speed change: a little over 1 meter per second - Small maneuver on December 19 after solar conjunction Mercury mass relative to Earth: a little more than 5% - Used to explain why orbit insertion requires very low relative speed Mercury flyby encounters before orbit insertion: 4 total encounters with Mercury - First flyby plus three more flybys before orbit insertion in 2011 Mercury orbit insertion date: 2011 - Final capture into orbit after multiple gravity assists Time between second and third Mercury flybys: 11 months - October 2008 flyby to September 2009 flyby Time between third flyby and orbit insertion: 18 months - Final stretch before Mercury orbit capture Mariner 10 surface coverage in sunlight: about 45% - Because flybys occurred one Mercury solar day apart Mercury polar crater temperature: as cold as about 90 K - Permanent shadow cold traps at the poles Voyager solar wind speed comparison: 4 times faster than spacecraft before the termination shock - Emily Lochtawalla’s explanation of supersonic solar wind Speed of sound at Earth sea level: about 0.33 km/s - Compared with sound speed in the solar wind Speed of sound in the solar wind: nearly 200 times faster than at Earth sea level - Because the solar wind is a very rarefied medium Mars rover operating time: almost 4 years - Bill Nye references Spirit and Opportunity Mars rover operating duration in Martian years: 2 Martian years - Another way of describing rover longevity Planetary Radio listener contest deadline: January 14, 2008 at 2 p.m. Pacific - Deadline to enter the Surveyor legs question Surveyor 7 landing anniversary: 40 years - Referenced in the space history segment Surveyor question: How many legs did the Surveyor spacecraft have? - Prize contest prompt

Pivotal Quotes: "“We are barely a week from humanity’s first encounter with Mercury in 33 years.”" — Matt Kaplan: Introductory framing of the upcoming MESSENGER flyby "“The whole science team on the Messenger mission is excited.”" — Sean Solomon: Sean Solomon describes the anticipation around the Mercury encounter "“We believe in the PBJ, the passion, beauty, and joy of space exploration.”" — Bill Nye: Bill Nye explains the mission of the Planetary Society and his new recurring segment

Implications: Listeners get a preview of a major Mercury milestone and the science likely to follow, plus renewed enthusiasm for Mars and practical skywatching guidance. The episode reinforces how new data and better instruments can reopen old planetary mysteries.