On the Way to Pluto with New Horizons Principal Investigator Alan Stern

Episode Summary

Executive Summary: This Planetary Radio episode centers on Alan Stern’s update on New Horizons: the spacecraft is healthy, on course, and beginning instrument commissioning as it heads toward Jupiter in 2007 and Pluto in 2015. Stern also discusses his broader mission portfolio, including Rosetta, LRO, and search plans for Kuiper Belt objects after Pluto, while the show covers NASA budget scrutiny, shuttle spares, Pluto satellite observations, and skywatching updates.

Main Topics: New Horizons post-launch status and mission timeline: Alan Stern reports that New Horizons is performing well after launch, with successful trajectory corrections, higher-than-expected communications performance, and the start of instrument commissioning. He also outlines the long cruise to Jupiter and Pluto. Pluto system science and satellite searches: Stern explains that Hubble time was used to refine the orbits of Pluto’s moons and look for additional satellites, which is important for planning the Pluto encounter and identifying hazards or targets. Stern’s broader mission portfolio: Beyond New Horizons, Stern describes work on Rosetta, Mars Express, Venus Express, and the Lunar Reconnaissance Orbiter, emphasizing that he remains heavily engaged in multiple active missions. Post-Pluto Kuiper Belt object targeting: The mission plans to search for suitable Kuiper Belt objects before the Pluto flyby so New Horizons can redirect soon after encounter, enabling extended exploration beyond Pluto. NASA headlines and policy pressure: The episode notes congressional dissatisfaction with NASA’s proposed science and robotic exploration cutbacks, plus shuttle fleet maintenance concerns and honors for Walter Cronkite. Space Q&A and skywatching: Emily explains why the Pioneer anomaly cannot be tested on Voyagers, while Bruce Betts gives the night-sky lineup, a trivia segment, and a new contest question.

Key Arguments: New Horizons is healthy and ahead in checkout, proving the launch and early cruise are going well. The mission’s communications system is performing better than expected, reflecting strong engineering and DSN support. Hubble observations are strategically important because they can refine Pluto moon orbits and potentially reveal additional satellites. Stern’s workload is broad; New Horizons is only one of several missions he actively supports. Rosetta, LRO, and similar missions show how planetary science uses multiple spacecraft to build knowledge across different targets and timescales. After Pluto, New Horizons will search for and fly by Kuiper Belt objects if fuel and discoveries permit, maximizing scientific return. Voyager spacecraft cannot reveal the Pioneer anomaly because their thruster firings introduce uncertainties larger than the anomaly itself.

Data Points: Launch-to-Pluto cruise duration: about 9 years - New Horizons’ travel time from launch to Pluto encounter Jupiter gravity assist date: February 28 of the following year - Stern notes when New Horizons will be in the thick of Jupiter observations New Horizons cleanup burn: 10 times smaller than the previous burn - A final trajectory cleanup maneuver is planned in March Hubble observing time: 2 orbits - Used to refine Pluto satellite orbits and search for additional moons Pluto satellite team size: 9 people - Stern describes the discovery team for Pluto’s moons Rosetta mission duration to comet: about 2 years in transit - Rosetta en route to comet 67P/Churyumov-Gerasimenko Rosetta payload: 13 instruments and 1 small lander - Stern highlights the spacecraft’s science suite LRO launch timing: end of 2008 - Expected launch window for the Lunar Reconnaissance Orbiter LRO transit time to Moon: 4 days - Stern contrasts the short trip to the Moon with New Horizons’ long cruise Planned KBO size range: 30–100 km across - Objects New Horizons may target after Pluto Potential KBO candidates: 4 to 8 - Estimated number of accessible post-Pluto targets from Monte Carlo studies Chance of a ~100 km KBO flyby: about 10% - Stern estimates likelihood within the mission fuel budget Distance to centaur encounter: about 2.5 to 2.8 AU - Predicted early 2010 distant flyby target Voyager anomaly detectability: not measurable on Voyagers - Because thruster uncertainties exceed the tiny effect

Pivotal Quotes: "The spacecraft is very healthy. We're very far along in the spacecraft checkout." — Alan Stern: Status update on New Horizons shortly after launch "We may have something to say about whether there are additional satellites." — Alan Stern: Discussion of new Hubble observations of Pluto "We're built to do KBO flybys, and that's what that fuel's for." — Alan Stern: Explaining the post-Pluto mission strategy

Implications: New Horizons is on track to become a long-lived outer solar system explorer, with Pluto as a gateway rather than an endpoint. The episode also shows how planetary science depends on multiple missions, international collaboration, and opportunistic target selection.