Countdown to Ultima: Alan Stern and New Horizons

Episode Summary

Executive Summary: This Planetary Radio episode surveys the biggest planetary-science events of 2018 and then focuses on New Horizons’ imminent flyby of Kuiper Belt object 2014 MU69, dubbed Ultima Thule. Emily Lakdawalla reviews major missions and setbacks; Alan Stern explains the mission’s status, science goals, long-range plans, and why the encounter is uniquely significant; Bruce Betts closes with skywatching, trivia, and a scale-model comparison of New Horizons’ journey.

Main Topics: 2018 in planetary exploration: Emily Lakdawalla summarizes a busy year: multiple launches, key landings, asteroid mission milestones, and mission endings that shaped planetary science in 2018. New Horizons approach to Ultima Thule: Alan Stern details the spacecraft’s final approach to 2014 MU69, its excellent health, and the highly choreographed flyby sequence already uploaded to the spacecraft. Science mysteries of Ultima Thule: The team discusses what is known and unknown about Ultima, including its irregular shape, possible binary nature, unexplained light-curve behavior, and searches for moons, rings, atmosphere, and dust. Mission operations, data return, and constraints: Stern explains why the best images and full dataset will arrive slowly, including post-encounter downlinks, solar conjunction, and the 20-month data return timeline. New Horizons beyond the flyby: The conversation looks ahead to New Horizons’ extended mission, possible future Kuiper Belt targets, and whether the spacecraft could eventually reach interstellar space. Space trivia and skywatching with Bruce Betts: The show closes with observing tips, a meteor shower and eclipse preview, a scale-model of planetary distances, and the winner of the trivia contest.

Key Arguments: 2018 was an exceptionally productive year for planetary exploration, with four interplanetary missions launched and major developments at Mars, the Moon, asteroids, and the outer solar system. Ultima Thule is scientifically important because it is a pristine Kuiper Belt object that may preserve conditions from the early solar system. New Horizons’ flyby is unusually well-prepared: the spacecraft is healthy, navigation is accurate, and the encounter sequence is already on board. Despite extensive pre-flyby observation, Ultima still hides key properties, especially its missing light-curve signal, which suggests unexpected physics or geometry. The mission’s design and deep-space navigation capability make it possible not only to complete the Ultima flyby but potentially to extend exploration farther into the Kuiper Belt. A future Pluto orbiter using electric propulsion and Charon gravity assists could dramatically expand scientific return and even continue on to other dwarf planets. The show emphasizes that planetary exploration routinely reveals surprises, and Ultima is expected to be another example of discovery-driven science.

Data Points: Interplanetary missions launched in 2018: 4 - BepiColombo, InSight, Chang'e 4/Queqiao, and Parker Solar Probe InSight major instruments: 2 - Seismometer and heat probe discussed as primary science payload Time until InSight heat probe deployment: By the end of January - Emily’s update on Mars lander operations New Horizons flyby time: 0533 UTC / 12:33 a.m. Eastern - Scheduled closest approach to Ultima Thule on New Year’s Day 2019 Ultima Thule discovery year: 2014 - Object discovered in June 2014 Ultima orbit period: Nearly 300 years - Described as taking about 300 years to orbit the Sun once Ultima relative size to Comet 67P: About 1000 times bigger - Comparison made during the introduction Observation time requested from Hubble: Almost 200 orbits - Used to search for a reachable Kuiper Belt target Targets found by Hubble: 3 - Found within two weeks, leading to selection of Ultima Distance of Ultima from the Sun: 44 times Earth-Sun distance - Alan Stern notes current heliocentric distance Kuiper Belt extent mentioned: 70 times Earth-Sun distance - Used to describe the broader region New Horizons could still explore New Horizons data return duration: 20 months - Expected to continue through August or September 2020 Pluto data return duration: 16 months - Historical comparison for how long flyby data took to come down New Horizons power-limited operational horizon: Mid to late 2030s - Estimate for how long the RTG may support operations Potential distance at end of power life: About 90-100 AU - Estimated spacecraft distance when power runs low Hubble search start year: 2011 - Initial ground-based and Hubble search campaign timeline Mars dust storm impact on Opportunity: More than 6 months without contact - Solar-powered rover affected by global dust storm Partial solar eclipse date: January 6 - Bruce Betts’s skywatching segment Quadrantids meteor shower peak: Night of January 3-4 - Highlighted as well-placed due to new moon Trivia contest target star distance: About 178 light years - Ardoradus / HD 29712 explained as a huge red giant Trivia contest prize: 200-point iTelescope.net account - Awarded for the next contest Scale model comparison: Sun in Los Angeles; Pluto in Chicago; Ultima Thule in New York - Bruce Betts’s analogy for New Horizons’ voyage

Pivotal Quotes: "We are so excited about this flyby and can't wait to have you here and are just barreling towards New Year's Eve and New Year's Day with the close approach." — Alan Stern: Describing the team’s anticipation days before the Ultima Thule encounter "This is the Apollo 13 of planetary exploration." — Alan Stern: Referring to the dramatic Pluto flyby rescue when the spacecraft’s main computer failed "We know that there are always surprises ahead." — Matt Kaplan: Framing the broader lesson of planetary exploration during the interview

Implications: The episode captures a turning point: New Horizons is poised to open a new class of Kuiper Belt science while showing how long-duration, high-risk missions can still deliver transformative discoveries. It also reinforces that exploration is iterative, surprise-driven, and dependent on sustained public and institutional support.