OSIRIS-REx Readies for Asteroid Bennu

Episode Summary

Executive Summary: This episode of Planetary Radio spotlights NASA’s OSIRIS-REx mission with PI Dante Loretta, covering spacecraft assembly, launch and sample-return plans, and the science instruments that will study Bennu. It also updates New Horizons’ Pluto discoveries with Emily Lakdawalla and closes with Bruce Betts on skywatching, space history, trivia, and a promo for Loretta’s game Extronaut.

Main Topics: OSIRIS-REx mission status and launch preparations: Dante Loretta reports that the spacecraft is nearly complete and entering full-spacecraft environmental testing, with launch planned for the following year and final integration milestones underway. Bennu science goals and sample-return strategy: The mission aims to collect pristine material from asteroid Bennu to study organics, water-bearing minerals, and the origin of life while preserving most of the sample for future researchers. OSIRIS-REx instruments and mission design: Loretta explains the imaging suite, spectrometers, and laser altimeter, emphasizing how each supports navigation, mapping, composition analysis, and sample-site selection. New Horizons Pluto imagery and scientific caution: Emily Lakdawalla discusses the flood of new Pluto images, stressing the importance of distinguishing observations from inferences when interpreting unfamiliar geology. Extronaut board game and public outreach: Loretta describes Extronaut as a game about planning solar system missions that teaches rocket physics and the real-world political and funding obstacles of space exploration. What’s Up: skywatching, space history, and trivia: Bruce Betts covers visible planets, an upcoming lunar eclipse, a Lost in Space anniversary, Voyager 1’s distance, and the trivia contest winner and prize.

Key Arguments: OSIRIS-REx is transitioning from component-level testing to full spacecraft environmental testing, indicating the mission is close to launch readiness. Bennu is scientifically valuable because it may preserve organic compounds and hydrated minerals that can address questions about life’s origins and Earth’s water. Sample return is irreplaceable because laboratory analyses can reach parts-per-billion sensitivity and preserve material for decades of future study. Mission target selection balanced engineering limits (solar power, thermal constraints, re-entry design) with science priorities, narrowing candidates to about two dozen asteroids. The instrument suite is designed to map Bennu globally, characterize composition, and capture the sampling event in detail, but the returned sample remains the mission’s highest-value asset. New Horizons data should be treated carefully: exciting surface features do not automatically imply erosion or tectonics until the science team can justify those inferences. Extronaut is intended to teach the public that space missions are constrained by physics, engineering, politics, and funding—not just rocket power.

Data Points: Launch window: 39 days - OSIRIS-REx has a long launch window beginning Sept. 3, 2016. Preferred launch date: Around September 17, 2016 - Loretta said this is the lowest-energy point and could enable an earlier return. Arrival at Bennu: 2018 - Mission timeline given by the host and confirmed in the interview. Sample return year: 2023 or possibly 2022 - Depending on launch timing and mission trajectory. Sample return mass target: 2 kilograms - If the sampling head is filled completely. Minimum sample pickup design: 150 grams - Engineered minimum capability of the TagSAM system. Science requirement sample mass: 60 grams - Mission science requirement Loretta cited. Spacecraft power source: Solar-powered - A key engineering constraint in selecting Bennu as the target. Voyager 1 distance: More than 18 light hours away - Bruce Betts’ update on the probe’s distance from Earth. Moon radius comparison: Io: 1,818 km; Moon: 1,737 km - Trivia answer identifying Io as the closest-sized moon to Earth’s Moon besides the Moon itself. Europa radius: 1,561 km - Bruce noted Europa as the next closest-sized moon after Io. New Horizons mosaic imaging: 15 camera repositionings - To create a global mosaic of Pluto. OSIRIS-REx mission acronym: Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer - Expanded form of OSIRIS-REx. Round-trip light time to Voyager 1: More than a day and a half - Because it is more than 18 light hours away.

Pivotal Quotes: "“This is really a geologist’s paradise, isn’t it?”" — Matt Kaplan: Reaction to the varied Pluto surface imagery shown by New Horizons. "“You really can’t replace sample return for understanding the key questions that we’re going after.”" — Dante Loretta: Loretta explaining why returning Bennu material is central to the mission. "“My goal was to bring the excitement of planetary exploration to a wide audience and to teach people about some common misconceptions.”" — Dante Loretta: Describing the purpose of his board game Extronaut.

Implications: Listeners get a clear view of how planetary missions move from engineering to discovery: careful testing now, major science later. The episode also highlights the value of sample return and public engagement tools like games and image blogs.