OPAG - Fall 2020 (2020) 6031.pdf NEPTUNE ODYSSEY: MISSION TO THE NEPTUNE-TRITON SYSTEM. A. M. Rymer1, B. Clyde1, K. Runyon1 and the Neptune Odyssey Study team. 1Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA. [email protected] ocean world? What causes its plumes? What is the The Neptune Odyssey mission concept is a nature of its atmosphere? (4) How can Triton’s Flagship-class orbiter and atmospheric probe to the geophysics and composition expand our Neptune-Triton system. This bold mission of knowledge of dwarf planets like Pluto? (5) What exploration would be the first to orbit an ice giant are the connections between Neptune’s rings, arcs, planet to study the planet, its rings, small satellites, surface weathering, and small moons (some of space environment, and the planet-sized moon, which are captured from the Kuiper Belt or the Triton. Triton is, itself a captured dwarf planet from protoplanetary disk). the Kuiper Belt and a geophysically reactivated twin of Pluto. Odyssey addresses Neptune system-level We present our mission concept as a “shovel- science, with equal priorities placed on Neptune, its ready,” concept maturity level of 4 and a total rings, moons, space environment, and Triton. modeled cost (including 50% margin) of less than Between Uranus and Neptune, the latter is unique in $3.4B; this is a mission NASA could choose to providing simultaneous access to both an ice giant stand up now without waiting for significant and a Kuiper Belt dwarf planet. The spacecraft—in advances in technology. An SLS rocket with a a class with Cassini—would launch in 2033 on a Centaur upper stage (fitting in the payload fairing) Space Launch System (SLS) or equivalent launch allows direct-to-Neptune launch opportunities vehicle on a 16-year cruise to Neptune for a 4-year every calendar year. Our example spacecraft will prime orbital mission. Our solution provides annual launch with 3520 kg to Neptune orbit and utilize launch opportunities and allows for easy upgrade to three RTGs (radioisotope thermoelectric a shorter (12-year) cruise phase that can utilize a generators), requiring 28.8 kg of plutonium. A Jupiter gravity assist (JGA), if NASA chooses to JGA, although enhancing, is not required. If NASA stand up this mission in time for a launch before selects a mission like Odyssey for a new start and 2032. Odyssey would orbit Neptune retrograde an SLS-class vehicle is not available, a Falcon (prograde with respect to Triton), providing New Heavy-class vehicle could deliver the same Horizons-quality science from Triton every month, payload mass using a solar electric propulsion using the moon’s gravity to shape the orbital tour kickstage. and allow coverage of a range of latitudes and From the start of this long mission, preserving longitudes on Triton, on Neptune, and in the space knowledge and cultural continuity would be a environment. The atmospheric entry probe would priority. Observations along the way (for example, descend in ~37 minutes to the 10-bar pressure level stereo observations of the edges of our heliosphere, in Neptune’s atmosphere just before Odyssey’s asteroid and Centaur flybys, and using Odyssey’s orbit-insertion engine burn. Odyssey’s mission cameras for a rear-view look back at our solar would end by conducting a Cassini-like Grand system) will sustain interest and provide Finale tour, passing inside the rings very close to the unprecedented opportunities for discovery. giant planet, and ultimately taking a final great Finally, equipping both the orbiter and probe with plunge into Neptune’s atmosphere. cameras specially purposed for public engagement As part of defining the science traceability matrix will help to share the joy of exploration and (STM) a family of instruments for both the orbiter discovery with those who help make space and the probe were selected, drawing from proven exploration possible—the general public. flight heritage designs. Broadly, the STM Acknowledgments: This work was supported by addresses the following questions: (1) How do the the NASA Planetary Mission Concept Studies interiors and atmospheres of ice giant (exo)planets solicitation: NNH18ZDA001N-PMCS. form and evolve? (2) What causes Neptune’s strange magnetic field, and how do its magnetosphere and aurora work? (3) Is Triton an OPAG - Fall 2020 (2020) 6031.pdf .