DPS 2001 meeting, November 2001
Session 14. Decadal Survey Posters

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[14.14] Exploration of the Neptune System

H. B. Hammel (SSI), J. Perry (LPL/U. Az.), K. Rages (SPRI/Ames), J. Stansberry (U. Az.)

Voyager 2, ground-based, and HST studies leave many questions regarding the Neptune system. How deep is the zonal structure? What is the composition of discrete features, and of the atmosphere as a function of altitude? Why are the winds and thermal structure on Uranus and Neptune similar, when the internal heat sources are so different? Why are the magnetic fields more asymmetric in ice giants than in gas giants? What is Triton's atmospheric composition and structure, and how has it changed since Voyager? Is Triton's surface extremely young? Is there convection in Triton's interior? How does composition relate to geologic terrain? How do ring arcs remain stable? Do Neptune's inner satellites show the effect of extreme tidal stress?

Significant progress in understanding the Neptune system has been made with Earth-based telescopes, and there is much work that remains to be done with such facilities. High angular resolution (HST, AO, NGST) studies will grow in importance, as will observations in new wavelength regimes (e.g. SIRTF). However, the answers to many of the questions require observations made from within the Neptune system. These include: 1) high spatial resolution images spanning a wide range of solar phase angles for surface, cloud, and ring studies; 2) high spatial resolution spectra for compositional mapping; 3) UV and radio occultations for atmospheric sounding; 4) resolved thermal imaging for atmospheric and surface energetics; and 5) in situ particles and fields measurements for magnetic and magnetospheric studies.

A recent NASA study (C. Porco et al., 1999) gave a Neptune System mission a top ranking for rich scientific yield and connections to astrophysical problems outside the Solar System (pre-biotic chemistry on Triton; local extrasolar planet analog). A Neptune mission's unmatched diversity of science return should place it at the top of the queue for outer planet exploration.

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