Continued Volatile Transport on Pluto: First Results from the 2014 Observing Season
Abstract
With its high eccentricity and obliquity, Pluto should exhibit seasonal volatile transport on its surface. This transport should be detectable through changes in its historical rotational light curve, once all variations due to viewing geometry have been modelled. Observations of Pluto’s light curve between 1950 and 1999 suggest a stable albedo pattern. Starting in the early part of this millennium, both new Hubble Space Telescope maps and light curve measurements obtained at JPL’s Table Mountain Observatory show evidence of small changes in Pluto’s distribution of surface albedo (Hicks et al. 2008, B.A.A.S. 40, 460.; Buie et al., 2010, Astron. J. 139, 1128). Supporting possible surface volatile transport is the doubling of Pluto’s atmospheric pressure over the past two decades (Young et al., 2013, Ap. J. 766, L22). With the New Horizons spacecraft due to encounter Pluto in July 2015, close scrutiny of this dwarf ice planet has begun in earnest. Ground-based observations are especially critical for context and for a larger temporal excursion. Rotational light curves of Pluto have been created in two recent epochs: 2007-2008, and 2012-2014. Both light curves show a smaller amplitude than that expected for a static frost model based on albedo maps from the earliest HST images (Stern et al. 1997, Astron. J. 113, 827). Observations of both Buie et al. (2010) and our own between 2007 and 2014 show that Pluto is becoming redder. This observation makes sense if nitrogen frost is being removed from the surface to uncover a red, photolyzed substrate of methane. Funded by NASA.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #46
- Pub Date:
- November 2014
- Bibcode:
- 2014DPS....4640406B