Publication Date:
2018-04-15
Description:
Publication date: June 2018 Source: Icarus, Volume 307 Author(s): D.P. Hinson, I.R. Linscott, D.F. Strobel, G.L. Tyler, M.K. Bird, M. Pätzold, M.E. Summers, S.A. Stern, K. Ennico, G.R. Gladstone, C.B. Olkin, H.A. Weaver, W.W. Woods, L.A. Young On 14 July 2015 New Horizons performed a radio occultation (RO) that sounded Pluto’s neutral atmosphere and ionosphere. The solar zenith angle was 90.2° (sunset) at entry and 89.8° (sunrise) at exit. We examined the data for evidence of an ionosphere, using the same method of analysis as in a previous investigation of the neutral atmosphere (Hinson et al., 2017). No ionosphere was detected. The measurements are more accurate at occultation exit, where the 1-sigma sensitivity in integrated electron content (IEC) is 2.3 × 10 11 cm − 2 . The corresponding upper bound on the peak electron density at the terminator is about 1000 cm − 3 . We constructed a model for the ionosphere and used it to guide the analysis and interpretation of the RO data. Owing to the large abundance of CH 4 at ionospheric heights, the dominant ions are molecular and the electron densities are relatively small. The model predicts a peak IEC of 1.8 × 10 11 cm − 2 for an occultation at the terminator, slightly smaller than the threshold of detection by New Horizons.
Print ISSN:
0019-1035
Electronic ISSN:
1090-2643
Topics:
Physics
