Ultraviolet observations of the hydrogen coma of comet C/2013 A1 (Siding Spring) by MAVEN/IUVS

Matteo M. J. Crismani (1) , Nicholas M. Schneider (1) , Justin I. Deighan (1) , A. Ian F. Stewart (1) , Michael Combi (2) , Michael S. Chaffin (1) , Nicolas Fougere (2) , Sonal K. Jain (1) , Arnaud Stiepen (1) , Roger V. Yelle (3) , William E. Mcclintock (1) , John T. Clarke (4) , Gregory M. Holsclaw (1) , Franck Montmessin (5) , Bruce M. Jakosky (1)

1 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
2 AOSS - Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor]
3 LPL - Lunar and Planetary Laboratory [Tucson]
4 CSP - Center for Space Physics [Boston]
5 PLANETO - LATMOS

We used the Imaging Ultraviolet Spectrograph (IUVS) aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiting spacecraft to construct images of the hydrogen coma of comet C/2013 A1 (Siding Spring) days before its close encounter with Mars. We obtain a water production rate of 1.1 ± 0.5 × 10²⁸ molecules/s and determine the total impacting fluence of atoms and molecules corresponding to the photodissociation of water and its daughter species to be 2.4 ± 1.2 × 104 kg. We use these observations to confirm predictions that the mass of delivered hydrogen is comparable to the existing reservoir above 150 km. Furthermore, we reconcile disparity between observations and predictions about the detectability of the hydrogen perturbation and thermospheric response.

Keywords: Comet Siding Spring; Mars upper atmosphere

Domains: Earth and Planetary Astrophysics [astro-ph.EP]; Solar and Stellar Astrophysics [astro-ph.SR]

Matteo M. J. Crismani, Nicholas M. Schneider, Justin I. Deighan, A. Ian F. Stewart, Michael Combi, et al.. Ultraviolet observations of the hydrogen coma of comet C/2013 A1 (Siding Spring) by MAVEN/IUVS. Geophysical Research Letters, 2015, 42 (21), pp.8803-8809. ⟨10.1002/2015GL065290⟩. ⟨insu-01238183⟩