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

Matteo M.J. Crismani, Nicholas M. Schneider, Justin I. Deighan, A. Ian F. Stewart, Michael Combi, Michael S. Chaffin, Nicolas Fougere, Sonal K. Jain, Arnaud Stiepen, Roger V. Yelle, William E. McClintock, John T. Clarke, Gregory M. Holsclaw, Frank Montmessin, Bruce M. Jakosky

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)8803-8809
Number of pages7
JournalGeophysical Research Letters
Issue number21
StatePublished - Nov 16 2015


  • Comet Siding Spring
  • Mars upper atmosphere

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)


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