Cometary Science Newsletter

February 2022
Michael S. P. Kelley (

Postdoctoral Research Associate in Planetary Science

Applications are invited for a position as a postdoctoral Assistant Research Professor in planetary science at the U.S. Naval Academy (USNA) Physics Department in support of Assistant Professor Matthew Knight, to begin as early as Spring 2022. The successful applicant will lead analyses of comets observed with heliophysics assets and will assist in observational support and analyses of NASA’s Double Asteroid Redirection Test (DART). The position will involve collaboration with colleagues at the Naval Research Laboratory, University of Maryland, and Johns Hopkins University Applied Physics Laboratory, and may require travel to obtain new observations in Chile and/or Flagstaff, AZ. The successful candidate will also be encouraged to pursue research of their own choosing.

This is a federal excepted service position with a one-year initial appointment and the possibility of renewing for an additional year. For additional information on the position and how to apply, please visit

Applications will be reviewed beginning March 1, 2022 and the position will remain open until filled.

PDS Small Bodies Node Ice Sublimation Tools

The sublimation of ices is an important problem in cometary science. In 2003, the Small Bodies Node (SBN) of the Planetary Data System made available a web-accessible tool for calculating sublimation rates of water, carbon dioxide, and carbon monoxide ices in vacuum and a solar radiation field, based on the work of Cowan and A'Hearn (1979, Moon and Planets 21, 155-171). The tool was recently taken offline following updates to computing resources at the University of Maryland. The tool has been re-implemented and integrated into a new web-based application, available via the SBN website. The FORTRAN code behind the previous version of the tool and the new Python implementation are publicly available in a GitHub repository.

Refereed Articles

Abstracts of articles in press or recently published. Limited to 3000 characters.

Volatile Abundances, Extended Coma Sources, and Nucleus Ice Associations in Comet C/2014 Q2 (Lovejoy)

  • Dello Russo, N. 1
  • Vervack, R. J. Jr. 1
  • Kawakita, H. 2
  • Bonev, B. P. 3
  • DiSanti, M. A. 4, 5
  • Gibb, E. L. 6
  • McKay, A. J. 3, 4
  • Cochran, A. L. 7
  • Weaver, H. A. 1
  • Biver, N. 8
  • Crovisier, J. 8
  • Bockelée-Morvan, D. 8
  • Kobayashi, H. 9
  • Harris, W. M. 10
  • Roth, N. X. 11, 12
  • Saki, M. 13
  • Khan, Y. 6
  1. Space Exploration Sector, Johns Hopkins University Applied Physics Laboratory
  2. Koyama Astronomical Observatory, Kyoto Sangyo University, Japan
  3. Department of Physics, American University
  4. Solar System Exploration Division, NASA Goddard Space Flight Center
  5. Goddard Center for Astrobiology, NASA Goddard Space Flight Center
  6. Department of Physics and Astronomy, University of Missouri-St. Louis
  7. McDonald Observatory, University of Texas
  8. LESIA, Observatoire de Paris, France
  9. Kyoto Nijikoubou, Japan
  10. Lunar and Planetary Laboratory, University of Arizona
  11. Universities Space Research Association
  12. Solar System Exploration Division Astrochemical Laboratory, NASA GSFC
  13. Physics Department, Auburn University

High-resolution infrared spectra of comet C/2014 Q2 Lovejoy were acquired with NIRSPEC at the W. M. Keck Observatory on two post-perihelion dates (UT 2015 February 2 and 3). H2O was measured simultaneously with CO, CH3OH, H2CO, CH4, C2H6, C2H4, C2H2, HCN, and NH3 on both dates and rotational temperatures, production rates, relative abundances, H2O ortho-to-para ratios, and spatial distributions in the coma were determined. The first detection of C2H4 in a comet from ground-based observations is reported. Abundances relative to H2O for all species were found to be in the typical range compared with values for other comets in the overall population to date. There is evidence of variability in rotational temperatures and production rates on time scales that are small compared with the rotational period of the comet. Spatial distributions of volatiles in the coma suggest complex outgassing behavior. CH3OH, HCN, C2H6, and CH4 spatial distributions in the coma are consistent with direct release from associated ices in the nucleus, and are peaked in a more sunward direction compared with co-measured dust. H2O spatial profiles are clearly distinct from these other four species, likely due to a sizeable coma contribution from icy grain sublimation. Spatial distributions for C2H2, H2CO, and NH3 suggest substantial contributions from extended coma sources, providing further evidence for distinct origins and associations for these species in comets. CO shows a different spatial distribution compared with other volatiles, consistent with jet activity from discrete nucleus ice sources.

Planetary Science Journal (Published)

DOI: 10.3847/PSJ/ac323c