Ellen Susanna Howell (born 1961;[1] also published as Ellen S. Bus) is an American astronomer and planetary scientist who studies the composition and structure of asteroids and comets within the Solar System. She is a research professor at the Lunar and Planetary Laboratory of the University of Arizona, and a team member for the OSIRIS-REx sample-and-return space mission.[2]

Education and career

Howell majored in geophysics at the California Institute of Technology, graduating in 1981. Returning to graduate study, she completed a Ph.D. in planetary sciences at the University of Arizona in 1995.[3]

After postdoctoral research at the Arecibo Observatory from 1995 to 1999, and continuing as a research associate at Arecibo until 2015, she returned to the University of Arizona in 2015 as a senior research scientist.[3]


In 1977, Howell discovered asteroid 3598 Saucier using the Palomar Observatory. She named it after her grandmother, Agnes Elizabeth Saucier.[4] In the same year, Schelte J. Bus, whom she later married, discovered asteroid 2735 Ellen; he named it after her.[5] Howell discovered comet 88P/Howell at Palomar in 1981.[6]

At Arecibo, Howell's research included radar observations of asteroids including triple asteroid (136617) 1994 CC[7] and near-Earth asteroid 2014 HQ124.[8] After her undergraduate discovery of comet 88P/Howell, Howell has also maintained her interests in the observation of comets, including making radar observations of comet 46P/Wirtanen in 2018[9] using the Arecibo Observatory, one of the last observations from Arecibo before its 2020 collapse.[10]

Her work with OSIRIS-REx has included the discovery of water-related chemical compounds on asteroid 101955 Bennu, the target of the OSIRIS-REx mission.[11]


  1. ^ Macho Stadler, Marta (May 3, 2016), "Ellen Howell, astrónoma", Mujeres con Ciencia (in Spanish), University of the Basque Country, retrieved 2023-07-29
  2. ^ "Ellen Howell", Lunar and Planetary Laboratory Faculty, University of Arizona, retrieved 2023-07-29
  3. ^ a b "Curriculum vitae" (PDF), Lunar and Planetary Laboratory, University of Arizona, January 2020, retrieved 2023-07-29
  4. ^ Schmadel, Lutz D. (2015), "Catalogue of Minor Planet Names and Discovery Circumstances Addendum 2012–2014", Dictionary of Minor Planet Names, Springer International Publishing, p. 36, doi:10.1007/978-3-319-17677-2_2
  5. ^ Schmadel, Lutz D. (2023), Dictionary of Minor Planet Names (3rd ed.), Springer, p. 353, ISBN 9783662066157
  6. ^ King, Bob (September 9, 2020), "Stormy times on Jupiter, Comet Howell steps up, and more", Sky & Telescope, retrieved 2023-07-29
  7. ^ Triple asteroid system triples asteroid observers interest, Jet Propulsion Laboratory, August 6, 2009, retrieved 2023-07-29
  8. ^ "'Beast' asteroid looks like a beauty in radar images", NBC News, June 12, 2014, retrieved 2023-07-29
  9. ^ Morton, Erin (December 20, 2018), "UA Researcher Captures Rare Radar Images of Comet 46P/Wirtanen", Lunar and Planetary Laboratory, University of Arizona, retrieved 2023-07-29
  10. ^ Cantwell, Elizabeth R. (November 23, 2020), Lamenting the Loss of the Arecibo Observatory, University of Arizona, retrieved 2023-07-29
  11. ^ Morton, Erin (December 10, 2018), "UA-Led OSIRIS-REx Discovers Water on Asteroid Bennu", Lunar and Planetary Laboratory, University of Arizona, retrieved 2023-07-29