Ellen Susanna Howell (born 1961; also published as Ellen S. Bus) is an American astronomer and

planetary scientist Planetary science (or more rarely, planetology) is the scientific study of planets (including Earth), celestial bodies (such as moons, asteroids, comets) and planetary systems (in particular those of the Solar System) and the processes of their ...

who studies the composition and structure of

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

s and

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

s within the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

. She is a research professor at the Lunar and Planetary Laboratory of the

University of Arizona The University of Arizona (Arizona, U of A, UArizona, or UA) is a Public university, public Land-grant university, land-grant research university in Tucson, Arizona, United States. Founded in 1885 by the 13th Arizona Territorial Legislature, it ...

, and a team member for the

OSIRIS-REx OSIRIS-REx was a NASA asteroid-study and sample-return mission that visited and collected samples from 101955 Bennu, a C-type asteroid, carbonaceous near-Earth object, near-Earth asteroid. The material, returned in September 2023, is expected ...

sample-and-return space mission.

Education and career

Howell majored in

geophysics Geophysics () is a subject of natural science concerned with the physical processes and Physical property, properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct i ...

at the

California Institute of Technology The California Institute of Technology (branded as Caltech) is a private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small group of institutes ...

, graduating in 1981. Returning to graduate study, she completed a Ph.D. in planetary sciences at the

in 1995. After postdoctoral research at the

Arecibo Observatory The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science F ...

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.

Research

In 1977, Howell discovered asteroid 3598 Saucier using the

Palomar Observatory The Palomar Observatory is an astronomical research observatory in the Palomar Mountains of San Diego County, California, United States. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

. She named it after her grandmother, Agnes Elizabeth Saucier. In the same year, Schelte J. Bus, whom she later married, discovered asteroid

2735 Ellen __NOTOC__ Year 735 ( DCCXXXV) was a common year starting on Saturday of the Julian calendar. The denomination 735 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Euro ...

; he named it after her. Howell discovered comet

88P/Howell 88P/Howell is a periodic comet with a 5.5 year orbital period. It was discovered on 29 August 1981, by Ellen Howell. In 1975 the comet's perihelion (closest approach to the Sun) was 1.9 AU, but a close approach to Jupiter in 1978 perturbed th ...

at Palomar in 1981. At Arecibo, Howell's research included radar observations of asteroids including triple asteroid (136617) 1994 CC and near-Earth asteroid 2014 HQ124. After her undergraduate discovery of comet 88P/Howell, Howell has also maintained her interests in the observation of comets, including making

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

observations of comet 46P/Wirtanen in 2018 using the Arecibo Observatory, one of the last observations from Arecibo before its 2020 collapse. Her work with

has included the discovery of water-related chemical compounds on asteroid

101955 Bennu 101955 Bennu ( provisional designation ) is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on 11 September 1999. It is a potentially hazardous object that is listed on the Sentry Risk Table and has the second hig ...

, the target of the OSIRIS-REx mission. Howell's current research is funded by the following grants: Combining thermal and radar observations of near-Earth asteroids, Water and OH on Primitive Bodies: Expanding the Frontier, Volatiles, Regolith and Thermal Investigations Consortium for Exploration and Science (VORTICES), and In the Eye of the Storm: Inner coma remote sensing of three Jupiter Family Comets.

References

{{DEFAULTSORT:Howell, Ellen 1961 births Living people American astronomers American women astronomers California Institute of Technology alumni University of Arizona alumni University of Arizona faculty