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]
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]
Deimos is the smaller and outermost of the two natural satellites of Mars, the other being Phobos. Deimos has a mean radius of 6.2 km (3.9 mi) and takes 30.3 hours to orbit Mars. Deimos is 23,460 km (14,580 mi) from Mars, much farther than Mars' other moon, Phobos. It is named after Deimos, the Ancient Greek god and personification of dread and terror.
Radar astronomy is a technique of observing nearby astronomical objects by reflecting radio waves or microwaves off target objects and analyzing their reflections. Radar astronomy differs from radio astronomy in that the latter is a passive observation and the former an active one. Radar systems have been conducted for six decades applied to a wide range of Solar System studies. The radar transmission may either be pulsed or continuous. The strength of the radar return signal is proportional to the inverse fourth-power of the distance. Upgraded facilities, increased transceiver power, and improved apparatus have increased observational opportunities.
46P/Wirtanen is a small short-period comet with a current orbital period of 5.4 years. It was the original target for close investigation by the Rosetta spacecraft, planned by the European Space Agency, but an inability to meet the launch window caused Rosetta to be sent to 67P/Churyumov–Gerasimenko instead. It belongs to the Jupiter family of comets, all of which have aphelia between 5 and 6 AU. Its diameter is estimated at 1.2 kilometres (0.75 mi). In December 2019, astronomers reported capturing an outburst of the comet in substantial detail by the TESS space telescope.
Daphne is a large asteroid from the asteroid belt. It is a dark-surfaced body 174 km in diameter is probably composed of primitive carbonaceous chondrites. The spectra of the asteroid displays evidence of aqueous alteration. It was discovered by H. Goldschmidt on May 22, 1856, and named after Daphne, the nymph in Greek mythology who was turned into a laurel tree. Incorrect orbital calculations initially resulted in 56 Melete being mistaken for a second sighting of Daphne. Daphne was not sighted again until August 31, 1862.
Carl William Hergenrother is an American astronomer and discoverer of minor planets and comets.
A sample-return mission is a spacecraft mission to collect and return samples from an extraterrestrial location to Earth for analysis. Sample-return missions may bring back merely atoms and molecules or a deposit of complex compounds such as loose material and rocks. These samples may be obtained in a number of ways, such as soil and rock excavation or a collector array used for capturing particles of solar wind or cometary debris. Nonetheless, concerns have been raised that the return of such samples to planet Earth may endanger Earth itself.
Dante S. Lauretta is a professor of planetary science and cosmochemistry at the University of Arizona's Lunar and Planetary Laboratory. He is the principal investigator on NASA's OSIRIS-REx mission.
The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of furthering the understanding of the Solar System. The program selects medium-class missions which can provide high science returns.
1777 Gehrels, also designated 4007 P-L, is a stony asteroid from the middle region of the asteroid belt, approximately 13 kilometers in diameter. It was discovered during the Palomar–Leiden survey in 1960, and named for astronomer Tom Gehrels, one of the survey's principal investigators and credited discoverer.
(450894) 2008 BT18 is a sub-kilometer asteroid and synchronous binary system, classified as near-Earth object and potentially hazardous asteroid of the Apollo group. It was discovered on 31 January 2008, by the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, United States. The eccentric asteroid measures approximately 600 meters in diameter and has a composition of a basaltic achondrite.
101955 Bennu (provisional designation 1999 RQ36) 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 highest cumulative rating on the Palermo Technical Impact Hazard Scale. It has a cumulative 1-in-1,750 chance of impacting Earth between 2178 and 2290 with the greatest risk being on 24 September 2182. It is named after the Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth.
OSIRIS-REx is a NASA asteroid-study and sample-return mission. The mission's primary goal is to obtain a sample of at least 60 g (2.1 oz) from 101955 Bennu, a carbonaceous near-Earth asteroid, and return the sample to Earth for a detailed analysis. The material returned is expected to enable scientists to learn more about the formation and evolution of the Solar System, its initial stages of planet formation, and the source of organic compounds that led to the formation of life on Earth.
Michael Julian Drake, regent's professor, was the director of the University of Arizona's Lunar and Planetary Laboratory and head of the Department of Planetary Sciences. He was the principal investigator of the Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission of NASA's New Frontiers Program. The OSIRIS-REx mission, launched on September 8, 2016, and scheduled to arrive at Asteroid Bennu in December 2018, is the most ambitious University of Arizona planetary science project to date and will retrieve a sample of the asteroid and return it to Earth. He also made significant contributions to the study of HED meteorites and studied the origin of water in terrestrial planets.
(7335) 1989 JA, provisional designation 1989 JA, is a stony asteroid of the Apollo group, classified as near-Earth object and potentially hazardous asteroid, approximately 1 kilometer in diameter. It was discovered on 1 May 1989, by American astronomer Eleanor Helin at the U.S. Palomar Observatory in California. On 27 May 2022, the asteroid made a close approach 0.027 astronomical units from Earth. During the close approach, optical observations detected signs of an orbiting satellite, which was later confirmed by radar imaging at NASA's Goldstone Solar System Radar in California.
(285263) 1998 QE2, provisional designation 1998 QE2, is a dark asteroid and synchronous binary system, classified as near-Earth object and potentially hazardous asteroid of the Amor group, approximately 3 kilometers in diameter. It was discovered on 19 August 1998, by astronomers of the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, in the United States. Its sub-kilometer minor-planet moon was discovered by radar on 30 May 2013.
Donald B. Campbell is an Australian-born astronomer and Professor of Astronomy at Cornell University. Prior to joining the Cornell faculty he was Director of the Arecibo Observatory in Puerto Rico for seven years. Campbell's research work is in the general area of planetary studies with a concentration on the radio-wavelength-scattering properties of planets, planetary satellites, and small bodies. His work includes studies of Venus, the Moon, the Galilean satellites of Jupiter, Titan, as well as comets and asteroids. Campbell observed near-Earth asteroid 433 Eros, which was the first asteroid detected by the Arecibo Observatory radar system.
2017 YE5 is a binary pair of asteroids of approximately equal size and mass, each about 0.9 km (0.56 mi) in diameter. Classified as a near-Earth asteroid and potentially hazardous object of the Apollo group, 2017 YE5 was discovered by amateur astronomer Claudine Rinner at the Oukaïmeden Observatory on 21 December 2017. On 21 June 2018, the pair of asteroids passed within 15.5 lunar distances or approximately 6 million km (3.7 million mi) from Earth. During the close encounter, 2017 YE5 was resolved in high detail by concurrent radar observations by the Arecibo and Green Bank observatories, along with individual observations by the Goldstone Solar System Radar. 2017 YE5 is likely an extinct or dormant comet due to its distant elliptical orbit and dark red surface.
2020 BX12 is a sub-kilometer binary asteroid, classified as a near-Earth asteroid and potentially hazardous object of the Apollo group. It was discovered on 27 January 2020 by the Asteroid Terrestrial-impact Last Alert System survey at the Mauna Loa Observatory during its approach to Earth of 0.02915 AU (4.361 million km; 11.34 LD). Radar observations of the asteroid were carried out by the Arecibo Observatory on 4 February 2020, revealing a natural satellite orbiting 360 m (1,180 ft) from the primary body.
Daniella ("Dani") Mendoza DellaGiustina is a Mexican American planetary scientist and academic. She is the principal investigator for NASA's OSIRIS-APEX Mission to asteroid (99942) Apophis, Deputy Principal Investigator of NASA's OSIRIS-REx Asteroid Sample Return Mission, and assistant professor at the University of Arizona's Lunar and Planetary Laboratory.