Steins (asteroid)

Steins (asteroid)
Name	Steins
Designation	2867
Discovery date	1969-09-03
Discoverer	Tamara Mikhaylovna Smirnova
Discovery site	Crimean Astrophysical Observatory
Epoch	2459000.5
Aphelion	2.369 AU
Perihelion	1.864 AU
Semimajor	2.116 AU
Eccentricity	0.119
Period	3.08 yr
Inclination	9.93°
Spectral type	E-type
Diameter	5.2 km
Albedo	0.40

Steins (asteroid) is a small main-belt asteroid notable for its E-type classification and for being the target of a flyby by the European Space Agency's Rosetta mission. Discovered in 1969 at an observatory on Crimea, it has been the subject of photometric, spectroscopic, and spacecraft studies that informed models of enstatite-rich bodies and constrained hypotheses about early Solar System processes involving Ceres (dwarf planet), Vesta, Pallas, Hygiea (asteroid), and other minor planets.

Discovery and Naming

Steins was discovered on 3 September 1969 by Soviet astronomer Tamara Mikhaylovna Smirnova at the Crimean Astrophysical Observatory. The provisional designation assigned at discovery was later replaced by the number 2867 and the name honoring Finnish writer Christian Steins, selected through asteroid naming conventions administered by the International Astronomical Union. The naming process involved citation preparation and approval by the Committee on Small Body Nomenclature and was published in the Minor Planet Circulars, linking the object into a catalog maintained alongside entries for (1) Ceres, (4) Vesta, (2) Pallas, (10) Hygiea and numerous numbered minor planets cataloged by the Minor Planet Center.

Orbital Characteristics

Steins orbits within the main asteroid belt, with semimajor axis and eccentricity values placing it in the inner-to-middle belt region near families studied in dynamical surveys by teams at Jet Propulsion Laboratory, Copenhagen University Observatory, and Instituto de Astrofísica de Canarias. Its orbital period of roughly 3.08 years, inclination near 10 degrees, and perihelion and aphelion distances have been refined via astrometry campaigns using facilities such as the Palomar Observatory, Mount Palomar Observatory, Kitt Peak National Observatory, and the La Silla Observatory. Dynamical analyses reference resonances with Jupiter, comparisons with orbit libraries maintained by the AstDyS and NEODyS projects, and studies of collisional families like those near Eunomia (asteroid) and Flora (asteroid), while long-term integrations consider perturbations from Mars, Saturn, and non-gravitational effects cataloged in databases operated by the European Space Agency and the NASA Planetary Data System.

Physical Properties

Physical characterization determined Steins to be a small body roughly 5.2 kilometers across with a high geometric albedo typical of enstatite-rich surfaces; values were constrained by thermal modeling using data from instruments comparable to those aboard IRAS, WISE, and ground-based radiometry at IRTF (Infrared Telescope Facility). Lightcurve inversion studies performed by researchers affiliated with Max Planck Institute for Solar System Research, Uppsala Astronomical Observatory, and Instituto de Astrofísica de Canarias revealed a rotation period near 6.05 hours and an irregular, angular shape consistent with imaging from the Rosetta (spacecraft) flyby. Size, bulk density estimates, and surface porosity have been compared with measurements for small E-type asteroids analogous to meteorite classes described by the Meteoritical Society and curated at institutions like the Smithsonian Institution and the Natural History Museum, London.

Spectral Classification and Composition

Steins is classified as an E-type asteroid in the Tholen and SMASS taxonomies as determined by spectroscopic campaigns led by teams at University of Arizona, Caltech, and Observatoire de Paris. Spectra show a strong high-albedo continuum and features consistent with iron-poor, enstatite-rich minerals similar to the enstatite chondrite meteorites studied by specialists at JAXA, NASA Johnson Space Center, and the Lunar and Planetary Institute. Compositional interpretations draw on laboratory spectral libraries curated at Brown University, Massachusetts Institute of Technology, and University of Western Ontario, and have been integrated into models of early Solar System differentiation and volatility depletion that reference work by A. G. W. Cameron, E. Anders, and contemporary researchers at ETH Zurich and University of Chicago.

Exploration and Observations

Steins was imaged up-close by ESA's Rosetta (spacecraft) during its 2008 mission cruise, a campaign coordinated by the European Space Operations Centre and science teams at ESA, Max Planck Institute for Solar System Research, University of Bern, and Observatoire de Paris. Instruments including the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) produced mosaics and multispectral datasets that were analyzed by collaborators from University of Padova, University of Helsinki, and Paris Observatory. Ground-based support observations included photometry from Mauna Kea Observatory, spectrometry from La Silla Observatory, and radar experiments involving facilities like Arecibo Observatory and Goldstone Deep Space Communications Complex. Data were archived in repositories such as the Planetary Data System and utilized in comparative studies with spacecraft datasets from missions like Hayabusa, NEAR Shoemaker, and Dawn.

Scientific Significance and Studies

Steins serves as a reference body for studying high-albedo, enstatite-dominated asteroids and their links to meteorite populations cataloged by the Meteoritical Bulletin Database. Analyses of Rosetta data informed models of surface geology, regolith processes, and space weathering discussed in journals produced by American Geophysical Union, Nature Publishing Group, and Icarus (journal). Studies involving researchers from University of Bern, Max Planck Institute for Solar System Research, Imperial College London, University of California, Berkeley, and University of Arizona explored collisional histories and spectral diversity across asteroid families, comparing Steins to targets like 433 Eros, 25143 Itokawa, 162173 Ryugu, and 101955 Bennu. Ongoing research leverages Steins observations in dynamical simulations at NASA Jet Propulsion Laboratory, isotopic and mineralogical synthesis at Carnegie Institution for Science, and mission planning for future small-body exploration by agencies such as ESA, NASA, Roscosmos, and JAXA.

Category:Main-belt asteroids