Astronomy and Astrophysics

Observations of Ceres indicate that asteroids might be camouflaged

MOUNTAIN VIEW – The appearance of small bodies in the outer solar system could be deceiving. Asteroids and dwarf planets may be camouflaged with an outer layer of material that actually comes from somewhere else.

Using data primarily gathered by SOFIA, NASA’s Stratospheric Observatory for Infrared Astronomy, a team of astronomers has detected the presence of substantial amounts of material on the surface of Ceres that appears to be fragments of other asteroids. This is contrary to the currently accepted surface composition classification of Ceres, suggesting that the largest body in the asteroid belt between Mars and Jupiter is cloaked by material that has partially disguised its real makeup.

“We find that the outer few microns of the surface is partially coated with dry particles,” says Franck Marchis, senior planetary astronomer at the SETI Institute. “But they don’t come from Ceres itself. They’re debris from asteroid impacts that probably occurred tens of millions of years ago.”

Ceres is considered to be both an asteroid and a dwarf planet, the only dwarf planet located in the inner solar system. Astronomers have classified Ceres, as well as 75 percent of all asteroids, as belonging to composition class “C” based on their similar colors. But the mid-infrared spectra from SOFIA show that Ceres differs substantially from C-type asteroids in nearby orbits, challenging the conventional understanding of the relationship between Ceres and smaller asteroids.

“By analyzing the spectral properties of Ceres we have detected a layer of fine particles of a dry silicate called pyroxene. Models of Ceres based on data collected by NASA’s Dawn as well as ground-based telescopes indicated substantial amounts of water-bearing minerals such as clays and carbonates,” explains Pierre Vernazza, research scientist in the Laboratoire d’Astrophysique de Marseille. “Only the mid-infrared observations made using SOFIA were able to show that both types of material are present on the surface of Ceres.”

Ceres' surface is contaminated by a significant amount of dry material while its the area below the crust contains essentially water-bearing materials. The mid-infrared observations revealed the presence of dry pyroxene on the surface probably coming from interplanetary dust particles.  The  Internal structure of the Dwarf Planet Ceres was derived from the NASA Dawn spacecraft data.  Click for larger

To identify where the pyroxene on the surface of Ceres came from, Vernazza and his collaborators, including researchers from the SETI Institute and NASA’s Jet Propulsion Laboratory, turned to interplanetary dust particles (IDPs) that are commonly seen as meteors when they streak through Earth’s atmosphere. The research team had previously shown that IDPs blasted into space by asteroid collisions are an important source of material accumulated on the surfaces of other asteroids. The implication is that a coating of IDPs has caused Ceres to mimic the coloration of some of its dry and rocky neighbors.

Ceres and asteroids are not the only instance in which material transported from elsewhere has affected the surfaces of solar system bodies. Dramatic examples include the red material seen by New Horizons on Pluto’s moon Charon and Saturn’s two-faced moon Iapetus. Planetary scientists also hypothesize that material from comets and asteroids provided a final veneer to the then-forming Earth – a coating that included substantial amounts of water plus the organic substances of the biosphere.

This study resolves a long standing question about whether surface material accurately reflects the intrinsic composition of an asteroid. These results show that by extending observations to the mid-infrared, one can better identify the composition of an asteroid. According to Vernazza, “the detection of some ammoniated clays mixed with the watery clays on Ceres raises the possibility that the dwarf planet might have formed in the outer reaches of the solar system and somehow migrated to its current location.”

“SOFIA, is the only observatory, currently operating or planned, that can make such observations, essential to understanding the true nature of these objects” says Marchis. “The bottom line is that seeing is not believing when it comes to asteroids. We shouldn’t judge these objects by their covers, as it were.”

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NASA Kepler Visionary Honored By American Association for the Advancement of Science

William J. Borucki, principal investigator for NASA's Kepler mission at the agency's Ames Research Center in Silicon Valley, California, has been named a Fellow by the American Association for the Advancement of Science (AAAS).

Borucki is recognized for distinguished contributions to the field of astrophysics, with his leadership of the Kepler Mission leading to the discovery of thousands of exoplanets.

"This is a worthy acknowledgment of Bill Borucki's vision and the commitment of the Kepler mission team," said Michael Bicay, director for science at Ames. “Kepler has re-written the narrative in contemporary astronomy by proving what scientists long suspected—that planets are common in our Milky Way galaxy. This essential leap in knowledge allows us to take the next important steps in ascertaining whether life could exist elsewhere."

Click to see large imageKepler is the first NASA mission to find Earth-size planets in the habitable zone--the region in a planetary system where liquid water might pool on the surface of an orbiting planet. To date, Kepler has identified more than 5,100 planet candidates, of which more than 2,500 have been verified as bona fide planets confirming that planets are everywhere.

Beginning in 1992, with the first proposal for the Kepler mission to NASA Headquarters, Borucki led a determined team through a decade of tackling questions about technology that had not been flown in space yet. With the final concerns addressed, the mission once deemed impossible was approved for flight in 2000. 

"I am truly honored to be named a fellow by an organization that has a proud history of promoting advances in the sciences," said Borucki. 

Borucki will be presented with an official certificate and a gold and blue (representing science and engineering, respectively) rosette pin at a ceremony Feb. 18, 2017 at the 2017 AAAS Annual Meeting in Boston, Massachussetts.

Previous honors Borucki has received include the 2016 Franklin Institute Bower Award and Prize; the 2015 Shaw Prize; the 2013 Samuel J. Heyman Service to America Medals presented by United States President Obama; and the 2013 Henry Draper Medal.

Borucki earned a Master of Science degree in physics from the University of Wisconsin at Madison in 1962 and joined Ames as a space scientist that same year. The results of Borucki's early work developing spectroscopic instrumentation to determine the plasma properties of hypervelocity shock waves was used in the design of the heat shields for the Apollo mission. In July 2015, Borucki retired from NASA after 52 years of service at the agency. 

Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate. JPL managed Kepler mission development. Ball Aerospace & Technologies Corporation operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

For more information about the Kepler and K2 missions, visit:

http://www.nasa.gov/kepler

For more information on the AAAS Fellows program, visit:

https://www.aaas.org/program/aaas-fellows

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