SPITZER OBSERVATIONS OF COMET 67P/CHURYUMOV-GERASIMENKO AT 5.5-4.3 AU FROM THE SUN

Journal Article · Mon Jun 15 00:00:00 EDT 2009 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/137/6/4633; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21255766

Kelley, Michael S ^[1]; Wooden, Diane H ^[2]; Tubiana, Cecilia; Boehnhardt, Hermann ^[3]; Woodward, Charles E ^[4]

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1. Department of Physics, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL 32816-2385 (United States)
2. NASA Ames Research Center, Space Science Division, MS 245-3, Moffett Field, CA 94035 (United States)
3. Max Planck Institute for Solar System Research, Max-Planck-Str. 2, 37191 Katlenburg-Lindau (Germany)
4. Department of Astronomy, University of Minnesota, 116 Church St SE, Minneapolis, MN 55455 (United States)

We report Spitzer Space Telescope observations of comet 67P/Churyumov-Gerasimenko at 5.5 and 4.3 AU from the Sun, post-aphelion. Comet 67P is the primary target of the European Space Agency's Rosetta mission. The Rosetta spacecraft will rendezvous with the nucleus at heliocentric distances similar to our observations. Rotationally resolved observations at 8 and 24 {mu}m (at a heliocentric distance, r{sub h} , of 4.8 AU) that sample the size and color-temperature of the nucleus are combined with aphelion R-band light curves observed at the Very Large Telescope (VLT) and yield a mean effective radius of 2.04 {+-} 0.11 km, and an R-band geometric albedo of 0.054 {+-} 0.006. The amplitudes of the R-band and mid-infrared light curves agree, which suggests that the variability is dominated by the shape of the nucleus. We also detect the dust trail of the comet at 4.8 and 5.5 AU, constrain the grain sizes to be {approx}<6 mm, and estimate the impact hazard to Rosetta. We find no evidence for recently ejected dust in our images. If the activity of 67P is consistent from orbit to orbit, then we may expect the Rosetta spacecraft will return images of an inactive or weakly active nucleus as it rendezvous with the comet at r{sub h} = 4 AU in 2014.

• OSTI ID: 21255766
• Journal Information: Astronomical Journal (New York, N.Y. Online), Vol. 137, Issue 6; Other Information: DOI: 10.1088/0004-6256/137/6/4633; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ALBEDO
COLOR
COMETS
DISTANCE
DUSTS
GRAIN SIZE
METEOROIDS
ORBITS
SOLAR SYSTEM
SUN
TELESCOPES