Mueller, Michael and Delbo, M. and Hora, J. L. and Trilling, D. E. and Bhattacharya, B. and Bottke, W. F. and Chesley, S. and Emery, J. P. and Fazio, G. and Harris, A. W. and Mainzer, A. and Mommert, M. and Penprase, B. and Smith, H. A. and Spahr, T. B. and Stansberry, J. A. and Thomas, C. A. (2011) ExploreNEOs. III. Physical Characterization of 65 Potential Spacecraft Target Asteroids. Astronomical Journal, 141 (4). Art. No. 109. ISSN 0004-6256 http://resolver.caltech.edu/CaltechAUTHORS:20110329-095918373
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Space missions to near-Earth objects (NEOs) are being planned at all major space agencies, and recently a manned mission to an NEO was announced as a NASA goal. Efforts to find and select suitable targets (plus backup targets) are severely hampered by our lack of knowledge of the physical properties of dynamically favorable NEOs. In particular, current mission scenarios tend to favor primitive low-albedo objects. For the vast majority of NEOs, the albedo is unknown. Here we report new constraints on the size and albedo of 65 NEOs with rendezvous Δv <7 km s^(–1). Our results are based on thermal-IR flux data obtained in the framework of our ongoing (2009-2011) ExploreNEOs survey using NASA's "Warm-Spitzer" space telescope. As of 2010 July 14, we have results for 293 objects in hand (including the 65 low-Δv NEOs presented here); before the end of 2011, we expect to have measured the size and albedo of ~700 NEOs (including probably ~160 low-Δv NEOs). While there are reasons to believe that primitive volatile-rich materials are universally low in albedo, the converse need not be true: the orbital evolution of some dark objects likely has caused them to lose their volatiles by coming too close to the Sun. For all our targets, we give the closest perihelion distance they are likely to have reached (using orbital integrations from Marchi et al. 2009) and corresponding upper limits on the past surface temperature. Low-Δv objects for which both albedo and thermal history may suggest a primitive composition include (162998) 2001 SK162, (68372) 2001 PM9, and (100085) 1992 UY4.
|Additional Information:||© 2011 American Astronomical Society. Received 2010 September 22; accepted 2011 January 25; published 2011 February 22. Michael Mueller gratefully acknowledges the Henri Poincaré Fellowship, which is funded by the CNRS-INSU and the Conseil Général des Alpes-Maritimes. The work of M.M. and M.D. is supported by ESA grant SSA-NEO-ESA-MEM-017/1. We thank Patrick Michel for helpful discussions. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by JPL/Caltech under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. Facilities: Spitzer(IRAC)|
|Subject Keywords:||infrared: planetary systems – minor planets, asteroids: general – radiation mechanisms: thermal – space vehicles – surveys|
|Classification Code:||PACS: 96.30.Ys, 96.25.Bd|
|Official Citation:||Michael Mueller et al. 2011 The Astronomical Journal 141 109 doi: 10.1088/0004-6256/141/4/109|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Benjamin Perez|
|Deposited On:||29 Mar 2011 18:06|
|Last Modified:||26 Dec 2012 13:07|
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