The WISE Survey of the Near-Earth Asteroids (NEOWISE)
Abstract
The Wide-field Infrared Survey Explorer (WISE) is a NASA Explorer class mission that has imaged the entire sky twice between January, 2010 and January, 2011 at four wavelengths spanning the near through mid-IR with sensitivities hundreds of times greater than previous surveys. Through a NASA funded project, called NEOWISE, we have systematically searched the WISE data for new and previously known asteroids, detecting over 158,000 objects (of which more than 30,000 were new discoveries). The NEOWISE project have resulted in a highly uniform survey of the near-Earth object (NEO) population at thermal infrared wavelengths ranging from 3 to 22 μm, allowing us to refine estimates of their numbers, sizes, and albedos. The survey detected NEOs the same way whether they were previously known or not, subject to the availability of ground-based follow-up observations, resulting in the discovery of more than 130 new NEOs. The survey's uniform sensitivity, observing cadence, and image quality have permitted extrapolation of the 429 near-Earth asteroids (NEAs) detected by NEOWISE during the fully cryogenic portion of the WISE mission to the larger population. An additional 88 NEAs were observed in the post-cryogenic phase of the mission, with 12 of these being discoveries. Using the dataset and debiasing the results, we find that there are 981 ± 19 NEAs larger than 1 km and 20,500±3000 NEAs larger than 100 m [3]. We show that the Spaceguard goal of detecting 90% of all 1 km NEAs has been met, and that the cumulative size distribution is best represented by a broken power law with a slope of 1.32±0.14 below 1.5 km. This power-law slope produces about 13,200±1900 NEAs with diameter larger than 140 m. The results show that the overall number for the NEA population between 100 and 1000 m is somewhat lower than previous estimates. We also present the results of an analysis of the sub-populations within the near-Earth asteroids, including the Atens, Apollos, Amors, and those that are considered potentially hazardous objects (PHAs). Again using our debiasing techniques, we are able to place constraints on the number of potentially hazardous asteroids larger than 100 m and find that there are about 4700±1450 such objects.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- June 2013
- Bibcode:
- 2013AAS...22240201G