Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session X05: Detecting, and Defending Earth from, Earth-crossing AsteroidsInvited Undergraduate
|
Hide Abstracts |
Sponsoring Units: DAP FPS Chair: David Gerdes, University of Michigan Room: Sheraton Governor's Square 14 |
Tuesday, April 16, 2019 10:45AM - 11:21AM |
X05.00001: NASA’s Planetary Defense Coordination Office at NASA HQ Invited Speaker: Lindley Johnson NASA and its partners maintain a watch for Near-Earth Objects (NEOs), asteroids and comets that
|
Tuesday, April 16, 2019 11:21AM - 11:57AM |
X05.00002: Ground-based Searches for Near-Earth Objects Invited Speaker: Emily Kramer Despite recent advances in space-based telescope technology, ground-based searches for Near-Earth Objects (NEOs) continue to dominate the discovery statistics. While the discovery rate of NEOs is somewhat stochastic, these surveys discover, on average, roughly 5-10 new NEOs per day. By 2010, over 90% of the largest NEOs (those with diameter > 1 km) had been discovered, but that fraction drops precipitously with decreasing object size. Since 1998, NASA’s NEO Observations program, now under the auspices of the Planetary Defense Coordination Office, has funded and coordinated the efforts of the survey programs in order to meet the congressional mandate to discover 90% of the NEOs greater than 140 m in diameter. Current and former NEO surveys include the Catalina Sky Survey, LINEAR, Spacewatch, Pan-STARRS, ATLAS, LONEOS, NEAT, ZTF, and the Mt. Lemmon Survey. By employing facilities with a range of capabilities and geographic locations (to hedge against down time due to poor weather), the NEO detection community is best able to discover the maximum number of NEOs. We present here an overview of the different ground-based surveys, highlighting recent discoveries and the strengths of each facility. |
Tuesday, April 16, 2019 11:57AM - 12:33PM |
X05.00003: Finding Near Earth Objects from Space with NEOWISE and NEOCam Invited Speaker: A. Mainzer Asteroids and comets periodically impact the Earth; the key questions are how often do they do so, and with what energy? Systematic telescopic searches to find, track, and characterize these objects are key to addressing these questions. The issue of identifying when a potential impact might occur is answered by discovering the objects and tracking them for sufficient time to enable a reliable prediction of close approaches to be made over the next century. The impact energy scales as the kinetic energy, which in turn depends roughly on the object’s diameter cubed. Thus, estimating sizes reliably is also important. Today, most surveys consist of ground-based telescopes operating at visible light wavelengths; for such telescopes, detectability depends on the amount of sunlight reflected by the asteroid or comet. With visible light alone, only approximate sizes can be determined, because asteroid and comet surface reflectivity in visible wavelengths varies significantly from objects as dark as coal to nearly white. A complementary approach to surveying for and characterizing asteroids and comets is to search using thermal infrared wavelengths that measure the heat emitted by the objects. Such telescopes are approximately equally sensitive to bright and dark objects, and can offer more robust constraints on effective size. When visible light data are also available, the reflectivity (albedo) can be computed, which offers insight into composition and density. The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) is an Earth-orbiting NASA mission that is currently searching for and characterizing asteroids and comets using two infrared channels, 3.4 and 4.6 microns. It began life as the Wide-field Infrared Survey Explorer (WISE), with its purpose to survey the entire sky in four channels (3.4, 4.6, 12 and 22 microns) in order to search for low mass stars and ultraluminous infrared galaxies. Although not originally designed to search for asteroids, it has successfully discovered many large, dark near-Earth objects, a complementary dataset to the ground-based surveys. Additionally, NEOWISE has provided the largest catalog of asteroid physical properties such as diameters and albedos to date, including more distant asteroids in the main belt, the Jovian Trojan population, Centaurs, and comets. Launched in late 2009 with a planned 7-month lifetime, the spacecraft is now nearly 10 years old; its two longest channels no longer function. However, its lifetime is limited by orbital decay. A successor mission, the Near-Earth Object Camera (NEOCam), has been proposed to make a comprehensive survey of Earth-approaching asteroids and comets using a design optimized for this objective. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700