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MRO’s 2.4-meter Telescope: A New Facility for Follow-up and Characterization of Near-Earth Objects. William H. Ryan and Eileen V. Ryan (MRO/NM Tech). Asteroid Belt. Collisions are a fundamental process in the solar system & are not yet well understood. - PowerPoint PPT Presentation
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AMOS 2008
MRO’s 2.4-meter Telescope: A New Facility for Follow-up and
Characterization of Near-Earth Objects
William H. Ryan and Eileen V. Ryan (MRO/NM Tech)
AMOS 2008
Asteroid Belt
• Collisions are a fundamental process in the solar system & are not yet well understood.
• Applications: planetary accretion, evolution of ring systems, evolution of the asteroid and Kuiper belts, planetary cratering, meteorite ejection and delivery, etc.
• Also: Earth-Crossers (NEAs) are a potential hazard to the Earth if on impacting orbits.
Locations of asteroids: April 8, 2003
AMOS 2008
Origin of NEAs: Resonance
AMOS 2008
Kirkwood Gaps
AMOS 2008
Objective: Find and Characterize PHAs
• Need Search & Discovery Telescopes for Cataloging
• Need Follow-up Telescopes for Orbit Refinement & Characterization -- Composition -- Internal Structure -- Size (Albedo)
• Need Continual Surveying for Orbit Variations
(i.e., first line of defense is know the enemy…)
AMOS 2008
Easy Astrometry: NEOCP BL04704 (now K08R24Q)
AMOS 2008
Trickier Example: 2007 WD5
Images were 2 minute exposures, over 1.5 hours (42 stacked images). Object was moving 0.25"/min & V~24.
AMOS 2008
Time-resolved Photometry
• Asteroids/satellites shine from reflected sunlight– proportional to cross-sectional area at small solar phase angles (0 is sun behind observer).
• As the object rotates, the amount of light varies.
• By measuring the light variation over time, we derive a rotation rate and constrain orientation & shape.
Asteroid Ida(Rotation Images, Galileo Spacecraft)
AMOS 2008
Direct Model Lightcurve
Origin for doubly periodic behavior– reproduced even by irregular shapes.
AMOS 2008
3782 Celle: 5 Jan 2003
AMOS 2008
3782 Celle Model
AMOS 2008
NEO studies are now ‘Real Work’ at MRO!
September 6 - 7, 2008 - 1.5 nights
• Astrometry – 7 targets ranging from V~18-22• Color and time-series photometry on 2 targets
Supported by:• NASA’s NEO Program• NM Tech R&ED• DOD funding that made MRO possible
AMOS 2008
NEOCP Object BL04704
6 - 7 Sept 2008
AMOS 2008
AMOS 2008
More Complex Lightcurve: 3155 Lee
Ryan et al. 2000
Vesta Family Asteroid
AMOS 2008
NEOCP BL04704 (K08R24Q)
B-V: 0.76 0.08
V-R: 0.51 0.05
V-I: 0.93 0.05
HR: 20.7
HV: 20.2
Prot: 7.97 0.01 hr
Higher Albedo S-type
Assuming S-type G~0.23
D ~ 270 m (using pV = 0.2)
AMOS 2008
Torino Hazard Scale:
No Hazard
Normal
Meriting Attention by
Astronomers
Threatening
Certain
Collisions
As of February 2008, 927 asteroids have been tagged as potentially hazardous.
AMOS 2008