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Asteroid 1950 DA's Encounter with Earth in 2880: Physical Limits of Collision Probability Prediction
J. D. Giorgini,1*S. J. Ostro,1L. A. M. Benner,1P. W. Chodas,1S. R. Chesley,1R. S. Hudson,2M. C. Nolan,3A. R. Klemola,4E. M. Standish,1R. F. Jurgens,1R. Rose,1A. B. Chamberlin,1D. K. Yeomans,1J.-L. Margot5
Integration of the orbit of asteroid (29075) 1950 DA, which is
based on radar and optical measurements spanning 51 years,reveals a
20-minute interval in March 2880 when there could bea nonnegligible
probability of the 1-kilometer object collidingwith Earth. Trajectory
knowledge remains accurate until then becauseof extensive astrometric
data, an inclined orbit geometry thatreduces in-plane perturbations,
and an orbit uncertainty spacemodulated by gravitational resonance.
The approach distance uncertaintyin 2880 is determined primarily by
uncertainty in the accelerationsarising from thermal re-radiation of
solar energy absorbed bythe asteroid. Those accelerations depend on
the spin axis, composition,and surface properties of the asteroid, so
that refining the collisionprobability may require direct inspection
by a spacecraft.
1 Jet Propulsion Laboratory, California
Institute of Technology, Pasadena, CA 91109-8099, USA.
2 School of Electrical Engineering and Computer
Science, Washington State University, Pullman, WA 99164-2752, USA.
3 Arecibo Observatory, Arecibo, Puerto Rico 00612, USA.
4 Lick Observatory, University of California,
Santa Cruz, CA 95064, USA.
5 California Institute of
Technology, Pasadena, CA 91125, USA.
*
To whom correspondence should be addressed. E-mail:
Jon.Giorgini{at}jpl.nasa.gov
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