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Change in MUSES-C Target Body Announced

Don Yeomans, NASA MUSES-CN Project Scientist
August 1, 2000

As a result of a tight launch schedule, the Japanese MUSES-C project has announced that their target asteroid has been switched from 10302 (1989 ML) to 1998 SF36.

The new mission time line is:

Launch:              Nov. - Dec. 2002
Earth Swingby:       May 2004
Asteroid arrival:    Sept. 2005
Asteroid departure:  Jan. 2006
Earth sample return: June 2007  

Information on the new target body:  1998 SF36
Orbit (J2000)
Epoch of osculation:        2000 Feb. 26.0  ET
Perihelion passage time:    1999 Oct. 25.01552 ET
Perihelion distance:        0.953828 AU
Aphelion distance:          1.69567 AU   
Semi-major axis:            1.32475 AU
Orbital period:             1.525 years
Eccentricity:               0.2799948 
Arg. Of perihelion:       160.10020  deg.
Long. Asc. Node:           71.61882  deg.
Inclination:                1.71649  deg.

Absolute magnitude:  18.8
  Diameter ~ 1.2 km if albedo = 0.04
             0.7 km if albedo = 0.11
             0.5 km if albedo = 0.20

This asteroid is classified as a "Potentially Hazardous Object" since its orbit approaches that of the Earth to within 0.05 AU (less than 7.5 million km). The orbit is still uncertain since it is based upon a data interval of 46 days only. The next two Earth close approaches are in 2001 and 2004.

   Date               Close Approach     Brightest App. Magn.
   2001 Mar. 29       0.043 AU            14.2
   2004 June 25       0.014 AU            12.7 

Before, during, and after these Earth close approaches, we hope that observers will make an effort to characterize this asteroid's rotation rate, rotation pole direction, albedo, thermal properties, size, shape, and spectral classification. Astrometric observations will also be necessary to update its orbit.

For asteroid 1998 SF36, an interactive orbit animation as well as an ephemeris generation capability is located at:

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