Discoverer

LINEAR - 26 Sep 1998

Diameter (km)

0.36

Mass (kg)

?

Rotation period (hrs)

12.15

Orbital period (yrs)

1.52258

Semimajor axis (AU)

1.49175

Orbital eccentricity

0.37113

Orbital Inclination (deg)

6.29870

Albedo

0.32

Type

QRS

1998 SF36, a roughly 0.5-km object discovered in Sep. 1998 by LINEAR, is the target of the joint Japanese/NASA MUSES-C mission to land upon and return a sample from an asteroid. Thorough radar characterization of this target (e.g., for design of close orbit maneuvers and to guide surface sampling strategies) is of extreme importance for mission success.

Arecibo observations will give much stronger echoes than are obtainable at Goldstone. However, the asteroid's 12.15-hour spin period is so close to being commensurate with 24 h that observations just at Arecibo, where the view period is always less than three hours on any given day, cannot ensure the thorough rotation-phase coverage needed to construct an accurate physical model of the entire object. Therefore nine dates of Goldstone coarse-resolution are planned for imaging.

The population of near-Earth asteroids at least as large as 1998 SF36 probably is at least 5000. Of the roughly 500 of those that have been discovered, 1998 SF36 is distinguished by having the lowest delta-v for a spacecraft rendezvous (4.29 km/s vs. 5.95 for 433 Eros).

R. P. Binzel and A. S. Rivkin, Massachusetts Institute of Technology, report that they obtained spectra of 1998 SF36, a candidate target for the Japanese MUSES-C sample-return mission, at 0.5-1.0 microns. Measurements, obtained on Mar. 6.4 UT using the Kitt Peak 4-m reflector, reveal an S-type asteroid reflectance.

M. Hicks, P. Weissman, A. Chamberlin, and S. Lowry, Jet Propulsion Laboratory, write: "We have obtained low-resolution CCD spectroscopy of 1998 SF_36 from 0.35 to 1.0 microns, using the Palomar 5-m Hale reflector on Mar. 17.43 UT. The object exhibits a spectrum dominated by olivine. The modest spectral slope between 0.55 and 0.70 microns and deep 1-micron absorption suggests a vclassification of type QRS, similar to other small basaltic near-earth objects.

Images of 25143 (1998 SF36)