Discoverer

E. Bowell - 1981

Diameter (km)

15-20

Mass (kg)

?

Rotation period (hrs)

?

Orbital period (yrs)

?

Semimajor axis (AU)

2.57012

Orbital eccentricity

0.11125

Orbital Inclination (deg)

12.13364

Albedo

?

Type

S

Named in honor of Harold Masursky (1923-1990), planetary geologist at the Branch of Astrogeologic Studies of the U.S. Geological Survey, Flagstaff. He has been active in nearly every U.S. program of lunar and planetary exploration including Ranger, Surveyor, Lunar Orbiter, Apollo, Mariner 9, Viking, Pioneer Venus, and Voyager. He was involved in planning future space missions, including the Galileo mission (Jupiter orbiter probe) and the Venus Radar Mapper.

Asteroid 2685 was imaged by Cassini spacecraft in January 2000.

A series of wide angle and narrow angle images, through a variety of spectral and polarizing filters, was taken of the asteroid between 7 and 5.5 hours before closest approach, from a distance of 1.6 million km, in the hopes of determining the body's size, reflectivity, asteroid type and possibly its rotation period. The face of Masursky seen by the Cassini Imaging Science Subsystem (ISS) at a Sun-asteroid-spacecraft angle of 90 degrees has been measured to be roughly 15 - 20 km in diameter, assuming a spherical shape. Preliminary determination of its reflectivity indicates that it may not, in fact, be an S-type asteroid like Gaspra, Ida and Eros, a puzzling result given its dynamical association with the Eunomia family of S-type asteroids. Examination and analysis of the remaining images may settle this matter as well as place limits on the body's rotation period.

This image is the first wide angle image taken of Masursky on January 23,2000 at 3:01 UTC. In this 32 second exposure, the cameras were continuously pointed to Masursky which was traveling roughly right to left across the constellation of Aquila. The stars in this 3.5 degree field of view are streaked due to this target-motion compensation. Some of the streaks and point-like sources in this frame are in fact the images left by cosmic rays which hit the CCD of the camera during the exposure

This narrow angle 1.2 second exposure was shuttered simultaneously with the wide angle image above, and is a factor of ten higher in resolution. It is from images like this that the size of Masursky was determined. Some of the streaks and point-like sources in this 0.35 degree frame are in fact the images left by cosmic rays which hit the camera's CCD.

(Credit: NASA/JPL/University of Arizona)