Initial Observation and Current Status of the XRS onboard HAYABUSA

Abstract

We present the results of initial operation, the current status, and the future observation plan of the X-ray fluorescence spectrometer (XRS) onboard Hayabusa, which was launched with the fifth M-V launch vehicle on May 9th, 2003. The XRS observes X-rays characteristic of elements excited by solar irradiation, to determine major elemental composition of asteroid Itokawa (1998SF36). Then we classify the S-class asteroid and prospect the degree of evolution processes. During the two-year long cruising phase, the XRS are checked out its function and the detectors against radiation damage, and observes X-ray bodies such as super nova remnants or active galactic cores as well as cosmic backgrounds of X-rays for in-flight calibration. The XRS also monitors solar X-rays using the standard sample. Flight demonstration of the newly developed onboard computer proves usability for more than 20 days.