Calibration and Performance of the REgolith X-Ray Imaging Spectrometer (REXIS) Aboard NASA's OSIRIS-REx Mission to Bennu
Abstract
The REgolith X-ray Imaging Spectrometer (REXIS) instrument on board NASA's OSIRIS-REx mission to the asteroid Bennu is a Class-D student collaboration experiment designed to detect fluoresced X-rays from the asteroid's surface to measure elemental abundances. In July and November 2019 REXIS collected ∼615 hours of integrated exposure time of Bennu's sun-illuminated surface from terminator orbits. As reported in Hoak et al. (Results from the REgolith X-ray Imaging Spectrometer (REXIS) at Bennu, 2021) the REXIS data do not contain a clear signal of X-ray fluorescence from the asteroid, in part due to the low incident solar X-ray flux during periods of observation. To support the evaluation of the upper limits on the detectable X-ray signal that may provide insights for the properties of Bennu's regolith, we present an overview of the REXIS instrument, its operation, and details of its in-flight calibration on astrophysical X-ray sources. This calibration includes the serendipitous detection of the transient X-ray binary MAXI J0637-430 during Bennu observations, demonstrating the operational success of REXIS at the asteroid. We convey some lessons learned for future X-ray spectroscopy imaging investigations of asteroid surfaces.
- Publication:
-
Space Science Reviews
- Pub Date:
- December 2021
- DOI:
- 10.1007/s11214-021-00853-4
- arXiv:
- arXiv:2110.07690
- Bibcode:
- 2021SSRv..217...83H
- Keywords:
-
- Asteroids;
- X-ray fluorescence;
- X-ray astrophysics;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Instrumentation and Methods for Astrophysics
- E-Print:
- 36 pages, 18 figures, accepted for publication in Space Science Reviews