In-Flight Calibration and Performance of the OSIRIS-REx Visible and IR Spectrometer (OVIRS)

Amy Simon,Dante Lauretta,Dennis Reuter,Allen Lunsford,Richard Cosentino,Galina Wind,Nicolas Gorius

doi:10.3390/rs10091486

Abstract

Performance of the Origins, Spectral Interpretation, Resource Identification, Security–Regolith Explorer (OSIRIS-REx) Visible and InfraRed Spectrometer (OVIRS) instrument was validated, showing that it met all science requirements during extensive thermal vacuum ground testing. Preliminary instrument radiometric calibration coefficients and wavelength mapping were also determined before instrument delivery and launch using NIST-traceable sources. One year after launch, Earth flyby data were used to refine the wavelength map by comparing OVIRS spectra with atmospheric models. Near-simultaneous data from other Earth-orbiting satellites were used to cross-calibrate the OVIRS absolute radiometric response, particularly at visible wavelengths. Trending data from internal calibration sources and the Sun show that instrument radiometric performance has been stable to better than 1% in the 18 months since launch.

Highlights

OVIRSdelivery radiometric calibration coefficients and wavelength maps no were determined before instrument and launch
Radiometric stability is in the months since launch, exceeding the
Solar data show that the signal-to-noise ratio (SNR) response exceeds the requirement by a factor of two

Summary

Introduction

OVIRS is designed to obtain spectra of OSIRIS-REx mission target asteroid (101955) Bennu from 0.4 to 4.3 microns to quantify space weathering, constrain surface mineralogy, and measure contributions to the Yarkovsky effect [1]. To achieve these science objectives, OVIRS has a required in-flight radiometric stability of 50 from 0.4 to 4 μm for a 3% solar reflectance target. There are ~64 pixels within a spectral resolution element (two columns) to improve the SNR, and data may be summed onboard, after known bad pixels are removed, to reduce data volume. The standard science mode sums all data in 8-pixel averages in each column to reduce the frame to 512 × 23 pixels; it is possible to Remote Sens. 2018, 10, 1486; doi:10.3390/rs10091486 www.mdpi.com/journal/remotesensing

Methods

Results

Conclusion