MODIS on-orbit calibration and characterization

TLDR

The MODIS Protoflight Model, launched on NASA’s EOS Terra in December 1999, has operated for over two years, delivering calibrated data across 36 spectral bands from 412 nm to 14 200 nm at spatial resolutions ranging from 0.25 km to 1 km for global land, ocean, and atmospheric studies. This paper describes how the on‑board calibrators are employed for radiometric calibration and characterization of MODIS and evaluates the on‑orbit degradation of the solar diffuser and optics. The on‑board calibrators consist of a solar diffuser with a stability monitor for reflective bands and a V‑grooved blackbody for emissive bands, which are used to calibrate the instrument’s radiometric response and assess performance over time.

Abstract

The MODIS Protoflight Model, launched on-board the NASA EOS Terra spacecraft on 18 December 1999, has been in operation for more than two years, providing the science community with calibrated data sets for global studies of the Earth's land, oceans and atmosphere. MODIS has 36 spectral bands, covering the spectral range from 412 nm to 14 200 nm, and provides spatial resolutions of 0.25 km (two bands), 0.5 km (five bands) and 1 km (29 bands) at nadir. The key on-board calibrators (OBCs) include a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) system for calibration of the reflective solar bands, and a V-grooved flat-panel blackbody (BB) for calibration of the thermal emissive bands. In this paper, we describe the use of OBCs for the sensor's radiometric calibration and characterization and discuss on-orbit performance. In addition, we provide an assessment of the on-orbit degradation of the SD and MODIS optics.