Dr. Xiaoxiong Xiong received a B.S. degree in optical engineering from the Beijing Institute of Technology, Beijing, China, and a Ph.D. degree in physics from the University of Maryland, College Park, Maryland, USA. He is an Optical Physicist with the Sciences and Exploration Directorate, NASA Goddard Space Flight Center (GSFC), Greenbelt, Maryland, USA, currently supporting several satellite missions on optical sensor calibration and characterization. He also serves as the MODIS Project Scientist and the technical lead for both the MODIS and VIIRS Characterization Support Team (MCST and VCST). Before joining the NASA GSFC, he had also worked in optical instrumentation, nonlinear optics, laser and atomic spectroscopy, and resonance ionization mass spectrometry at universities and the National Institute of Standards and Technology (NIST).