Charles came to work at the Jet Propulsion Laboratory in 1984 having previously worked as an environmental consultant. With a background in astrophysics (Michigan State University) and atmospheric science (Purdue University), he actually works on instruments that look down at the Earth.

His first assignment was with the NASA Ocean Data System (now called the Physical Oceanography Distributed Active Archive System) developing software to produce sea ice maps from an instrument called the Special Sensor Microwave Imager (SSM/I) which is flown on a defense department satellites.

More recently,Charles has been involved in the calibration and verification of a number of spaceborne instruments. These include TOPEX/Poseidon (launched 1992), which measures sea level, NSCAT (launched 1996), which measured winds over the ocean, and most recently, the Shuttle Radar Topography Mission (SRTM), which flew on the shuttle in February 2000.

His research includes developing methodology for estimating lake levels using data from spaceborne altimeters. Charles has also been involved with research on comets. He maintains The Comet Observation Home Page (http://encke.jpl.nasa.gov), which includes information and images on recent comets. Charles has observed over 200 comet apparitions and is an expert on cometary brightness.

In 1988, asteroid 3783 was named "Morris" in honor of his work on comets.