Donald J. Kessler retired from NASA in 1996 as NASA's Senior Scientist for Orbital Debris Research. He has more than 40 years of experience in scientific research associated with orbital debris, meteoroids, and interplanetary dust. He began his career at NASA modeling the interplanetary meteoroid environment. He later applied these modeling techniques to artificial satellites in Earth orbit, predicting that man-made orbital debris soon would exceed the natural meteoroid environment. This prediction, coupled with verifying data, led to the official establishment of NASA's Orbital Debris Program Office at the Johnson Space Center in 1979. There he continued to develop more complex orbital debris models, recommended and developed experiments to test those models, and analyzed data which led to the discovery of new sources of orbital debris. He conducted classes, workshops, and symposia on orbital debris, and recommended cost effective techniques to control the environment. He also participated in national and international reviews of other agencies' orbital debris programs, leading to the establishment of the Inter-Agency Space Debris Coordination Committee (IADC), an international agency to address orbital debris issues. Kessler participated in U.S. Air Force (USAF) and Strategic Defense Command tests and measurements programs, studies of orbital debris by various organizations such as the USAF Scientific Advisory Board, the AIAA, the Office of Technology Assessment (OTA), and the General Accountability Office. In 1989, he was awarded the NASA Medal for Exceptional Scientific Achievement. Since retiring, Kessler has continued to consult with NASA and other organizations. In 2000, he received the AIAA Losey Atmospheric Sciences Award, in 2008, received the IAASS Jerome Lederer Space Safety Pioneer Award, and in 2010 the AAS Dirk Brouwer Award for his career in astrodynamics. Kessler has published more than 100 technical papers on meteoroids and orbital debris and has been a contributing author or editor of 10 major reports; select publications can be downloaded from his website at http://webpages.charter.net/dkessler. However, he may be recognized by the general public for the "Kessler Syndrome", a term propagated by the popular press to describe his 1978 publication. This publication predicted the increasing orbital debris environment from random collisions between satellites that is being observed today. Kessler's recent activates include supporting the educational IMAX film Space Junk 3D, now opening at various museums,and he was chairman of the National Research Council committee report Limiting Future Collision Risk to Spacecraft: An Assessment of NASA's Meteoroid and Orbital Debris Programs, available at http://www.nap.edu/catalog.php?record_id=13244.