From the NASA job website:
Planetary Protection Officer
This position is assigned to Office of Safety and Mission Assurance for Planetary Protection. Planetary protection is concerned with the avoidance of organic-constituent and biological contamination in human and robotic space exploration. NASA maintains policies for planetary protection applicable to all space flight missions that may intentionally or unintentionally carry Earth organisms and organic constituents to the planets or other solar system bodies, and any mission employing spacecraft, which are intended to return to Earth and its biosphere with samples from extraterrestrial targets of exploration. This policy is based on federal requirements and international treaties and agreements.
Current Agency policy requires the SL appointments be time-limited. The initial appointment will be for 3 years, with the possibility of extending for an additional 2 years. The selectee for this position will receive a temporary promotion. Employee will then return to a grade level no lower than the grade previously held at the home center. This temporary promotion may be converted to permanent without further competition.