WASHINGTON — Nick Johnson, NASA’s chief scientist for orbital debris and one of the world’s foremost authorities on the topic, retired from the space agency March 28, the NASA Office of Safety and Mission Assurance said on its website that same day.

Johnson served in that position for 18 years; for 10 of those years he was program manager of the Orbital Debris Program Office at NASA’s Johnson Space Center in Houston. In those capacities he was responsible for, among other things, ensuring the safety of the international space station against debris threats, including debris from a controversial Chinese anti-satellite test in 2007.

He is credited for helping the U.S. government develop debris mitigation practices and represented the country in negotiations that led to the United Nations’ adoption or debris mitigation guidelines in 2007.

Johnson also played a key role in assessing a threat posed by a failed intelligence satellite that was headed toward an uncontrolled atmospheric re-entry. He was also tasked with informing the international community of the U.S. plan to shoot down the satellite with a U.S. Navy missile, which was successfully executed in early 2008. 

“We were really concerned about the world’s reaction, but the president was intent on mitigating or eliminating the risk and being transparent, so we told the entire world what we were going to do,” Johnson said, according to the website.