During medical school, Clark did active duty training with the Diving Medicine Department at the
United States Navy Experimental Diving Unit in March 1987. After completing medical school, she underwent postgraduate medical education in pediatrics from 1987 to 1988 at the
National Naval Medical Center. The following year, Clark completed Navy undersea medical officer training at the Naval Undersea Medical Institute in
Groton, Connecticut, and diving medical officer training at the Naval Diving and Salvage Training Center in
Panama City, Florida. She was designated a Radiation Health Officer and Undersea Medical Officer. Clark was then assigned as the
Submarine Squadron 14 Medical Department Head in
Holy Loch, Scotland. During that assignment, she dove with Navy divers and
Naval Special Warfare Unit Two SEALs and performed many medical evacuations from US submarines. After two years of operational experience, Clark was designated as a Naval Submarine Medical Officer and Diving Medical Officer. Clark underwent six months of aeromedical training at the Naval Aerospace Medical Institute at
NAS Pensacola in
Pensacola, Florida, and was designated as a Naval Flight Surgeon. She was stationed at
MCAS Yuma,
Arizona, and assigned as Flight Surgeon Marine Attack Squadron 211 (VMA-211), a Marine Corps
AV-8B Harrier squadron. Clark made several deployments, including one overseas to the Western Pacific, practiced medicine in austere environments, and flew on multiple aircraft. Her squadron won the Marine Attack Squadron of the Year award for its successful deployment. Clark was then assigned as the Group Flight Surgeon for
Marine Aircraft Group 13 (MAG-13). Before her selection as an astronaut candidate, Clark served as a Flight Surgeon for Training Squadron 86 (
VT-86), the
Naval Flight Officer advanced training squadron for tactical jets at NAS Pensacola. She was Board Certified by the National Board of Medical Examiners and held a Wisconsin Medical License, and her military qualifications included Radiation Health Officer, Undersea Medical Officer, Diving Medical Officer, Submarine Medical Officer, and Naval Flight Surgeon. Clark was also a Basic Life Support Instructor, Advanced Cardiac Life Support Provider, Advanced Trauma Life Support Provider, and Hyperbaric Chamber Advisor. ==NASA career==