Background: Grace Brewster Murray Hopper (nee Murray; December 9, 1906 - January 1, 1992) was an American computer scientist and United States Navy rear admiral. One of the first programmers of the Harvard Mark I computer, she was a pioneer of computer programming who invented one of the first compiler related tools. She popularized the idea of machine-independent programming languages, which led to the development of COBOL, an early high-level programming language still in use today. Hopper had attempted to enlist in the Navy during World War II, but she was rejected by the military because she was 34 years of age and thus too old to enlist.
Context: In accordance with Navy attrition regulations, Hopper retired from the Naval Reserve with the rank of commander at age 60 at the end of 1966. She was recalled to active duty in August 1967 for a six-month period that turned into an indefinite assignment. She again retired in 1971 but was again asked to return to active duty in 1972. She was promoted to captain in 1973 by Admiral Elmo R. Zumwalt, Jr.  After Republican Representative Philip Crane saw her on a March 1983 segment of 60 Minutes, he championed H.J.Res. 341, a joint resolution originating in the House of Representatives, which led to her promotion to commodore by special Presidential appointment. She remained on active duty for several years beyond mandatory retirement by special approval of Congress. Effective November 8, 1985, the rank of commodore was renamed rear admiral (lower half) and Hopper became one of the Navy's few female admirals.  Following a career that spanned more than 42 years, Admiral Hopper took mandatory retirement from the Navy on August 14, 1986. At a celebration held in Boston on the USS Constitution to commemorate her retirement, Hopper was awarded the Defense Distinguished Service Medal, the highest non-combat decoration awarded by the Department of Defense.  At the time of her retirement, she was the oldest active-duty commissioned officer in the United States Navy (79 years, eight months and five days), and had her retirement ceremony aboard the oldest commissioned ship in the United States Navy (188 years, nine months and 23 days). (Admirals William D. Leahy, Chester W. Nimitz, Hyman G. Rickover and Charles Stewart were the only other officers in the Navy's history to serve on active duty at a higher age. Leahy and Nimitz served on active duty for life due to their promotions to the rank of fleet admiral.)
Question: What did she do after retirement?

Answer:
She was recalled to active duty in August 1967 for a six-month period that turned into an indefinite assignment. She again retired in 1971