CREATE TABLE table_7598 ("Mission name" CLOB, "Lunar lander" CLOB, "Lunar landing date" CLOB, "Lunar blastoff date" CLOB, "Lunar landing site" CLOB, "Duration on lunar surface" CLOB, "Crew" CLOB, "Number of s EVA" FLOAT, "Total EVA Time  ( HH:MM ) " CLOB)

Where was the landing site when the duration on the lunar surface was 21:31?
SELECT "Lunar landing site" FROM table_7598 WHERE "Duration on lunar surface" = '21:31'
SELECT "Lunar landing site" FROM "table_7598" WHERE "Duration on lunar surface" = '21:31'