What Launched has Time elapsed of 1991 days (5 yr, 5 mo, 12 d)?
CREATE TABLE "1990s" (
  "spacecraft" text,
  "destination" text,
  "launched" text,
  "closest_approach" text,
  "time_elapsed" text
);
SELECT "launched" FROM "1990s" WHERE "time_elapsed"='1991 days (5 yr, 5 mo, 12 d)';