The spaceflight lasted 15 minutes 30 seconds, it reached an altitude of more than 102. 8 nautical miles (190. 4 km), and it flew 262. 5 nautical miles (486. 2 km) downrange, landing in the Atlantic Ocean. The flight went as expected until just after splashdown, when the hatch cover, designed to release explosively in the event of an emergency, accidentally blew. Grissom was at risk of drowning, but he was recovered safely via a U. S. Navy helicopter. The spacecraft sank into the Atlantic, and it was not recovered until 1999.