Later, Guenter Wendt, pad leader for the early American crewed space launches, wrote that he believed a small cover over the external release actuator was accidentally lost sometime during the flight or splashdown. Another possible explanation was that the hatch's T-handle may have been tugged by a stray parachute suspension line, or was perhaps damaged by the heat of re-entry, and after cooling upon splashdown it contracted and caught fire. In early 1964 Alan Shepard was grounded after being diagnosed with Ménière's disease and Grissom was designated command pilot for Gemini 3, the first crewed Project Gemini flight, which flew on March 23, 1965. This mission made Grissom the first NASA astronaut to fly into space twice. The two-man flight on Gemini 3 with Grissom and John W. Young made three revolutions of the Earth and lasted for 4 hours, 52 minutes and 31 seconds. Grissom was one of the eight pilots of the NASA paraglider research vehicle. Grissom, the shortest of the original seven astronauts at five feet seven inches tall, worked very closely with the engineers and technicians from McDonnell Aircraft who built the Gemini spacecraft. Because of his involvement in the design of the first three spacecraft, his fellow astronauts humorously referred to the craft as "the Gusmobile". By July 1963 NASA discovered 14 out of its 16 astronauts could not fit themselves into the cabin and the later cockpits were modified. During this time Grissom invented the multi-axis translation thruster controller used to push the Gemini and Apollo spacecraft in linear directions for rendezvous and docking. In a joking nod to the sinking of his Mercury craft, Grissom named the first Gemini spacecraft "Molly Brown" (after the popular Broadway show, "The Unsinkable Molly Brown"). Some NASA publicity officials were unhappy with this name and asked Grissom and his pilot, John Young, to come up with a new one. When they offered "Titanic" as an alternate, NASA executives decided to allow them to use the name of "Molly Brown" for Gemini 3, but did not use it in official references. Much to the agency's chagrin, CAPCOM Gordon Cooper gave Gemini 3 its sendoff on launch with the remark to Grissom and Young, "You're on your way, "Molly Brown"!" Ground controllers also used it to reference the spacecraft throughout its flight. After the safe return of Gemini 3, NASA announced new spacecraft would not be nicknamed. Hence, Gemini 4 was not called "American Eagle" as its crew had planned.