Grissom was born in Mitchell, Indiana, on April 3, 1926, the second child of Dennis David Grissom (1903–1994) and Cecile King Grissom (1901–1995). His father was a signalman for the Baltimore and Ohio Railroad, and his mother a homemaker. His older sister died shortly before his birth, and he was followed by three younger siblings, Wilma, Norman and Lowell. As a child he attended the local Church of Christ where he remained a lifelong member and joined the Boy Scouts’ Troop 46. He earned the rank of Star Scout. He was enrolled in public elementary schools and went on to attend Mitchell High School. Grissom met and befriended Betty Lavonne Moore at school through their extracurricular activities. He worked delivering newspapers for the Indianapolis Star and in a local meat market for his first jobs.

Grissom occasionally spent time at a local airport in Bedford, Indiana, where he first became interested in flying. A local attorney who owned a small plane would take him on flights for a $1 fee and taught him the basics of flying an airplane. World War II broke out while Grissom was still in high school, and he was eager to enlist upon graduation. Grissom enlisted as an aviation cadet in the United States Army Air Forces and completed an entrance exam in November 1943. He graduated from high school in 1944, and was inducted into the army at Fort Benjamin Harrison on August 8, 1944. He was sent to Sheppard Field in Wichita Falls, Texas, for basic training after which he was assigned as a clerk at Brooks Field in San Antonio, Texas.

As the war neared its end, Grissom sought to be discharged. He married Betty Moore on July 6, 1945, while on leave, and secured his discharge in September. He took a job at Carpenter Body Works, a local bus manufacturing business, and rented an apartment in Mitchell. However, he had trouble providing a sufficient income and was determined to attend college. Taking advantage of the G.I. Bill for partial payment of his school tuition, Grissom enrolled at Purdue University in September 1946. During his time in college, Betty returned to live with her parents and took a job at the Indiana Bell Telephone Company while he worked part-time as a cook at a local restaurant. Grissom took summer classes to finish early and graduated with a Bachelor of Science degree in Mechanical Engineering in 1950.  Gus Grissom was a Master Mason, a member of Mitchell Lodge # 228 of Mitchell, Indiana.

In 1958, Grissom received an official teletype message instructing him to report to an address in Washington, D.C. wearing civilian clothes. The message was classified “Top Secret” and Grissom was not to discuss its contents with anyone. Grissom discovered that he was one of 110 military test pilots whose credentials had earned them an invitation to learn more about the space program in general and Project Mercury in particular. Grissom liked the sound of the program, but knew that competition for the final spots would be fierce.  Grissom was sent to the Lovelace Clinic and Wright-Patterson Air Force Base to receive extensive physical examinations and to submit to a battery of psychological tests. He was nearly disqualified when doctors discovered that he suffered from hay fever, but was permitted to continue on when it was determined that his allergies would not be a problem due to the absence of ragweed pollen in space. On April 13, 1959, Grissom received official notification that he had been selected as one of the seven Project Mercury astronauts.

On July 21, 1961, Grissom was pilot of the second Project Mercury flight, Mercury-Redstone 4, popularly known as Liberty Bell 7. This was a suborbital flight that lasted 15 minutes and 37 seconds. After splashdown, emergency explosive bolts unexpectedly fired and blew the hatch off, causing water to flood into the spacecraft. Quickly exiting through the open hatch and into the ocean, Grissom was nearly drowned as water began filling his spacesuit. A recovery helicopter tried to lift and recover the spacecraft, but the flooding spacecraft became too heavy, and it was ultimately cut loose before sinking.  Grissom asserted he had done nothing to cause the hatch to blow, and NASA officials eventually concluded that he was correct. Initiating the explosive egress system required hitting a metal trigger with the side of a closed fist, which unavoidably left a large, obvious bruise on the astronaut’s hand, but Grissom was found not to have any of the tell-tale bruising. Still, controversy remained, and fellow Mercury astronaut Wally Schirra, at the end of his October 3, 1962 flight, remained inside his spacecraft until it was safely aboard the recovery ship, and made a point of deliberately blowing the hatch to get out, bruising his hand.

Grissom’s spacecraft was recovered in 1999, but no further evidence was found which could conclusively explain how the explosive hatch release had occurred. Later, Guenter Wendt, pad leader for the early American manned space launches, wrote that he believed a small cover over the external release actuator was accidentally lost sometime during the flight or splashdown and the T-handle may have been tugged by a stray parachute shroud line, or was perhaps damaged by the heat of re-entry and after cooling upon splashdown, contracted and fired.  Grissom was surrounded by reporters in a news conference after his space flight in America’s second manned ship. When asked how he felt, he replied, “Well, I was scared a good portion of the time; I guess that’s a pretty good indication.”

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 manned Project Gemini flight, which flew on March 23, 1965. This mission made him the first NASA astronaut to fly into space twice. This flight 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 was one of the smaller astronauts, and he worked very closely with the engineers and technicians from McDonnell Aircraft who built the Gemini spacecraft. The first three spacecraft were built around him and the design was humorously referred to as “the Gusmobile”. However by July 1963 NASA discovered 14 out of the 16 astronauts could not fit themselves into the cabin and 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.

Before its planned February 21, 1967 launch, the Command Module interior caught fire and burned on January 27, 1967 during a pre-launch test on Launch Pad 34 at Cape Kennedy, killing all three men. The fire’s ignition source was never determined, but their deaths were attributed to a wide range of lethal hazards in the early Apollo Command Module design and conditions of the test, including a pressurized 100% oxygen pre-launch atmosphere, many wiring and plumbing flaws, flammable materials used in the cockpit and in the astronauts’ flight suits, and an inward-opening hatch which could not be opened quickly in an emergency and could not be opened at all with full internal pressure. After the tragedy, NASA adopted a new flight numbering system for Apollo, and honored the crew by making Apollo 1 official. The spacecraft problems were corrected, and the Apollo program carried on successfully to reach its objective of landing men on the Moon.

Grissom had attained the rank of Lieutenant Colonel at the time of his death, and had logged a total of 4,600 hours flying time, including 3,500 hours in jet airplanes. Chief astronaut Deke Slayton wrote that he wanted one of the original Mercury Seven astronauts to be the first on the Moon and, “Had Gus been alive, as a Mercury astronaut he would have taken the step … My first choice would have been Gus, which both Chris Kraft and Bob Gilruth seconded.”  Gus Grissom is buried in Section 3 38.873115°N 77.072755°W of the Arlington National Cemetery, near Roger Chaffee. Ed White is buried at the West Point Cemetery, West Point, New York.