Apollo 1 in the context of AS-202

Apollo 7 (October 11–22, 1968) was the first crewed flight in NASA's Apollo program, and saw the resumption of human spaceflight by the agency after the fire that had killed the three Apollo 1 astronauts during a launch rehearsal test on January 27, 1967. The Apollo 7 crew was commanded by Walter M. Schirra, with Command Module Pilot Donn F. Eisele and Lunar Module pilot R. Walter Cunningham (so designated even though Apollo 7 did not carry a Lunar Module).

The three astronauts were originally designated for the second crewed Apollo flight, and then as backups for Apollo 1. After the Apollo 1 fire, crewed flights were suspended while the cause of the accident was investigated and improvements made to the spacecraft and safety procedures, and uncrewed test flights made. Determined to prevent a repetition of the fire, the crew spent long periods monitoring the construction of their Apollo command and service modules (CSM). Training continued over much of the 21-month pause that followed the Apollo 1 disaster.

As part of the Apollo program by NASA, 24 astronauts flew nine missions to the Moon between December 1968 and December 1972. During six successful two-man landing missions, twelve men walked on the lunar surface, six of whom drove Lunar Roving Vehicles as part of the last three missions. Three men have been to the Moon twice, one orbited once and took a circumlunar trajectory the second time, while the other two landed once apiece. Apart from these 24 men, no human being has gone beyond low Earth orbit. As of December 2025, five of the 24 remain alive. A number of non-human animals have circled or orbited it, including two tortoises, several turtles, and five mice.

Apollo missions 8 and 10–17 were the nine crewed missions to the Moon. Apollo 4–6 and AS-201 and AS-202 were uncrewed, while AS-203 is considered a test flight. The Apollo program included three other crewed missions: Apollo 1 (AS-204) did not launch and its crew died in a ground-based capsule fire, while Apollo 7 and Apollo 9 were low Earth orbit missions that tested spacecraft components and docking maneuvers. Apollo missions 18, 19, and 20 were canceled. Twelve astronauts later flew unused Apollo command modules in the Apollo Applications Program's Skylab and Apollo–Soyuz Test Project. Of the 24 astronauts who flew to the Moon, two went on to command a Skylab mission, one commanded Apollo–Soyuz, one flew as commander for Approach and Landing Tests of the Space Shuttle, and two commanded orbital Space Shuttle missions.

This article lists verifiable spaceflight-related accidents and incidents resulting in human death or serious injury. These include incidents during flight or training for crewed space missions and testing, assembly, preparation, or flight of crewed and robotic spacecraft. Not included are accidents or incidents associated with intercontinental ballistic missile (ICBM) tests, death or injury to test animals, uncrewed space flights, rocket-powered aircraft projects of World War II, or conspiracy theories about alleged unreported Soviet space accidents.

As of January 2025, 19 people have died during spaceflights that crossed, or were intended to cross, the boundary of space as defined by the United States (50 miles above sea level). Astronauts have also died while training for space missions, such as the Apollo 1 launch pad fire that killed an entire crew of three. There have also been some non-astronaut deaths during spaceflight-related activities. As of 2025, more than 188 people have died in spaceflight-related incidents.

The Apollo command and service module (CSM) was one of two principal components of the United States Apollo spacecraft, used for the Apollo program, which landed astronauts on the Moon between 1969 and 1972. The CSM functioned as a mother ship, which carried a crew of three astronauts and the second Apollo spacecraft, the Apollo Lunar Module, to lunar orbit, and brought the astronauts back to Earth. It consisted of two parts: the conical command module, a cabin that housed the crew and carried equipment needed for atmospheric reentry and splashdown; and the cylindrical service module which provided propulsion, electrical power and storage for various consumables required during a mission. An umbilical connection transferred power and consumables between the two modules. Just before reentry of the command module on the return home, the umbilical connection was severed and the service module was cast off and allowed to burn up in the atmosphere.

The CSM was developed and built for NASA by North American Aviation starting in November 1961. It was initially designed to land on the Moon atop a landing rocket stage and return all three astronauts on a direct-ascent mission, which would not use a separate lunar module, and thus had no provisions for docking with another spacecraft. This, plus other required design changes, led to the decision to design two versions of the CSM: Block I was to be used for uncrewed missions and a single crewed Earth orbit flight (Apollo 1), while the more advanced Block II was designed for use with the lunar module. The Apollo 1 flight was cancelled after a cabin fire killed the crew and destroyed their command module during a launch rehearsal test. Corrections of the problems which caused the fire were applied to the Block II spacecraft, which was used for all crewed spaceflights.

Several planned missions of the Apollo crewed Moon landing program of the 1960s and 1970s were canceled, for reasons which included changes in technical direction, the Apollo 1 fire, the Apollo 13 incident, hardware delays, and budget limitations. After the landing by Apollo 12, Apollo 20, which would have been the final crewed mission to the Moon, was canceled to allow Skylab to launch as a "dry workshop" (assembled on the ground in an unused S-IVB Saturn IB second stage). The next two missions, Apollos 18 and 19, were later canceled after Apollo 13 and further budget cuts. Two Skylab missions also ended up being canceled. Two complete Saturn V rockets remained unused and were put on display in the United States.

Clifton Curtis Williams Jr. (September 26, 1932 – October 5, 1967), was an American naval aviator, test pilot, mechanical engineer, major in the United States Marine Corps, and NASA astronaut, who was killed in a plane crash; he never went into space. The crash was caused by a mechanical failure in a NASA T-38 jet trainer, which he was piloting to visit his parents in Mobile, Alabama. The failure caused the flight controls to stop responding, and although he activated the ejection seat, it did not save him. He was the fourth astronaut from NASA's Astronaut Group 3 to have died, the first two (Charles Bassett and Theodore Freeman) having been killed in separate T-38 flights, and the third (Roger B. Chaffee) in the Apollo 1 fire earlier that year. The aircraft crashed in Florida near Tallahassee within an hour of departing Patrick AFB.

Before becoming an astronaut, Williams received his Bachelor of Science degree in Mechanical Engineering from the Auburn University in 1954 and joined the U.S. Marine Corps through the Naval Reserve Officers Training Corps (NROTC). He became a Naval Aviator in 1956 and joined the Fleet Marine Force. In 1961, he graduated from the U.S. Naval Test Pilot School. As a test pilot, he worked for three years in the Carrier Suitability Branch of the Flight Test Division at NAS Patuxent River. In 1962, Williams, then a Captain, became the first pilot to land a two-seat jet on the aircraft carrier from the rear cockpit. At the time of his death, he was 35 and held the rank of Major.