Apollo 4 (November 9, 1967), also known as SA-501, was the uncrewed first test flight of the Saturn V launch vehicle, the rocket that eventually took astronauts to the Moon. The space vehicle was assembled in the Vehicle Assembly Building, and was the first to be launched from Kennedy Space Center (KSC) in Florida, ascending from Launch Complex 39, where facilities built especially for the SaturnV had been constructed.
Apollo 4 was an "all-up" test, meaning all rocket stages and spacecraft were fully functional on the initial flight, a first for NASA. It was the first time the S-IC first stage and S-II second stage flew. It also demonstrated the S-IVB third stage's first in-flight restart. The mission used a BlockI command and service module modified to test several key BlockII revisions, including its heat shield at simulated lunar-return velocity and angle.
The launch was planned for early 1967, but delayed to November9 because of problems with various elements of the spacecraft and difficulties during pre-flight testing. Additional inspections were also required after a fire killed the Apollo 1 crew in January 1967.
The mission splashed down in the Pacific Ocean slightly less than nine hours after launch, having achieved its objectives. NASA considered the mission a complete success, proving that the SaturnV worked, an important step towards achieving the main objective of landing astronauts on the Moon, and bringing them back safely, before the end of the 1960s.
Background
thumb|[[NASA Documentary of the Apollo 4 mission.]]
In 1961 U.S. President John F. Kennedy proposed that his nation land an astronaut on the Moon by the end of the decade, with a safe return to Earth. One of the early choices that had to be made to accomplish this goal was what launch vehicle to use. NASA decided on the SaturnC-5 rocket, a three-stage launch vehicle based on rockets already in development. In 1962 this was approved by NASA, which contemplated an initial test launch in 1965 and a first crewed flight by 1967, leaving plenty of time to accomplish Kennedy's goal. In early 1963, NASA redesignated the C-5 as the Saturn V.
After considerable debate within NASA, it was decided in late 1962 that lunar missions would have a "lunar orbit rendezvous" mode whereby the complete Apollo spacecraft would be propelled towards lunar orbit by the third stage of the launch vehicle, the S-IVB. Once in lunar orbit, the astronauts who would land would enter what was then known as the Lunar Excursion Module, which would separate from the rest of the spacecraft, land, and after taking off again be discarded once the crew had transferred back. The remainder of the vehicle would then return to Earth. The launch facilities under development would not be sufficient for the new launch vehicle, and in 1962, NASA announced plans for a new complex on the Florida coast from which the Apollo lunar missions could be launched. This was dubbed the Launch Operations Center, but after Kennedy's assassination in November 1963 was renamed the John F. Kennedy Space Center (KSC). Apollo4 was the first flight from KSC, and the first using Launch Complex 39 (LC-39) there, built to accommodate the SaturnV.
The first three flights carrying Apollo equipment were launched using Saturn IBs. This smaller launch vehicle did not use the facilities at KSC, but issues resolved by SaturnIB flights would be valid for those to be launched by the SaturnV. Both the SaturnIB and the SaturnV would use a S-IVB, though the IB would use it as its second, final stage, rather than the third stage as on the SaturnV. Thus, many of the flight qualifications for the payload the SaturnV would carry could be resolved without having to expend one of the large launch vehicles. In addition to flight-qualifying the hardware, it was necessary to prove that the ground systems at KSC could successfully launch a Saturn V before risking the lives of astronauts on one.
Three Saturn IB launches (in order of launch, AS-201, AS-203 and AS-202) took place in 1966; all were successful. According to Charles D. Benson and William B. Flaherty in their history of KSC, "The Apollo-SaturnIB launches of 1966 represented important gains for NASA's launch team. LC-34 and LC-37, testbeds for automated checkout, were found wanting. In the twenty months between AS-201 and SA-501 [Apollo4], KSC corrected the major automation problems. Without these trial and error advances, SA-501, the toughest launch in Apollo's history, would have been far more difficult."
Delays
thumb|right|alt=A rocket inside a high, narrow building with multiple levels surrounding it|Apollo 4 inside the [[Vehicle Assembly Building|VAB]]
In January 1965 Major General Samuel C. Phillips, the Apollo Program Director, scheduled SA-501, the first test flight of the SaturnV, for January 1967. This left little spare time for delay, especially since two additional SaturnV launches were planned to follow in 1967. Many Apollo officials lacked confidence in the proposed launch date, and these misgivings proved accurate. After an explosion involving a liquid oxygen line flowing to LC-39, from which SA-501 was to be launched, there was a potential for a delay of several weeks. Technicians found cracks in the S-II, delaying its test firings prior to acceptance by NASA. As North American worked to fix the S-II, parts of the rocket began to arrive at KSC, beginning with the S-IVB on August 14, 1966, (by Pregnant Guppy aircraft) and followed closely by the first stage S-IC on September 12 (by barge). A spool-shaped "spacer" that took the place of the S-II allowed NASA to stack the vehicle as its checkout proceeded in the Vehicle Assembly Building (VAB). With the S-II still not arrived by November 1966 (it had originally been planned for July), NASA planned January 1967 for its arrival, with launch three months later. The CSM arrived on December 24, 1966, with the S-II arriving on January 21, 1967. Last to arrive was the aft interstage (the structure between the first and second stages), on January 31.
The Apollo 1 fire on January 27, 1967, which killed three astronauts during a launch pad test, threw NASA's schedules into further questioneven though SA-501 was uncrewed, NASA officials wanted to closely examine its CSM. NASA had planned to restack the vehicle once this was done,
thumb|left|alt=A tall rocket on a platform is rolled out along a track towards a launch site|The Apollo 4 launch vehicle (right) is rolled out from the [[Vehicle Assembly Building (far left) past the Mobile Servicing Structure.]]
Other problems were discovered, such as an extra, out-of-place bolt in one of the J-2 engines; NASA was concerned not only with retrieving the surplus hardware, but also with discovering how it got there. A meeting in March 1967, with Phillips in attendance, disclosed twelve hundred problems with the SaturnV, which the technicians proposed to deal with at the rate of eighty per day. While the CSM was undergoing repairs, the spacer was removed from the vehicle stack, and the S-II positioned. On May 24 it was announced that the S-II would be removed for inspection following the discovery of hairline cracks in another S-II then being constructed, this work being completed by mid-June, after which the CSM was also returned to the stack, the first time the launch vehicle and spacecraft had been fully assembled. It was rolled out to LC-39 on August 26, 1967, Concerned about the potential for leaks in the Teflon seal rings and drain valves of the liquid oxygen tanks on board the vehicle due to the long time it had been sitting on the launch pad in the Florida sun, on November2 Phillips postponed the launch until November9.
Objectives
thumb|Manned Spaceflight: Quarterly Report No. 67 (1967) Official [[NASA Apollo 4 information film reel.]]
The purpose of Apollo 4 (together with the SaturnV's other uncrewed test flight, Apollo6) was to qualify the launch vehicle, the Apollo spacecraft, and the ground systems, for the crewed lunar landing missions that would follow. In addition to being the first flight of the SaturnV, Apollo4 marked the first flight for two of its stages: the S-IC first stage and the S-II second stage (the S-IVB had flown as part of the SaturnIB).
Objectives for the Apollo 4 mission were to gain flight data on the SaturnV and spacecraft structural integrity and mutual compatibility, including on flight loads and during the separations as each SaturnV stage was exhausted and was discarded. NASA also wanted data on subsystem operations, including the emergency detection subsystem, and sought to evaluate the Apollo CM's heat shield under conditions simulating a return from a lunar mission. NASA was also seeking to test the restart capability of the S-IVB in space.
Several significant Block II modifications were made to CSM-017 for certification purposes, since no BlockII spacecraft would fly without a crew. These included upgrading the heat shield to BlockII standards, using a BlockII CM-to-SM umbilical connector, and installing BlockII-style VHF and S-band antennae. Additionally, there were modifications to the CM's hatch. The fact that the spacecraft hatch could not be readily opened in case of emergency had trapped the Apollo1 astronauts in the fire that took their lives, and led to a redesign of the hatch. The new hatch was not scheduled to fly until the second SaturnV test (Apollo 6), but its seals were to be flight-qualified on Apollo4the hatch window was replaced with a test panel simulating the seals and exterior heat shield. The heat shield was upgraded to BlockII standards since Apollo4's high-speed re-entry into Earth's atmosphere was intended to simulate a return from the Moon. Special equipment had been installed to allow Mission Control to operate the CSM's systems remotely, and there was a camera that would automatically take pictures out of one of the CM's windows on its final orbit. Since Apollo4 carried no crew the CM lacked couches, controls and displays.
Public interest and media coverage
VIPs swarmed to KSC in the days before the launch. Von Braun arrived on November 6, scheduled for an exclusive executive dinner and conference that evening. NASA executives, figures from industry, Congressional leaders and diplomats also came for the launch. Each NASA center involved had a list of VIP guests, as did NASA headquarters in Washington, and duplications were sorted out so each center's director could invite guests personally. They watched the launch from uncovered bleachers near the VAB. NASA set up press headquarters in Cocoa Beach, where media representatives were accredited, and offered tours of KSC to visiting journalists, as well as a half-hourly shuttle service. NASA provided extensive telephone facilities for the media at the press site near LC-39, at their expense. KSC workers and their dependents watched the launch from near their work assignments. In addition, 43 employees of contractors who had performed in an exemplary manner were selected as "Manned Flight Awareness" honorees, given a VIP tour of KSC, a social evening in which six astronauts participated, and a view of the launch.
Apollo 4, being the first flight of the SaturnV, gained intense media coverage, and writers struggled to convey to the public the size of the launch vehicle, stating that it would tower well over the Statue of Liberty and be thirteen times as heavy. North American, in a handout to the media, noted that the 3000-ton SaturnV comfortably outweighed a "good-sized navy destroyer". On the day before launch, Mueller, Phillips, von Braun, Deputy Administrator Robert C. Seamans and Kennedy Space Center Director Kurt Debus held an outdoor press conference for more than a thousand journalists, including some from the Soviet Union, with the SaturnV in the background.
Launch and flight
On November 6, 1967, at 10:30pm EST (03:30 November7 UTC), the -hour countdown sequence began with propellant loading. In total there were 89 trailer-truck loads of liquid oxygen, 28 trailer loads of LH2 (liquid hydrogen), and 27 rail cars of RP-1 (highly refined kerosene). This time the problems encountered were few and minor, William Donn of Columbia University described the blast as one of the loudest noises, natural or artificial, in human history, excepting nuclear explosions. CBS's commentator, Walter Cronkite, and producer Jeff Gralnick put their hands on their trailer's observation window to stop it from shattering as ceiling tiles fell from above. Cronkite found Apollo4 to be the most frightening space mission he covered.
thumb|left|alt=Rows of men at consoles watching screens|Mission controllers watch Apollo4 climb to orbit.
The launch placed the S-IVB and CSM into a nearly circular orbit, a nominal parking orbit that would be used on the lunar missions. After two orbits, in a simulation of the trans-lunar injection burn that would take later Apollo missions towards the Moon, the S-IVB's first in-space re-ignition put the spacecraft into an elliptical orbit with an apogee of and a perigee deliberately aimed below the Earth's surface; this would ensure both a high-speed atmospheric re-entry of the command module, and destruction after re-entry of the S-IVB. Shortly after this burn, the CSM separated from the S-IVB and fired its service module engine to adjust the apogee to . After passing apogee, the service module engine fired again for 281 seconds to increase re-entry speed to , at an altitude of and a flight path angle of −6.93 degrees, simulating conditions on a return from the Moon.
The CM landed approximately from the target landing site northwest of Midway Island in the North Pacific Ocean. Its descent was visible from the deck of the aircraft carrier , the prime recovery ship, which within two hours had recovered it and one of its parachutes, the first time an Apollo parachute had been recovered for inspection. The spacecraft was brought to Hawaii for deactivation, after which it was taken to North American's facility in Downey, California, for post-flight analysis.
Onboard cameras
thumbtime=2:29 |thumb |right |200px |alt=Two cameras captured the staging event; one clip is shown. The first stage falls away, followed by the [[Adapter (rocketry)|interstage ring. |Two cameras captured the staging event; one clip is shown. The first stage falls away, followed by the interstage ring.]]
Two motion-picture cameras were aboard Apollo4. These were mounted on the SaturnV so as to capture the separation of the first stage and interstage from the launch vehicle. They would then be ejected, descend to the Atlantic Ocean in pods with parachutes and radio beacons, and be recovered about downrange of KSC.
The command module contained an automatic 70mm film camera which captured photographs of almost the entire Earth. For a period of two hours and thirteen minutes as the craft approached and passed its apogee, a total of 755 color images were taken through the Command Pilot's (left-hand) forward-looking window, at altitudes ranging from . These were the color images taken from the highest altitude at that time. The photographs were not of sufficient resolution to obtain detailed scientific data, but were still of interest to those involved in the Earth sciences.