Apollo Missions Explained

apollo missions explained

President Kennedy made clear his goal when urging Congress to fund NASA’s Apollo program: “One small step for man, one giant leap for mankind.”

NASA responded to that challenge by developing innovative vehicles such as the Saturn V rocket, which featured three-stages that transported astronauts between Earth and Moon.

The Apollo Missions

NASA’s Apollo program, undertaken between 1961 and 1974, saw 11 moon landings by American astronauts under Neil Armstrong’s lead between 1969 and 1977, fulfilling President John F. Kennedy’s challenge that humans reach and return safely from lunar surfaces within 10 years.

Armstrong and Aldrin set up several scientific experiments upon reaching the Sea of Tranquility surface, such as setting up a laser-ranging retroreflector to measure distances between Earth and Moon, and an active seismometer, while gathering samples of rock and soil.

Eagle’s crew reentered its ascent stage, rejoined Collins in the command module and fired its engine to leave lunar orbit en route back home; finally splashing down in the Pacific Ocean on December 19, this mission made history as it marked the first time humans ever left low Earth orbit without protection of a spacecraft lander.

Apollo 1

Apollo 1, an AS-204 spacecraft test flight, was intended to mark America’s inaugural crewed mission and low Earth orbit test of the Apollo Command and Service Module (CSM). On January 27, 1967 tragedy struck when fire erupted during a pad rehearsal, killing astronauts Virgil “Gus” Grissom, Ed White and Roger B. Chaffee due to unprotected wiring containing both power supply cables and coolant supplies that became ignited due to excessive heat build-up inside their cabin.

NASA astronauts were trapped inside a cramped spacecraft when fire spread quickly through it, forcing technicians on the launch pad to struggle for five minutes in vain to open its hatch and rescue them. The tragedy put a stop to NASA’s Moon program as well as review of safety procedures; lessons learned about mitigating risks in spacecraft design have since enabled humanity to reach the Moon and beyond.

Apollo 2

NASA was able to meet President Kennedy’s goal of landing people on the moon by the end of the decade through numerous missions besides Apollo 11. These other missions demonstrated human capabilities in space exploration while also contributing to NASA’s overall goals of exploring space further.

On January 27, 1967, astronauts Gus Grissom, Edward White and Roger Chaffee entered their Apollo 1 spaceship for a routine prelaunch test when an unexpected fire quickly spread within its cabin, filling it with thick smoke that quickly asphyxiated all three before ground crews could open its hatch and rescue them.

Apollo 8 astronauts Frank Borman, Jim Lovell and William Anders left low Earth orbit on December 21, 1968 for an eight-day lunar orbital mission, capturing the iconic “Earthrise” picture which has since been used on posters and stamps across America. Additionally, this mission served as an important test to dock both command and lunar modules successfully.

Apollo 3

NASA conducted an introspective examination following the fire aboard Apollo 1 spacecraft on Jan. 27, 1967 which killed astronauts Virgil “Gus” Grissom, Edward White and Roger Chaffee and decided to continue its space program renaming all its missions “Apollo” in honor of their fallen colleagues.

North American Aviation was forced to redesign the Apollo spacecraft, consisting of a command module and lunar module, after switching the composition from oxygen/nitrogen mixtures to pure oxygen; this presented serious fire risks and required an opening hatch that could be operated quickly with one finger.

Charles “Pete” Conrad and Alan Bean endured two lightning strikes during launch to reach a different spot on the Moon than Apollo 11. Their goals included retrieving pieces from Surveyor III probe which had been stuck there for two years as well as conducting scientific experiments.

Apollo 4

Apollo 4 took off on November 9, 1967 without any major difficulties from Kennedy’s special launch pad, with its first stage firing up precisely at 7 pm and then disengaging, enabling engineers to capture close-up video footage of this historic momentous occasion.

This was an “all-up” test flight, meaning all three Saturn V stages would be used simultaneously for the first time ever. Additionally, this marked the inaugural use of S-IC first stage and S-II second stages as well as S-IVB third stage restart.

After two orbits, the command module adjusted itself so as to place maximum thermal stress on its heat shield, and fired its service propulsion system engine for four minutes and 40 seconds to simulate lunar return trajectory. Onboard cameras recorded 755 images of Earth including iconic “smoking crescent.” Ultimately, its capsule was returned by USS Bennington aircraft carrier which served as its recovery ship.

Apollo 5

Apollo 5, the inaugural crewed test of a lunar module designed to carry astronauts down to the lunar surface, launched early 1968. It began its mission by spending 10 days in low Earth orbit and running both CSM Gumdrop and LM Spider through all the maneuvers they would need for future lunar landing missions.

Moments after liftoff, during a brief respite from the storm, lightning struck and shut down numerous systems onboard the spacecraft, including its engines which had failed to reach their targeted thrust due to computer software errors. Engineers immediately identified this cause.

First firings onboard the LM tested its abort staging system with two 39-second abort staging system (APS) burns separated by one minute each to complete this abort staging test. Flight Director Eugene F. “Gene” Kranz then completed a two-orbit checkout of all systems before prepping for its descent propulsion system (DPS) burn.

Apollo 6

Apollo 6 would finally allow NASA to begin crewed test missions necessary to meet President John F. Kennedy’s goal of landing men on the Moon by the end of the decade, yet would also become marred with controversy and tragedy: civil rights leader Martin Luther King Jr.’s assassination was carried out only four days prior to its launch.

Though faced with several obstacles, this Apollo flight yielded spectacular photographic results. Images captured from Maurer DAC cameras jettisoned from the second stage and recovered after launch provided some of the most remarkable color stereo photographs ever captured from space of Earth from space.

On Apollo’s final lunar return, its S-IVB burned for seven minutes — nearly double what would typically occur during an ordinary lunar-bound mission — simulating a trans-Lunar Injection maneuver and producing an orbit with higher orbit and slower return velocity. This allowed Apollo to enter a higher orbit with slower return velocity.

Apollo 7

After the Apollo 1 mission was derailed by a launchpad fire, NASA officials made plans for an immediate lunar orbit mission. Gemini and Mercury astronaut Walter “Wally” Schirra would serve as commander while two rookies, Walt Cunningham and Donn Eisele would assume these roles respectively.

The crew quickly adjusted to their new spacecraft, which was much larger than what had been available during Gemini missions, even venturing outside in what became known as extravehicular activity or EVA for the first time ever.

Apollo 7 crew landed successfully near Bermuda, inflating airbags and flipping their craft upright. Though there were a few minor complications, overall the mission was considered successful and qualified the CSM for Apollo 8 flight to the Moon. Apollo 7 gave renewed excitement for space exploration across America; its accomplishments led to front page stories all across the nation.

Apollo 8

Apollo 8 astronauts–Commander Frank Borman, Lunar Module Pilot Jim Lovell and Photographer William Anders–were the first humans to break free of Earth orbit and see beyond it to the far side of the Moon where they captured an iconic “Earthrise” photo that gave humanity a fresh view on our home planet.

Mission A was also notable because it demonstrated how the Saturn V rocket and its support systems could work effectively together to transport astronauts all the way to the Moon – an essential step leading up to 1969 moon landing.

Apollo 8 captured global attention, particularly on Christmas Eve as America mourned an unforgiving year that included the assassinations of Robert Kennedy and Martin Luther King as well as violent protests across the US and an ongoing Vietnam War. People needed something positive to cheer about and Apollo 8 provided it.

Apollo 9

Apollo 9 marked the inaugural test flight of the lunar module (LM) in Earth orbit. Commander James McDivitt, Command Module Pilot Dave Scott and Lunar Module Pilot Rusty Schweickart successfully separated and redocked it from its command module while also testing out engines, backpack life support systems and navigational systems onboard the lunar module.

Block II Apollo Command Module, known as Gumdrop due to how it appeared when delivered, and Lunar Module (known as Spider), were launched separately aboard a Saturn V rocket and would later allow us to take that iconic “one small step” on the Moon after extensive tests and preparation on missions such as Apollo 9. Thus began our race toward space exploration.

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