The Apollo program marked humanity’s first journey beyond Earth orbit and into another world. NASA astronauts made historic steps onto the Moon’s surface and collected samples from its soil.
NASA designed its rocket to use a special descent engine that could be throttled for optimal power usage; more power was reserved for final plunge and less for lingering around near Moon while astronauts selected an landing site.
The Challenge
The National Aeronautics and Space Administration’s Apollo program sought to send astronauts safely to the Moon and back, an enormous undertaking requiring decades of planning and development – but not without its share of uncertainty and tensions.
President John F. Kennedy set the lofty goal of sending humans to the Moon by the end of 1961, and NASA set about to achieve it by the end of that decade. Project Mercury began sending single-person capsules into orbit. Later that year, two-person Gemini programs were also started; both provided scientists with better insight into human endurance in space travel.
To meet its goals, Apollo relied on a Saturn V rocket weighing more than 360,000 pounds at launch and featuring five stages. It took less than one minute for Apollo’s spacecraft to enter orbit before its second stage fired for over four minutes to propel it towards the Moon at speeds of more than 25,000mph.
After one and a half orbits around Earth, Apollo’s third stage fired for one minute to propel it toward lunar surface. Thereafter, its command-service module (CSM) and lunar module (LM) separated.
An engineer on the ground made a mistake which delayed separation of LM, impacting Armstrong’s landing time. Spacecraft relative positions also affected this aspect of their descent.
As they approached the Moon, Armstrong and Aldrin activated Eagle’s descent engine to slow it and bring it safely onto lunar surface. Once on-board, crew performed an intensive examination of all systems before commencing their historic walk across it.
On their moonwalk, astronauts deployed seismometers and a laser retroreflector for measuring moonquakes as well as collecting 21.6 kilograms of samples from lunar surface.
Armstrong, Aldrin and Collins spent several days after returning to the CSM in a precautionary quarantine to detect possible alien microbes that might threaten human life on Earth. Unfortunately, it proved unnecessary.
The Mission
NASA’s Apollo program had several national goals that it aimed to meet, such as developing technology for human spaceflight and making America an international leader in space exploration. On July 20, 1969, astronauts Neil Armstrong and Edwin “Buzz” Aldrin became the first people ever to walk on the moon.
Prior to Apollo, NASA had already successfully completed Mercury and Gemini programs – sending single-person crews into orbit to test spacecraft systems and demonstrate human ability. A massive launch vehicle called Saturn V was then developed specifically for Apollo astronauts as they journeyed toward space and the Moon.
Command Module (CM). Behind that was Service Module, or SM, which housed propulsion and support systems of the spacecraft. Finally, Lunar Module, or LM, would transport astronauts from Earth orbit to lunar surface where support services would provide them. Before returning them back into orbit and back home.
On launch day, stage one of the rocket consumed approximately 20 tonnes per second of kerosene and hydrogen fuel to send Apollo into low Earth orbit. A third stage engine fired to send Apollo into an intermediate transfer orbit which brought it within 42 miles of the Moon — known as translunar injection or TLI.
This maneuver allowed the spacecraft to exploit the Moon’s gravitational force to return home without needing more rocket fuel, in what’s known as extravehicular activity (EVA). Once on the moon, Armstrong and Aldrin deployed a television camera which broadcast live images back to Earth; collected samples from its surface; collected seismometer readings for measuring intensity of Moonquakes; deployed an EVA suit that allowed for extravehicular activity (EVA); deployed seismometer readings of Moonquakes for EVA missions (EVAs).
After four hours of rest, the astronauts retrieved their LM from the CM and prepared for an EVA. Armstrong set foot on the Moon at 9:56 PM CDT and gave his immortal speech: “That’s one small step for man, one giant leap for mankind.” Aldrin soon after collected 21.6 kilograms of samples while also deploying seismometers, laser reflectors to enable precise measurements between Earth and Moon and solar wind composition experiments.
The Spacecraft
Mission to Moon set out to fulfill President Kennedy’s dream of sending humans to the moon and, according to Neil Armstrong, it proved one small step for humans and one giant leap for mankind. On July 21, 1969, Neil Armstrong and Buzz Aldrin descended from Apollo Lunar Module Eagle into the Sea of Tranquility where they conducted EVA (Extra Vehicular Activity) operations and collected scientific samples – setting in motion five additional Moon landings over time.
This Apollo mission utilized the Command/Service Module (CSM), designed to accommodate three astronauts for their trip from Earth orbit to the Moon and back again. It was larger than any Mercury capsule used on previous Project Mercury flights.
The Lunar Module (LM), equipped with a ladder to descend onto the lunar surface and capable of accommodating two astronauts. Additionally, this craft was equipped with a TV camera for live lunar surface observations as well as carrying early Apollo Scientific Experiments Package experiments that could be deployed via EASEP deployments. Furthermore, this craft also contained a rover that could be left parked on its landing spot on the Moon.
On Day 7, astronauts Stafford and Cernan detached the Lunar Module (LM) from their CSM, and performed a flyby to come within 9 miles of its surface before rejoining its CSM and concluding its lunar trajectory.
On the evening of Day 10, the crew began preparations for lunar reentry. First, the LM was detached from its CSM and repositioned as heat shield forward position. A lunar reentry burn conducted on Day 11 significantly increased its velocity relative to Earth and further enhanced by lunar reentry atmosphere which was denser and warmer than Earth’s.
At 195 hours and 44 minutes, the LM detached from its parent CM and deployed its parachutes for landing at 13 degrees 19 minutes north latitude and 169 degrees nine minutes west longitude – approximately 250 miles away from recovery ship USS Hornet. Reentry was so violent that its windows shattered upon impact with Earth; further damage occurred during recovery later and it now resides on display at Smithsonian National Air and Space Museum in Washington D.C.
The Final Mission
On December 19, 1972, the final Apollo mission rolled out of Cape Kennedy. Comprised of Neil Armstrong, Buzz Aldrin and Michael Collins — they would become the last humans to step foot upon the moon before its conclusion was sealed by NASA due to rising costs that outshone any funds available at that time.
The spacecraft reached Earth orbit 11 minutes after launch and began its rendezvous with the Moon. During its third stage burn, it performed a maneuver known as trans lunar insertion (TLI), which set them onto what’s called a free-return trajectory – using gravity from Earth rather than burning huge amounts of fuel to travel homeward.
Once they had successfully landed the LM in Taurus-Littrow region, the astronauts spent almost 71 hours exploring its surface with Lunar Roving Vehicle driving and conducting various experiments, such as heat flow research; measuring magnetic fields on Moon; lunar seismic profiler; and recording lunar quakes.
At the conclusion of their mission, the astronauts jettisoned the LM and returned to their CSM. A few hours later, one of them (it remains unknown which) captured an iconic photograph showing Earth gliding above the horizon, its green landmasses and sapphire oceans set against black space – an image later known as “Blue Marble,” used extensively to promote environmental causes over subsequent years.
As soon as the Apollo capsule splashed down in the Pacific, NASA’s Apollo program ended and was replaced by Skylab space station and Space Shuttle missions. Since then, they haven’t returned to land astronauts on the moon but their more powerful spacecraft are getting closer. It could take another 50 years until another human steps onto its surface but that day will come. Last month alone, NASA unveiled a prototype version of Orion spacecraft – their successor spacecraft for future moon landing missions.