Computer control of spacecraft systems assisted Armstrong during descent. At certain altitudes, an abort was no longer an option and an abort procedure could only be carried out with clearance from NASA.
On 20 July, Armstrong detached Eagle from Collins and began its powered descent towards the lunar surface, eventually conducting his inaugural two and a half hour moon walk.
What We Learned
The Apollo program began as an effort to prove America’s technological, economic and political superiority over Soviet Russia – something it accomplished admirably. Yet its scientific legacy also was immense: scientists gained valuable insights about our Moon as well as solar system dynamics, cosmic evolution and ourselves from participating in this endeavour.
Lunar samples and data gathered by astronauts fueled research long after Apollo missions concluded in 1972, and technology collected during Apollo was utilized in creating Skylab, America’s inaugural space station. Apollo hardware allowed NASA engineers to develop more maneuverable spacecraft as well as refine safety protocols.
Lesson #6: Sticky Thinking
Engineers, astronauts and administrators at NASA used sticky thinking during the Apollo program to address many obstacles they faced. By connecting previously-known concepts to new ideas and possibilities, they were able to come up with solutions they hadn’t considered previously; by visualizing what might go wrong during a mission and then devising plans accordingly, sticky thinking enabled NASA engineers, astronauts and administrators to overcome multiple difficulties successfully.
Armstrong and Aldrin deployed experimental instruments in the Sea of Tranquility beyond just collecting and analyzing Moon rocks. Among these were seismometers to record any moonquakes or meteoroid impacts that might happen; seismometers would measure any lunarquakes; seismographs measured moonquake intensity or meteorite impact rates on surface; laser Ranging Retroreflector measured how fast laser beams traveled from Earth to Moon and back again; laser Ranging Retroreflector provided measurements that helped scientists understand more fully how the Moon formed; differences from Earth; what might happen deep within lunar crust; among many other experiments they helped scientists understand how and when its formation occurred.
Astronauts discovered that the Moon was covered with a layer of fine dust known as regolith that closely resembles Earth’s. This led them to conclude that it may once have been covered with magma oceans, explaining its uneven and rugged surface. Armstrong and Aldrin brought back samples which shed light on how our solar system formed over time; among these was one rock with natural glass formation from a meteorite impact over four billion years ago!
Getting to the Moon
Breaking free of Earth’s gravity required an aircraft that could accelerate beyond atmospheric drag; this required the use of rockets. By the time President Kennedy declared in May 1961 that America would place a man on the Moon, Russia already had done it.
Rockets offer an infinite acceleration capability, making them the ideal means of transport for Apollo missions. A massive rocket needed to be constructed, with stages and tanks providing fuel, propulsion, avionics, crew accommodation in their pressurised capsule (Command Module CSM), unmanned service modules carrying main rocket engines and supplies as well as lunar excursion modules (LEM).
Once in low Earth orbit and with all systems functioning correctly, the CSM separated from the third stage and fired its thrusters to begin its journey towards translunar injection. At translunar injection, CSM docked with lunar module and astronauts prepared for EVA.
Armstrong and Aldrin completed a two-hour moonwalk which included science experiments and photography, leaving behind flags and plaques to honor three Apollo 1 astronauts who perished due to an accident on launch pad, as well as microminiaturized goodwill messages from 73 countries.
EVA saw astronauts transitioning from light-weight flight suits into bulkier pressurised spacesuits equipped with gloves and boots specifically designed for lunar surface exploration, which were both hot and dusty processes. Furthermore, radio transmissions were required with mission control during EVA; nevertheless, its completion was successful.
Landing on the Moon
On July 20, 1969, Armstrong and Aldrin made history when they stepped from the Eagle into the Moon’s “Sea of Tranquility,” while millions across America watched on TV. It marked a tremendous national effort to beat Soviet rivals to the Moon; first-ever humans had ever set foot on its surface and represented an extraordinary accomplishment which belonged to more people than just its astronauts themselves.
Mission planners had spent two years carefully considering where to make history’s landing on the Moon. Utilizing high-resolution images from Lunar Orbiter and Surveyor programs, they carefully evaluated all potential landing sites before making their selection. Comparing all prospective landing spots against each other allowed for maximum sampling while considering technical considerations related to landing. Specifically, mission planners avoided going near areas which might trap their lunar module as it descended; also they avoided going near any places which might make egress too challenging for crewmembers from leaving Eagle safely.
Armstrong and Aldrin conducted a quick check of the Lunar Module systems before embarking on their lunar walk. Wearing protective spacesuits and spiked-heeled shoes, they prepared for their journey across its surface.
The astronauts spent approximately two hours walking along their route. During that time they collected samples, set up science experiments (such as one to measure solar wind composition reaching the Moon and a laser reflector that sent back beams back to Earth to measure distance between Earth and Moon down to centimeter accuracy), took numerous photographs, and made deposits of samples on the Moon surface.
After their Moon walk, the astronauts returned to Eagle and re-docked with its command module, before following a procedure practiced during a rehearsal two months earlier and firing its descent engine for an orbit less than 200 kilometers above Moon’s surface. At approximately 12:50 p.m. Eastern on July 24th, two astronauts splashed down in the Sea of Tranquility just a few miles from their recovery ship, the U.S.S. Hornet. Wearing biological isolation garments and applying iodine in order to prevent any transference of potentially hazardous microbes they had collected on the Moon, they entered a large Lunar Receiving Laboratory aboard their ship for 21 days of quarantine.
Returning to Earth
Apollo 11 astronauts’ 21-hour-and 36-minute stay on the Moon was one of humanity’s great feats, yet there was much work still to do before returning home. They collected scientific specimens, data, photographs and live video transmissions that will continue to fuel research long after their mission ended.
After their lunar excursion was complete, the astronauts prepared for a long journey back home. But first they needed to complete a series of complex maneuvers in order to reunite their command module and lunar module before entering Earth’s atmosphere at precisely the right moment and in ideal conditions.
To prepare for reentry, astronauts needed to perform a deorbit burn that set their spacecraft into motion for descent. Furthermore, they needed to orient their lunar module so its heat shield faced Earth and be ready for entry; and at just the right moment fire their service module’s engine so as to propel themselves toward home.
Armstrong and Aldrin prepared to depart the Moon by making their descent back down to their lunar module’s surface, where they collected their instruments before deploying the Early Apollo Scientific Experiments Package, Passive Seismic Experiments Package, Laser Ranging Retroreflector, as well as extensive photographs and movies of themselves, their deployments, lunar terrain, deployments and each other using still and movie cameras.
At 10:52 p.m. on July 24th, they prepared to reenter Earth’s atmosphere once more. When this occurred, Donald K. “Deke” Slayton, Director of Flight Crew Operations and an expert at managing Apollo missions advised them to fly their lift vector up for as long as reentry lasted, adding approximately 215 miles to their flight path while decreasing the chances of debris colliding with their Command Module during reentry.
Re-entry was successful for both astronauts, and soon thereafter they were picked up by the USS Hornet, which had arrived to assist with landing. They were exhausted but fulfilled their national mission, returning home safely with national accomplishment.