2019 marks the 50th anniversary of human beings setting foot on the surface of our Moon. The Apollo programme may have first and foremost been driven out of political need / desires, but it nevertheless stands as a remarkable achievement, given it came n the same decade when a human being first flew in space, and a little under 12 years since the very first satellite orbited the Earth.
To this day, Apollo stands as one of the most remarkable space programmes ever witnessed in terms of scale, cost, and return. It propelled a generation of American school children to pursue careers in engineering, flight, the sciences and more. In all, the Apollo lunar programme flew a total of 11 crews in space between 1967 and 1972, nine of them to the Moon, with two crewed missions to Earth orbit.
After the tragedy of the Apollo 1 fire in January 1967, which claimed the lives of Virgil “Gus” Grissom, Edward White II and Roger B. Chaffee, NASA worked hard to redesign the Apollo Command Module, providing far greater insulation against the risk of fire, as well as altering the vehicle’s atmosphere (from 100% oxygen to a 60/40 oxygen / nitrogen mix) and altering the main hatch so that the crew could escape in the event of a launch pad emergency. In October 1968, the redesigned vehicle, along with its supporting Service Module (together referred to as the Command and Service Module, or CSM) was tested in Earth orbit for the first time by the crew of Apollo 7.
Scheduled for launch towards the end of 1968, Apollo 8 had originally been planned as the first orbital flight test of the CSM and Lunar Module (LM). However, two events encouraged NASA to revisit their plans. Due to continued delays in the delivery of a flight-ready LM, the agency decided to swap the Apollo 8 and Apollo 9 missions and crews around; Apollo 9 would flight-test CSM and LM, once available. Meanwhile, Apollo 8, carrying Frank Borman, Jim Lovell and Bill Anders, and marking the first crewed flight of the mighty Saturn V rocket, would be used in an orbital flight designed to simulate the atmospheric re-entry at the speeds a Command Module would face on a return from the Moon without actually sending the crew to the Moon.
Then, in August and September 1969 photographs captured by US spy satellites suggested the Soviet Union had one of its massive N1 rocket, easily the equal of Saturn V, sitting on a launch pad. With fears that the Soviet Union was perhaps approaching the point where it could launch a crewed mission to the Moon, Apollo 8 was further revised and Borman, Lovell and Anders were informed they’d be spending Christmas 1968 where no other person had spent Christmas before: in orbit around the Moon, allowing them to fully check-out the CSM as it would be flown in an actual lunar landing mission.
So it was that on Saturday, December 21st, 1968, Borman, Lovell and Anders were strapped into their seats atop the 110.6 metre (363 ft) tall Saturn V, about to undertake the longest journey ever undertaken by humans up until that point in time. At 07:51 local time (12:51 UTC) the five massive F-5 engines of the rocket’s first stage thundered into life, slowly lifting the 2,812 tonne (US 3,100 short tons) vehicle into the sky.
On reaching orbit, the CSM still attached to the Saturn V’s third stage, spent some 2 hours and 30 minutes in orbit while the crew performed a final check of their systems. Then the S-IVB motor was re-started, and in five minutes accelerated the vehicle from 7,600 to 10,800 metres per second (25,000 to 35,000 ft/s), pushing it away from Earth and on course for the Moon. With TLI – Trans-Lunar Injection successfully completed, the crew separated the CSM and rotated it to photograph the expended third stage, still following behind.
After a mid-course correction, and around 55 hours and 40 minutes after launch, the crew of Apollo 8 became the first humans to enter the gravitational sphere of influence of another celestial body as the effect of the Moon’s gravitational force on the vehicle had become stronger than that of the Earth. Nine hours later, the crew performed the second of two mid-course corrections using the CSM’s reaction control system, bringing them to within 115.4 km (71.7 m) of the lunar surface and oriented ready for a burn of the Service Module’s main motor to slow them into lunar orbit.