Apollo 11 - Return to Orbit

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GET 124:03 - With twenty minutes to go before lift off Armstrong and Aldrin begin the final check list to clear the spacecraft for take off. Capcom Ron Evans reminds them of a revised procedure to leave the radar circuit breakers open to prevent another computer overload. Evans clears them for take off. Aldrin quips, 'Roger, Understand, We're number one on the runway.'

GET 124:05 - Armstrong test fires the attitude control thrusters to confirm that they are functioning correctly. Aldrin fires two squibs, small explosive charges that open valves in the craft's helium tanks to pressurize the engine's propellant tanks. The helium tank's pressure gauge does not show the expected drop that it should if it has opened correctly. They try again, repeating the process, but the pressure remains constant. They continue with the countdown checks, as the propellant tank gauges are showing that the tanks are fully pressurized. Aldrin arms the circuits to the circuits to the explosive bolts that will sever the ascent and descent stages just before the ascent engine's ignition. A communication check with Collins in Columbia brings them to the last two minutes of the countdown.

GET 124:20:58 - Aldrin arms the ascent engine and begins the final countdown.

GET 124:22:00 - The explosive bolts blow, separating the ascent stage; and, at the same instant, the ascent engine fires. Eagle lifts off from the moon's surface for its final flight. The four foot high, 3,500 pound thrust ascent engine accelerates Eagle out of the Sea of Tranquillity while the 'aggs and pings' guidance system fires the attitude thrusters to pitch the flight path west over the nearby craters Sabine and Ritter, to intercept the approaching Columbia's orbital path.

Eagle continued to gain height, wallowing slightly; and after seven minutes, having obtained an orbital height of over 60,000 feet, the engine shut down. The flight path took them into a 9.5 by 47 mile high elliptical orbit over the lunar equator to the far side of the moon, where they begin a number of manoeuvres, using the attitude thrusters to create a circular orbit about 15 miles below and 67 miles behind Columbia, closing at about 130 feet per second.

GET 127:55 - As Eagle and Columbia reappear from behind the moon for the second time they are lined up and closing to docking distance. Collins docks smoothly with Eagle; but, as he throws the switch for the hard dock, in his own words, '...all hell breaks loose'. The alignment of the two craft is slightly off; and, as the docking mechanism pulls the two craft together into a hard dock, the computers in both craft sense the yawing movement and try to compensate by firing their thrusters in competition with one another. It requires both Collins and Armstrong to isolate the LM's computer and correct the pitching craft's movement with their thrusters.

Under control once more the docking tunnel hatch was opened; and, after vacuuming themselves and the 'million dollar' sample boxes thoroughly, Armstrong and Aldrin transferred back into Columbia. Eagle was closed off and jettisoned to be left in orbit around the moon. It was abandoned in orbit with all its systems still running; but with the cooling water supply to its electronic systems cut off to allow flight engineers to monitor its demise. It was another eight hours before its signals faded and contact was lost. Eagle eventually crashed back on the lunar surface, as its orbit decayed; but the information obtained would later prove critical to the Apollo 13 mission. Eagle's final point of impact remains unknown.

GET 135:25 - Once more above the far side of the moon the service module's engine is fired for a two and a half minute burn to build up speed to an escape velocity of 5,300 mph, pushing Columbia out of lunar orbit and into a return path to earth.

GET 150:04 - The crew carry out a mid course correction in an otherwise largely uneventful return trip.

In one mid-course correction, the SM's thrusters were fired retrograde to slow the craft by 4.8 feet per second to align the flight path with the re-entry corridor, bringing it over the Pacific Ocean where the recovery fleet were awaiting its return. No further course adjustments proved necessary. Back on earth scientists were beginning to receive data from the moon bound seismometer; but they were having difficulty in locating the laser reflector, as they had not yet pinpointed Apollo 11's exact landing spot.

GET 177:31 - The crew send back their last television transmission to earth audiences. They give their impressions of the mission; they thank the scientists and technicians who had built the craft and developed the technology; and salute the will of the American people that had made the mission possible. Around the world a force of nine ships and 54 aircraft are taking up station, while 19 tracking stations are preparing for their return. The recovery ship, the aircraft carrier USS Hornet steams around the predicted splashdown point, some 1,000 miles south-west of Honolulu in the Pacific Ocean. The use of the carrier, the USS John F Kennedy had been vetoed by the Nixon administration.

Re-entry and Splashdown

GET 194:50 - Collins 'deadfaces' the circuits between the command and service modules, then arms and fires the pyrotechnics to separate the two parts of the craft. An explosive charge operates a guillotine that cuts through the connecting wiring and links between the two craft; and a ring of explosive bolts severs the final connection, allowing the service module to separate. The SM is jettisoned, leaving the CM weighing 12,250 pounds, one fifth of a percent of the original craft that lifted off the launch pad eight days previously, and the only part of Apollo 11 to return under controlled flight to earth. The CM manoeuvres to place its two inch thick heat shield forward, ready to protect the craft from the heat produced by friction with the atmosphere as it plunges in at 24,000 mph.

GET 195:03 - Heat begins to build up as Apollo re-enters the outer fringe of the earth's atmosphere. The heat shield, composed of carbon fibre plugs in a honeycomb matrix, protects the crew from a 5,000 degree external temperature, which ionises the surrounding air, cutting off radio waves and causing a total communication blackout with the craft during the re-entry flight, lasting about four minutes. The outer layers of the ablation material burn away taking heat from the craft, while blue and violet flames curl around the edge of the heat shield. The flames can be seen by the crew through their observation window, as they travel across the dawn sky, leaving a glowing ionised trail from 1,700 miles up range of the splashdown target area. The friction also begins to slow Apollo's velocity through the atmosphere.

As the craft plunged through the upper layers of the atmosphere, the computer began to manoeuvre the capsule through a parabolic, switchback-like curve designed to relieve the g forces being experienced by the crew. It also slowed the capsules rate of descent, allowing it to cool for a few moments, before continuing its downward flight into the denser atmosphere at a reduced velocity.

GET 195:12 - Apollo has slowed sufficiently to deploy drogue parachutes at 23,000 feet to stabilize the craft and slow its rate of descent still further. One of the tracking aircraft operating west of the target area gets a visual contact with Apollo. The drogues continue to slow the descent, until at 175 mph the three main recovery parachutes are deployed at 10,000 feet. Apollo descends through an eighteen knot wind speed and into a sea running a seven foot swell.

GET 195:18:35 - Splashdown in the Pacific at Latitude 13 degrees 19 min North, Longitude 169 degrees 9 min West. The end of Apollo 11's flight to the moon finally realises President John F Kennedy's challenge.

Recovery and Isolation

Four Navy Sea King helicopters from the recovery ship Hornet were already airborne and on their way to the spacecraft, which had been dragged upside down by the collapsing parachutes in the sea swell, into a 'Stable 2' position. Inflation of buoyancy bags brought the craft upright to a 'Stable 1' position. Divers from one of the Sea Kings jumped into the water and attached a flotation collar around the capsule and then withdrew to a dingy upwind of the spacecraft. Mindful of the possibility of 'Back Contamination', the crew were to be kept in isolation for 18 days to insure against the possible spread of any harmful bacteria brought back from the moon. One diver clad in a biological isolation suit remained with the spacecraft as the hatch was opened. He passed three more isolation suits to the Apollo crew to wear during their transfer to USS Hornet. The suits, which included respirators, permitted the crew to breath fresh air, but their exhalations were filtered to prevent the escape of bacteria.

As the Apollo crew left the capsule they were scrubbed down with a decontaminating iodine solution by the diver; who, in return, was brushed down by the astronauts. The outside of Apollo's hatch was also cleaned and sealed. The crew were picked up by the helicopter and transferred to Hornet, which on landing, was immediately lowered to one of the hanger decks and placed alongside an isolation cabin. The cabin, which displayed a notice, 'Hornet plus 3', above its observation window was to be the astronauts home until they were transferred to the Lunar Receiving Laboratory (LRL) quarantine quarters at Houston, Texas. The astronauts transferred between the helicopter and the isolation cabin; and a final cleaning of the helicopter and the deck where they had walked completed the transfer. They were later greeted by President Nixon, who had flown out to Hornet for the homecoming.

The Apollo crew in the isolation cabin were initially transferred to Honolulu, along with the Apollo spacecraft, and then on to more permanent quarters at the Lunar Receiving Laboratory at Houston, where they were debriefed on all aspects of the flight and recuperated, before being returned to the outside world two and a half weeks later. During one of the debriefings Collins was asked if he had any further comments, his reply: 'I want out!'

The samples returned by Apollo 11 provided the first tangible evidence of the moon's make up. The 44 pounds of moon rock and dust also provided some surprises. On opening the sample bags in the LRL, in view of full television coverage, the first sight of the rocks covered with dust looked like 'Dirty coal'. When cleaned and analysed, half of the rock samples proved to be igneous basalt, which had originated from the lava flows that had created the maria, proving that the moon had at one time been hot and active. Dating the samples showed them to be around 3.65 billion years old. The lava samples proved to have a high titanium content, indicating a low viscosity when molten and explaining their apparent dark colouring. A new titanium bearing mineral was also found and given the name Armalcolite, derived from the first letters of the crew's surnames, ARMstrong ALdrin and COLlins.

Other rocks were regolith breccias, rocks created by the fusing together of components of the regolith soil by the forces generated in high speed meteoric impact. Many of the rocks also exhibited minute 'zap pits', where they had been exposed to the rain of micro meteorites over aeons. The soil samples, which were mainly comprised of pulverised basalt, also provided a surprise in the form of a proportion of minute glass spherules, thought to have originated from the fusion of the rocks by the heat of high-speed impact. What the samples did not show was any sign of life. No evidence was found of any water, sedimentation or organic compounds, from which it was concluded that the moon had always been dry and lifeless.

The image of Columbia's descent and splash down was picked up on a television camera on one of the waiting recovery helicopters, and relayed to audiences throughout the world. The pictures were also displayed on one of the large screens on mission control's status board. Alongside, another screen bore the words:

I believe that this nation should commit itself to achieving the goal, before the decade is out, of landing a man on the moon and returning him safely to earth.
- John F Kennedy , 25 May, 1961

A second screen showed the words:

Task accomplished, 24 July, 1969.

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