Category How Apollo Flew to the Moon

A catalogue of 37 stars distributed across the sky was programmed into the rope memory of the onboard computer. There w’ere some quite faint stars in the list, but this w’as only because the brightest stars are unevenly distributed across the sky. Planners had w’anted to ensure that irrespective of the direction in which the fixed line of sight of the optics was pointed, the crew7 would find a star sufficiently bright within the range of the movable line of sight to view through the sextant. Haeh star had a numerical code in base eight (octal) so that the crewman could tell the computer which star he wished to use. or in other cases the computer w’ould indicate the star that it had chosen for a specific operation.

Some of the objects in the Apollo star list were not stars at all. Three numbers were set aside so that the Sun. Moon and Harth could be referenced by the crewman for other tasks, and there w’as also a code that allowed a ‘planet’ to be defined if needed. In fact this could be any celestial object and in some cases, this ’planet’ was actually a star, just not one that the computer knew about.

Three of the fainter stars in this list have unconventional names that were added as a practical joke by the crew of the ill-fated Apollo 1 during their training. Star 03,

Navi, is the middle name of Gus Grissom (Ivan) spelled backwards. Likewise, his two crewmates added oblique references to themselves among the Apollo star list: Star 17, Regor, is the first name of Roger Chaffee spelled backwards; and Edward White II gave his generational suffix to the prank by spelling ‘second’ backwards as Dnoces and applying it to Star 20. The people of Apollo kept these names in their literature as a mark of respect to a fallen crew and they have been known to appear in a few star atlases and books in succeeding years.

Soon after the crew of Apollo 8 had begun their coast to the Moon, they removed their suits and never put them back on for the rest of the flight. After all, there were no plans for a spacewalk or any undocking event to pose a risk to the integrity of the cabin’s pressure hull. After the flight, Frank Borman wondered whether they had been required at all. “I would not have hesitated to launch on Apollo 8 without pressure suits,” he said at the debriefing after the mission. He continued, "We wore them for about three hours and stowed them for 141 hours. I see no reason to include the pressure suits on a spacecraft that’s been through an altitude chamber.” However, suits were needed for the ascent to allow the crew to breathe pure oxygen, and for the whole flight in case the spacecraft’s hull was breached for some reason.

All subsequent flights did require the crews to suit up regularly, either for operational reasons (a walk on the Moon is an obvious example) or as a precaution when pyrotechnic charges were cutting pieces from the spacecraft. For example, the final jettison of the lunar module required an explosive cord to cut through the

tunnel wall just in front of the forward hatch.

In some ways, a spacesuit can be seen as the ultimate in extreme out­door gear. Just as a climber on the peak of Mount Everest has to dress up appropriately, an Apollo astro­naut had to protect himself from the conditions he was about to encoun­ter. Like the mountaineer, he had a supply of oxygen as well as protec­tion from the cold and the heat in the rays of the Sun. Two distinct types of suit were produced for Apollo. The CMP had a simpler suit while the surface crews’ suits were designed to support a back pack that allowed them to work on the lunar surface. The following refers to the surface suit.

Air to breathe was fed into the suit either from the back pack, called the

portable life support system (PLSS,

pronounced ‘pliss’), or from the spacecraft via hoses. A fine network of water-filled tubes worn next to the skin kept control of the suit’s internal temperature as the crewman worked. The main part of the suit had an airtight bladder with layers of Dacron fibre, Mylar foil and woven Teflon cloth to protect against heat and cold. The outermost of the suit’s 18 layers was white Teflon cloth that helped to protect against abrasion.

Instead of sunglasses or goggles, a polycarbonate helmet was worn over the head that allowed almost all-round vision. An additional cover, which was worn over the helmet, included a visor that was thinly plated with gold to reflect light and infra-red radiation. It also had a set of pull-down shades at the top and to each side that the crewman could deploy to protect his eyes from the intense lunar sunlight.

When inflated to a pressure of 250 millibars, the suits ballooned and stiffened, which made them difficult to bend and hold in a set position. To counter this, flexible joints were built into various parts of the suit and a network of cables within the layers allowed a posture to be adopted and held. The gloves contained thermal insulation and the fingertips were made from silicone rubber to help to improve the astronaut’s sense of touch. On Apollo 15, David Scott arranged to have his fingertips up against the end of his gloves with the result that, over the course of his 18 hours on the surface, his bruised fingernails had begun to lift from his fingers.

The PLSS carried batteries to power the pumps and communications gear, high – pressure oxygen for breathing, a lithium hydroxide canister for removing carbon dioxide from the suit’s air, and a supply of water for cooling. The cooling element was a clever piece of kit called a sublimator. Water was fed through a porous metal plate where, on reaching a vacuum, it evaporated, thereby removing heat to form ice. From that point on, the ice would continue to sublimate to space and take heat with it as long as more water was fed to replace the lost ice. This cooled the separate water circuit that went around the crewman’s skin.

By the end of a J-mission’s lunar stay, a crewman’s suit was a heavily abused item of clothing that had undergone 20 hours of intense work in the hostile environment of the Moon. Often a crewman would accidentally fall and cover himself in dirt, or the guards over the w’heels of the rover would break off and the crew would be sprayed with dust as they drove. The suit’s outer layer was therefore heavily ingrained with dirt and its locking rings around the neck and wrists w ould threaten to seize owing to the highly abrasive nature of the all-pervasive lunar dust. These multimillion-dollar wonders of engineering are now museum fodder.

After they woke up on the final day of their coast to the Moon, a crew would set about their usual post-sleep chores of reporting their condition to mission control and preparing their breakfast. Normally the spacecraft w’as slowly turning around in its barbecue roll, spreading the heat of the Sun across its surface. While the crew slept, engineers at the ground stations on Earth had taken precise measurements of the spacecraft’s position and velocity to accurately monitor its trajectory. Using this data, FIDO, the flight dynamics flight controller in the MOCR, calculated the amount by which the approach to the Moon needed to be adjusted, if at all. Was the spacecraft coming in too quickly or Loo slowly to pass around the far side at the correct altitude? Was it within the correct orbital plane to pass over the desired landscape? Based on the results of overnight radio tracking, and with the help of the big computers in the real-time computer complex (RTCC), FIDO calculated the details of a burn to be carried out at the fourth opportunity for a mid-course correction, usually scheduled to occur five hours prior to entry into lunar orbit. The details of this corrective burn w’ere read up to the crew1, along with the results of calculations by the Retro flight controller.

While FIDO had been deciding w’here they wanted the spacecraft to fly. Retro was busily working out what to do if something w’ent w’rong. He had Lw’o scenarios to consider: the first was if something were to prevent or impair the LOI burn; and the second was for the situation in w’hich the LOI burn w’as completed successfully but the crew7 were required Lo return Lo Earth at the earliest opportunity. Having decided the manoeuvres that the crew’ should make in these scenarios, it was then important that the details be passed up to the spacecraft while it w’as still in communication with Earth. The mantra was that they should always have the data necessary to get home without further assistance from mission control, in case communications w’ere lost.