Category How to Find the Apollo Landing Sites

Moon Observing. Basics and Book. Tutorial: What. You Need to Know

Moon Observing. Basics and Book. Tutorial: What. You Need to Know

Fig. 1.1 Courtesy of NASA

J. L. Chen, How to Find the Apollo Landing Sites,

The Patrick Moore Practical Astronomy Series, DOI 10.1007/978-3-319-06456-7_1, © Springer International Publishing Switzerland 2014

The Moon has long held the fascination of mankind. It is the biggest and the brightest object in the night sky. Man has gazed upon the Moon for centuries with awe and imagined journeys there. Great, and not-so-great, literature has been written over the centuries, both prose and poetry, about the Moon. Nature itself has adapted to and has synchronized to the rhythms and timing of the lunar cycle in determining reproduction, migrations, and other organic activities. The contribution of the Moon to life on Earth, and to mankind and his culture is extensive.

Before proceeding to the pictorial portion of this book, there are some basics about the Moon that will help with observing it and appreciating the photos herein.

The Moon is the largest natural moon in proportion to its primary planet in the solar system. It orbits the Earth in an elliptical orbit, with a perigee of 225,741 miles and an apogee of 251,968 miles at an orbital inclination to the ecliptic of 5.125°. This inclination translates to between 18.29° to 28.58° to the Earth’s equa­tor. The Moon has a mean radius of 1,737.1 miles, is spherical in shape, although it is slightly flattened due the gravitational force of the Earth. The lunar mass is

0. 0123 that of Earth. Gravity on the Moon is 0.165.4 g. To launch back into lunar orbit, Apollo Lunar Module (LM) astronauts needed only an escape velocity of 2.38 km/s, as compared to the escape velocity of Earth of 11.2 km/s.

The Moon is the second brightest celestial object that can be seen from Earth, with only the Sun outshining it. At full phase, the Moon shines at -12.74 magni­tude. Unlike the Sun, where direct viewing can cause permanent eye damage with­out proper equipment and eye protection, the Moon can be readily observed safely. The Moon has an albedo of 0.136, which is the ratio of reflected sunlight to the sunlight that hits it. Moonlight does not possess the heat that is characteristic of direct sunlight, and thus cannot cause eye damage. A full Moon can be uncomfortably bright, but it is safe to view. The angular diameter of the Moon for Earth bound observers varies from 29.3 to 34.1 arc minutes.

Commonly thought of as being airless, the Moon possesses a very, very slight atmosphere. Atmospheric pressure varies from a daylight level of 0.0000001 to 0.0000000001 pascals This thin lunar atmosphere consists of argon, helium, hydro­gen, potassium, and radon gases.

The Moon is in synchronous rotation with the Earth, thus always showing the same face towards Earth. Because of the Moon’s orbital inclination and it’s ellipti­cal orbit, roughly 64 % of its near face can be seen and mapped from Earth, but not all at one time.

Apollo 14

Dates: 31 January – 9 February 1971

Crew: Commander – Alan Shepard CM Pilot – Stuart Roosa LM Pilot – Edgar Mitchell

Command Module: Kitty Hawk Lunar Module: Antares

Accomplishments: Third Lunar Landing, completed Apollo 13 mission for Fra Mauro Region. Most famous for Alan Shepard’s golf shots on the Moon.

J. L. Chen, How to Find the Apollo Landing Sites,

The Patrick Moore Practical Astronomy Series, DOI 10.1007/978-3-319-06456-7_6, © Springer International Publishing Switzerland 2014

Apollo 14

Fig. 6.1 Apollo 14 Insignia. Courtesy of NASA

Apollo 14

Apollo 14 was the third lunar landing, the last of the H series missions, and marked the return to space by America’s first astronaut in space, Alan Shepard. Apollo 14 featured Stuart Roosa as the CM pilot and Edgar Mitchell as the LM pilot, both on their first and, as it turned out, only space missions. With two space rookies, and one astronaut with only a suborbital 15 minutes space ride under his belt, the crew of the Apollo 14 were affectionately called “The Rookies.”

The Apollo mission almost did not happen for Shepard. From 1964 to 1968, Shepard found himself grounded because of Meniere’s Disease, an inner ear condi­tion that affects hearing and balance. It is characterized by episodes of vertigo, tin­nitus, and hearing loss. Meniere’s Disease greatly affected Shepard’s sense of balance, resulting in random and debilitating attacks of extreme vertigo. The condition obvi­ously prevents pilots and astronauts from performing aviation and space related tasks.

According to Andrew Chaikin, in his book “A Man on the Moon,” original Mercury Seven astronaut Gordon “Gordo” Cooper was scheduled to serve as mission commander of Apollo 14. However, since his remarkable Mercury flight of “Faith 7”, Cooper had gradually fallen out of favor with NASA officials due to his casual approach to training and his critical attitude towards NASA management. The best assignments for Cooper were as backup pilot for Gemini 12, and as backup commander for Apollo 10. Historically, a backup crew at NASA would receive a prime crew assignment two or three missions later. Faith 7 proved to be Cooper’s only spaceflight, and Alan Shepard became the only Mercury Seven astro­naut to reach the Moon. NASA had lost faith in Gordo.

Alan Shepard’s inner ear condition was cured with a new surgical method for treating Meniere’s Disease. And with the internal politics of NASA and Gordon Cooper’s somewhat casual and rebellious attitude, Shepard worked hard to regain flight status, and was named mission commander of Apollo 14, over the protests of Gordon Cooper.

As with the previous Apollo flights, not all went as planned on Apollo 14. The mission experienced an extended early problem in its mission. At the beginning of the mission, the Kitty Hawk had difficulty achieving capture and docking with the LM Antares. The standard Apollo maneuver called for the Command/Service Module to separate, turnaround and dock with the LM stored in the fairing behind the CSM. Problems for CM pilot Roosa occurred immediately. Although the docking probe was properly maneuvered, the docking latches did not engage. Repeated attempts to dock went on for 1 hour and 42 minutes, until CM pilot Roosa received directions from Gene Cernan at Mission Control to hold Kitty Hawk against Antares using its thrusters. The docking probe was then retracted out of the way, with the hope of triggering the docking latches. The docking was successful, and no further docking problems were encountered during the mission. The best guess for the problem was that a stray piece of debris had gotten caught up in the docking mechanism.

The docking problem was just the first of three events that could have caused a mission abort. After separating from Kitty Hawk in lunar orbit, the Antares experi­enced two other major problems.

The first occurred when the LM computer began getting an abort signal from a faulty switch. NASA initially believed that the LM computer was receiving errone­ous readings from a rogue solder bead shaking loose and closing the circuit as it floated between the switch and the contact. Tapping on the panel next to the switch to dislodge the debris seemed to work at first, but the circuit soon closed again. If the erroneous signal recurred after the descent engine fired, the computer would think the signal was real and would initiate an auto-abort, causing the ascent stage to separate from the descent stage and climb back into orbit. Or if the problem occurred during the Dead Man’s Zone, a major disaster was in store for the mission and would prove fatal for its crew. NASA and the software development engineers at MIT struggled and fortunately found a solution by reprogramming the flight software to ignore the false signal. With time being of essence, the software modi­fications were communicated to the crew verbally, and Mitchell manually entered the machine language changes into the LM computer.

A second problem occurred during the powered descent, when a previously unknown design bug in the LM radar altimeter caused the radar to fail and lock auto­matically onto the Moon’s surface, depriving the LM computer of critical LM altitude and groundspeed information. The radar altimeter successfully acquired a signal near 18,000 feet after the astronauts toggled the landing radar breaker off and on, just in time to save the landing. Shepard then manually landed the LM, a landing that historically was closer to its intended target than any of the other six Apollo Moon landings.

Apollo 14

Fig. 6.3 Wide view of Apollo 14 site. Courtesy of the author

Apollo 14

Fig. 6.4 Closer view of Apollo 14 landing site. Courtesy of the author

Apollo 14

Fig. 6.5 Close-up zoom of Apollo 14 landing site. Courtesy of the author

Assuming success in sighting the Apollo 12 landing site, the amateur astrono­mer probably has spotted the Apollo 14 site in the same field of view. The Fra Mauro landing site is basically next door to the Apollo 12 Sea of Oceans site. The starting point for the backyard observer is again the terraced crater Copernicus. South of Copernicus, and east of crater Reinhold, is the crater Gambart. From there, the observer needs to go south and slightly west to locate Fra Mauro crater. The Apollo 14 landing site is actually just outside the Fra Mauro crater on the northern end.

Apollo 14

Fig. 6.6 LRO view of Apollo 14 Landing Site. Photo courtesy of NASA and Arizona State University

Apollo 14 inherited the Apollo 13 mission, which was targeted to land in the geologic unit known as the Fra Mauro Formation. The landing site selected for Apollo 14 was in the Fra Mauro Formation near Cone Crater, with the primary objective of sampling material excavated by the Imbrium impact.

With the successful pinpoint landing of Apollo 12, NASA mission planners were more confident in achieving landings in more challenging but geologically more interesting regions. However, planned landing sites were still restricted to regions near the equator. Also factored into the site selection was the requirement for the astronauts to accomplish scientific objectives within the confines of two 4-hours-long walking EVAs.

Fra Mauro was formed from ejected lunar material from the large impact that formed the Imbrium Basin. The widely distributed Fra Mauro material can be seen through backyard and research telescopes across the nearside of the Moon.

The Apollo 14 landing site therefore provides a geologically stratified or layered marker, dividing features that are older than the Imbrium impact from those that are younger. A precise age could be assigned to this geologic transition by geolo­gists studying the returned samples from Fra Mauro. Also, because the Fra Mauro was ejected by the Imbrium impactor, scientists hoped that samples col­lected would have originated deep in the Moon’s crust, perhaps from tens of kilometers below the surface. The specific landing site within the Fra Mauro was near the younger Cone Crater. Cone Crater was chosen because it is large enough to penetrate through the lunar surface and exposed the layered rocks that were to be sampled.

Apollo 14

Fig. 6.7 Apollo 14 ALSEP. Courtesy of NASA

Figure 6.7 shows a photo taken by Alan Shepard of the SIDE/CCIG toward the Central Station, which is northwest of the instruments. The Suprathermal Ion Detector Experiment (SIDE) is at bottom center and the Cold Cathode Ion Gauge (CCIG) is at bottom right. Nearer the Central Station, from left to right are the MET, the geophone anchor (the stack tilted to the right), the Central Station, the mortar package for the Active Seismic Experiment, the Radioisotope Thermoelectric Generator (RTG), the Passive Seismic Experiment (PSE), and the Charged-Particle Lunar Environment Experiment (CPLEE). Note the inbound MET track coming into the picture at the right.

Apollo 14

Fig. 6.8 Apollo 14 RTG, Central Station, and part ofLRRR. Courtesy ofNASA

The radioisotope thermoelectric generator, or RTG, was used as a power generator using an array of thermocouples to convert the plutonium-238 decay heat into electricity. The RTG served as the main power source for each ALSEP deployed by the Apollo missions.

Apollo 14

Fig. 6.9 Apollo 14 CPLEE, some of the equipment Apollo 14 astronauts Alan Shepard and Edgar Mitchell set up on Fra Mauro landing site. Courtesy of NASA

The Charged Particle Lunar Environment Experiment, or CPLEE (in Fig. 6.9), was deployed on Apollo 14 to measure plasmas on the Moon. It measured electrons and both positively and negatively charged ions near the Moon’s surface with ener­gies between 50 and 50,000 eV. Less energetic ions were studied by the Suprathermal Ion Detector Experiment and more energetic particles were studied by the Cosmic Ray Detector experiment.

An unexpected result of CPLEE was recorded as the Apollo 14 lunar module ascent stage impacted the Moon after the crew had returned to lunar orbit and jetti­soned it. Not one, but two distinct clouds of material from this impact were recorded by the CPLEE. The ascent stage impact occurred at a distance of about 66 km from the Apollo 14 landing site with approximately 180 kg of unspent rocket fuel left on board. The two clouds were about 14 and 7 km across and had expanded away from the impact site at velocities of about 1 km per second. This expansion velocity is simi­lar to that measured by the Suprathermal Ion Detector for other impacts on the Moon.

Apollo 14

Fig. 6.10 Modular Equipment Transporter (MET) with Apollo 14 Commander Alan Shepard nearby. Courtesy of NASA

Nicknamed the “rickshaw,” the MET seen in Fig. 6.10 was a cart for carrying around tools, cameras and sample cases on the lunar surface. Shepard can be identi­fied by the vertical stripe on his helmet. After Apollo 13, the commander’s spacesuit had red stripes on the helmet, arms, and one leg, to help identify them in photo­graphs. Apollo 14 was the only mission that the MET was used, as the functionality of the MET was superseded by the lunar rover.

Apollo 14

Fig. 6.11 The results of Shepard and Mitchell’s Lunar Sports. Courtesy of NASA

Alan Shepard’s extraterrestrial six-iron golf shot became the most famous extracurricular lunar activity ever planned and executed. Shepard smuggled on board a golf head from a six-iron, modified to attach to the handle of a lunar excavation tool, and two golf balls. As designed, the Apollo lunar spacesuit was limited in flex­ibility and range of motion. Shepard had to take single handed swings at the two golf balls. The first golf ball was topped, and can be seen in the small crater in Fig. 6.11. The second ball went “miles and miles and miles” according to Shepard, but was later estimated to have traveled a distance as 200-400 yards, which to a golfer is a remarkable distance for a six-iron. Mitchell then threw a lunar scoop handle as if it were a javelin, landing it near the first golf ball, and also seen in Fig. 6.11.

Even Stuart Roosa joined in with his own extracurricular activity of sorts. As a young man, Stuart Roosa worked in forestry, and for Apollo 14 he took several hundred tree seeds on the flight. These were germinated after the return to Earth, and these commemorative Moon Trees were widely distributed around the world.

Apollo 14

Fig. 6.12 ALSEP showing the CCG/SIDE with the Central Station, RTG, PSE, and CPLEE in the background. Courtesy of NASA

In the same implementation as Apollo 12, the Cold Cathode Gauge (CCG) mea­suring the atmospheric pressure of the lunar atmosphere is mounted on the Suprathermal Ion Detector Experiment (SIDE). These experiments provided data on the lunar environment by measuring the various properties of positive ions in the lunar ionosphere, collecting data on the plasma interaction between solar wind and the Moon, and measuring the electrical potential of the Lunar surface. In the ALSEP setup, the Central Station served as the command and control center for the ALSEP station. It received commands from Earth, transmitted data, and distributed power to each experiment. Communications with Earth were achieved through an antenna mounted on top of the Central Station and pointed towards Earth by the astronauts. Transmitters, receivers, data processors and multiplexers were housed within the Central Station.

Figure 6.12 includes the PSE that added additional seismic recording capability to that available from the Apollo 12 PSE. Apollo 14 also carried an Active Seismic Experiment, where seismic data was gathered from a “thumper” carried in the MET and activated as the astronauts traversed. Some explosive charges were also part of the setup. These charges were to be activated after the astronauts returned, but the charges failed.

As with the previous Apollo missions, our old friend the Solar Wind Composition Experiment (SWCE) was part of the Apollo 14 experiment complement. Additionally, a Lunar Portable Magnetometer (LPM) was included to measure how the Moon’s magnetic field varies in local regions. The LPM was not part of the ALSEP, but was mounted on the MET. Its data was measured as the astronauts traversed the local lunar region during their two EVAs’.

Apollo 14

Fig. 6.13 Astronaut Edgar Mitchell, LM pilot, photographed this view showing astronaut Alan Shepard Jr. and the LM Antares. Mitchell took this picture during the second scheduled moon walk, on February 6, 1971. Courtesy of NASA

In addition to the lunar surface activities, Stuart Roosa kept busy performing several studies of the Moon from lunar orbit. Two experiments performed specifi­cally from the CM Kitty Hawk while in orbit over the Moon were as follows:

The S-Band Transponder Experiment measured regional variations in the Moon’s gravitational acceleration. The S-band Transponder Experiment was per­formed on Apollo 14 and all the following Apollo missions. The frequency of radio waves transmitted by the spacecraft was accurately measured by Earthbound receivers, and compared with the frequency of the waves as transmitted by the spacecraft. The Doppler Effect caused by changes in the frequency of the radio waves from the Apollo 14 spacecraft’s motion was measured. By comparing the difference between the frequency of the radio waves from the spacecraft and at Earth reference, the spacecraft’s velocity was determined with very high accuracy. As the Apollo CM passed over gravity variations, the changes in the spacecraft’s velocity were measured. The primary gravitational influence on the spacecraft is the Moon’s gravity. Other objects, particularly the Earth and Sun, also affect the spacecraft, but the contributions of these objects can be readily calculated and fac­tored out of the equation. As a result, this experiment provided maps of how the Moon’s gravity varies with location across its surface. This experiment attempted to explain the gravity variations of the Moon and the presence of mascons. This experiment predated GRAIL, as mentioned in Chap. 5 that finally solved the vari­able gravity caused by mascons.

The Bistatic Radar Experiment measured scattering of radar waves from the lunar surface. The Bistatic Radar Experiment was performed on Apollo 14, 15, and 16. In this experiment, radio waves were transmitted from the Command and Service Modules, bounced off the Moon’s surface, and recorded at tracking stations in California. The properties of the waves recorded on Earth were analyzed to determine the roughness of the Moon’s surface in the region where the radio beam was reflected. In addition, the electrical properties of the lunar surface, specifically the dielectric constant of the lunar rocks, were also determined. The region ana­lyzed by this method was a swath of about 10 km across the Moon’s surface as the spacecraft moved in its orbit.

Performed primarily to and from the Moon, the Apollo 14 crew performed sev­eral experiments intended to explore various aspects of the space environment:

• The Window Meteoroid Experiment studied impacts on the windows of the Apollo 14 Command Module to obtain information about the size and distribu­tion of very small micrometeorites. Only two micrometeorite impacts were identified following Apollo 14s return to Earth and examination under an elec­tron microscope. One meteoroid impact was identified as 25 qm in diameter, while the other measured 85 x 130 qm.

• The Composite Casting Experiment studied the solidification of immiscible compositions in microgravity. Eleven samples of various immiscible composi­tions were heated, mixed by either premixed or mixed by shaking, and allowed to solidify by cooling in 0-g. The samples were heated in a small chamber and returned to Earth for examination and testing. Post-mission laboratory analysis indicated that a more homogeneous mixing was achieved than is possible with similar samples on Earth.

• The Electrophoresis Demonstration studied the separation of organic molecules in an electric field. Many organic molecules, when placed in water solutions, will migrate if an electric field is applied. Molecules of different substances move at different speeds; thus, they will separate. Gravity and thermal convection tend to diminish this separation if the solution density changes upon concentration of these molecules. A small unit was used to demonstrate the separations obtained with three sample mixtures having widely different molecular weights: (1) a mix of red and blue organic dyes, (2) human hemoglobin, and (3) DNA from salmon sperm. Post-mission review of the filmed data reveals that the red and blue organic dyes separated better and sharper than on Earth, as expected; however, separation of the hemoglobin and DNA could not be detected. Post-flight exami­nation of the apparatus indicated that the samples were not released effectively (due to injection problems caused by the slide valve) to permit good separation, causing the dyes to streak. The hemoglobin and DNA samples did not separate because they contained bacteria that consumed the organic molecules prior to activation of the apparatus. Oops!

• The Heat Flow and Convection Demonstration studied convective flow and heat transport driven by surface tension. Three different types of test cells were used to detect convection directly, or detect convective effects by measurement of heat flow rates in fluids: radial, flow pattern, and zone. The heat flow rates were visu­ally displayed by color-sensitive, liquid crystal thermal strips and the color changes filmed with the Data Acquisition Camera. It was demonstrated that sur­face tension in fluids under weightless conditions develops a regular pattern of convection cells known as Benard cells. Zone heating of liquid samples pro­duced an unexpected cyclic heat-flow pattern.

• The Liquid Transfer Demonstration studied how different types of tank design influenced the pumping of liquids between tanks in microgravity. The demon­stration had two sets of tanks, one set containing baffles and the other without baffles. Transfer of liquid between the un-baffled tanks was unsuccessful, as expected. Transfer between the baffled tanks demonstrated the effectiveness of two different baffle designs. The liquid-transfer demonstration clearly showed that suitable baffles inside a tank at 0-g permit positive expulsion of liquid con­tents, taking advantage of the surface-tension properties of the liquid. Orderly inflow into the receiver tank with no liquid loss through the gas vent was also successful.

• The Light Flashes Experiment studied light flashes seen by the crew that are related to charged particles in space. This experiment concluded that some of the flashes observed in space may be caused by direct ionization interactions of cosmic rays with the retina.

An experiment on extra-sensory perception, ESP, was independently performed

by Edgar Mitchell. This ESP experiment was not sanctioned by NASA. Prior to the

mission, Mitchell made arrangements with test subjects to receive his mentally

“transmitted” images of random symbols that he would project during his rest periods. This somewhat “New Age” experiment produced some unexpected results. The test subjects were wrong far more often than random probabilities would dic­tate. Mitchell provided a possible explanation for this result. He felt the test sub­jects did not factor in the 40 minutes weather delay that occurred during the Apollo 14 launch. Hence, Mitchell’s projection of these images were not synchronized with the test subjects ESP reception periods. Mitchell proposed that the test sub­ject’s subconscious minds knew something was amiss, and that the experiment was not a failure. The more likely grade for the experiment would be that the results were inconclusive, at best, and at worst “New Age” pablum.

The return of the Apollo 14 astronauts marked the final time that returning Apollo astronauts were subjected to quarantine following their mission. The Apollo 11, 12, and 14 crews were isolated in a special quarantine chamber following their missions as a precaution to any potential lunar microbes infecting them and pre­venting any spread to the Earth environment. It was concluded that the Moon was lifeless, with no microbes, viruses, or bug-eyed monsters. The crews of Apollo 15, 16, and 17 were able to intermingle with the NASA and U. S. Navy personnel immediately following their reentry and landings. As a reminder, quarantine for Apollo 13 was not necessary, since they never landed on the Moon.

Upon the return of the crew to the CM Kitty Hawk, the ascent stage of Antares was sent to the surface of the Moon to provide seismic data. The ascent stage of Lunar Module Antares impacted the Moon on February 6, 7:45 PM EST, at longi­tude 3.42° S latitude 19.67° W. Both the Apollo 12 PSE and the newly setup Apollo 14 PSE recorded the Antares’s impact, which occurred between the two seismom­eters. The resulting impact rang for an hour-and-a-half, with both ASE setups recording the event. Antares’ descent stage and the mission’s other equipment remain at Fra Mauro at 3.65° S and 17.47° W.

With the precedent established with the Apollo 13 S-IVB third stage, the Apollo 14 Saturn third stage was intentionally impacted onto the Moon at longitude 8.09° South and latitude 26.02° West. Again, this event provided data to the Apollo 12 PSE using a known size and mass.

The Apollo 14 Command Module Kitty Hawk is on display at the Apollo/Saturn V building at the Kennedy Space Center.

Human Risks and Safety

Throughout the history of manned spaceflight, both astronauts and cosmonauts have experienced both short term and long term effects from their time away from Earth’s gravity. In the relatively short period the Apollo astronauts traveled to the Moon and back, mostly short term effects were experienced, but the longer periods spent on the ISS have shown some long term effects that can be detrimental to Mars-bound space explorers.

The human cardiovascular system circulates fluids through the body, pushing against gravity to prevent blood from pooling in the legs and bringing blood to the brain. In the microgravity of space, the cardiovascular system is not taxed as hard, triggering a fluid shift. As fluids move up from the lower body to the trunk, the heart rate increases and blood pressure rises. Astronauts experience puffy faces, headaches, nasal congestion and skinny “bird” legs as a result. Additionally, over a third of all astronauts experience some form of motion sickness in space because of the blood circulation changes. Symptoms of space sickness, including nausea and vomiting, headaches, malaise and dizziness, usually subside within 2 or 3 days.

Some evidence suggests that microgravity causes astronauts’ red blood cells to change. The red blood cells appear to change shape in space, becoming more spherical, and fewer cells populate bone marrow. Cells do return to normal once back under Earth-normal gravity however, even after a long-term mission.

Astronauts returning from missions have been found to be more prone to infec­tion, both viral as well as bacterial and fungal. Long term studies in space and Antarctica have shown that isolation and sleep deprivation may result in a weakened T-lymphocyte system, leading to compromised immunity. A high probability of increased allergy symptoms has been noted. The immune system is unable to adapt under microgravity conditions. A future Mars-bound crew will need a supply of antibacterial, anti-fungal, and antiviral drugs and medications. A Mars mission that extends beyond 6 months will mean these drugs will reach their expiration dates, thus inviting the need for some pharmaceutical capability onboard. A shorter 39-day-to-Mars mission reduces this risk.

A well known effect of microgravity is the atrophy the muscular structure. Astronauts onboard the ISS counter these effects by exercising up to 2 hours a day.

The microgravity of space triggers the human body to excrete calcium and phos­phorus (in urine and feces), resulting in rapid bone loss. On the shorter duration Apollo missions, the calcium and phosphorus loss was minimal, and the Apollo astronauts quickly recovered their bones density. A 2 year or longer Mars mission can result in an astronaut’s bone density loss to be equivalent to a lifetime on Earth. Like osteoporosis on Earth, bone loss in space can lead to fractures, weakness and painful urinary stones. The most dramatic changes occur in the heel bone, femoral neck, lumbar spine and pelvis. Exercise in space and upon return can help slow the loss, but it will take 2 years or more of dedicated, consistent training upon return to repair it. Artificial gravity would also serve to mitigate this problem if it is a part of the mission design.

All Apollo missions conducted the Light Flashes Experiment in an effort to explain the flashes of light that seem to appear behind the astronaut’s eyelids. The result of the experiment showed that galactic cosmic rays passed through the astro­naut’s brains causing the retinal flashes. These flashes are just symptomatic of a much larger problem. Cosmic rays and the radiation effects of solar flares expose astronauts to high levels of ionizing radiation. The Apollo astronauts were fortunate that during their missions, other than the light show they experienced when they closed their eyes, no solar flares occurred. A solar flare had the potential of causing the loss of the LM crew on the lunar surface. The LM construction and the lunar spacesuits provided minimal radiation shielding.

Unrelated to the light flashes, medical doctors and scientists are showing some concern over a possible loss of eyesight from extended microgravity exposure. NASA has reported that 15 male astronauts returning from extended missions in space have experienced confirmed visual and anatomical changes during or after long-duration flights. It is continuing to be studied, with current thought being related to ocular fluid shifts due to microgravity as a contributing factor.

The radiation in deep space can damage atoms in human cells, leading to decreased immunity and a higher risk of cataracts, cancer, heart disease, damage to the central nervous system and brain damage. Recognize that Mars does not have a global magnetic field to shield the planet from solar radiation particles, nor does it have a thick atmosphere to help filter out cosmic rays. Long-term exposure to ion­izing radiation in open space and on the planet surface is a significant concern for the crew of the Mars mission.

The Radiation Assessment Detector (RAD) aboard the Mars rover Curiosity produced detailed measurements of the absorbed dose, and dose equivalent from galactic cosmic rays, and solar energetic particles en route and from the surface of Mars. The numbers from the RAD are startling high. For the round trip, based on Curiosity’s RAD data, an astronaut would receive radiation from both cosmic gamma rays and solar activity approximately 0.66 Sv during a 180 day flight to Mars.

A 500 day exposure on the surface of Mars would result in each astronaut receiv­ing approximately 1 Sv. Long-term population studies have shown that exposure to radiation increases a person’s lifetime cancer risk; exposure to a dose of 1 Sv is associated with a 5 % increase in fatal cancer risk. NASA has established a 3 % increased risk of fatal cancer as an acceptable career limit for astronauts in low earth orbit, such as extended stays on the ISS. NASA has not established a limit for deep space missions.

A number of solutions are being explored to help protect astronauts, including antioxidant-rich foods, such as blueberries and strawberries and close monitoring of radiation levels combined with the use of radiation shields. Protection from solar flares, however, poses a technological problem that is solvable at the price of addi­tional weight of protective shielding.

Astronauts returning to Earth risk low blood pressure. A sudden reintroduction of gravity makes the blood in astronauts’ bodies rush down, resulting in dizziness and lightheadedness. Tiny muscles in veins that send blood uphill can atrophy after prolonged periods of microgravity, and can fail to push blood back up to the heart. Astronauts can experience fainting or be unable to remain standing. Mir cosmo­nauts had to be carried off their landing craft by stretcher due to the severe drop their blood pressure following long missions. A prolonged mission to Mars will result in returning astronauts needing to drink salt water to increase the volume of fluids in their bodies, wear G-suits (rubberized full body suits which are inflated to squeeze the extremities) or potentially use new drugs to increase blood pressure.

Apollo moon missions took several days to transition from Earth orbit to the Moon, with the Earth within of a few days reach and communications links with only a handful of seconds latency. The manned mission to Mars will not have those luxuries. The travel time to and from Mars will be measured in terms of months or years, not days. Communication latency will be measured in terms of a maximum of 22 minutes, not seconds.

Medical aid for Space Shuttle missions and ISS missions can be accommodated with near real-time communications, on board supplies, and in an emergency, a relatively timely re-entry and return to Earth. A Mars mission, as it progresses towards its goal, will not have the luxury of a quick and timely return to Earth in case of medical emergency. Any real-time communications to guide the crew through a medical procedure will be severely handicapped by the communications delay because of the distance.

A different medical philosophy is required, utilizing lessons learned from the Apollo, Space Shuttle, long-term Antarctic, and ISS experiences. Five decades of American and Russian spaceflight have yielded a greater understanding of space medicine and the effects of weightlessness on the human body. The development of a comprehensive Mars healthcare system will allow for autonomous health care, with a combination of advanced medical instrumentation, medical training of the crew, and the possible selection of a medical doctor for inclusion as part of the Mars crew. It will need to support the Mars crew members for both the journey to and from Mars, and surface activities. The medical system must accommodate a wide array of human illness and conditions, while being prepared for emergencies caused by accidents. In addition, the medical system will incorporate both environ­mental monitoring and exercise countermeasures to ensure wellness and maintain crew health.

The return to Earth from Mars will likely require a quarantine period for the same reasons the crews of Apollo 11, 12, and 14 experienced. It is unknown if there is any microbial life on Mars, harmful or otherwise. A quarantine in an environment external to Earth would be prudent to avoid any possible contamination of Earth. A likely site might be at or near an established Moon base. Isolation could be conducted on an Earth-orbital quarantine module, perhaps in conjunction and monitored by personnel with the ISS.

Lunar Phases

Waxing, waning, first quarter, gibbous Moon, half Moon, full Moon, third quarter, waning Moon – the vocabulary for the different phases of the Moon can be and is daunting and confusing. Since sighting and observing the Apollo landing sites is dependent on the phase of the Moon for best views, it is best to review and clarify the various terms.

1. The Crescent Moon can be seen in the first 5 days after the New Moon. The line that differentiates the sunlit Moon and the dark shadowed Moon is known as the terminator (the reader can insert their own sci fi movie joke here). The crescent moon also represents the waxing phase of the Moon, with waxing describing the gradual illumination towards the full Moon. During the waxing phase of the Moon, the terminator begins on the eastern edge of the Moon and on subsequent days proceeds westward. The crescent Moon is a very attractive phase of the Moon, with deep shadows from the mountains and within craters. Look for the peaks of lunar mountains being illuminated while the lower elevations are still enshrouded in darkness. However, this early phase is of little interest to the observer seeking to discover the Apollo landing sites, since none are illuminated by sunlight at this time.

2. The next 3 days, days 6, 7, and 8, are the half Moon phase. This term is clearly named as half of the Moon being illuminated by sunlight. Confusingly, this phase can also be referred to as the first quarter. The lunar cycle proceeds from new Moon, first quarter, full Moon, last Quarter, and back to new Moon. The Moon is still waxing towards full. This is when the first opportunity is provided to view the Apollo landing sites. The earliest Apollo site to be clearly visible is the Apollo 17 on day 6, although sometimes Day 5 provides a glimpse. By Day 8, all Apollo landing sites with the exception of Apollo 12 can be seen during this half Moon phase.

3. Days 9 through 11 represents the gibbous Moon, which for all intents and pur­poses means more than half but less than full. The Moon is still waxing towards a full Moon. By now all the Apollo sites are visible to the earthbound observer. For amateur astronomers, the lead up to the full Moon is the best observing period since the terminator (the line separating sunlight lit and dark) provides shadows that can provide a 3D effect in lunar observations.

4. The Full Moon on days 12-16 are obviously days for locating the Apollo sites, although the full Moon can appear very bright. The brightness of the Moon will not damage the viewer’s eyesight (never look at the Sun unless properly equipped.), although some personal comfort benefits can be gained from using neutral density filters or polarizing filters to calm down the brightness of the moonlight. Because of the lack of shadows, the Moon tends to look a little flat from the direct reflection of sunlight and the lack of shadows.

5. The last 2 weeks of the lunar phases represent the Waning Moon, as the Moon passes through from Full, to waning gibbous, to half or Last Quarter Moon, to waning crescent. After the Full Moon, the terminator moves towards the western limb of the Moon. Like the waxing Moon, the waning Moon can afford very pleasing views cause of increasing amounts of dark shadows from the mountains and in the craters. Although the Apollo landing sites are observable during the waning Moon, but disappear in reverse order of their appearance during the wax­ing phase. The waning phases appear between midnight, gradually towards dawn, when most of us are asleep. Those readers with insomnia are invited to enjoy the still and quiet of these early a. m. hours and enjoy lunar observing.

Apollo 15

Dates: 26 July – 7 August, 1971

Crew: Commander Dave Scott CM Pilot Al Worden LM Pilot James Irwin

Command Module: Endeavor Lunar Module: Falcon

Accomplishments: Longest Lunar Stay 66 hours 54 minutes, Landing in the Apennine Mountains

J. L. Chen, How to Find the Apollo Landing Sites,

The Patrick Moore Practical Astronomy Series, DOI 10.1007/978-3-319-06456-7_7, © Springer International Publishing Switzerland 2014

Apollo 15

Fig. 7.1 Mission insignia. Courtesy of NASA

Apollo 15

Fig. 7.2 Apollo 15. Courtesy of NASA

Apollo 15 was the first of the final three Apollo missions, and the first of the “J” missions. NASA had its funding cut by the Nixon Administration, with Apollo 18 and subsequent missions terminated. In light of the budget cuts, NASA planners placed a greater emphasis on scientific activities for the J missions, and maximized the scientific opportunities of the final three missions.

The J missions were designed to extend the lunar stay for longer periods, con­duct lunar exploration over a greater area, and were equipped with a larger array of scientific instruments than on the Apollo 11, 12, and 14 missions. Both the CSM and the LM included major renovations to make room for additional scien­tific experiments. The installation of a scientific instrument module in one of the service module bays was included for scientific investigations from lunar orbit. The LM received modifications to accommodate a longer stay on the lunar sur­face and carry a greater payload. The major innovation of the J mission series was the introduction and use of the Lunar Roving Vehicle, or LRV. The landing site chosen for Apollo 15 was at the foot of the Appenine Mountains, and next to Hadley Rille.

As with all Apollo missions, Apollo 15 was not without technical problems that potentially could have scrubbed the mission.

Following the launch, during the initial docking of the CSM with the LM and extraction from the S-IVB third stage, the “SPS Thrust” light on the Entry Monitor System of the control panel came on. The Service Propulsion System (SPS) was the rocket engine of the CSM and the SPS Thrust light was used to indicate that the valves in the engine were open and that the rocket should be firing, something that was not occurring. Just in case, the crew opened the circuit breakers that controlled the valves to prevent them from being opened by a short circuit and initiating the engine to fire.

After some period of troubleshooting, it was determined that there was a short circuit in the “Delta-V Thrust” switch. This switch opened the valves in the SPS. Having discovered that the technical problem was in the switch meant that the engine itself was fine, but new procedures would have to be used when operating the engine to stop accidental ignition.

One of the reasons for the success of the Apollo program was the redundancy of critical systems. In the case of the SPS, there were two independent valve systems for the engine, and with the proper reconfiguration of the valves and switches, any problems could be worked around. Similar redundancies of systems and system reconfigurations enabled successful missions, as seen for instance in the Apollo 12 SCE-to-Aux event. But redundancy has its downside. In a very counter-intuitive concept that is familiar to many logistical engineers, redundancy actually lowers system reliability while increasing the system availability. What? In brief, avail­ability is a measure of the percent of time the equipment is in an operable state, while reliability is a measure of how long the item performs its intended function. A dual redundant system implies two identical systems performing the same function, thus doubling the number of component parts. A failure on one side of the system results in the activation of the redundant system, thus assuring the continued function. With twice the number of parts to assure continued function, the chance of part failure increases and reliability actually decreases. But the redundancy increases the availability of the function.

Apollo 15

Fig. 7.3 Wide zoom-in of the Apollo 15 landing site. Courtesy of the author

Apollo 15

Fig. 7.4 Mid-range zoom-in of Apollo 15 landing site. Courtesy of the author

Apollo 15

Fig. 7.5 Close-up zoom-in of Apollo 15 landing site. Courtesy of the author

The Apollo 15 landing site is a bit of a challenge to spot visually an is shown in Figs. 7.3, 7.4 and 7.5. It is located on the eastern edge of Mare Imbrium, or the Sea of Rains, just south of the “channel” opening to the Sea of Serenity. The landing site is just east of the Julienne Crater and north of the Mons Hadley in the region known as the Mons Hadley Delta. Visually, the telescopic view of this landing site is impressive when compared to the previous three missions because of the tight landing area selected by NASA. Apollo 11, 12, and 14 landed in relatively open terrain, whereas the Apollo 15 site required precision in landing in a restricted area.

Apollo 15, 16, and 17 represented the J missions, which expanded the capabili­ties for doing science on and near the Moon. NASA planned three 7-hour-long EVAs for Apollo 15, with extensive use of the lunar rover, significantly extending the distance the LM astronauts Dave Scott and Jim Irwin could travel over the lunar surface. Additionally, the restriction on landing near the equator was lifted. A new suite of science experiments was also carried in the service module, giving the CM pilot Al Worden the additional activity of mapping the Moon from orbit.

The landing site chosen for Apollo 15 was on the eastern margin of the Imbrium Basin in the region known as Palus Putredinis. There were two main objectives for this landing site: (1) the rim of the Imbrium Basin could be sampled along the Appenine Mountains, and (2) this site provided an opportunity to explore Hadley Rille, which scientists felt was formed by volcanic processes. Researchers expected that material from Hadley Rille would provide samples from deeper in the lunar crust than was sampled in the Fra Mauro Formation by Apollo 14.

Apollo 15

Fig. 7.7 Apollo 15 Lunar Laser Ranging Retroreflector (LRRR). Courtesy of NASA

The Lunar Laser Ranging Retroreflector (LRRR) left by NASA at the Apollo 15 site served as a plot point in a popular television show. An episode of the CBS television sitcom “The Big Bang Theory” featured the television show’s characters measuring the distance to the Moon using the Apollo 11 LRRR and a ground based laser. In the series third season, episode 23 called The Lunar Excitation, the “Big Bang Theory” cast is on the roof of their apartment building with a laser, tele­scopes, electronics, and computers to accomplish the distance measuring experiment.

Apollo 15

Fig. 7.8 Astronaut James Irwin, LM pilot, works at the Lunar Rover during the first Apollo 15 lunar surface extravehicular activity at the Hadley-Apennine landing site in the shadow of the LM Falcon, and with Mount Hadley in the background. Courtesy of NASA

As a precaution, NASA designed the Apollo 15 mission to limit the total radius of the Lunar Rover to 3 miles from the LM. This was done just in case the LRV failed to function (NASA doesn’t build equipment that breaks down! Equipment has a failure or fails to function.), the astronauts would be within walking distance back to the Falcon.

A few years ago, the Lunar Rover was an auction item on eBay as an April Fool’s Day joke, with the auction winner required to pick up the item after winning. The LRV was listed as having very low mileage and driven very little for the past two or three decades. Tires in great shape. A little dusty, but a good car wash would make it look like new. A real collector’s car. No rust and mint condition. No UPS, FedEx, or Parcel Post delivery was available.

The Lunar Rover is still on the Moon, so the auction winner has not made arrangements for pickup yet.

Apollo 15

Fig. 7.9 Preparing for the first EVA traverse with the LRV, Apollo 15 LM pilot James Irwin loads-up the LRV with tools and equipment in preparation for the first lunar extravehicular activity at the Hadley-Apennine landing site. The un-deployed Laser Ranging Retro-Reflector (LRRR) lies atop the LM’s Modular Equipment Stowage Assembly (MESA). Courtesy of NASA

Apollo 15

Fig. 7.10 The Lunar Roving Vehicle is still parked at the Hadley-Apennine landing site, wait­ing pickup by its eBay winner. This view is looking north. The west edge of Mount Hadley is at the upper right of the picture. It rises approximately 14,765 feet above the landing site. Compare this photo with the LRO photo in Fig. 7.6. Courtesy of NASA

Apollo 15

Fig. 7.11 Earthbound laser aimed at the Apollo 15 LRRR, a “Star Wars” dramatic depiction of a ground-based laser measurement of the distance to the Moon using the LRRR left in the Apennine Mountains by Apollo 15. Courtesy of NASA

Apollo 15

Fig. 7.12 savor with the Scientific Instrument Module open. Courtesy of NASA

In addition to their studies on the lunar surface, the Apollo 15 crew performed intensive studies of the Moon from lunar orbit. In addition to photography per­formed with hand-held cameras in the Command Module, a series of experiments were carried in the Scientific Instrument Module on the Service Module. The same suite of SIM bay instruments was also flown on Apollo 16.

• The metric and panoramic cameras provided systematic photography of the lunar surface. Apollo 15, 16, and 17 carried a set of cameras in the SIM bay.

These cameras were used to obtain high-resolution photographs of the lunar surface, for use both in studying the geology of the surface and for producing detailed topographic maps of the surface.

• The Laser Altimeter measured the heights of lunar surface features. The laser altimeter used a pulse from a laser aimed at the lunar surface. The reflection of the pulse from the surface was then detected with a small telescope. The length of time the pulse took to travel from the spacecraft to the Moon and back translated to the height of the spacecraft above the surface of the Moon. Measure­ments were made roughly every 30 km across the Moon’s surface. These mea­surements are sufficiently accurate to distinguish height variations of 10 m between adjacent measurement points. Apollo 15 performed these measurements for a total of 4 1/2 orbits.

• The S-Band Transponder Experiment measured regional variations in the Moon’s gravitational acceleration. This experiment was identical to that carried on Apollo 14.

• The X-ray Fluorescence Spectrometer Experiment and the Gamma ray Spectrometer Experiment measured the composition of the lunar surface. The X-ray Fluorescence Spectrometer detected the ratio of aluminum to silicon and magnesium to silicon in the soil, while the gamma ray spectrometer detected the presence of iron, thorium, and titanium. The X-ray Fluorescence Spectrometer Experiment was limited to the sunlit side of the Moon since it relied on the fluo­rescence of aluminum, magnesium, and silicon in the presence of X-rays from the Sun. It measured the mare regions, such as the Sea of Serenity and the Sea of Tranquility, and found low abundances of aluminum and high abundances of magnesium. Over the lunar highlands, an opposite pattern of high aluminum abundances and low magnesium abundances were measured. The Gamma ray Spectrometer Experiment had no limitation and could function in both light and dark regions of the Moon. It found high iron abundances over all mare regions and lower abundances elsewhere. Thorium and titanium abundances were also highest over mare regions, but these two elements were not evenly distributed across the maria.

• The Alpha Particle Spectrometer Experiment measured radon emission from the lunar surface. It was flown on both Apollo 15 and 16. The Alpha Particle Spectrometer measured the alpha particles emitted by the surface, specifically by radon-222 and polonium-210 by detecting particles of energies of 4.7-9.1 MeV. When Uranium-238 undergoes radioactive decay, radon-222 and eventually polonium-210 are among the series of lighter isotopes that result. Rn-222 gas has a radioactive half-life of 3.8 days, which is long enough to allow some of it to diffuse through the lunar regolith and enter the lunar atmosphere. A later step in the same decay results in Po-210. Both Rn-222 and Po-210 undergo radioactive decay by releasing alpha particles (the equivalent of a Helium-4 nucleus). The experiment worked by detecting the alpha particles released when these isotopes decayed radioactively. Both Rn-222 and Po-210 were successfully detected in lunar orbit. Apollo 15 detected higher levels of Rn-222 around the Aristarchus

crater area. Higher levels of Po-210 were observed between Sea of Crisis (Mare Crisium) and the crater Van de Graaf on the Moon’s far side.

• The Orbital Mass Spectrometer Experiment (OMSE) measured the composition of the lunar atmosphere. The OMSE was deployed from the SIM on a 7.3-m boom. Most of the gases detected by the OMSE were associated with the Apollo spacecraft itself. However, Neon-20 was detected. Believed to be from external sources, it was about one-third of that expected to be found at the Moon due to capture of gases from the solar wind.

• The Bistatic Radar Experiment measured the scattering of radar waves from the lunar surface. This experiment was identical to that carried on Apollo 14.

• The PFS-1 Subsatellite was a small satellite released into lunar orbit from the SIM bay. The PFS-1 main objectives were to study the plasma, particle, and magnetic field environment of the Moon and map the lunar gravity field. The subsatellite was designed to measure plasma and energetic particle intensities, vector magnetic fields, and facilitate tracking of the satellite velocity to high precision. A basic requirement was that the satellite acquire fields and particle data everywhere on the orbit around the Moon. The Moon’s roughly circular orbit about the Earth at approximately 250,000 miles carried the subsatellite into both interplanetary space and various regions of the Earth’s magnetosphere. The PFS-1 orbited the Moon and remained operational from August, 1971 until January 1973.

• In later years, through a study of many lunar orbiting satellites, scientists came to discover that most low lunar orbits are unstable. Fortunately, the Apollo 15 subsatellite had been placed, unknown to mission planners at the time, very near to one of only four Lunar stable orbital slots known as frozen orbits, where a Lunar satellite may remain indefinitely.

Apollo 15 was the last mission in which a contingency sample was collected. Seven samples taken within 12 m west of the LM Falcon, and were collected to ensure that some lunar material would be returned for study on Earth in the event that an emergency required the rapid, unplanned end to the EVA.

I n addition to their geologic studies, the Apollo 15 crew performed several experiments on the lunar surface. The results of some of these experiments were either radioed to Earth by the crew or returned to Earth for laboratory analysis. The Soil Mechanics Investigation studied the properties of the lunar soil.

Our old friend, the Solar Wind Composition Experiment collected samples of the solar wind for analysis on Earth. Again, the foil used to collect the ions from the solar wind. The sampling foil was collected at the end of EVA-3, stored in the LM for its eventual return to Earth for analysis.

Other experiments were deployed by the crew and then monitored from Earth by radio telemetry after the crew departed.

Apollo 15

Fig. 7.13 Apollo 15 ALSEP deployed. Courtesy of NASA

The Apollo 15 ALSEP included some experiments that were part of previous missions, plus some new investigations were added. Each experiment was con­nected by a cable to the ALSEP central station, which provides radio communica­tion to Earth and electrical power from a radioisotope thermal generator. Some of these experiments continued to return data until September 1977, when the entire ALSEP network was turned off due to lack of funding for the ground support team.

• Added to the network from Apollo 12 and 14, Apollo 15 ALSEP added another PSE that detected lunar quakes, and provided information about the internal structure of the Moon. This experiment was identical to that carried on Apollo 14.

• The Heat Flow Experiment measured the amount of heat coming out of the Moon. This experiment was identical to that carried on Apollo 14.

• The Lunar Surface Magnetometer measured the strength of the Moon’s magnetic field. On Apollo 12, 15, and 16, the Lunar Surface Magnetometer was included in the ALSEP experiment package.

• The Laser Ranging Retroreflector measured very precisely the distance between the Earth and Moon. This experiment was identical to that carried on Apollo 14.

• The Cold Cathode Gauge measured the abundance of gases in the lunar atmo­sphere. This experiment was identical to that carried on Apollo 14.

• The Suprathermal Ion Detector Experiment studied the lunar ionosphere. This experiment was identical to that carried on Apollo 14, studying the lunar iono­sphere by measuring the various properties of positive ions in the Lunar environ­ment, collecting data on the plasma interaction between solar wind and the Moon, and measuring the electrical potential of the Lunar surface.

• The Solar Wind Spectrometer measured the composition of the solar wind, by continually sampling the solar wind to measure the effects of the Earth’s mag­netic field on the constitution of the solar wind. This experiment was identical to that carried on Apollo 12 and 14.

• The Lunar Dust Detector studied the effects of lunar dust on the operation of the experiment package.

And, as in Apollo 14, the Apollo 15 crew also performed the following


• The Window meteoroid Experiment studied impacts on the windows of the Apollo 15 Command Module to obtain information about the size distribution of very small micrometeorites. This experiment was identical to that carried on Apollo 14.

• The Light Flashes Experiment studied light flashes seen by the crew that are related to charged particles in space. This experiment was identical to that car­ried on Apollo 14.

Apollo 15

Fig. 7.14 Dave Scott, Commander of Apollo 15, works at the Lunar Roving Vehicle (LRV) during the third lunar surface extravehicular activity (EVA) of the mission at the Hadley – Apennine landing site. Hadley Rille is at the right center of the picture. Hadley Delta, in the background, rises approximately 4,000 m (about 13,124 feet) above the plain. St. George Crater is partially visible at the upper right edge. This view is looking almost due South. Courtesy of NASA

After returning to the LM at the end of EVA-3, Dave Scott famously performed a scientific demonstration for the television audience, using a feather and hammer to demonstrate Galileo’s theory that all objects, regardless of mass, in a given grav­ity field fall at the same rate, in the absence of aerodynamic drag. Scott dropped a hammer and a feather at the same time and the television audience on Earth were able to see both objects land on the lunar surface at the same time. The demonstra­tion worked on the Moon, since there was no drag on the feather due to the negli­gible lunar atmosphere.

Apollo 15

Apollo 15

Fig. 7.16 Genesis Rock. Courtesy of NASA

During their second lunar EVA, Irwin and Scott retrieved a lunar rock sample that has become known as the Genesis Rock. Apollo 15 sample #15415 became the most famous lunar rock returned by any Apollo mission.

The early excitement of the sample, enhanced by the media dubbing it as the Genesis Rock, was a piece of the Moon’s primordial crust. Chemical analysis of the Genesis Rock has shown it is an anorthosite, composed mostly of anorthite. The dating of the rock was only 4.1 ± 0.1 billion years old, which is younger than the Moon itself. The rock was formed after the Moon’s crust had solidified. Dating of pyroxenes from other anorthosite samples gave a samarium neodymium age of crystallization of 4.46 billion years, with the solar system forming approximately 100 million years earlier.

Although not quite the Genesis Rock as the name implies, the sample is an extremely old rock and was a significant find by the Apollo 15 astronauts. It is cur­rently stored at the Lunar Sample Laboratory Facility at the Johnson Space Center, and is available for study by scientists.

As with all Apollo flights, not all phases of the mission went as planned. Whereas the launch of Apollo 15 was relatively uneventful, one of the parachutes failed to open during the landing. Apollo capsules were designed to land safely with only two parachutes, with the third parachute being redundant in case of failure. With two good parachutes, Apollo 15 landed with a slightly higher velocity of 24 mph, instead of the more gentle 19 mph if all three parachutes had deployed. The post mission analysis of the failure, as reported in the NASA Aeronautics book Coming Home, revealed the parachute lines had been damaged by the fuel from the Reaction Control System, or RCS. The raw fuel from the RCS was vented prior to landing in a depletion firing, and this firing caused a failure in the parachute riser and lines. The failure was regarded as a 1-in-17,000 chance of reoccurring.

Upon landing, Scott, Worden, and Irwin were the first lunar landing crew who were not subjected to quarantine, since the results of the previous missions clearly showed the lifelessness of the lunar environment. The LM Falcon, after returning Scott and Irwin to Endeavor, was jettisoned and impacted the Moon on August 3, 1971 at 26.36° N and 0.25° E. The Saturn S-IVB third stage impacted the Moon on an earlier date of July 29, 1971 at latitude 1.51° S and longitude 11.81° W. Both the Falcon and the S-IVB impacts were recorded by the PSE network which now included the PSE at the newly deployed Apollo 15 ALSEP at Hadley Rille and the Apennine Mountains.


Funding for scientific space exploration often is met with resistance by politicians and the general public. In a parallel example, the development and building of the International Station has been shared among several spacefaring nations with great success. A mission to Mars offers the opportunity for the development of new industries and new jobs to the benefit of all.

There is an enormous cost associated with space exploration. Traditionally, government-funded agencies such as NASA and the European Space Agency (ESA) have used monies obtained through tax dollars to pay for the expense of space. In many cases, such as the Department of Defense Global Positioning System, commonly known as GPS or SatNav, there are benefits that can be derived by the everyday man. Weather services are reliant on meteorological photo tracking of weather fronts and storms. The Apollo Program was funded using public funds, with the impetus of the Cold War driving the effort.

New funding sources may be needed to finance the herculean effort of a mission to Mars. Cost estimates for a Mars effort range from a paltry $6 billion to an enor­mous estimate of $500 billion.

An innovative and precedent making approach may need to be explored. In 2009, a science fiction television show called Defying Gravity offered a commercial solution to raising funds. In an episode called “Fear”, an in-space promotional event using the astronauts was scheduled, with the proceeds funding experiments conducted during the mission. Selling advertising space, naming rights, and com­mercials is an unexplored avenue for paying the expenses of space exploration, such as a Mars mission. Just imagine if this had been done during the Apollo era. The Saturn V could have been launched displaying the name brand of a leading soda, with the astronauts eating and endorsing freeze dried foods on camera during broadcasts to American television networks. General Motors, the developer of the lunar rover, could have taken better advantage of their participation in the Apollo program. One wonders if funding had been obtained in this fashion, would Apollo 18 have been a lunar landing instead of an orbiting handshake?

Lunar Geography

It is important to be familiar with the type of major features of the Moon prior to search­ing for the Apollo landing sites. In 1651, a Jesuit astronomer named Giovanni Battista Riccioli created and published a system of nomenclature still in use today. Originally written in Latin, many of the lunar names have been Anglicized. For the comfort of the readers, Seas, Ocean, Bay, and other English nomenclature will henceforth be used in this book, except in one case. Mare Cognitum will be used in its Latin form, because it translates to “the sea that has become known”, which is extraordinarily awkward.

• Mare or Sea – The near side of the Moon is characterized by large, dark, seem­ingly smooth areas that early astronomer Riccioli called Mare, or Sea (with the plural Marias or Seas). From the Apollo missions, scientists now know that what looked like water to early astronomers is comprised of vast fields of basalt lava flows. In keeping with the water-based nomenclature for the Moon, Riccioli named one oceanus (ocean), and several dark areas as lacus (lake), palus (marsh) and sinus (bay). The ocean, lake, marsh and bay have the same nature and characteristics, but differ in size.

• Major craters – The Moon is obviously pockmarked with craters, the majority being impact craters left from meteors over the eons. Two of the larger craters are named for the pioneering astronomers Tycho Brache and Copernicus. The meteor impacts that created these landmark craters spread lunar debris across the near face of the Moon, and influenced NASA planners in their selection of Apollo landing sites, as will be seen in the Apollo mission chapters of this book.

• Highlands and Mountain Ranges – The highlands and mountain ranges of the Moon provide the brightest images of the Moon. Some mountain ranges, such as the Apennines and the Alps are actually parts of the crater rim surrounding the Sea of Rains. Other peaks are part of mountain ranges that project above the surface as part of fluid dynamics resulting from the liquefaction of surface rock following a meteor impact. Apollo landing sites in the highlands gathered scien­tific data, rock and soil samples from these regions to provide a comparison with the basin material, as detailed in the Apollo mission chapters of this book.

Apollo 16

Dates: 16-27 April, 1972

Crew: Commander John Young CM Pilot Tom Mattingly LM Pilot Charlie Duke

Command Module: Casper Lunar Module: Orion

Accomplishments: Landing in the highlands of the Descarte Region.

J. L. Chen, How to Find the Apollo Landing Sites,

The Patrick Moore Practical Astronomy Series, DOI 10.1007/978-3-319-06456-7_8, © Springer International Publishing Switzerland 2014

Apollo 16

Fig. 8.1 Apollo 16 insignia. Courtesy of NASA


Apollo 16

Fig. 8.2 Apollo 16 crew. Courtesy of NASA


The primary objectives of the penultimate Apollo mission were as follows:

• to perform geologic surveys and sampling of materials and surface features in

the area of the Hadley-Appennius region

• to deploy and activate surface experiments included in a new ALSEP suite

• to evaluate the capability of the Apollo equipment to operate extended lunar

surface stay time

• to conduct inflight experiments and photographic tasks from lunar orbit, includ­ing new photographic surveys and orbital spectrometric data collection

Apollo 16 marked Ken Mattingly’s opportunity to finally fly as CM pilot on a Moon mission. Mattingly (who looks nothing like the Actor Gary Sinise from the movie Apollo 13) had originally been assigned to the prime crew of Apollo 13, but was exposed to the measles through Charlie Duke, a member of the back-up crew for Apollo 13, who contracted the illness from one of his children. Mattingly never contracted the measles, but was nevertheless removed from the crew and replaced by his backup, Jack Swigert, 3 days before the launch. Duke had never flown in space, and both rookie astronauts Mattingly and he were teamed on Apollo 16 with space veteran John Young. Young had previously flown on Gemini 3, Gemini 10, and Apollo 10, and had Space Shuttle STS-1 and STS-9 in his future.

Although not officially announced, the original backup crew consisted of Fred Haise as mission commander, William Pogue as CM pilot, and Gerald Carr as LM pilot, and would have been the prime crew for Apollo 19 under the normal crew rotation scheme. However, after the cancellations of Apollo 18 and 19 in September 1970 due to budget cuts, this crew would not rotate to a lunar mission as planned. With Haise still assigned as backup commander, Stu Roosa and Ed Mitchell were recycled to serve as members of the backup crew after returning from Apollo 14, while Pogue and Carr were re-assigned to the NASA’s first space station Skylab program as part of the Skylab 4 crew.

As a historical note, there was an Apollo 18 mission, but it was not a mission to the Moon. The Apollo portion of the Apollo-Soyuz Test Project (ASTP), the first joint U. S.-Russian space mission, was officially known as Apollo 18. The ASTP was primarily a political space mission which demonstrated detente between the two great nations, by rendezvousing an Apollo space craft with a Soyuz in Earth orbit. This mission marked the final spaceflight for the Apollo command module. Apollo 18 ASTP also was the first and only spaceflight for Deke Slayton, the last of the Mercury 7 astronauts. Slayton was selected to pilot the second U. S. manned orbital spaceflight (eventually flown by Scott Carpenter), but was grounded in 1962 by a heart murmur. He served as NASA’s director of flight crew operations from November 1963 until March 1972, and was responsible for crew assignments at NASA for the Gemini and Apollo programs. Later, he was granted medical clear­ance to fly, and was assigned as the docking module pilot of Apollo 18, becoming the oldest person at the time to fly in space at age 51.

Apollo 16

Apollo 16

Apollo 16

Up to this point of the Apollo Program, three Apollo Moon landings were in mare regions and the fourth was in ejecta from the Imbrium impact. The objective of the Apollo 16 landing site was to land in the lunar highlands.

There is no easy way to describe in words how to find the Apollo 16 landing site, because of all the Apollo missions, this is the most challenging to spot visually through a telescope. The observer must first spot Sinus Asperitatis, or the Bay of Roughness, just south of the Sea of Tranquility. At the southern end of the Bay of Roughness is a large double crater called Theophilus and Cyrillus. Move westward to spot the Descarte crater, and then slightly north to identify the Apollo 16 site.

The Descartes region west of Mare Nectaris and Alphonsus crater was the main alternative considered for the Apollo 16 mission. Scientists believed prior to Apollo 16, that the Descartes and Cayley Formations were of volcanic origin. The objective for the astronauts was to sample the Descartes Formation and the Cayley Formation. There was observational evidence, gathered from telescope and orbital images, that both formations were volcanic in origin, although formed of magmas that were more viscous than mare lavas. Samples obtained by Apollo 16 have since been analyzed and are actually breccias produced by impacts rather than volcanic activ­ity. From the density of impact craters, the Cayley Formation was thought to be comparable in age to the Imbrium impact. These pre-mission geologic studies sug­gested that these two formations covered about 11 % of the lunar nearside, making them important for the overall understanding of the Moon’s history. Also, the large distance between the Descartes site and previous landing sites was helpful for the network of geophysical instruments created by the Apollo 12 through 16 missions.

The Alphonsus crater site was considered as an Apollo 16 landing site so as to gather samples from the crater fill itself, possible pre-Imbrium material from the crater wall, and possible young volcanics at some so-called dark halo craters on the floor of Alphonsus. However, some geologists felt that the Alphonsus site had been contaminated by ejecta from the Imbrium Basin impact. The Apollo 16 landing site was selected in June 1971, before the Apollo 14 samples had yet been completely analyzed and the Apollo 15 mission had not yet flown. It was considered possible that the objective of obtaining samples of old highland material (older than the Imbrium impact) might have been met with some of the Apollo 14 or 15 samples.

Therefore, the Descartes landing site was chosen for Apollo 16. The precision of this Moon landing is clearly shown in Fig. 8.6.

Apollo 16

Fig. 8.6 Zoom in on the Cayley Plains of the Descartes Region. Courtesy of NASA

Once in lunar orbit, Ken Mattingly was scheduled to perform an engine bum to position Casper for a rescue in the event of an aborted landing. Meanwhile, the LM astronauts Young and Duke powered up the lander and separated from the Command Module. However, during tests of the control systems for the Command Service Module’s steerable rocket engine, an error light lit, indicating a malfunction in the backup system. Mission rules dictated that, at this point, the two spacecraft rendezvous in case it was decided that the crew would have to use the LM engines to get back to Earth, a la Apollo 13. However, after 6 hours of tests and analysis, Mission Control decided that the engine problem could be worked around and that the landing could proceed. The lunar landing was delayed, but not scrubbed.

Apollo 16

Apollo 16

Apollo 16

Apollo 16

Apollo 16

Fig. 8.12 Charlie Duke with the Far/Ultraviolet Camera/Spectrograph. Courtesy of NASA

The Apollo 16 crew performed several experiments on the lunar surface. The results of some of these experiments were either radioed to Earth by the crew or returned to Earth for laboratory analysis.

• The Soil Mechanics Investigation studied the properties of the lunar soil.

• The Solar Wind Composition Experiment collected samples of the solar wind for analysis on Earth. In addition to the aluminum foil used in previous Apollo mis­sions, Apollo 16 included a platinum sheet. This foil was exposed to the Sun for 45 hours. The foil was then returned to Earth for laboratory analysis.

• The Lunar Portable Magnetometer measured the strength of the Moon’s mag­netic field at different locations in the vicinity of the landing site. This experi­ment was identical to the device carried on Apollo 14.

• The Far/Ultraviolet Camera/Spectrograph took pictures and spectra of astronom­ical objects in ultraviolet light, and marked the first time a telescope was used from the Moon. Unique to Apollo 16, it used a 3-in. telescope to obtain images and spectra at wavelengths between 500 and 1,600 A. The telescope consisted of a tripod-mounted, 3-in. Schmidt camera with a cesium iodide cathode and film cartridge. For reference, visible light corresponds to wavelengths of 4,000­7,000 A. Emission at these wavelengths comes primarily from very hot stars of spectral classes O, B, and A, with surface temperatures of 10,000° to 50,000°K. For comparison, the temperature at the visible surface of the Sun is about 5,800°K or 11,000 ° F. Stars as faint as magnitude 11, or 100 times fainter than can be seen with the human eye, were recorded. Results were recorded on a film car­tridge and returned to Earth for analysis. A total of 178 frames of film were obtained. The telescope was periodically reoriented by the astronauts in order to study various parts of the sky. Among the objects studied were the Earth’s upper atmosphere and aurora, various nebulae and star clusters, and the satellite galaxy of the Milky Way galaxy known as the Large Magellanic Cloud.

• The Cosmic Ray Detector measured very high energy cosmic rays from the Sun and other parts of our galaxy. The detector was physically attached to one of the legs of LM Orion, but the deployment proved to be problematic. The detector was to be deployed by pulling a lanyard on the unit. The deployment lanyard broke. It was only partially deployed due to incorrectly installed screws which interfered with the travel of the plates. This degraded portions of the experiment. By the beginning of EVA-2, the temperature labels indicated that the detector was nearing overheating. The detector was removed from the LM and was placed on one of the foot pads so that it faced away from the Sun. A layer of lunar dust on the equipment contributed to the overheating. The experiment was redesigned for the Apollo 17 mission.

The Apollo 16 crew deployed another ALSEP, with experiments now familiar to

the reader:

• The Passive Seismic Experiment detected lunar tremors and provided informa­tion about the internal structure of the Moon. The deployed Apollo 16 PSE gathered seismic data as part of the network that included the ALSEP PSEs’ from Apollo 12, 14, and 15.

• The Active Seismic Experiment provided information about the structure of the upper 100 m of the lunar regolith. On Apollo 16, three of four mortar shells were used to lob explosive charges to distances of up to 900 m from the ALSEP. The fourth mortar shell went unused when a calibration error was detected. The mor­tars were activated by radio after the astronauts had returned to CM Casper. Hexanitrostilbene was the main explosive fill in the seismic source generating mortar ammunition canisters used as part of the experiment due to its high heat resistance and high insensitivity to impact. The astronauts were also equipped with an astronaut-activated “Thumper” device, which was designed to detonate individually 22 smaller charges, to create a small shocks in the lunar surface. The Apollo 16 crew fired off 19 of the 22 Thumper charges.

• The Heat Flow Experiment attempted to measure the amount of heat coming out of the Moon. Unfortunately, the HFE was damaged when John Young inadver­tently caught his foot on the cable that connected the experiment to the Central Station, and pulled the cable out of its connector at the Central Station. Although the damage was repairable, Mission Control ultimately decided that the repair time would adversely impact the completion of other lunar surface tasks. Apollo astronauts on all the missions complained about the presence of the many inter­connecting ALSEP cables and the problems of tripping over, stepping on, or snagging a cable was a real issue. So to the surprise of no one, the HFE experi­ment was terminated.

• The Lunar Surface Magnetometer measured the strength of the Moon’s mag­netic field. The magnetometers from Apollo 12, 15, and 16 showed large varia­tions in the magnetic field of the Moon. These variations indicate the presence of strong localized sources in the crust for the Moon’s magnetic field, a conclu­sion that is also consistent with observations from lunar orbit measurements gained from unmanned lunar probes such as Explorer 35. The Earth’s magnetic field is generated by the flow of fluids in the core and has a global dipole geom­etry, as seen in a simple handheld compass. The ALSEP results show no evi­dence of a global encompassing dipole field on the Moon.

Apollo 16

Fig. 8.13 Looking up the crater. Courtesy of NASA

The navigation system on the lunar rover failed during the return drive from EVA-2 and, since their outbound lunar rover tracks are out of sight to the east, John Young used horizon features as a guide. The fact that he was aimed directly at the LM is a testament to his landmark recognition skill.

Apollo 16

Fig. 8.14 A view of the CM Casper from the LM Orion during the rendezvous before heading home to Earth. Courtesy of NASA

In addition to their studies on the lunar surface, the Apollo 16 crew performed intensive studies of the Moon from lunar orbit. In addition to photography per­formed with hand-held cameras in the Command Module, a series of experiments were carried in the Scientific Instrument Module on the Service Module. The same suite of SIM bay instruments was also flown on the predecessor mission Apollo 15.

• The Metric and Panometric cameras provided systematic photography of the lunar surface.

• The Laser Altimeter measured the heights of lunar surface features

• The S-Band Transponder Experiment measured regional variations in the Moon’s gravitational acceleration.

• The X-Ray Fluorescence Spectrometer Experiment measured the composition of the lunar surface.

• The Gamma Ray Spectrometer Experiment measured the composition of the lunar surface.

• The Alpha Particle Spectrometer Experiment measured radon emission from the lunar surface.

• The Orbital Mass Spectrometer Experiment measured the composition of the lunar atmosphere. The results of this experiment proved to be as inconclusive as the identical experiment from the Apollo 15 mission.

• The Bistatic Radar Experiment measured the scattering of radar waves from the lunar surface.

• The Subsatellite measured regional variations in the Moon’s gravitational accel­eration and magnetic field and the distribution of charged particles around the Moon. The Apollo 16 subsatellite PFS-2 was a small satellite released into lunar orbit from the Service Module. Its principle objective was to measure charged particles and magnetic fields all around the Moon as the Moon orbited Earth, similar to its sister Apollo 15 deployed spacecraft PFS-1. PFS-1 and PFS-2 were deployed in similar elliptical orbits, ranging from 55 to 76 miles above the Moon. However, the orbit of PFS-2 rapidly changed shape and distance from the Moon. Within 2-1/2 weeks of deployment, the subsatellite’s orbit was scrapping over the lunar surface of 6 miles at perigee. The orbit kept changing to the point where PFS-2 perigee was 30 miles. The orbital instability continued, and the subsatellite’s orbit degraded again. On May 29, 1972, PFS-2 crashed into the lunar surface, lasting only 35 days and 425 orbits. In later years, through a study of many lunar orbiting satellites, scientists came to discover that most low lunar orbits (LLO) are unstable. Unlike its predecessor PFS-1, PFS-2 had been unlucky and was placed into one of the most unstable of orbits, with an orbital inclination of 11°, far from the four frozen lunar orbits discovered only later at 27°, 50°, 76°, and 86° inclination.

Upon the return of the crew to the CM Casper, the ascent stage of Orion was sent to the surface of the Moon to provide seismic data. The ascent stage of Lunar Module Orion separated on 24 April 1972, but a loss of attitude control rendered it out of control. It orbited the Moon for about a year. The Orion impact site on the Moon is unknown.

With the precedent established with the Apollo 13, 14, and 15 S-IVB third stages, the Apollo 16 Saturn third stage was intentionally impacted onto the Moon at longitude 1.3° North and latitude 23.8° West. This event provided data to the PSE network created by Apollo 12, 14, 15 and 16 using a known size and mass.

The lunar samples returned by Apollo 16 brought the biggest scientific surprise of the entire Apollo program. During mission planning, scientists believed the Descartes region to be volcanic plains of comparable age to the Imbrium impact basin. The Apollo 16 crew collected 731 individual rock and soil samples, including a deep drill core that included material over 6 feet below the Moon’s surface, for a record total of 208 pounds.

The samples turned out not to be of volcanic nature. Almost every rock collected on Apollo 16 was a breccia. Breccias are rocks that are composed of fragments of older rocks. Rather than being volcanic in nature, the lunar rocks returned by Apollo 16 showed the Descartes region to be composed of breccia created by mete­orite impacts. Meteor impacts broke many rocks up into small fragments, and sometimes fused small rock fragments into new breccia rocks. Continual meteorite bombardment of the lunar surface resulted in breccias forming larger breccias.

Apollo 16 geological findings changed the nature of scientific thought over the formation of the lunar crust. The previously held belief of a lunar crust formed by volcanic lava flows was dispelled, and replaced by a more complex concept of some magma flows caused by meteor impacts, followed by layers of meteorite impacts that formed the Moon’s crust. The meteorite impact source of the Descartes breccia is still under debate, whether the breccias were from the Imbrium impact or in combination with earlier meteorite impacts remains to be discovered.

The process of returning and decommissioning CM Casper was not without incident. Following the landing, the aircraft carrier USS Ticonderoga delivered the CM Casper to the North Island Naval Air Station, near San Diego, California, on May 5, 1972. Three days later, ground service equipment being used to empty the residual toxic reaction control system fuel in the Command Module tanks exploded in a Naval Air Station hangar. This is the same type of residual fuel and reaction control system that, when vented during landing, caused the Apollo 15 parachute failure. Forty-six people were sent to the hospital suffering from toxic fumes inha­lation. A technician suffered the most serious injury when a ground service equip­ment cart overturned on him and fractured his kneecap. Physical damage included a hole in the hangar roof 250 feet above the hanger floor, 40 windows in the hangar were shattered, and the CM Casper suffered a 3-in. gash.

LM Casper now resides at the U. S. Space and Rocket Center, Huntsville, AL.

As recently as 2006, the Apollo 16 mission was in the news, as an 11 year old boy discovered a piece of debris following Hurricane Ernesto off the coast of Bath, North Carolina. The yard wide flat sheet of metal had a very faded Apollo 16 mis­sion insignia on it. NASA confirmed the object to be a remnant of the first stage of the Saturn V that launched Apollo 16 towards the Moon. As a reward for returning the historic remnant to NASA, the young man was treated to a tour of the Kennedy Space Center, and was provided with a prime seat to witness the launch of the final mission of the Space Shuttle program STS-135, launched on July 11, 2011.

System Reliability, Availability, and Repairability

As seen in the Apollo Program, there were malfunctions, software glitches, mechanical and electronic failures, and accidents that occurred on every mission. Apollo 11 had its 1201 and 1202 overflow problems. Apollo 12 had the lightning strike during launch that led to the SCE to Aux activation. The near catastrophic oxygen tank explosion that cost the Apollo 13 crew the lunar landing and nearly cost them their lives. The faulty abort switch on Apollo 14 nearly ruined the lunar landing. Apollo 15 experienced a failed parachute during its return to Earth. There were broken lunar rover fenders on two missions. And the list goes on, many not publicly reported by NASA.

The Apollo spacecraft, the Saturn V, and Mission Control were extremely com­plex machines, built from hundreds of thousands of individual parts, and with computers both onboard and at Mission Control containing thousands of lines of software code.

One of the reasons for the success of the Apollo program was the redundancy of critical systems. During Apollo 15, there was a short circuit in the “Delta-V Thrust” switch. This switch opened the valves in the SPS. The short circuit of this switch meant that the engine itself was fine, but new procedures would have to be used when operating the engine to stop accidental ignition. In the case of the SPS, there were two independent valve systems for the engine, and with the proper reconfigu­ration of the valves and switches, any problems could be worked around. Similar redundancies of systems and system reconfigurations enabled successful missions, as seen for instance in the Apollo 12 SCE-to-Aux event.

But redundancy has its downside. As stated in the Apollo 15 chapter, redundancy actually lowers system reliability while increasing the system availability. To reiter­ate, availability is a measure of the percent of time the equipment is in an operable state, while reliability is a measure of how long the item performs its intended function. A dual redundant system implies two identical systems performing the same function, thus doubling the number of component parts. A failure on one side of the system results in the activation of the redundant system, thus assuring the continued function. With twice the number of parts to assure continued function, the chance of part failure increases and reliability actually decreases. At the same time, the redundancy increases the availability of the function.

A Mars mission with a duration of months or years will stretch the limits of tech­nological durability. Lessons of long term reliability and maintainability are now being learned on the International Space Station. Inherent in the design of both the ISS and a future Mars spacecraft is not only reliability and system maintainability, but also repairability. In the language of logistics engineers, a Mars mission will require an extraordinary set of mean-time-between-failures (MTBF), mean-time-to-repair (MTTR), and functional and service availability requirements that will be historic.

During the writing of this book, a pump on one of the ISS’s two external cooling loops shut down after hitting a temperature limit. The external cooling loops are systems that circulate ammonia outside the space station to keep equipment cool.

Two loops of circulating ammonia cool equipment on the station. The problem started with a malfunction of a valve inside the pump, located on one of the ISS exterior trusses. ISS flight controllers shut down the malfunctioning cooling loop, with the remaining loop provides sufficient for regulating the temperature of critical equipment, and there was no immediate danger to the six crew members aboard at the time. Astronauts aboard the ISS executed three spacewalks, each lasting 6.5 hours, to replace a malfunctioning pump.

An extended mission to Mars will necessitate an ability for the astronauts to repair any malfunctions aboard the Mars spacecraft. But unlike the ISS, which periodically receives supplies of consumables and spare parts, the Mars spaceship will have to carry a supply of repair items for any emergency.

Apollo 13 gave NASA the experience of reconfiguring a damaged spacecraft in times of emergency. A Mars mission will not have the luxury of a quick return to Earth, as Apollo 13 had. A major failure could occur at the mission’s furthest point, necessitating a return to Earth in terms of months. A Mars bound mission will require extraordinary logistical planning, while challenging the aerospace engi­neers to design a spacecraft with reliability, redundancy, and flexibility in configu­ration that allows for survivability in case of malfunctions.

For the Mars spacecraft to carry a warehouse of space parts for its journey would be a waste of resources, storage space, and added fuel costs. It is con­ceivable that a Mars mission could fabricate at least some of its spare parts and tools on the fly by using additive manufacturing, more commonly known as 3-D printer technology. This concept is reminiscent of the replicator technology proposed by the television series and movie franchise Star Trek. NASA has announced that it intends to send a 3-D printer to the International Space Station in 2014. NASA says that astronauts living aboard the ISS would use the 3-D printer to make spare parts and tools in zero gravity. Once the printer arrives at the ISS, it will mark the first time a 3-D printer has been used in space. 3-D printers typically use a polymer material, but there are 3-D printers able to use titanium and nickel-chromium materials to build stronger compo­nents. The 3-D printer technology will have to be modified to use raw materials in a form other than the powders used on Earth. Typical 3-D printers on Earth utilize polymer powders to form plastic 3-D objects, but in a weightless envi­ronment, powders of any kind will impact the onboard environment. Contamination of the breathable air and migration of any powder material into the electronics and mechanical systems onboard the ISS or a Mars bound space­craft could have disastrous results.

Moon Geology

The lunar crust is a three layer cake affair, with an upper regolith, lower regolith, and then the mantle layer. The upper regolith extends from 3 feet to 60 feet in depth, and is the result of millions of years of constant bombardment of meteorites and geologic stress from heating and cooling. The lower regolith extends to a depth of 12 miles, and is made up of basalt rocks. Below the two layers of regolith is the mantle, consisting of less rigid material that is low in iron content. Scientists have postulated from the available data gathered from Apollo and unmanned lunar mis­sions that the core of the Moon is small and iron-rich.

There are three major types of features that dominate the surface of the Moon: impact craters, marias (or seas), and highlands. Most familiar are the many craters, caused by the eons of meteorite impacts on the surface. The wide, dark seas are composed of iron and titanium rich volcanic rock known as basalts. And the high­lands are made up of various types of silicate type rocks.

Unique to the Moon’s geology in the highlands, and not found on Earth, is the presence of a type of rock called KREEP. This acronym is formed from potassium (chemical symbol K), rare-earth elements (REE), and phosphorus (chemical sym­bol P). First discovered from the samples brought back by Apollo 12, KREEP is made up of normally incompatible elements, and represents part of the evidence for the formation of the Moon. The leading theory for the Moon’s formation is that it was formed from the remains of an ancient impact between the Earth and a Mars­sized proto-planetary body.

The Apollo missions provided detailed knowledge of the nature of the lunar soil and rocks, and evidence for the impact theory of the lunar genesis.