Recap: Apollo

-Jules Verne, (From the Earth to the Moon, 1865)

The Decision to Go to the Moon 

"I believe this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space, and none will be so difficult or expensive to accomplish." 

-President John F. Kennedy, speech to U.S. Congress, May 25, 1961. 

President Kennedy's speech to Congress was made in the context of the Cold War between the United States and the Soviet Union. At that time, the U.S. feared that it was falling behind the U.S.S.R. both in technological advances and international prestige. The U.S.S.R. launched the first artificial satellite into Earth orbit in October 1957. On April 12, 1961, just six weeks before Kennedy's speech, the Soviets launched the first human into Earth orbit. 

Although the U.S. launched astronaut Alan Shepard on a brief, sub-orbital flight on May 5, 1961, they did not put an astronaut in orbit until February 1962. The failure of the U.S.-backed invasion of the Bay of Pigs, Cuba, in April 1961 added to this 'space race' mentality. President Kennedy sought an inspirational goal to rally the country. With the advice of Vice President Lyndon Johnson and the nation's scientific leadership, Kennedy settled on a manned lunar journey as a goal dramatic enough to capture the world's attention. The difficulty of reaching this goal ensured that it could not be achieved quickly, allowing the U.S. time to overcome the Soviet Union's lead in space exploration. 

The tragic Apollo 1 launch pad fire in January 1967 killed the three-man crew (Edward H. White II, Virgil I. "Gus" Grissom, and Robert B. Chaffee). 

The accident delayed the Apollo program while the spacecraft was redesigned for greater safety. Between October 1968 and May 1969, Apollo 7 through Apollo 10 tested the various components of the Apollo system. Apollo 7 tested the Command and Service Modules in Earth orbit. Apollo 8 was mankind's first trip beyond Earth orbit, a dramatic Christmas trip to the Moon. Apollo 9 tested the Lunar Module in Earth orbit. Apollo 10 was a final dress rehearsal in lunar orbit, clearing the way for Apollo 11's historic flight

Throughout this time, the Soviet Union continued planning for the moon. Although they did not publicly announce their plans at the time, they too were planning a manned lunar voyage, which never actually occurred due to repeated failures of their giant booster rocket. However, they did attempt to steal Apollo 11's thunder by returning a small sample of lunar soil with the Luna 15 spacecraft just a few days prior to Apollo 11. This effort also failed when Luna 15 crashed on the Moon's surface on July 21, 1969. President Kennedy's goal was finally achieved when Apollo 11 landed on the moon on July 20, 1969, and returned to Earth on July 24, 1969. 

Top Ten Scientific Discoveries Made During Apollo Exploration of the Moon

The extensive record of meteorite craters on the Moon, when calibrated using absolute ages of rock samples, provides a key for unravelling time scales for the geologic evolution of Mercury, Venus, and Mars based on their individual crater records. Photogeologic interpretation of other planets is based largely on lessons learned from the Moon. Before Apollo, however, the origin of lunar impact craters was not fully understood and the origin of similar craters on
Earth was highly debated. 

3. The youngest Moon rocks are virtually as old as the oldest Earth rocks. The earliest processes and events that probably affected both planetary bodies can now only be found on the Moon. 

Moon rock ages range from about 3.2 billion years in the maria (dark, low basins) to 4.5 billion years in the terrae (light, rugged highlands). Active geologic forces, including plate tectonics and erosion, continuously repave the oldest surfaces on Earth whereas old surfaces persist with little disturbance on the Moon. 

4. The Moon and Earth are genetically related and formed from different proportions of a common reservoir of materials. 

Oxygen isotopic compositions of Moon rocks and Earth rocks clearly show common ancestry. Relative to Earth, however, the Moon was highly depleted in iron and in volatile elements that are needed to form atmospheric gases and water. 

5. The Moon is lifeless; it contains no living organisms, fossils, or native organic compounds. 

Extensive testing revealed no evidence for life, past or present, among the lunar samples. Even non-biological organic compounds are amazingly absent; traces can be attributed to contamination by meteorites. 

6. All Moon rocks originated through high-temperature processes with little or no involvement with water. They are roughly divisible into three types: basalts, anorthosites, and breccias. 

Basalts are dark lava rocks that fill mare basins; they generally resemble, but are much older than lavas that comprise the oceanic crust of Earth. Anorthosites are light rocks that form the ancient highlands; they generally resemble, but are much older than most ancient rocks on Earth. Breccias are composite rocks formed from all other rock types through crushing, mixing, and melting during meteorite impacts. The Moon has no sandstones, shales, or limestones such as testify to the importance of water-borne processes on Earth. 

7. Early in its history, the Moon was melted to great depths to form a "magma ocean." The lunar highlands contain the remnants of early, low density rocks that floated to the surface of the magma ocean. 

The lunar highlands were formed about 4.4-4.5 billion years ago by flotation of an early, feldspar-rich crust on a magma ocean that covered the Moon to a depth of many tens of kilometers or more. Innumerable meteorite impacts through geologic time reduced much of the ancient crust to curved mountain ranges between basins. 
 

8. The lunar magma ocean was followed by a series of huge asteroid impacts that created basins which were later filled by lava flows. 

The large, dark basins such as Mare Imbrium are gigantic impact craters, formed early in lunar history, that were later filled by lava flows about 3.2-3.9 billion years ago. Lunar volcanism occurred mostly as lava floods that spread horizontally; volcanic fire fountains produced deposits of orange and emerald-green glass beads. 
 

9. The Moon is slightly asymmetrical in bulk form, possibly as a consequence of its evolution under Earth's gravitational influence. Its crust is thicker on the far side, while most volcanic basins -- and unusual mass concentrations -- occur on the near side. 

Mass is not distributed uniformly inside the Moon. Large mass concentrations ("mascons") lie beneath the surface of many large lunar basins and probably represent thick accumulations of dense lava. Relative to its geometric center, the Moon's center of mass is displaced toward Earth by several kilometers. 

10. The surface of the Moon is covered by a rubble pile of rock fragments and dust, called the lunar regolith, that contains a unique radiation history of the Sun which is of importance to understanding climate changes on Earth. 

The regolith was produced by innumerable meteorite impacts through geologic time. Surface rocks and mineral grains are distinctively enriched in chemical elements and isotopes implanted by solar radiation. As such, the Moon has recorded four billion years of the Sun's history to a degree of completeness that we are unlikely to find elsewhere. 

Moon Research continues and more than 60 research laboratories throughout the world continue studying the Apollo lunar samples today. Many new analytical technologies, which did not exist when the Apollo missions were returning lunar samples, are now being applied by the third generation of scientists. The deepest secrets of the Moon remain to be revealed. 

Recent Missions 

The SMART-1 (Small Missions for Advanced Research in Technology 1) is a lunar orbiter designed to test spacecraft technologies for future missions. It launched on September 27, 2003 and entered initial lunar orbit on November 13, 2004. The primary technology being tested is a solar-powered ion drive. The primary scientific objectives of the mission are to return data on the geology, morphology, topography, mineralogy, geochemistry, and exospheric environment of the Moon in order to answer questions about planetary formation accretional processes, origin of the Earth-Moon system, the lunar near/far side dichotomy, long-term volcanic and tectonic activity, thermal and dynamical processes involved in lunar evolution, and water ice and external processes on the surface.

The Lunar-A mission's scientific objectives are to image the surface of the Moon, to monitor moonquakes, measure the near-surface thermal properties and heat flux, and to study the lunar core and interior structure. The launch has been delayed a number of times for technical and financial reasons, it is now being re-evaluated.

SELENE is a project by the Japanese NASDA and hopes to launch in 2008. SELENE will carry 13 instruments including imagers, a radar sounder, laser altimeter, X-ray fluorescence spectrometer and gamma-ray spectrometer to study the origin, evolution, and tectonics of the Moon from orbit. Selene will carry out observations for approximately one year.

Apollo produced a wealth of new knowledge about the Moon, but our nearest neighbor in space remains an attractive target of exploration, both because of its scientific interest and as a testbed for developing techniques for exploring further into the solar system.