About Lunar Exploration From Apollo to the Future
The six Apollo landings between 1969 and 1972 provided scientists with huge amounts of lunar data in the form of photography and orbital experiment results, sample collections and surface operations.
Early missions (Apollo 7, 8, 9, and 10) tested the spacecraft and systems capabilities.
The successful mission of Apollo 11 was to land two men on the lunar surface and return them safely to Earth. Apollo 11 launched on July 16, 1969 and landed the first manned spacecraft on the Moon at 3:17 pm Central Daylight Time on July 20, 1969. The spacecraft carried a crew of three: Mission Commander Neil Armstrong, Command Module Pilot Michael Collins, and Lunar Module Pilot Edwin E. Aldrin Jr. Armstrong and Aldrin landed the Apollo 11 Lunar Module (the Eagle) in Mare Tranquillitatis (the Sea of Tranquility).
Apollo missions 12, 14, 15, 16, and 17 successfully landed in a variety of sites on the near side of the Moon; the Apollo 13 mission was aborted due to an accident, but the astronauts were safely returned to Earth.
The first sites were in smooth, flat terrain for safety, while later missions landed in more rugged and scientifically interesting regions: Oceanus Procellarum, the Fra Mauro Formation, the Hadley-Apennine region, the Descartes Mountains, and the Taurus-Littrow valley. Astronauts conducted 14 extra-vehicular activities (EVAs), for a total of 80.1 hours. Their longest traverse was 18 km. They returned 382 kg samples of lunar samples, which are now stored in a dry nitrogen environment at NASA’s Johnson Space Center.
Conditions on the Moon
The Moon is covered with circular patches. Some of these are huge, covering more area than the state of Texas. Some are miniscule, smaller than the tip of a pin. The large craters were created when large meteoroids — asteroids — impacted the Moon. Smaller ones were made by smaller meteoroids. These impacts pulverized rocks on the lunar surface, reducing them to a dusty, rock material called regolith that covers the Moon's surface — in some cases deeper than 50 feet (15 meters).
The Moon has no atmosphere, so there is no wind and the sky is dark. There are extreme temperatures: an average of 225°F (107°C) during the day and –243°F (–153°C) at night.
Space is filled with radiation and charged particles, primarily from our Sun. Earth's atmosphere and magnetic field offers us a safe-haven. The Moon, on the other hand, has no protective atmosphere and virtually no magnetic field, and so the radiation and charged-particle levels are very high.
Because it is less dense and smaller than Earth, the Moon has less gravity. The surface gravity is one-sixth Earth's gravity, so the same simple push to take a step on Earth would propel an astronaut several feet high on the Moon.
Astronauts living on the Moon would experience daylight for almost two Earth weeks and then darkness for the same time. The Moon orbits Earth once every 27 days — and spins on its axis once every 27 days, so the nearside faces Earth constantly. Since our Moon is only tilted on its axis a tiny amount, there essentially are no seasons.
The Explore Marvel Moon module has additional information about the Moon’s influence on us.
We Have Only Begun to Understand the Moon
The six Apollo landings provided scientists with huge amounts of lunar data; we have learned much about the Moon:
- The Moon’s surface is ancient — it still preserves records of an early history--the first billion years of our Solar System.
- The lunar surface covered by a powdery layer (“lunar soil” or regolith), produced by shattering of its bedrock by prolonged meteorite bombardment.
- The dark lunar maria (“seas”) and lightcolored highlands are composed of very different rocks. The maria formed from dark basalt lavas in huge volcanic eruptions billions of years ago, while the highlands are older.
- The samples show evidence for primordial melting and the formation of outer “magma ocean” early in the Moon’s history.
- The Moon is lifeless.
- The Moon is chemically similar to Earth, but significantly different in details, with less volatile (easily vaporized) elements like water.
- The Moon is divided (like Earth) into outer crust, inner mantle, and possibly a small metal core.
- The Moon is asymmetric (slightly egg-shaped), with a thicker crust on its farside, and most maria deposits (lava flows) on the nearside.
- The Moon has no magnetic field, but “fossil” magnetism is preserved in lunar rocks.
A view of the mountains that surround the Imbrium impact basin. The smooth, dark mare on the right side of the image is younger lava flows. Credit: NASA
Orbiters have helped to add more detail to the picture. The Lunar Prospector (1998-1999) and Clementine (1994) missions provided scientists with detailed information about the surface features and composition of much of the Moon's surface. The instruments on those missions returned exciting data — particularly evidence for ice at shadowed regions at the poles.
Today’s instruments are even better! Cameras and detectors onboard the Lunar Reconnaissance Orbiter (LRO) provide much more detailed information than what was collected by earlier missions. LRO is one of several missions that are building upon our knowledge. India's Chandrayaan-1 and 2, Japan's Kaguya, and China's Chang'E missions are studying the Moon; and even sending robotic rovers to the far side of the Moon. NASA’s Solar System Exploration site has a complete list and description of lunar spacecraft missions.
LRO Leads the Way to the Moon and Beyond!
NASA's Lunar Reconnaissance Orbiter (LRO) is a robotic spacecraft gathering high-resolution data about the Moon’s surface and surrounding environment. LRO launched in 2009 and continues to orbit the Moon, gathering data.
LRO is outfitted with seven scientific instruments that are helping us learn more about the lunar environment. A radio antenna transmits the instruments' data back to Earth. LRO is helping scientists and engineers understand the slope, roughness, and lighting of the terrain and identify potential landing hazards — and potential exploration sites rich in resources, including water. LRO is also measuring the daytime and nighttime temperatures and the amount of radiation near the lunar surface.
Artist's conception of LRO orbiting the Moon with Earth pictured in the distance. Image courtesy of NASA.
Water on the Moon
Comets made out of water ice and other materials have hit the Moon throughout its history. If the comet has struck in an area that does not receive much sunlight, like the south polar region of the Moon, that ice may still be there.
Scientists have evidence that water ice exists on the Moon's surface in some of the permanently shadowed regions near the north and south poles. Water is a critical resource for sustained human exploration. If water ice exists it can be used for water and can be broken into its parts — oxygen and hydrogen for air and fuel. LRO has mapped the cold shadowed regions to locate water ice on the Moon. The amount discovered may be enough to supply the population of a lunar base for a long time.
Future Lunar Explorers
The Moon holds the key to many scientific discoveries. The Moon has preserved the geologic record of the early solar system and may give us clues about our origins. Its airless environment provides clear viewing for studying the universe.
Future human outposts can mine the Moon for resources, such as oxygen, water, fuel, and building materials — but they will need to know where these resources are in more detail than we understand now. Based on earlier missions, we know that the rocks and soil contain aluminum, iron, silica, titanium, and other elements that can be used in buildings and solar panels. The loose lunar regolith can be used to make "lunar bricks" for building structures.
Image courtesy of Pat Rawlings/NASA.
The Lunar Reconnaissance Orbiter and other missions will help us identify the most promising locations for mining for water and for minerals and will provide valuable, detailed data about the lunar environment. The areas of potential occupation need to be easily reached (the terrain needs to be somewhat smooth). The temperatures need to be in a range that can be controlled by our technology so that humans or robotic missions can operate. If humans are involved, radiation will have to be blocked by shielding or buildings and spacesuits. (For more about human exploration and an outpost on the Moon, see Space Exploration. For more about health in space, check out the Effects of Space on the Human Body.)
Spacecraft instruments will help us identify locations that are a balance between meeting these needs, accessing resources, and undertaking science and engineering experiments.
More than 45 years since we last set foot on the Moon, NASA is renewing the nation’s focus on expanding humanity’s presence beyond Earth. Space Policy Directive-1 provides the direction for NASA to organize more effectively government, commercial and international efforts to develop a permanent presence off Earth that generates new markets and opportunities, both scientific and economic.
- We are going quickly and sustainably with a reusable architecture.
- We are going with commercial and international partners to explore faster and explore more together.
- We will bring new knowledge and opportunities.
- We will use the resources of the Moon to enable farther exploration.
- We will prove out the technologies that will take us to Mars and beyond.