What's our Moon like

Our Moon has relatively young dark smooth lowlands (mare), and ancient light rough highlands (terrae). The highlands are covered with craters from asteroid and comet impacts; there are fewer craters on the younger lowlands. 

The surface is covered with dusty rock material called regolith — in some cases deeper than 15 meters (50 feet). Regolith is rock that has been pulverized by the impacts.

The Moon has no atmosphere, so there is no wind and the sky is dark — like the Earth’s sky on a clear night. There are extreme temperatures: 130°C (265°F) during the day and –155°C (–250°F) at night. There is no flowing water at the surface of the Moon; any existent water is frozen in the areas that are permanently shadowed; these are the only areas not exposed to the Sun’s heat during part of the lunar day.

Space is filled with radiation, primarily from our Sun; this radiation is deadly to humans unless they are protected from it. While Earth’s magnetic field offers us protection from incoming solar radiation, the Moon has virtually no magnetic field and so the radiation levels are very high.

Because it is less dense and smaller than Earth, the Moon has less gravity. The surface gravity is 1/6 Earth’s gravity.  Our Moon is tilted on its axis only a tiny amount, so there essentially are no seasons. The Moon orbits Earth once every 27 days — and turns on its axis once every 27 days. This means that the lunar “day” is equal to a lunar “year.” It also means that the near side faces Earth constantly. Astronauts would experience daylight for almost two Earth weeks and then darkness for the same time.

How did the Moon form?

Most scientists now believe that about 4.5 billion years ago — shortly after the planets in our solar system formed — a planetary body the size of Mars collided with Earth. The impactor broke apart and pieces of the impactor and Earth’s outer layers were blown out into orbit around Earth. Over a short time — perhaps a hundred years or less, these pieces collided and stuck together — accreted — to form our Moon. 

The heat from accretion caused the Moon, or at least its outer layer, to melt, creating a magma ocean. Eventually the crust cooled. For the first 600 million years of its existence, large asteroids continued to strike the Moon and the planets in our solar system, creating the large basins and craters we see on the Moon. After about 3.9 billion years, much of the “debris” in the solar system had been swept up into the pl While cool on the outside, the interior was still hot. Molten rock would still rise to the Moon’s surface and break through cracks or erupt at volcanos. The lava filled the basin and crater floors — the low areas on the Moon. It cooled quickly, forming fine-grained dark, volcanic rocks called basalt; basalt is the most common type of volcanic rock we find Earth. When you look at the Moon, you can see the large, somewhat circular, dark basins. These are the basalt-filled ancient impact basins. In spite of this exciting beginning and history, the Moon has been geologically inactive for at least the last billion years. anets and their moons, and impact strikes were smaller and less frequent.

Why do we expect water to be 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. Earlier missions to the Moon — Clementine and Lunar Prospector — provided evidence for the presence of water ice. The Lunar Prospector spacecraft detected large amounts of hydrogen in the polar regions, which scientists interpret to be coming from water ice. According to these data, frozen soil and ice at the poles may contain as much as 1–10 billion tons of water locked into deeply shaded craters. That is an amount equal to what is consumed by U.S. cities in 10 days. It would be enough to supply the population of a lunar base for a long time. In addition to sustaining life in a colony, water can be used for rocket fuel and for air by breaking it into its separate chemicals of hydrogen and oxygen.

Why are we going to the Moon if we really want to go to Mars?
Building a human presence on the Moon will allow us to develop and test some of the technology that will be needed to send a human mission to Mars — and beyond!  The Moon is closer and therefore more cost-effective to visit. In unexpected situations, critical materials can be sent to the Moon in a few days compared to the months it takes to send something to Mars. By establishing a base on the Moon, we will learn what we need to be prepared for living and working on Mars.

Also it will be easier to launch rockets filled with necessary resources to Mars from the Moon’s lower gravity than from Earth. 

Finally, a Moon base will allow us to learn much more about Earth’s nearest neighbor, and provide a stable airless environment for studying the Universe.

What will it be like to live and work on the Moon?
If humans are to live on the Moon, even for brief periods, they will need a wide range of support systems. They'll need a place to work, rest, and live that protects them from the cold and dangerous radiation of the space environment. They will need power, light, air, food, water, and heat. They'll need robust transportation and equipment able to operate in low temperatures and the hostile environment of space. They will need to be able to communicate with Earth, other colonies, and shuttles.

They will also need to deal with health issues. Reduced gravity is a challenge to people living on the Moon with one-sixth Earth's gravity. Under reduced gravity conditions, there is less “load” on bones and muscles, so living organisms lose bone mass, muscle tissue, and fluids. Even the heart — a muscle — loses mass because it does not have to work as hard. Humans on the Moon must exercise to maintain their bone and tissue mass so that they can return to Earth's gravity and function well. More research is needed to understand the effects of reduced gravity on the human body — and how to counter these effects.

Any habitat would have to provide shelter from the extreme temperatures and from incoming radiation. Moon bases may include subsurface buildings to increase protection from radiation and micrometeorites.  

There probably would be three basic types of modules: habitation, laboratory, and support modules. The habitat would have sleeping quarters, a kitchen (or galley), and bathroom facilities. Windows would have to be small and made of multiple thick glass sheets to block cosmic radiation. Laboratory modules would be used for conducting experiments. A colony would also need several types of support modules and facilities, including a greenhouse to grow food; a power plant — either solar or nuclear; a place to store construction equipment and do maintenance; a central control, life support, and communications center; resource utilization facilities for processing mined materials; and a landing/launch pad. Accidents or fires could occur or meteorites might strike the base. If an accident occurs in a large structure, it might be necessary to abandon the entire building. However, in a module system, a damaged module could simply be isolated from the rest by closing the hatches shared with other modules, similar to the plan currently onboard the International Space Station. The colonists will need some type of evacuation strategy, such as emergency escape transportation in the event of a severe accident. The colony team would initially include scientists and engineers. These individuals would probably have many other capabilities, such as medical training and construction training. As the colony grew, other personnel would need to be added. They would conduct research and experiments in the laboratories, work on colony construction, maintain the base, and mine resources. Medical specialists, cooks, safety specialists, administrative staff, and cleaning crews would be needed to support the efforts. These crews would be replaced on a regular basis in the same way as teams who work at Antarctic bases on Earth.

When will humans be back on the Moon?
NASA plans to have humans on the Moon possibly by about 2020. That means that today’s 10 year old child will be 25 — and may be helping NASA build and operate a new Moon base as a geologist, resource manager, engineer, emergency medical technician, lab technician, safety officer, pilot, mechanic, or chef.  All of these people — and others — will be needed to make our future Moon Base operate smoothly!

On the Moon, many of the things that can kill you are invisible: breathtaking vacuum, extreme temperatures and space radiation top the list. Vacuum and temperature NASA can handle; spacesuits and habitats provide plenty of air and insulation. Radiation, though, is trickier.
The surface of the Moon is baldly exposed to cosmic rays and solar flares, and some of that radiation is very hard to stop with shielding. Furthermore, when cosmic rays hit the ground, they produce a dangerous spray of secondary particles right at your feet. All this radiation penetrating human flesh can damage DNA, boosting the risk of cancer and other maladies.
According to the Vision for Space Exploration, NASA plans to send astronauts back to the Moon by 2020 and, eventually, to set up an outpost. For people to live and work on the Moon safely, the radiation problem must be solved.

"We really need to know more about the radiation environment on the Moon, especially if people will be staying there for more than just a few days," says Harlan Spence, a professor of astronomy at Boston University.

To carefully measure and map the Moon's radiation environment, NASA is developing a robotic probe to orbit the Moon beginning in 2008. Called the Lunar Reconnaissance Orbiter (LRO), this scout will pave the way for future human missions not only by measuring space radiation, but also by hunting for frozen water and mapping the Moon's surface in unprecedented detail. LRO is a key part of NASA's Robotic Lunar Exploration Program, managed by the Goddard Space Flight Center. It has six main instruments: CRaTER, DIVINER, LAMP, LOLA, LEND, and LROC.

One of the instruments onboard LRO is the Cosmic Ray Telescope for the Effects of Radiation (CRaTER).

"Not only will we measure the radiation, we will use plastics that mimic human tissue to look at how these highly energetic particles penetrate and interact with the human body," says Spence, who is the Principal Investigator for CRaTER.

By placing the radiation detectors in CRaTER behind various thicknesses of a special plastic that has similar density and composition to human tissue, Spence and his colleagues will provide much-needed data: Except for quick trips to the Moon during the Apollo program, most human spaceflight has occurred near Earth where our planet's magnetic field provides a natural shield.

In low-Earth orbit, the most dangerous forms of space radiation are relatively rare. That's good for astronauts, but it leaves researchers with many unanswered questions about what radiation does to human tissue. CRaTER will help fill in the gaps.

Out in deep space, radiation comes from all directions. On the Moon, you might expect the ground, at least, to provide some relief, with the solid body of the Moon blocking radiation from below. Not so.

When galactic cosmic rays collide with particles in the lunar surface, they trigger little nuclear reactions that release yet more radiation in the form of neutrons. The lunar surface itself is radioactive!

So which is worse for astronauts: cosmic rays from above or neutrons from below? Igor Mitrofanov, a scientist at the Institute for Space Research and the Russian Federal Space Agency, Moscow, offers a grim answer: "Both are worse."

Mitrofanov is Principle Investigator for the other radiation-sensing instrument on LRO, the Lunar Exploration Neutron Detector (LEND), which is partially funded by the Russian Federal Space Agency. By using an isotope of helium that's missing one neutron, LEND will be able to detect neutron radiation emanating from the lunar surface and measure how energetic those neutrons are.

The first global mapping of neutron radiation from the Moon was performed by NASA's Lunar Prospector probe in 1998-99. LEND will improve on the Lunar Prospector data by profiling the energies of these neutrons, showing what fraction are of high energy (i.e., the most damaging to people) and what fraction are of lower energies.

With such knowledge in hand, scientists can begin designing spacesuits, lunar habitats, Moon vehicles, and other equipment for NASA's return to the Moon knowing exactly how much radiation shielding this equipment must have to keep humans safe.