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The Moon Portal


The Moon is Earth's only natural satellite and is the fifth largest satellite in the Solar System. It is the largest natural satellite in the Solar System relative to the size of its planet, a quarter the diameter of Earth and 1/81 its mass, and is the second densest satellite after Io. It is in synchronous rotation with Earth, always showing the same face; the near side is marked with dark volcanic maria among the bright ancient crustal highlands and prominent impact craters. It is the brightest object in the sky after the Sun, although its surface is actually very dark, with a similar reflectance to coal. Its prominence in the sky and its regular cycle of phases have since ancient times made the Moon an important cultural influence on language, the calendar, art and mythology. The Moon's gravitational influence produces the ocean tides and the minute lengthening of the day. The Moon's current orbital distance, about thirty times the diameter of the Earth, causes it to be the same size in the sky as the Sun—allowing the Moon to cover the Sun precisely in total solar eclipses.

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An artist's rendering of the Orion spacecraft

Orion is a spacecraft which was designed by Lockheed Martin for NASA, the space agency of the United States. Orion development began as part of the Constellation program, where Orion would fulfill the function of a Crew Exploration Vehicle. Each Orion spacecraft is projected to carry a crew of four astronauts. The spacecraft was originally designed to be launched by the Ares I launch vehicle, for the Constellation Program. As of 11 October 2010, with the canceling of the Constellation Program the Orion vehicle is now planned to be launched onto top of a Shuttle-Derived Heavy Lift Vehicle. Orion would launch from Launch Complex 39 at Kennedy Space Center, the same launch complex used by the Space Shuttle and the Saturn V. While shuttle operations continued from launch pad 39A, 39B was readied for Ares launches. The first crewed Orion flight is anticipated in 2016. Subsequent flights would visit the International Space Station. If commercial orbital transportation services are unavailable, Orion would handle logistic flights to the station. After that, Orion may become a key component of human missions beyond low earth orbit which may included missions to lagrange points, Near-Earth objects, the Moon and Mars. The federal government proposed cancellation of the Constellation program in February 2010 and was signed into law October 11. The bill is basically a retooling of the Constellation Program, moving the objective away from a moon base and more towards a NEO mission and an eventual Mars landing.

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Apollo 15 flag, rover, LM, Irwin.jpg
Credit: NASA

Astronaut James B. Irwin, lunar module pilot, gives a military salute while standing beside the deployed U.S. flag during the Apollo 15 lunar surface extravehicular activity (EVA) at the Hadley-Apennine landing site.

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Aerial photo of the Descartes Highlands with features and Apollo 16 mission traverses labeled.

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