Carlsbad Caverns National Park is an American national park in the Guadalupe Mountains of southeastern New Mexico. The primary attraction of the park is the show cave Carlsbad Cavern. Visitors to the cave can hike in on their own via the natural entrance or take an elevator from the visitor center. The park entrance is located on US Highway 62/180, approximately 18 miles (29 km) southwest of Carlsbad, New Mexico. Carlsbad Caverns National Park participates in the Junior Ranger Program. The park has two entries on the National Register of Historic Places: The Caverns Historic District and the Rattlesnake Springs Historic District. Approximately two-thirds of the park has been set aside as a wilderness area, helping to ensure no future changes will be made to the habitat. Carlsbad Cavern includes a large limestone chamber, named simply the Big Room, which is almost 4,000 ft (1,220 m) long, 625 ft (191 m) wide, and 255 ft (78 m) high at its highest point. The Big Room is the largest chamber in North America and the 32nd largest in the world.In 1930, Carlsbad Caverns was established as a national park and was also recognized as...

A light-year, alternatively spelled light year, is a unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (9.46×1012 km), or 5.88 trillion miles (5.88×1012 mi). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the word "year", the term is sometimes misinterpreted as a unit of time.The light-year is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years) which derives from astrometry; it is the distance at which one astronomical unit (au) subtends an angle of one second of arc. Definitions As defined by the International Astronomical Union (IAU), the...

Canadarm or Canadarm1 (officially Shuttle Remote Manipulator System or SRMS, also SSRMS) is a series of robotic arms that were used on the Space Shuttle orbiters to deploy, manoeuvre, and capture payloads. After the Space Shuttle Columbia disaster, the Canadarm was always paired with the Orbiter Boom Sensor System (OBSS), which was used to inspect the exterior of the shuttle for damage to the thermal protection system. Development In 1969, Canada was invited by the National Aeronautics and Space Administration (NASA) to participate in the Space Shuttle program. At the time what that participation would entail had not yet been decided but a manipulator system was identified as an important component. Canadian company DSMA ATCON had developed a robot to load fuel into CANDU nuclear reactors; this robot attracted NASA's attention. In 1975, NASA and the Canadian National Research Council (NRC) signed a memorandum of understanding that Canada would develop and construct the Canadarm.NRC awarded the manipulator contract to Spar Aerospace (now MDA). Three systems...