NASAThe National Aeronautics and Space Administration (NASA ˈnæsə) is an independent agency of the U.S. federal government responsible for the civil space program, aeronautics research, and space research. Established in 1958, NASA succeeded the National Advisory Committee for Aeronautics (NACA) to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science.
Geostationary orbitA geostationary orbit, also referred to as a geosynchronous equatorial orbit (GEO), is a circular geosynchronous orbit in altitude above Earth's equator, in radius from Earth's center, and following the direction of Earth's rotation. An object in such an orbit has an orbital period equal to Earth's rotational period, one sidereal day, and so to ground observers it appears motionless, in a fixed position in the sky. The concept of a geostationary orbit was popularised by the science fiction writer Arthur C.
MoonThe Moon is Earth's only natural satellite. Its diameter is about one-quarter of Earth's (comparable to the width of Australia), making it the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet. It is larger than all known dwarf planets in the Solar System. The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term. It lacks any significant atmosphere, hydrosphere, or magnetic field.
Moon landingA Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon. This includes both crewed and robotic missions. The first human-made object to touch the Moon was the Soviet Union's Luna 2, on 13 September 1959. The United States' Apollo 11 was the first crewed mission to land on the Moon, on 20 July 1969. There were six crewed U.S. landings between 1969 and 1972, and numerous uncrewed landings, with no soft landings happening between 22 August 1976 and 14 December 2013.
Space tourismSpace tourism is human space travel for recreational purposes. There are several different types of space tourism, including orbital, suborbital and lunar space tourism. During the period from 2001 to 2009, seven space tourists made eight space flights aboard a Russian Soyuz spacecraft to the International Space Station, brokered by Space Adventures in conjunction with Roscosmos and RSC Energia. The publicized price was in the range of US$20–25 million per trip.
Full moonThe full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (when the ecliptic longitudes of the Sun and Moon differ by 180°). This means that the lunar hemisphere facing Earth—the near side—is completely sunlit and appears as an approximately circular disk. The full moon occurs roughly once a month. The time interval between a full moon and the next repetition of the same phase, a synodic month, averages about 29.
Colonization of the MoonColonization of the Moon is a process or concept employed by some proposals for robotic or human exploitation and settlement endeavours on the Moon. Settling of the Moon is therefore a more specific concept, for which the broader concept of colonization is often used as a synonym, a use that is contested in the light of colonialism. Laying claim to the Moon has been declared illegal through international space law and no state has made such claims, despite having a range of probes and artificial remains on the Moon.
Geostationary transfer orbitA geostationary transfer orbit (GTO) or geosynchronous transfer orbit is a type of geocentric orbit. Satellites that are destined for geosynchronous (GSO) or geostationary orbit (GEO) are (almost) always put into a GTO as an intermediate step for reaching their final orbit. A GTO is highly elliptic. Its perigee (closest point to Earth) is typically as high as low Earth orbit (LEO), while its apogee (furthest point from Earth) is as high as geostationary (or equally, a geosynchronous) orbit.
Low Earth orbitA low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never more than about one-third of the radius of Earth. The term LEO region is also used for the area of space below an altitude of (about one-third of Earth's radius). Objects in orbits that pass through this zone, even if they have an apogee further out or are sub-orbital, are carefully tracked since they present a collision risk to the many LEO satellites.
Outer spaceOuter space, commonly referred to simply as space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty; it is a near-perfect vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is .
Lunar orbitIn astronomy, lunar orbit (also known as a selenocentric orbit) is the orbit of an object around the Moon. As used in the space program, this refers not to the orbit of the Moon about the Earth, but to orbits by spacecraft around the Moon. The altitude at apoapsis (point farthest from the center of attraction) for a lunar orbit is known as apolune, apocynthion, or aposelene, while the periapsis (point closest to the center of attraction) is known as perilune, pericynthion, or periselene, from names or epithets of the moon goddess.
Orbit of the MoonThe Moon orbits Earth in the prograde direction and completes one revolution relative to the Vernal Equinox and the stars in about 27.32 days (a tropical month and sidereal month) and one revolution relative to the Sun in about 29.53 days (a synodic month). Earth and the Moon orbit about their barycentre (common centre of mass), which lies about from Earth's centre (about 73% of its radius), forming a satellite system called the Earth–Moon system. On average, the distance to the Moon is about from Earth's centre, which corresponds to about 60 Earth radii or 1.
Geosynchronous orbitA geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day.
Lunar GatewayThe Lunar Gateway, or simply Gateway, is the first planned extraterrestrial space station. It will be placed in lunar orbit and is intended to serve as a solar-powered communication hub, science laboratory, and short-term habitation module for government-agency astronauts, as well as a holding area for rovers and other robots. It is a multinational collaborative project involving four of the International Space Station partner agencies: NASA, European Space Agency (ESA), Japan Aerospace Exploration Agency (JAXA), and Canadian Space Agency (CSA).
