The Moon is Earth's only natural satellite. It orbits at an average distance of 384,400 km (238,900 mi), about 30 times the diameter of Earth. Tidal forces between Earth and the Moon have synchronized the Moon's orbital period with its rotation period at 29.5 Earth days, causing the same side of the Moon to always face Earth. The Moon's gravitational pull—and, to a lesser extent, the Sun's—are the main drivers of Earth's tides.
Space exploration is the use of astronomy and space technology to explore outer space. While the exploration of space is currently carried out mainly by astronomers with telescopes, its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight. Space exploration, like its classical form astronomy, is one of the main sources for space science.
The Interplanetary Transport Network (ITN) is a collection of gravitationally determined pathways through the Solar System that require very little energy for an object to follow. The ITN makes particular use of Lagrange points as locations where trajectories through space can be redirected using little or no energy. These points have the peculiar property of allowing objects to orbit around them, despite lacking an object to orbit, as these points exist where gravitational forces between two celestial bodies are equal. While it would use little energy, transport along the network would take a long time.
The Vision for Space Exploration (VSE) was a plan for space exploration announced on January 14, 2004 by President George W. Bush. It was conceived as a response to the Space Shuttle Columbia disaster, the state of human spaceflight at NASA, and as a way to regain public enthusiasm for space exploration.
Colonization of the Moon is a process or concept employed by some proposals for robotic or human exploitation and settlement endeavours on the Moon. Often used as a synonym for its more specific element of settling the Moon, lunar or space colonization as a whole has become contested for perpetuating colonialism and its exploitive logic in space.
Paul D. Spudis (1952–2018) was an American geologist and lunar scientist. His specialty was the study of volcanism and impact processes on the planets, including Mercury and Mars.
The Exploration Systems Architecture Study (ESAS) is the official title of a large-scale, system level study released by the National Aeronautics and Space Administration (NASA) in November 2005 of his goal of returning astronauts to the Moon and eventually Mars—known as the Vision for Space Exploration. The Constellation Program was cancelled in 2010 by the Obama Administration and replaced with the Space Launch System, later renamed as the Artemis Program in 2017 under the Trump Administration.
In orbital mechanics, a free-return trajectory is a trajectory of a spacecraft traveling away from a primary body where gravity due to a secondary body causes the spacecraft to return to the primary body without propulsion.
In astronomy and spaceflight, a lunar orbit is an orbit by an object around Earth's Moon. In general these orbits are not circular. When farthest from the Moon a spacecraft is said to be at apolune, apocynthion, or aposelene. When closest to the Moon it is said to be at perilune, pericynthion, or periselene. These derive from names or epithets of the moon goddess.
A halo orbit is a periodic, three-dimensional orbit associated with one of the L1, L2 or L3 Lagrange points in the three-body problem of orbital mechanics. Although a Lagrange point is just a point in empty space, its peculiar characteristic is that it can be orbited by a Lissajous orbit or by a halo orbit. These can be thought of as resulting from an interaction between the gravitational pull of the two planetary bodies and the Coriolis and centrifugal force on a spacecraft. Halo orbits exist in any three-body system, e.g., a Sun–Earth–orbiting satellite system or an Earth–Moon–orbiting satellite system. Continuous "families" of both northern and southern halo orbits exist at each Lagrange point. Because halo orbits tend to be unstable, station-keeping using thrusters may be required to keep a satellite on the orbit.
The (Japanese) Lunar Exploration Program is a program of robotic and human missions to the Moon undertaken by the Japanese Aerospace Exploration Agency (JAXA) and its division, the Institute of Space and Astronautical Science (ISAS). It is also one of the three major enterprises of the JAXA Space Exploration Center (JSPEC). The main goal of the program is "to elucidate the origin and evolution of the Moon and utilize the Moon in the future".
A distant retrograde orbit (DRO), as most commonly conceived, is a spacecraft orbit around a moon that is highly stable because of its interactions with two Lagrange points (L1 and L2) of the planet–moon system.
The Lunar Gateway, or simply Gateway, is a space station which is planned to be assembled in orbit around the Moon. The Gateway is intended to serve as a communication hub, science laboratory, and habitation module for astronauts as part of the Artemis program. It is a multinational collaborative project: participants include NASA, the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA), the Canadian Space Agency (CSA), and the Mohammed Bin Rashid Space Centre (MBRSC). The Gateway is planned to be the first space station beyond low Earth orbit.
ArgoMoon is a CubeSat that was launched into a heliocentric orbit on Artemis 1, the maiden flight of the Space Launch System, on 16 November 2022 at 06:47:44 UTC. The objective of the ArgoMoon spacecraft is to take detailed images of the Interim Cryogenic Propulsion Stage following Orion separation, an operation that will demonstrate the ability of a cubesat to conduct precise proximity maneuvers in deep space. ASI has not confirmed nor denied whether this took place, but several images of the Earth and the Moon were taken.
Blue Moon is a family of lunar landers and their associated infrastructure, intended to carry humans and cargo to the Moon, under development by a consortium led by Blue Origin and including Lockheed Martin, Draper, Boeing, Astrobotic, and Honeybee Robotics. Two versions of Blue Moon are under development: a robotic lander planned to land on the Moon in 2024, and a larger human lander planned to land a crew of four astronauts on the lunar surface for the NASA Artemis V mission in 2029.
Cislunar Explorers is a pair of spacecraft that will show the viability of water electrolysis propulsion and interplanetary optical navigation to orbit the Moon. Both spacecraft will launch mated together as two L-shaped 3U CubeSats, which fit together as a 6U CubeSat of about 10 cm × 20 cm × 30 cm.
In orbital mechanics a near-rectilinear halo orbit (NRHO) is a halo orbit that passes close to the smaller of two bodies and has nearly stable behavior. The CAPSTONE mission, launched in 2022, is the first spacecraft to use such orbit in cislunar space, and this Moon-centric orbit is planned as a staging area for future lunar missions. In contrast with low lunar orbit which NASA characterizes as being deep in the lunar gravity well, NRHO is described as being "balanced on the edge" of the gravity well.
CAPSTONE is a lunar orbiter that is testing and verifying the calculated orbital stability planned for the Lunar Gateway space station. The spacecraft is a 12-unit CubeSat that is also testing a navigation system that is measuring its position relative to NASA's Lunar Reconnaissance Orbiter (LRO) without relying on ground stations. It was launched on 28 June 2022, arrived in lunar orbit on 15 November 2022, and was scheduled to orbit for six months. On 18 May 2023, it completed its primary mission to orbit in the near-rectilinear halo orbit for six months, but will stay on this orbit, continuing to perform experiments during an enhanced mission phase.
