Lunar orbit

SelenocentricSelenocentric orbitlunar orbit insertionLow Lunar OrbitLunarpericynthionorbit the Moonirregular gravity fieldlunar gravitational fieldLunar orbit § Perturbation effects
In astronomy, lunar orbit (also known as a selenocentric orbit) is the orbit of an object around the Moon.wikipedia
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Moon

lunarthe MoonLuna
In astronomy, lunar orbit (also known as a selenocentric orbit) is the orbit of an object around the Moon. The Soviet Luna 10 became the first spacecraft to actually orbit the Moon in April 1966.
The names Luna, Cynthia, and Selene are reflected in terminology for lunar orbits in words such as apolune, pericynthion, and selenocentric.

Apollo program

ApolloProject ApolloApollo space program
Five such spacecraft were launched over a period of thirteen months, all of which successfully mapped the Moon, primarily for the purpose of finding suitable Apollo program landing sites. The Apollo program's Command/Service Module (CSM) remained in a lunar parking orbit while the Lunar Module (LM) landed.
Kennedy's goal was accomplished on the Apollo 11 mission when astronauts Neil Armstrong and Buzz Aldrin landed their Apollo Lunar Module (LM) on July 20, 1969, and walked on the lunar surface, while Michael Collins remained in lunar orbit in the command and service module (CSM), and all three landed safely on Earth on July 24.

Apsis

perigeeperihelionapogee
The altitude at apoapsis (point farthest from the surface) for a lunar orbit is known as apolune, apocynthion, or aposelene, while the periapsis (point closest to the surface) is known as perilune, pericynthion, or periselene, from names or epithets of the moon goddess. The LM began its landing sequence with a Descent Orbit Insertion (DOI) burn to lower their periapsis to about 50,000 ft, chosen to avoid hitting lunar mountains reaching heights of 20,000 ft. After the second landing mission, the procedure was changed on Apollo 14 to save more of the LM fuel for its powered descent, by using the CSM's fuel to perform the DOI burn, and later raising its periapsis back to a circular orbit after the LM had made its landing.
During the Apollo program, the terms pericynthion and apocynthion were used when referring to orbiting the Moon; they reference Cynthia, an alternative name for the Greek Moon goddess Artemis.

Frozen orbit

frozenJ3 perturbationneeded an inclination of 63.4°
They are of particular interest in exploration of the Moon, but suffer from gravitational perturbation effects that make most unstable, and leave only a few orbital inclinations possible for indefinite frozen orbits, useful for long-term stays in LLO.
Through a study of many lunar orbiting satellites, scientists have discovered that most low lunar orbits (LLO) are unstable.

Apollo 11

1969 moon landingmoon landingfirst moon landing
The Apollo 11 first manned landing mission employed the first attempt to correct for the perturbation effect (the frozen orbits were not known at that time).
Command module pilot Michael Collins flew the command module Columbia alone in lunar orbit while they were on the Moon's surface.

Apollo 14

14Apollo 14: Recovery Aboard the USS New Orleansonly Mercury astronaut to walk on the Moon
The LM began its landing sequence with a Descent Orbit Insertion (DOI) burn to lower their periapsis to about 50,000 ft, chosen to avoid hitting lunar mountains reaching heights of 20,000 ft. After the second landing mission, the procedure was changed on Apollo 14 to save more of the LM fuel for its powered descent, by using the CSM's fuel to perform the DOI burn, and later raising its periapsis back to a circular orbit after the LM had made its landing.
While Shepard and Mitchell were on the surface, Roosa remained in lunar orbit aboard the command and service module Kitty Hawk, performing scientific experiments and photographing the Moon, including the landing site of the future Apollo 16 mission.

Luna 10

Luna-10
The Soviet Luna 10 became the first spacecraft to actually orbit the Moon in April 1966.
After a midcourse correction on 1 April, Luna 10, the second of two hastily prepared Soviet Ye-6S probes (that is, the backup), successfully entered lunar orbit two days later at 18:44 UT. A 245-kilogram instrument compartment separated from the main bus, which was in a 350 x 1,000-kilometer orbit inclined at 71.9° to the lunar equator.

Apollo 15

15Apollos 15Apollo 15 Command Module
The Apollo 15 subsatellite PFS-1 and the Apollo 16 subsatellite PFS-2, both small satellites released from the Apollo Service Module, contributed to this discovery.
The lunar module returned safely to the command module and, at the end of Apollo 15's 74th lunar orbit the engine was fired for the journey home.

LADEE

Lunar Atmosphere and Dust Environment ExplorerLunar Atmosphere and Dust Environment Explorer (LADEE)Lunar Laser Communication Demonstration
The most recent was the Lunar Atmosphere and Dust Environment Explorer (LADEE), which became a ballistic impact experiment in 2014.
Launched into a highly elliptical Earth orbit, the spacecraft made three increasingly larger laps around Earth before getting close enough to enter into Lunar orbit.

List of orbits

Luna 11

Luna-11
A follow-on mission, Luna 11, was launched on August 24, 1966 and studied lunar gravitational anomalies, radiation and solar wind measurements.

Lunar Orbiter 1

The first United States spacecraft to orbit the Moon was Lunar Orbiter 1 on August 14, 1966.

Apollo 16

16ApolloNASA UFO
The Apollo 15 subsatellite PFS-1 and the Apollo 16 subsatellite PFS-2, both small satellites released from the Apollo Service Module, contributed to this discovery.
Following the LM inspection, the crew reviewed checklists and procedures for the following days in anticipation of their arrival and the Lunar Orbit Insertion burn.

Apollo command and service module

command moduleApollo Command/Service ModuleApollo Command Module
The Apollo 15 subsatellite PFS-1 and the Apollo 16 subsatellite PFS-2, both small satellites released from the Apollo Service Module, contributed to this discovery. The Apollo program's Command/Service Module (CSM) remained in a lunar parking orbit while the Lunar Module (LM) landed.

Apollo Lunar Module

Lunar ModuleLunar Excursion ModuleLM
The Apollo program's Command/Service Module (CSM) remained in a lunar parking orbit while the Lunar Module (LM) landed.

Mass concentration (astronomy)

mass concentrationmasconsmascon
Gravitational anomalies slightly distorting the orbits of some Lunar Orbiters led to the discovery of mass concentrations (dubbed mascons) beneath the lunar surface caused by large impacting bodies at some remote time in the past.
*Lunar orbit § Perturbation effects

Astronomy

astronomicalastronomerastronomers
In astronomy, lunar orbit (also known as a selenocentric orbit) is the orbit of an object around the Moon.

Orbit

orbitsorbital motionplanetary motion
In astronomy, lunar orbit (also known as a selenocentric orbit) is the orbit of an object around the Moon.

Lists of space programs

space programspace programmeSpace power
As used in the space program, this refers not to the orbit of the Moon about the Earth, but to orbits by various manned or unmanned spacecraft around the Moon.

Orbit of the Moon

Moon's orbitits orbitorbit
As used in the space program, this refers not to the orbit of the Moon about the Earth, but to orbits by various manned or unmanned spacecraft around the Moon.

Earth

Earth's surfaceterrestrialworld
As used in the space program, this refers not to the orbit of the Moon about the Earth, but to orbits by various manned or unmanned spacecraft around the Moon.

Spacecraft

spaceshipspaceshipsspace ship
As used in the space program, this refers not to the orbit of the Moon about the Earth, but to orbits by various manned or unmanned spacecraft around the Moon.

Altitude

high altitudealtitudeshigh-altitude
The altitude at apoapsis (point farthest from the surface) for a lunar orbit is known as apolune, apocynthion, or aposelene, while the periapsis (point closest to the surface) is known as perilune, pericynthion, or periselene, from names or epithets of the moon goddess.

List of lunar deities

moon godlunar deitymoon goddess
The altitude at apoapsis (point farthest from the surface) for a lunar orbit is known as apolune, apocynthion, or aposelene, while the periapsis (point closest to the surface) is known as perilune, pericynthion, or periselene, from names or epithets of the moon goddess.

Perturbation (astronomy)

perturbationsperturbationperturbed
They are of particular interest in exploration of the Moon, but suffer from gravitational perturbation effects that make most unstable, and leave only a few orbital inclinations possible for indefinite frozen orbits, useful for long-term stays in LLO.