^{ [1] }

Orbit | Name |
---|---|

GEO | Geostationary orbit |

LEO | Low Earth orbit |

MEO | Medium Earth orbit |

SSO | Sun-synchronous orbit |

VLEO | Very Low Earth Orbit |

Orbit | Name |
---|---|

GSO | Geosynchronous orbit |

GTO | Geostationary transfer orbit |

HCO | Heliocentric orbit (aka Solar Orbit) |

HEO | Highly elliptical orbit |

NRHO | Near-rectilinear halo orbit |

The following is a list of types of orbits:

- Galactocentric orbit:
^{ [2] }An orbit about the center of a galaxy. The Sun follows this type of orbit about the Galactic Center of the Milky Way. - Heliocentric orbit: An orbit around the Sun. In the Solar System, all planets, comets, and asteroids are in such orbits, as are many artificial satellites and pieces of space debris. Moons by contrast are not in a heliocentric orbit but rather orbit their parent object.
- Geocentric orbit: An orbit around the planet Earth, such as that of the Moon or of artificial satellites.
- Selenocentric orbit (named after Selene): An orbit around Earth's Moon.
- Areocentric orbit (named after Ares): An orbit around the planet Mars, such as that of its moons or artificial satellites.

For orbits centered about planets other than Earth and Mars and for the dwarf planet Pluto, the orbit names incorporating Greek terminology is less commonly used

- Common abbreviations
- List of abbreviations of common Earth orbits
- List of abbreviations of other orbits
- Classifications
- Centric classifications
- Altitude classifications for geocentric orbits
- Inclination classifications
- Directional classifications
- Eccentricity classifications
- Synchronicity classifications
- Orbits in galaxies or galaxy models
- Special classifications
- Pseudo-orbit classifications
- See also
- Notes
- References

- Mercury orbit (Hermeocentric orbit, named after Hermes): An orbit around the planet Mercury.
- Venus orbit (Cytherocentric orbit, named after Cythera): An orbit around the planet Venus.
- Jupiter orbit (Zenocentric orbit, named after Zeus,
^{ [3] }or Latin equivalent Jovicentric): An orbit around the planet Jupiter. - Saturn orbit (Cronocentric orbit, named after Cronus,
^{ [3] }or Latin equivalent Saturnicentric): An orbit around the planet Saturn. - Uranus orbit (Uranocentric orbit, named after Uranus): An orbit around the planet Uranus.
- Neptune orbit (Poseidocentric orbit, named after Poseidon): An orbit around the planet Neptune.
- Pluto orbit (Hadeocentric orbit, named after Hades): An orbit around the dwarf planet Pluto.

- Very Low Earth Orbit (VLEO) is defined as altitudes between approximately 100 - 450 km above Earth’s surface.
^{ [4] }^{ [5] } - Low Earth orbit (LEO): geocentric orbits with altitudes below 2,000 km (1,200 mi).
^{ [6] } - Medium Earth orbit (MEO): geocentric orbits ranging in altitude from 2,000 km (1,200 mi) to just below geosynchronous orbit at 35,786 kilometers (22,236 mi). Also known as an intermediate circular orbit. These are used for Global Navigation Satellite System spacecraft, such as GPS, GLONASS, Galileo, BeiDou. GPS satellites orbit at an altitude of 20,200 kilometers (12,600 mi) with an orbital period of almost 12 hours.
^{ [7] } - Geosynchronous orbit (GSO) and geostationary orbit (GEO) are orbits around Earth matching Earth's sidereal rotation period.
^{ [1] }^{ [8] }Although terms are often used interchangeably, technically a geosynchronous orbit matches the Earth's rotational period, but the definition does not require it to have zero orbital inclination to the equator, and thus is not stationary above a given point on the equator, but may oscillate north and south during the course of a day. Thus, a geostationary orbit is defined as a geosynchronous orbit at zero inclination. Geosynchronous (and geostationary) orbits have a semi-major axis of 42,164 km (26,199 mi).^{ [9] }This works out to an altitude of 35,786 km (22,236 mi). Both complete one full orbit of Earth per sidereal day (relative to the stars, not the Sun). - High Earth orbit: geocentric orbits above the altitude of geosynchronous orbit (35,786 km or 22,236 mi).
^{ [7] }

For Earth orbiting satellites below the height of about 800 km, the atmospheric drag is the major orbit perturbing force out of all non-gravitational forces.^{ [10] } Above 800 km, solar radiation pressure causes the largest orbital perturbations.^{ [11] } However, the atmospheric drag strongly depends on the density of the upper atmosphere, which is related to the solar activity, therefore the height at which the impact of the atmospheric drag is similar to solar radiation pressure varies depending on the phase of the solar cycle.

- Inclined orbit: An orbit whose inclination in reference to the equatorial plane is not 0.
- Polar orbit: An orbit that passes above or nearly above both poles of the planet on each revolution. Therefore, it has an inclination of (or very close to) either 90 degrees or −90 degrees.
- Polar Sun-synchronous orbit (SSO): A nearly polar orbit that passes the equator at the same local solar time on every pass. Useful for image-taking satellites because shadows will be the same on every pass.

- Non-inclined orbit: An orbit whose inclination is equal to zero with respect to some plane of reference.
- Ecliptic orbit: A non-inclined orbit with respect to the ecliptic.
- Equatorial orbit: A non-inclined orbit with respect to the equator.

- Near equatorial orbit: An orbit whose inclination with respect to the equatorial plane is nearly zero. This orbit allows for rapid revisit times (for a single orbiting spacecraft) of near equatorial ground sites.

- Prograde orbit: An orbit that is in the same direction as the rotation of the primary (i.e. east on Earth). By convention, the inclination of a Prograde orbit is specified as an angle less than 90°.
- Retrograde orbit: An orbit counter to the direction of rotation of the primary. By convention, retrograde orbits are specified with an inclination angle of more than 90°. Apart from those in Sun-synchronous orbit, few satellites are launched into retrograde orbit on Earth because the quantity of fuel required to launch them is greater than for a prograde orbit. This is because when the rocket starts out on the ground, it already has an eastward component of velocity equal to the rotational velocity of the planet at its launch latitude.

There are two types of orbits: closed (periodic) orbits, and open (escape) orbits. Circular and elliptical orbits are closed. Parabolic and hyperbolic orbits are open. Radial orbits can be either open or closed.

- Circular orbit: An orbit that has an eccentricity of 0 and whose path traces a circle.
- Elliptic orbit: An orbit with an eccentricity greater than 0 and less than 1 whose orbit traces the path of an ellipse.
- Geostationary or geosynchronous transfer orbit (GTO): An elliptic orbit where the perigee is at the altitude of a low Earth orbit (LEO) and the apogee at the altitude of a geostationary orbit.
- Hohmann transfer orbit: An orbital maneuver that moves a spacecraft from one circular orbit to another using two engine impulses. This maneuver was named after Walter Hohmann.
- Ballistic capture orbit: a lower-energy orbit than a
*Hohmann transfer orbit*, a spacecraft moving at a lower orbital velocity than the target celestial body is inserted into a similar orbit, allowing the planet or moon to move toward it and gravitationally snag it into orbit around the celestial body.^{ [12] } - Coelliptic orbit: A relative reference for two spacecraft—or more generally, satellites—in orbit in the same plane. "Coelliptic orbits can be defined as two orbits that are coplanar and confocal. A property of coelliptic orbits is that the difference in magnitude between aligned radius vectors is nearly the same, regardless of where within the orbits they are positioned. For this and other reasons, coelliptic orbits are useful in [spacecraft] rendezvous".
^{ [13] }

- Parabolic orbit: An orbit with the eccentricity equal to 1. Such an orbit also has a velocity equal to the escape velocity and therefore will escape the gravitational pull of the planet. If the speed of a parabolic orbit is increased it will become a hyperbolic orbit.
- Escape orbit: A parabolic orbit where the object has escape velocity and is moving away from the planet.
- Capture orbit: A parabolic orbit where the object has escape velocity and is moving toward the planet.

- Hyperbolic orbit: An orbit with the eccentricity greater than 1. Such an orbit also has a velocity in excess of the escape velocity and as such, will escape the gravitational pull of the planet and continue to travel infinitely until it is acted upon by another body with sufficient gravitational force.
- Radial orbit: An orbit with zero angular momentum and eccentricity equal to 1. The two objects move directly towards or away from each other in a straight-line.
- Radial elliptic orbit: A closed elliptic orbit where the object is moving at less than the escape velocity. This is an elliptic orbit with semi-minor axis = 0 and eccentricity = 1. Although the eccentricity is 1, this is not a parabolic orbit.
- Radial parabolic orbit: An open parabolic orbit where the object is moving at the escape velocity.
- Radial hyperbolic orbit: An open hyperbolic orbit where the object is moving at greater than the escape velocity. This is a hyperbolic orbit with semi-minor axis = 0 and eccentricity = 1. Although the eccentricity is 1, this is not a parabolic orbit.

- Synchronous orbit: An orbit whose period is a rational multiple of the average rotational period of the body being orbited and in the same direction of rotation as that body. This means the track of the satellite, as seen from the central body, will repeat exactly after a fixed number of orbits. In practice, only 1:1 ratio (geosynchronous) and 1:2 ratios (semi-synchronous) are common.
- Geosynchronous orbit (GSO): An orbit around the Earth with a period equal to one sidereal day, which is Earth's average rotational period of 23 hours, 56 minutes, 4.091 seconds. For a nearly circular orbit, this implies an altitude of approximately 35,786 kilometers (22,236 mi). The orbit's inclination and eccentricity may not necessarily be zero. If both the inclination and eccentricity are zero, then the satellite will appear stationary from the ground. If not, then each day the satellite traces out an analemma (i.e. a "figure-eight") in the sky, as seen from the ground. When the orbit is circular and the rotational period has zero inclination, the orbit is considered to also be
*geostationary*. Also known as a Clarke orbit after the writer Arthur C. Clarke.^{ [7] }- Geostationary orbit (GEO): A circular geosynchronous orbit with an inclination of zero. To an observer on the ground this satellite appears as a fixed point in the sky. "All geostationary orbits must be geosynchronous, but not all geosynchronous orbits are geostationary."
^{ [7] } - Tundra orbit: A synchronous but highly elliptic orbit with significant inclination (typically close to 63.4°) and orbital period of one sidereal day (23 hours, 56 minutes for the Earth). Such a satellite spends most of its time over a designated area of the planet. The particular inclination keeps the perigee shift small.
^{ [14] }

- Geostationary orbit (GEO): A circular geosynchronous orbit with an inclination of zero. To an observer on the ground this satellite appears as a fixed point in the sky. "All geostationary orbits must be geosynchronous, but not all geosynchronous orbits are geostationary."
- Areosynchronous orbit (ASO): A synchronous orbit around the planet Mars with an orbital period equal in length to Mars' sidereal day, 24.6229 hours.
- Areostationary orbit (AEO): A circular areosynchronous orbit on the equatorial plane and about 17,000 km (10,557 miles) above the surface of Mars. To an observer on Mars this satellite would appear as a fixed point in the sky.

- Geosynchronous orbit (GSO): An orbit around the Earth with a period equal to one sidereal day, which is Earth's average rotational period of 23 hours, 56 minutes, 4.091 seconds. For a nearly circular orbit, this implies an altitude of approximately 35,786 kilometers (22,236 mi). The orbit's inclination and eccentricity may not necessarily be zero. If both the inclination and eccentricity are zero, then the satellite will appear stationary from the ground. If not, then each day the satellite traces out an analemma (i.e. a "figure-eight") in the sky, as seen from the ground. When the orbit is circular and the rotational period has zero inclination, the orbit is considered to also be
- Subsynchronous orbit: A drift orbit close below GSO/GEO.
- Semi-synchronous orbit: An orbit with an orbital period equal to half of the average rotational period of the body being orbited and in the same direction of rotation as that body. For Earth this means a period of just under 12 hours at an altitude of approximately 20,200 km (12,544.2 miles) if the orbit is circular.
^{ [15] }- Molniya orbit: A semi-synchronous variation of a Tundra orbit. For Earth this means an orbital period of just under 12 hours. Such a satellite spends most of its time over two designated areas of the planet. An inclination of 63.4° is normally used to keep the perigee shift small.
^{ [14] }

- Molniya orbit: A semi-synchronous variation of a Tundra orbit. For Earth this means an orbital period of just under 12 hours. Such a satellite spends most of its time over two designated areas of the planet. An inclination of 63.4° is normally used to keep the perigee shift small.

- Semi-synchronous orbit: An orbit with an orbital period equal to half of the average rotational period of the body being orbited and in the same direction of rotation as that body. For Earth this means a period of just under 12 hours at an altitude of approximately 20,200 km (12,544.2 miles) if the orbit is circular.
- Supersynchronous orbit: Any orbit in which the orbital period of a satellite or celestial body is greater than the rotational period of the body which contains the barycenter of the orbit.

- Box orbit: An orbit in a triaxial elliptical galaxy that fills in a roughly box-shaped region.
- Pyramid orbit: An orbit near a massive black hole at the center of a triaxial galaxy.
^{ [16] }The orbit can be described as a Keplerian ellipse that precesses about the black hole in two orthogonal directions, due to torques from the triaxial galaxy.^{ [17] }The eccentricity of the ellipse reaches unity at the four corners of the pyramid, allowing the star on the orbit to come very close to the black hole. - Tube orbit: An orbit near a massive black hole at the center of an axisymmetric galaxy. Similar to a pyramid orbit, except that one component of the orbital angular momentum is conserved; as a result, the eccentricity never reaches unity.
^{ [17] }

- Sun-synchronous orbit: An orbit which combines altitude and inclination in such a way that the satellite passes over any given point of the planets's surface at the same local solar time. Such an orbit can place a satellite in constant sunlight and is useful for imaging, spy, and weather satellites.
- Frozen orbit: An orbit in which natural drifting due to the central body's shape has been minimized by careful selection of the orbital parameters.
- Orbit of the Moon: The orbital characteristics of the Moon. Average altitude of 384,403 kilometres (238,857 mi), elliptical-inclined orbit.
- Beyond-low Earth orbit (BLEO) and beyond Earth orbit (BEO) are a broad class of orbits that are energetically farther out than low Earth orbit or require an insertion into a heliocentric orbit as part of a journey that may require multiple orbital insertions, respectively.
- Near-rectilinear halo orbit (NRHO): an orbit currently planned in cislunar space, as a selenocentric orbit that will serve as a staging area for future missions.
^{ [18] }^{ [19] }Planned orbit for the NASA Lunar Gateway in circa 2024, as a highly-elliptical seven-day near-rectilinear halo orbit around the Moon, which would bring the small space station within 3,000 kilometers (1,900 mi) of the lunar north pole at closest approach and as far away as 70,000 kilometers (43,000 mi) over the lunar south pole.^{ [20] }^{ [21] }^{ [22] } - Distant retrograde orbit (DRO): A stable circular retrograde orbit (usually referring to Lunar Distant Retrograde Orbit). Stability means that satellites in DRO do not need to use station keeping propellant to stay in orbit. The lunar DRO is a high lunar orbit with a radius of approximately 61,500 km.
^{ [23] }This was proposed^{[ by whom? ]}in 2017 as a possible orbit for the Lunar Gateway space station, outside Earth-Moon L1 and L2.^{ [19] } - Decaying orbit: A decaying orbit is an orbit at a low altitude that decreases over time due atmospheric resistance. Used to dispose of dying artificial satellites or to aerobrake an interplanetary spacecraft.
- Earth-trailing orbit, a heliocentric orbit that is placed such that the satellite will initially follow Earth but at a somewhat slower orbital angular speed, such that it moves further behind year by year. This orbit was used on the Spitzer Space Telescope in order to drastically reduce the heat load from the warm Earth from a more typical geocentric orbit used for space telescopes.
^{ [24] } - Graveyard orbit (or disposal, junk orbit) : An orbit that satellites are moved into at the end of their operation. For geostationary satellites a few hundred kilometers above geosynchronous orbit.
^{ [25] }^{ [26] } - Parking orbit, a temporary orbit.
- Transfer orbit, an orbit used during an orbital maneuver from one orbit to another.
- Lunar transfer orbit (LTO)
^{[ clarification needed ]}accomplished with trans-lunar injection (TLI) - Mars transfer orbit (MTO) also known as trans-Mars injection (TMI) orbit

- Lunar transfer orbit (LTO)
- Repeat orbit: An orbit where the ground track of the satellite repeats after a period of time.
- Gangale orbit: a solar orbit near Mars whose period is one Martian year, but whose eccentricity and inclination both differ from that of Mars such that a relay satellite in a Gangale orbit is visible from Earth even during solar conjunction.
^{ [27] }

- Horseshoe orbit: An orbit that appears to a ground observer to be orbiting a certain planet but is actually in co-orbit with the planet. See asteroids 3753 Cruithne and 2002 AA
_{29}. - Libration point orbits such as halo orbits and Lissajous orbits: These are orbits around a Lagrangian point. Lagrange points are shown in the adjacent diagram, and orbits near these points allow a spacecraft to stay in constant relative position with very little use of fuel. Orbits around the L
_{1}point are used by spacecraft that want a constant view of the Sun, such as the Solar and Heliospheric Observatory. Orbits around L_{2}are used by missions that always want both Earth and the Sun behind them. This enables a single shield to block radiation from both Earth and the Sun, allowing passive cooling of sensitive instruments. Examples include the Wilkinson Microwave Anisotropy Probe and the James Webb Space Telescope. L1, L2, and L3 are unstable orbits[6], meaning that small perturbations will cause the orbiting craft to drift out of the orbit without periodic corrections. - P/2 orbit, a highly-stable 2:1 lunar resonant orbit, that was first used with the spacecraft TESS (Transiting Exoplanet Survey Satellite) in 2018.
^{ [28] }^{ [29] }

- ↑ Orbital periods and speeds are calculated using the relations 4π
^{2}*R*^{3}=*T*^{2}*GM*and*V*^{2}*R*=*GM*, where*R*= radius of orbit in metres,*T*= orbital period in seconds,*V*= orbital speed in m/s,*G*= gravitational constant ≈ 6.673×10^{−11}Nm^{2}/kg^{2},*M*= mass of Earth ≈ 5.98×10^{24}kg. - ↑ Approximately 8.6 times when the Moon is nearest (363,104 km ÷ 42,164 km) to 9.6 times when the Moon is farthest (405,696 km ÷ 42,164 km).

In celestial mechanics, an **orbit** is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point. Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory. To a close approximation, planets and satellites follow elliptic orbits, with the center of mass being orbited at a focal point of the ellipse, as described by Kepler's laws of planetary motion.

A **geosynchronous orbit** is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds. 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. Over the course of a day, the object's position in the sky may remain still or trace out a path, typically in a figure-8 form, whose precise characteristics depend on the orbit's inclination and eccentricity. A circular geosynchronous orbit has a constant altitude of 35,786 km (22,236 mi).

A **geostationary orbit**, also referred to as a **geosynchronous equatorial orbit** (**GEO**), is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator, 42,164 km (26,199 mi) in radius from Earth's center, and following the direction of Earth's rotation.

A **synchronous orbit** is an orbit in which an orbiting body has a period equal to the average rotational period of the body being orbited, and in the same direction of rotation as that body.

A **low Earth orbit** (**LEO**) is an orbit around Earth with a period of 128 minutes or less 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.

A **trans-lunar injection** (**TLI**) is a propulsive maneuver used to set a spacecraft on a trajectory that will cause it to arrive at the Moon.

In astronautics, the **Hohmann transfer orbit** is an orbital maneuver used to transfer a spacecraft between two orbits of different altitudes around a central body. Examples would be used for travel between low Earth orbit and the Moon, or another solar planet or asteroid. In the idealized case, the initial and target orbits are both circular and coplanar. The maneuver is accomplished by placing the craft into an elliptical transfer orbit that is tangential to both the initial and target orbits. The maneuver uses two impulsive engine burns: the first establishes the transfer orbit, and the second adjusts the orbit to match the target.

A **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.

**Orbital mechanics** or **astrodynamics** is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and the law of universal gravitation. Orbital mechanics is a core discipline within space-mission design and control.

A **geocentric orbit**, **Earth-centered orbit**, or **Earth orbit** involves any object orbiting Earth, such as the Moon or artificial satellites. In 1997, NASA estimated there were approximately 2,465 artificial satellite payloads orbiting Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center. More than 16,291 objects previously launched have undergone orbital decay and entered Earth's atmosphere.

A **Sun-synchronous orbit** (**SSO**), also called a **heliosynchronous orbit**, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is an orbit arranged so that it precesses through one complete revolution each year, so it always maintains the same relationship with the Sun.

In astrodynamics and aerospace, a **delta-v budget** is an estimate of the total change in velocity (delta-*v*) required for a space mission. It is calculated as the sum of the delta-v required to perform each propulsive maneuver needed during the mission. As input to the Tsiolkovsky rocket equation, it determines how much propellant is required for a vehicle of given empty mass and propulsion system.

In astrodynamics, **orbital station-keeping** is keeping a spacecraft at a fixed distance from another spacecraft or celestial body. It requires a series of orbital maneuvers made with thruster burns to keep the active craft in the same orbit as its target. For many low Earth orbit satellites, the effects of non-Keplerian forces, i.e. the deviations of the gravitational force of the Earth from that of a homogeneous sphere, gravitational forces from Sun/Moon, solar radiation pressure and air drag, must be counteracted.

A **graveyard orbit**, also called a **junk orbit** or **disposal orbit**, is an orbit that lies away from common operational orbits. One significant graveyard orbit is a supersynchronous orbit well beyond geosynchronous orbit. Some satellites are moved into such orbits at the end of their operational life to reduce the probability of colliding with operational spacecraft and generating space debris.

**Spacecraft flight dynamics** is the application of mechanical dynamics to model how the external forces acting on a space vehicle or spacecraft determine its flight path. These forces are primarily of three types: propulsive force provided by the vehicle's engines; gravitational force exerted by the Earth and other celestial bodies; and aerodynamic lift and drag.

**AsiaSat 3**, previously known as **HGS-1** and then **PAS-22**, was a geosynchronous communications satellite, which was salvaged from an unusable geosynchronous transfer orbit (GTO) by means of the Moon's gravity.

A **supersynchronous orbit** is either an orbit with a period greater than that of a synchronous orbit, or just an orbit whose apoapsis is higher than that of a synchronous orbit. A synchronous orbit has a period equal to the rotational period of the body which contains the barycenter of the orbit.

A **medium Earth orbit** (**MEO**) is an Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between 2,000 and 35,786 km above sea level.

In celestial mechanics, the term **stationary orbit** refers to an orbit around a planet or moon where the orbiting satellite or spacecraft remains orbiting over the same spot on the surface. From the ground, the satellite would appear to be standing still, hovering above the surface in the same spot, day after day.

This **glossary of astronomy** is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a significant amount of jargon.

- 1 2 "Types of Orbits".
*Space Foundation*. - ↑ "Definition of GALACTOCENTRIC".
*www.merriam-webster.com*. Retrieved 3 June 2020. - 1 2 Parker, Sybil P. (2002).
*McGraw-Hill Dictionary of Scientific and Technical Terms Sixth Edition*. McGraw-Hill. p. 1772. ISBN 007042313X. - ↑ "Stingray VLEO Constellation".
- ↑ "Attitude control for satellites flying in VLEO using aerodynamic surfaces".
- ↑ "NASA Safety Standard 1740.14, Guidelines and Assessment Procedures for Limiting Orbital Debris" (PDF). Office of Safety and Mission Assurance. 1 August 1995. p. A-2. Archived from the original (PDF) on 15 February 2013.
Low Earth orbit (LEO) – The region of space below the altitude of 2000 km.

, pages 37–38 (6–1,6–2); figure 6-1. - 1 2 3 4 "Orbit: Definition".
*Ancillary Description Writer's Guide, 2013*. National Aeronautics and Space Administration (NASA) Global Change Master Directory. Archived from the original on 11 May 2013. Retrieved 29 April 2013. - ↑ "Types of orbits".
- ↑ Vallado, David A. (2007).
*Fundamentals of Astrodynamics and Applications*. Hawthorne, CA: Microcosm Press. p. 31. - ↑ Krzysztof, Sośnica (1 March 2015). "Impact of the Atmospheric Drag on Starlette, Stella, Ajisai, and Lares Orbits".
*Artificial Satellites*.**50**(1): 1–18. Bibcode:2015ArtSa..50....1S. doi: 10.1515/arsa-2015-0001 . - ↑ Bury, Grzegorz; Sośnica, Krzysztof; Zajdel, Radosław; Strugarek, Dariusz (28 January 2020). "Toward the 1-cm Galileo orbits: challenges in modeling of perturbing forces".
*Journal of Geodesy*.**94**(2): 16. Bibcode:2020JGeod..94...16B. doi: 10.1007/s00190-020-01342-2 . - ↑ Hadhazy, Adam (22 December 2014). "A New Way to Reach Mars Safely, Anytime and on the Cheap".
*Scientific American*. Retrieved 25 December 2014. - ↑ Whipple, P. H . (17 February 1970). "Some Characteristics of Coelliptic Orbits – Case 610" (PDF).
*Bellcom Inc*. Washington: NASA. Archived from the original (PDF) on 21 May 2010. Retrieved 23 May 2012. - 1 2 This answer explains why such inclination keeps apsidial drift small: https://space.stackexchange.com/a/24256/6834
- ↑ "Catalog of Earth Satellite Orbits".
*earthobservatory.nasa.gov*. NASA. 4 September 2009. Retrieved 4 May 2022. - ↑ Merritt and Vasilev, ORBITS AROUND BLACK HOLES IN TRIAXIAL NUCLEI", The Astrophysical Journal 726(2), 61 (2011).
- 1 2 Merritt, David (2013).
*Dynamics and Evolution of Galactic Nuclei*. Princeton: Princeton University Press. ISBN 9780691121017. - ↑ Leonard David (15 March 2018). "NASA Shapes Science Plan for Deep-Space Outpost Near the Moon".
*Space.com*. - 1 2
*How a New Orbital Moon Station Could Take Us to Mars and Beyond*Oct 2017 video with refs - ↑ Angelic halo orbit chosen for humankind's first lunar outpost. European Space Agency, Published by
*PhysOrg.*19 July 2019. - ↑ Halo orbit selected for Gateway space station. David Szondy,
*New Atlas*. 18 July 2019. - ↑ Foust, Jeff (16 September 2019). "NASA cubesat to test lunar Gateway orbit".
*SpaceNews*. Retrieved 15 June 2020. - ↑ "Asteroid Redirect Mission Reference Concept" (PDF).
*www.nasa.gov*. NASA. Retrieved 14 June 2015. - ↑ "About Spitzer: Fast Facts". Caltech. 2008. Archived from the original on 2 February 2007. Retrieved 22 April 2007.
- ↑ "U.S. Government Orbital Debris Mitigation Standard Practices" (PDF). United States Federal Government. Retrieved 28 November 2013.
- ↑ Luu, Kim; Sabol, Chris (October 1998). "Effects of perturbations on space debris in supersynchronous storage orbits" (PDF).
*Air Force Research Laboratory Technical Reports*(AFRL-VS-PS-TR-1998-1093). Bibcode:1998PhDT.......274L. Archived (PDF) from the original on 3 December 2013. Retrieved 28 November 2013. - ↑ Byford, Dorothy (September 2008). "Optimal Location of Relay Satellites for Continuous Communication with Mars".
`{{cite web}}`

: CS1 maint: url-status (link) - ↑ Keesey, Lori (31 July 2013). "New Explorer Mission Chooses the 'Just-Right' Orbit". NASA. Retrieved 5 April 2018.
- ↑ Overbye, Dennis (26 March 2018). "Meet Tess, Seeker of Alien Worlds".
*The New York Times*. Retrieved 5 April 2018.

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