''Orbiter'' is a

space flight simulator Space flight simulation is a Video game genres, genre of flight simulator video games that lets players experience space flight to varying degrees of Reality, realism. Common mechanics include space exploration, space trade and space combat. Over ...

program developed to simulate

spaceflight Spaceflight (or space flight) is an application of astronautics to fly objects, usually spacecraft, into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such ...

using realistic

Newtonian physics Classical mechanics is a physical theory describing the motion of objects such as projectiles, parts of machinery, spacecraft, planets, stars, and galaxies. The development of classical mechanics involved substantial change in the methods ...

. The simulator was released on 27 November 2000; the latest edition, labeled "Orbiter 2024", was released on 31 December 2024.https://www.orbiter-forum.com/threads/orbiter-2024-release.42062/ On 27 July 2021, its developer, Martin Schweiger, announced to the community that ''Orbiter'' is being published under open source

MIT License The MIT License is a permissive software license originating at the Massachusetts Institute of Technology (MIT) in the late 1980s. As a permissive license, it puts very few restrictions on reuse and therefore has high license compatibility. Unl ...

. ''Orbiter'' was developed by Martin Schweiger, a senior research fellow in the computer science department at

University College London University College London (Trade name, branded as UCL) is a Public university, public research university in London, England. It is a Member institutions of the University of London, member institution of the Federal university, federal Uni ...

,Martin Schweiger
/ref> who felt that space flight simulators at the time were lacking in realistic

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

-based flight models, and decided to write a simulator that made learning physics concepts enjoyable. It has been used as a teaching aid in classrooms, and a community of add-on developers have created a multitude of add-ons to allow users to fly assorted real and fictional spacecraft and add new planets or

planetary system A planetary system is a set of gravity, gravitationally bound non-stellar Astronomical object, bodies in or out of orbit around a star or star system. Generally speaking, systems with one or more planets constitute a planetary system, although ...

About the simulator

Features

''Orbiter'' is a realistic physics simulator which allows users to explore the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

in a number of

spacecraft A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...

, both realistic, such as the ; and fictional, such as the "Delta-Glider." Schweiger has included fictional spacecraft to allow for easier flights for less experienced users. The simulator is realistic enough to re-enact historical space flights, and the ability to fly fictional ships also allows the player to reach areas of the

that cannot be reached by human spaceflight at the present time. A spacecraft's engines are defined only by the amount of thrust they put out and amount of fuel they use, allowing anything from

solar sail Solar sails (also known as lightsails, light sails, and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigati ...

s to conventional

rocket engines A rocket engine is a reaction engine, producing thrust in accordance with Newton's third law by ejecting reaction mass rearward, usually a high-speed Jet (fluid), jet of high-temperature gas produced by the combustion of rocket propellants stor ...

to futuristic

nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...

and fusion drives to be simulated. Everything between ground movement and interplanetary travel is supported, including orbital and sub-orbital flight, although only vessel-ground collisions are supported. Docking and attachment systems allow the user to simulate docking with a

space station A space station (or orbital station) is a spacecraft which remains orbital spaceflight, in orbit and human spaceflight, hosts humans for extended periods of time. It therefore is an artificial satellite featuring space habitat (facility), habitat ...

or other spacecraft, and rendezvous with and retrieval of

satellites A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scientif ...

. Users can also build

s in orbit. The Solar System as presented in ''Orbiter'' consists of the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, the eight

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

s and their major

moons A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are colloquially referred to as moons, a deriva ...

. Many

dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

s (except Vesta), and

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

s not included in the simulator are available as add-ons. Although ''Orbiter'' contains a database of over 100,000 stars, these are for display purposes only and

interstellar travel Interstellar travel is the hypothetical travel of spacecraft between star systems. Due to the vast distances between the Solar System and nearby stars, interstellar travel is not practicable with current propulsion technologies. To travel between ...

is currently not possible in the simulator. The simulator also includes a planetarium mode that allows

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

and

celestial Celestial may refer to: Science * Objects or events seen in the sky and the following astronomical terms: ** Astronomical object, a naturally occurring physical entity, association, or structure that exists in the observable universe ** Celest ...

grids to be overlaid onto the star map, along with labels of the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

s and other celestial markers. The planetarium mode can also display labels indicating the location and identity of objects in the Solar System, such as planets, moons, or vessels, that appear within a certain proximity based on their type. This mode can also display labels on the celestial bodies in the Solar System at certain coordinates on their surface for indicating cities, historical markers, geological formations, and other interesting sites. The traditional simulated control interface in ''Orbiter'' consists of two

multi-function display A multifunction display (MFD) is a small-screen (CRT or LCD) surrounded by multiple soft keys (configurable buttons) that can be used to display information to the user in numerous configurable ways. MFDs originated in aviation, first in mili ...

s and a

head-up display A head-up display, or heads-up display, also known as a HUD () or head-up guidance system (HGS), is any transparent display that presents data without requiring users to look away from their usual viewpoints. The origin of the name stems from a ...

. Each features several modes of operation, with all commands given via the

keyboard Keyboard may refer to: Text input * Keyboard, part of a typewriter * Computer keyboard ** Keyboard layout, the software control of computer keyboards and their mapping ** Keyboard technology, computer keyboard hardware and firmware Music * Mus ...

or mouse. The simulator also supports customized control panels and instruments, including 3-D virtual cockpits and 2-D instrument panels. These allow the player to use the mouse to interact with the panels, and allows more complex systems and instruments that are customized for each ship. The addition of a virtual

cockpit A cockpit or flight deck is the area, on the front part of an aircraft, spacecraft, or submersible, from which a pilot controls the vehicle. The cockpit of an aircraft contains flight instruments on an instrument panel, and the controls th ...

also allows the player to freely look around from the perspective of the pilot. Since ''Orbiter 2006 Patch 1'', it has supported TrackIR, which allows the simulator to track the head-movements of the player and adjust the view accordingly.

Realism

''Orbiter'' was developed as a

simulator A simulation is an imitative representation of a process or system that could exist in the real world. In this broad sense, simulation can often be used interchangeably with model. Sometimes a clear distinction between the two terms is made, in ...

, with accurately modeled planetary motion,

gravitation In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force b ...

effects (including non-spherical gravity), free space, atmospheric flight and

orbital decay Orbital decay is a gradual decrease of the distance between two orbiting bodies at their closest approach (the periapsis) over many orbital periods. These orbiting bodies can be a planet and its satellite, a star and any object orbiting it, or ...

."Orbiter Technical Notes: Dynamic State Vector Propagation", Martin Schweiger, 2006P. Bretagnon and G. Francou
"Planetary theories in rectangular and spherical variables. VSOP87 solutions"
(PDF 840KB), Astronomy & Astrophysics 202 (1988) 309–315. The position of the planets in the solar system is calculated by the VSOP87 solution, while the Earth-Moon system is simulated by the

ELP2000 Éphéméride Lunaire Parisienne is a lunar theory developed by Jean Chapront, Michelle Chapront-Touzé, and others at the Bureau des Longitudes in the 1970s to 1990s. Method ELP gives a series expansion of the orbital elements and the coordinates ...

model. Only n-body

Newtonian mechanics Newton's laws of motion are three physical laws that describe the relationship between the motion of an object and the forces acting on it. These laws, which provide the basis for Newtonian mechanics, can be paraphrased as follows: # A body r ...

are simulated, not taking relativistic effects into account. This means that phenomena such as

time dilation Time dilation is the difference in elapsed time as measured by two clocks, either because of a relative velocity between them (special relativity), or a difference in gravitational potential between their locations (general relativity). When unsp ...

due to relativistic effects are not simulated. The default version of ''Orbiter'' before the 2024 edition had no sound, however popular add-ons called OrbiterSound and XRSound are available. Both of them provide engine noises, ambient sounds in the cabin, radio chatter and other sounds including playlists. Both of them contain options to maintain a realistic silence when the craft is viewed externally during spaceflight. There is no collision detection for objects in space, apart from defined docking ports. Since ''Orbiter 2024'', XRSound is now included in the base package, but must be enabled in the launchpad options to function. Since ''Orbiter 2016'', terrain elevation is modeled for Earth, the Moon, and Mars. Support was also added for higher definition surface textures and clouds.

Included spacecraft

''Orbiters standard distribution includes real and fictional spacecraft and space stations:

Real vessels

;: The ''Orbiter'' version of the Space Shuttle ''Atlantis'', a retired Space Shuttle orbiter formerly operated by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

, and the only player-controllable spacecraft based on a real world design that is included with the basic installation of ''Orbiter''. ;

Space Station A space station (or orbital station) is a spacecraft which remains orbital spaceflight, in orbit and human spaceflight, hosts humans for extended periods of time. It therefore is an artificial satellite featuring space habitat (facility), habitat ...

Mir ''Mir'' (, ; ) was a space station operated in low Earth orbit from 1986 to 2001, first by the Soviet Union and later by the Russia, Russian Federation. ''Mir'' was the first modular space station and was assembled in orbit from 1986 to ...

'': ''Orbiters model of the historic Russian space station. Unlike its real counterpart, it was not deorbited and is placed in an orbit which is closer to the ecliptic plane. This was done initially to make ''Mir'' a good origin of interplanetary flights in earlier versions of ''Orbiter'', when ''Orbiter'' also automatically refueled spacecraft on docking with a space station. Using the scenario editor, it's still possible to refuel in-flight or start the simulation docked and with full tanks. However, it is possible to move Mir into the correct orbit. ;

International Space Station The International Space Station (ISS) is a large space station that was Assembly of the International Space Station, assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United ...

:In a similar orbit as the real ISS and in a completed state, it shows modules which are no longer planned to be installed on the real ISS. ;

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

(HST): A model of the real HST, it gets used together with ''Orbiters Space Shuttle ''Atlantis''. ;

Long Duration Exposure Facility NASA's Long Duration Exposure Facility, or LDEF (pronounced "eldef"), was a cylindrical facility designed to provide long-term experimental data on the outer space environment and its effects on space systems, materials, operations and selected ...

(LDEF) Satellite: Like the Hubble Space Telescope, it's one of the example payloads for ''Orbiters Space Shuttle.

Fictional vessels

;Delta-Glider (DG): A

delta wing A delta wing is a wing shaped in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta (letter), delta (Δ). Although long studied, the delta wing did not find significant practical applications unti ...

spaceplane A spaceplane is a vehicle that can flight, fly and gliding flight, glide as an aircraft in Earth's atmosphere and function as a spacecraft in outer space. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. Orbit ...

, which is rather easy to fly and thus good for the first steps into ''Orbiter''. A variant of the Delta-glider is also included, the Delta-Glider-S (DG-S), which trades some of the propellant capacity for a

scramjet A scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully b ...

propulsion system, at the cost of requiring fuel from the main engine fuel tank. It's possible to travel from Earth to Mars with the DG, making it possible to practice interplanetary missions. It is technically a

single-stage-to-orbit A single-stage-to-orbit (SSTO) vehicle reaches orbit from the surface of a body using only propellants and fluids and without expending tanks, engines, or other major hardware. The term usually, but not exclusively refers to reusable launch sys ...

spaceplane. ;Shuttle-A: A small space freighter, which can transport six large cargo containers with a total mass of . It does not have an aerodynamic hull so it is at home on the Moon and Mars. While it is possible to launch and land the spacecraft from Earth, particularly when empty, the lack of aerodynamic lift coupled with Earth's high gravity and thick atmosphere make this a difficult and fuel-costly operation. Its cargo containers are however equipped with automatic parachutes. Using the parachutes, it's possible to simulate a cargo run from a lunar base to Earth and back, dropping the cargo while still in the upper atmosphere. Its high inertia and inferior aerodynamics make it harder to fly in an atmosphere than the Delta-glider. ;Shuttle-PB: A small personal spacecraft, with high agility and a futuristic performance. As its main purpose is to serve as simple SDK example for add-on developers, it lacks many complex details of other included ships in ''Orbiter'' like 2D or 3D cockpits or animations. ;Dragonfly: A complex crewed

space tug ''Space Tug'' is a young adult fiction, young adult science fiction novel by author Murray Leinster. It was published in 1953 in literature, 1953 by Shasta Publishers in an edition of 5,000 copies. It is the second novel in the author's Joe K ...

for the construction of

s. It simulates its various subsystems at a higher complexity than all other standard spacecraft in ''Orbiter'', being a good example of the technical possibilities of ''Orbiters SDK. Its flight model is also within the possibilities of current technology, making it a so-called "nearly realistic" spacecraft. ;Luna-OB1: A fictional wheel shaped station in lunar orbit, inspired by Space Station V from the beginning of '' 2001: A Space Odyssey''. It consists of a wheel, attached to a central hub with two spokes. The wheel has a diameter of and is spinning at a frequency of one cycle per 36 seconds, providing its occupants with a

centrifugal acceleration Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axi ...

of . ;Carina: A small fictional science satellite, which is used as payload on ''Orbiters Space Shuttle. It is a completely inert payload currently. It is based on a proposed European re-entry capsule experiment, to be launched on the

Ariane 4 The Ariane 4 was a European expendable rocket, expendable launch vehicle in the Ariane (rocket family), Ariane family, developed by the (CNES), the Government of France, French space agency, for the European Space Agency (ESA). The manufacturi ...

, which later resulted in the ARD.

''Orbiter'' add-ons

An extensive

API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...

enables ''Orbiter'' users to contribute by creating add-ons. Many spacecraft are available for download as add-ons, ranging from the

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

Vostok spacecraft Vostok (, translated as "East") was a class of single-pilot crewed spacecraft built by the Soviet Union. The first human spaceflight was accomplished with Vostok 1 on April 12, 1961, by Soviet cosmonaut Yuri Gagarin. The Vostok programme ma ...

Apollo program The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which Moon landing, landed the first humans on the Moon in 1969. Apollo followed Project Mercury that put the first Americans in sp ...

. Another popular category of add-ons are modifications of the standard spacecraft of ''Orbiter'', ranging from simple visual changes to complex simulations of the internal subsystems of these fictional crafts. Examples of these more advanced default spacecraft include the XR Series of vessels. Add-ons are also available for new surface bases, MFD modes, extensions of the simulation menu, space stations, planets, and even other planetary systems. Since ''Orbiter 2006'', a scenario editor is included, which can also be extended for supporting the special attributes of add-on vessels. A third party modlist installer by orbiter-mods.com called Orb can be used to automatically install mod bundles.

References

External links

* *
Orbiter: Manual

Orbiter forum

Official wiki

Orbiter mods
mods repo and automated modlist installer: ''Orb''
Official add-on repository
* * {{DEFAULTSORT:Orbiter (Simulator) 2000 video games Open-source video games Windows games Windows-only games Video games developed in the United Kingdom Space flight simulator games Lua (programming language)-scripted video games Freeware games Realistic space simulators