Kerbal Space Program

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Kerbal Space Program
Kerbal Space Program High Res Logo.png
Platform(s)Windows, Mac OS X, Linux
Release date(s)June 24, 2011 (alpha 0.7.3)[1]

December 17, 2013 (latest, alpha 0.23.0)[1]

Genre(s)Space flight simulator
Mode(s)Single-player sandbox, single-player career mode
DistributionDigital download
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Kerbal Space Program
Kerbal Space Program High Res Logo.png
Platform(s)Windows, Mac OS X, Linux
Release date(s)June 24, 2011 (alpha 0.7.3)[1]

December 17, 2013 (latest, alpha 0.23.0)[1]

Genre(s)Space flight simulator
Mode(s)Single-player sandbox, single-player career mode
DistributionDigital download

Kerbal Space Program (commonly abbreviated to KSP) is a sandbox-style space flight simulator with gameplay elements currently in development for Windows, Mac OS X, and Linux. The first public alpha was released on June 24, 2011 and updates have been continually released since. KSP has support for mods, which are hosted on an official modding website. It is currently sold on the official KSP Store or, since March 20, 2013, through Steam.


A rocket sitting on the launchpad with the Vehicle Assembly Building and Mün, one of the planet Kerbin's two moons, in the background.

The game places the player in control of a nascent space program operated by Kerbals, a race of small green humanoids, who have constructed a fully furnished and functional spaceport (Kerbal Space Center, or KSC) on their homeworld Kerbin. What they lack in engineering expertise and common sense they more than make up for in enthusiasm and willingness to furnish any materials needed to become a spacefaring civilization (although with the recent addition of career mode they have to "learn" how to make new parts), including a seemingly endless stream of volunteers for manned space missions.

Gameplay consists of constructing rockets and spaceplanes out of a provided set of components and launching them from the in-game space center's launch pad or runway respectively. Many intricate designs can be constructed out of a wide selection of different engines, fuel tanks, wings, and so on. Vehicles can also be equipped with solar panels, RCS thrusters, wheels, or other components. Possible designs range from massive multi-stage rockets to aerodynamic SSTO craft. Once launched, spacecraft can be docked in orbit, or navigated to other celestial bodies and landed for surface operations, including collecting scientific data.

Players can also construct Kerbal versions of their favorite aircraft or construct fanciful aircraft that have no real-world equivalent. The use of physics makes designing a regular jet aircraft just as difficult as designing a space plane. The game currently includes a variety of motorized wheels that allow players to create rovers. Because the physics of water are also implemented (complete with splashes and the craft sinking a bit), building ships is also possible to an extent.

Players can also manage the spaceport's roster of astronauts, who are referred to as the titular "Kerbals" all with the surname "Kerman", choosing personnel to assign to seats and having them exit the vehicle post-launch for extra-vehicular activity. These astronauts are ranked (as of version .22.0) by two factors: courage and stupidity. Kerbals all have randomly generated names with pseudo-randomly generated stats, with a 10% chance of having the badass ("badS") stat, except for the three starting crew whose names and stats are fixed.[2] There are approximately 11,713 unique Kerbal names that can be generated.[3]

Sandbox and a limited version of career mode have been implemented. In career mode, you start with a limited number of parts, and unlock more by doing science in different environments. In sandbox mode, players are free to attempt any mission for which they can construct a suitable vehicle. Typical self-assigned tasks include landing robotic vehicles on other planets in the system, or sending a Kerbal to the closest natural satellite and then returning him safely to his homeworld. Another popular activity is constructing large permanent space stations out of individually launched components. Historical spacecraft can be recreated and their accomplishments mimicked, such as the Apollo program, the Mars Science Laboratory rover, or the International Space Station. Players may also install mods which implement destinations and goals for the game, such as mining for resources or incrementally deploying an interplanetary communication network.

Development of the game remains ongoing and the studio, Squad, have promised that in the future new features will be added, such as damage from atmospheric friction, and a system for creating reusable spacecraft.[4]

The Kerbal Space Program main menu


The game has been praised for its realistic representation of orbital mechanics. Every object in the game except the celestial bodies themselves are under the control of a Newtonian dynamics simulation. Rocket thrust and aerodynamic forces are applied accurately to a vehicle's frame based on the positions in which the force-generating elements are mounted. The strength of the joints connecting parts together is finite and vehicles can be torn apart by excessive or inappropriately directed forces. Planets have atmospheres of varying heights and densities, affecting the efficiency of wings and parachutes and causing drag during flight. The simulations are accurate enough that real-world techniques such as Hohmann transfers and aerobraking are viable methods of navigating the solar system. The game simulates trajectories and orbits using patched conic approximation instead of a full n-body simulation, and thus does not support Lagrange points and halo orbits.

Notable inaccuracies include the perfect reliability of equipment (equipment usually only fails if the player either hits it too hard against something or it gets too close to a lit rocket engine, it can also fall off or possibly fail if the rocket is poorly designed or hits an atmosphere excessively fast) and the lack of life-support consumables. Kerbals can survive indefinitely in space either in a capsule or a space suit. This simplifies orbital rendezvous by making it practical to wait multiple orbits until a desirable alignment is reached. Also, Kerbals have extremely capable EVA suits with 600 m/s of Δv. This is 25 times the capability of NASA's manned maneuvering unit, sufficient to reach orbit from (Or even land on, return to orbit from, and rendezvous with an spacecraft orbiting around) small moons,[5] and allows EVA transfer between markedly different orbits. Additionally, the celestial bodies in the Kerbal solar system are about 1/10 the radius of their real-universe equivalents yet have comparable surface gravity, implying that they have unrealistically high densities. This change to scale makes many tasks considerably easier. For example, a surface to low-Kerbin-orbit launch requires a delta-v of about 4.5 km/s, compared to 9.5 km/s for a low-Earth-orbit launch. In particular, because of the game also having unrealistically efficient and flexible (in terms speed and altitude) turbojet engines, this means it is much easier to make a single-stage-to-orbit vehicle using jet engines to accelerate a vehicle to orbital speed on only a small fraction of its mass in jet fuel, then give a tiny boost with rockets to reach orbit, whereas in real life, a highly efficient but powerful and lightweight scramjet would be necessary to do the same with several times the amount of fuel. Another notable inaccuracy is the game's aerodynamic model. The unmodified game applies drag force to parts based on a "drag coefficient" multiplied by the part's mass (remaining mass for fuel tanks) multiplied by the air density at that altitude multiplied by the speed of the part multiplied by a constant. This results in conventionally aerodynamic designs being unaerodynamic, and most designs having unrealistic levels of drag (often by orders of magnitude for large needle-like rockets). This also means that nosecones actually add drag to a vessel. The relatively minor drag on the nosecone is added to the drag of the other parts. This drag also reduces the effects of steep reentry trajectories and high-speed flight by applying drag forces evenly distributed between the mass of the vessel (except for nosecones, which may go flying off of the front of the vessel, and parachutes, which may pull the back of it off). Lift is calculated in a similar manner and so some planes can have unrealistically far forward wings and not become aerodynamically unstable. Also, non-wing parts do not generate lift, meaning, for example, that re-entering space capsules are neutrally stable in all directions and free to rotate, whereas in reality, they are intended to point heat-shield-down. Additionally, there is no re-entry heating; although an effect exists to show the flames generated by re-entry, it currently is harmless to the spacecraft itself.


The game is currently in the beta stage of development and is considered by the developers to be only a small approximation of the final product.[6] New features are added regularly in updates to the game. No schedule or criteria for transition into beta or final release have been announced. KSP is written in C# and uses the Unity engine.

The game's first public release was Alpha 0.7.3 on June 24, 2011. The game has been moddable from the very early versions[1] and has steadily become more robust.[7] Versions 0.13.3 (March 3, 2012) and 0.18.3 (February 12, 2013) are available, in limited form, as demos; they are available at no cost, but have limited content and can not receive updates. The latest version of the game, 0.23.0, was released on December 17, 2013.[1]


KSP allows support for extensive modding, allowing anything from craft parts to whole autopilot systems and changes to the game's physics to be created. All mods can be hosted on the game's official mod site, Kerbal SpacePort, which can be accessed via a link in the main menu.

There are a wide variety of available mods; autopilot tools, geodetic mapping systems, resource scanning and harvesting, various methods of life support for crew members, data graphing systems, communications network systems, and extensive collections of new parts (including recreations of real and historic spacecraft, including Apollo and the Space Shuttle). Many mods have attempted to cover aspects of the game that have not yet been developed by Squad, and some modders have even been hired by Squad in order to do in-house work due to their comparatively high quality.

On January 27, 2014 it was revealed that Squad is working on an education-themed mod entitled KerbalEdu. It will include improved user interface for easier data gathering and summary, pre-made lessons that focus on certain constructions, options to use the metric system, and a "robust pedagogy" that includes information outside of the game that ties into its content.[8]

Squad is also Making an Asteroid Mission Pack in conjunction with NASA,to be released sometime after update .24 .[9]



Although the game is still in beta, KSP is already considered a success, having over 100,000 members registered on their forums with over 5,500 active users.[10] In the hours after its Steam release on March 20, 2013 it reached the top 5 of best sold games,[11] as well as the best seller on Steam for Linux.[12]


The public alpha releases have been well-received so far. Many publications have referred fondly to Kerbal Space Program and praised the game's replayability and creative aspects, including Kotaku,[13] Rock, Paper, Shotgun,[14][15] IGN,[16] PC Gamer,[17] Gamespy,[18] and The Torch.[19] It has also received a substantial following on Reddit with over 60,000 readers.[20]

Scientific community[edit]

The game has notably crossed over into the scientific community with scientists and members of the space industry having an interest in the game – including NASA[21] and Copenhagen Suborbitals.[22]

See also[edit]


  1. ^ a b c d "Version history – KSP Wiki". Kerbal Space Program Wiki. December 16, 2013. Retrieved December 16, 2013. 
  2. ^
  3. ^
  4. ^ "Planned features - Kerbal Space Program Wiki". Retrieved 2013-11-22. 
  5. ^ Escaping the Mun Using A Broken Ship & EVA Suit
  6. ^ "About". Kerbal Space Program. Retrieved July 18, 2013. 
  7. ^ "Plugins - Kerbal Space Program Wiki". February 22, 2013. Retrieved August 30, 2013. 
  8. ^ Matulef, Jeffrey (27 January 2014). "Kerbal Space Program lands on various schools' curriculum". Eurogamer. Gamer Network. Retrieved 28 January 2014. 
  9. ^
  10. ^ "Kerbal Space Program Forum". Squad. Retrieved June 20, 2013. 
  11. ^ Relaxnews (June 17, 2013). "PC Download Charts". xin.msn. Retrieved June 18, 2013. 
  12. ^ Silviu Stahie (April 1, 2013). "Kerbal Space Program Is the Best-Selling Game on Steam for Linux". softpedia. Retrieved June 18, 2013. 
  13. ^ Luke Plunkett (July 18, 2011). "Will You Help These Stupid Aliens Into Space?". Retrieved August 18, 2013. 
  14. ^ "Trans-Lunar: Kerbal Space Program". Rock, Paper, Shotgun. July 12, 2011. Retrieved August 18, 2013. 
  15. ^ Craig Pearson (May 24, 2013). "(Not) Rocket Science In Kerbal Space Program". Rock, Paper, Shotgun. Retrieved June 19, 2013. 
  16. ^ Anthony Gallegos (April 21, 2012). "Five Ridiculous Upcoming Games". IGN. Retrieved November 12, 2012. 
  17. ^ "Kerbal Space Program". PCGamer. Retrieved June 29, 2013. 
  18. ^ Mike Nelson (March 29, 2012). "Become a Terribly Awesome Rocket Scientist With Kerbal Space Program". GameSpy. Retrieved June 19, 2013. 
  19. ^ Atomp (January 31, 2013). "Kerbal Space Program (Beta) , SQUAD (P)review". The Torch. Retrieved June 19, 2013. 
  20. ^ "/r/KerbalSpaceProgram statistics". Retrieved September 23, 2013. 
  21. ^ Andrew Groen (June 18, 2013). "NASA’s Jet Propulsion Lab is obsessed with a certain game, and I bet you can guess what it is". The PA Report. Archived from the original on December 27, 2013. Retrieved June 19, 2013. 
  22. ^ "Copenhagen Suborbitals joins KSP Forums". KSP Forums. May 1, 2013. Retrieved August 6, 2013. 

External links[edit]