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For the playable Kerbals, see Kerbonaut.
Kerbal astronaut in EVA
Bob Kerman on EVA next to the Mun in version 0.25

Kerbals are the native denizens of the planet Kerbin, and cartoonish in-game analogs for humankind.

Kerbals display no variance in height or weight. They stand roughly 0.75 meters tall (2'5½"). As of 1.11, a Kerbal in an EVA suit, without jetpack nor parachute, has a mass of 45.0 kilograms (99.2 lbs.), which is 0.045 in-game Mass units. When including the parachute and jetpack, a Kerbonaut has a mass of 94 kg. When placed inside a command pod, a crew cabin (eg: PPD-10 Hitchhiker Storage Container) or the Mobile Processing Lab MPL-LG-2 , they add mass to the part; thus (compared to older version) anything that can hold a Kerbal was reduced to compensate for this change.[1]

Before 1.11, the Kerbal's mass only counted toward the mass of a craft if seated in an EAS-1 External Command Seat, and added no mass to any part that can hold a kerbal.

The only Kerbals seen in-game work at Kerbal Space Center or are found in orbit during specific contract missions. These Kerbals can be retrieved as part of the contract, and used as Kerbonauts.

Kerbal astronauts are often called "Kerbonauts".


Kerbal from Kerbalizer

Kerbals have massive heads with respect to their bodies, with roughly half of their total volume accounted for the head. Kerbal eyes protrude from their heads significantly, as do their corneas from the eyes. Kerbals appear to lack any irises, or they are perfectly black in color. They also possess no eyelids, and as a result do not blink.

Judging by official artwork and in-game models, Kerbals appear to have two large teeth that span the length of their gums, one on the mandible and one on the skull. However, this may be due to the cartoonish art style of the game and not actual fact. One of the load screen arts on the latest (1.x) versions of KSP shows Kerbals with multiple human-like teeth.

Their skin hues appear to range from light green to pale green, if they range at all. Although Kerbals appear mostly hairless, they have notable hair growth occurring on the top of their heads and Wernher von Kerman can be seen to have a mustache.

Kerbals also appear to be warm-blooded, given their ability to sweat, which is seen in the Asteroid Redirect teaser trailer on the KSP Youtube Channel.

Kerbals have an awkward, sprawling walk due to their wide pelvis and short legs. A Kerbal's walking speed on Kerbin is about 0.87 m/s, its running speed is about 2.35 m/s.

Anecdotal statements in the descriptions of the Rockomax HubMax Multi-Point Connector and the RoveMax Model XL3 suggest that Kerbals may die from shock when exposed to unexpected technological innovations. This could also be marketing hyperbole.

Kerbals seem to be in infinite supply, the in-game description of planet Kerbin saying its conditions support a "seemingly undepletable population of the eager green creatures".

Their most prominent personality traits are their Stupidity and Courage, as these are about the only individual traits to be seen beyond a name. Some Kerbals, such as Jebediah Kerman, have the rare "badass" trait, which makes them continually enthusiastic and without fear.


Artwork of Valentina Kerman

Up until 1.0, all incorporated Kerbals seemed to be male considering their masculine names and general appearance. C7— a developer at Squad— has said that, “There were no plans to add female Kerbals,” also noting that they didn't have any specific sex in mind.[2] Arguments have been made, though, that while no gender has been officially expressed, a clear masculine/male gender bias was placed on the models.[3][4][5]

On February 21st 2015, the KSP developer team Tumblr page posted an artwork of the first official female Kerbal named Valentina Kerman. Valentina is a reference to Valentina Tereshkova, who is the first woman to have flown in space.[6]

As of Version 1.0, Female Kerbals (aka Kerbalinas) are available for hire at the Astronaut Complex, and Valentina Kerman is a default kerbonaut.


Kerbonauts can be seen to spend years in space without showing any signs of muscle atrophy or other ill effects and can survive for years with vastly less food and oxygen than humans would require. There are various theories why this is possible:

  • They may enter a state of hibernation to endure long space travels
    • This is unlikely, as they appear always awake when controlling the craft (although they still might hibernate whenever their ship isn't active).
  • It is also possible that they have the ability to enter a known psychological state which slows their perception of time through utter joy, or adrenalin. Entering a mental subspace if you will. This can explain their constant grin, and why they don't seem to care about being in a tiny capsule for years.
  • Kerbals may also have a shorter emotional spectrum than humans, only able to experience a smaller number of mindstates than humans. The game and official trailers have told us that Kerbals can experience happiness, fear, sadness, confusion, courage, awe, curiosity, pride, and (maybe) anger, but no evidence for anything else. This is why loneliness and boredom do not seem to affect them, because they do not feel those emotions the same way humans do (if at all).
  • It was previously believed they may also not need oxygen to breathe, as they have no nose and can survive with their mouth closed, but as of 1.6 Kerbals with helmets removed die without oxygen, disproving this theory. However this theory only solved a small part of the problem - the question still remains how Kerbals get energy.
  • Their green skin may contain chlorophyll allowing them to photosynthesize. They would, like a plant, gather solar energy and use that to convert carbon dioxide and water into oxygen and sugar. The Kerbal could then respire the oxygen and sugar to make carbon dioxide, water and usable energy when needed, allowing the Kerbal to survive entirely on light. However, Kerbals can also survive without light seemingly indefinitely.
  • Kerbals are never seen eating, but life support simply has not been implemented into the game. However, many descriptions and parts throughout the game reference the Kerbals enjoying snacks.
  • Another theory states that worrying about life support might simply not be considered fun or, to put it another way: if you're wondering how they eat and breathe you should really just relax.

Kerbal eyes may be a vulnerable spot for injuries due to protrusion, size, and lack of eyelids. If Kerbal eyes truly lack irises, their eyes would be very sensitive to bright lights.

Kerbals' awkward, sprawling walk may indicate that their species only recently evolved to the point of bipedal movement.

  • They may have the green skin due to the fact that they may have to sneak up on their prey.


Kerbals speak backwards Spanish. Their speech can be heard in the Astronaut Complex as well as the end of the credits theme. However, the credits theme is cut-off at the end, so the music file has to be extracted from the game files to hear it. In trailers as well, they speak reverse Spanish (aka "loñapsE").[7] However, Wernher von Kerman and Gene Kerman do emit sounds like "a-ha" and disappointed groans during in-game tutorials and at Mission Control. Curiously, they seem to write in modern English, not appearing as backwards Spanish.

All kerbonauts have a randomly generated first name and "Kerman" as the surname. The first name is either a combination of phonetic syllables or chosen from a list of preset names.[2] There are also a few uniquely named Kerbals, most of whom are apparent homages to real-life figures in NASA.

Kerbals refer to their species as "Kerbalkind" in several in-game texts. This parallels the real-life term "mankind" or "humankind" English-speakers use.


Kerbal larynxes would need an interesting structure to be able to pronounce phonemes that humans either cannot or would at least have great difficulty pronouncing. In addition, their language is full of sudden sharp sounds, unmelodic syllables, and impressively difficult pronunciations, owing to its nature of being a reversed human language. Given the cartoonish nature of Kerbals, their language may "simply be" without any realistic explanation for their vocal abilities.

Material culture and technology

Limited observations make things difficult to determine.

The technology and architecture appears to share many similarities with the modernized nations of Earth during the 1960s-2000s. However, currently[outdated] Kerbin has no visible cities, homes, or any buildings other than those related to aerospace (barring a few easter eggs). The text for the EVA Report while flying in the lower atmosphere over Kerbin's Grasslands biome, however, mentions being able to "see my house from here", implying that Kerbals may live in houses visible above ground even though they are none to be seen in-game yet. Additionally, the text for a Temperature Scan while landed in the Grasslands biome says it "is quite pleasant, and would be a nice place to live." Coupled with reference to Kerbals' love of green, it suggests that Kerbals may have a preference for living in Kerbin's grassy plains.

From the humorous descriptions found in-game, it can be assumed that Kerbals are even more foolish and accident-prone than humans. Kerbals have accidentally mistaken planets for dust or smudges on a telescope lens or mistaken how telescopes work entirely.

In a scenario's instructions, Gene Kerman makes reference to an apparent video game called “Galaxy Intruders” which sounds similar to real-world classic arcade game Space Invaders.

Asteroids. Awesome to look at and great to have around; not so much when one lands on your house. Today we're going to learn how to keep that from happening. As anyone who has played Galaxy Intruders for more than ten minutes can tell you, it's not about firing at where they are, it's about aiming at where they're going to be.

Gene Kerman, Intro to scenario “Asteroid Redirect Mission, Part 1”

A necessarily short list of technologies Kerbals possess includes:

  • Liquid-fuel, air breathing, and solid-fuel engines, and ion-drives
  • Electric power generation and storage
  • Radio communications
  • Computers
  • Reaction Wheels
  • Telescopes and optical instruments
  • Steel and concrete building construction
  • Some understanding of atomic technologies (e.g. RTG, LV-N)

In some mods, they even have more advanced technologies than humans do. Interestingly, they still seem to have all kinds of random accidents and totally unsafe components according to the descriptions of some parts in-game.


It appears that their culture revolves solely around the process of designing, building, launching, riding (and crashing) rockets and planes, as every structure on Kerbin (excluding a certain Easter Egg) is devoted to either aviation or spaceflight.

One explanation of the scarcity of buildings on Kerbin theorizes that Kerbal civilization may live underground, or underwater, due to some unknown factor. Of course, this may be because KSP is a game that does not necessarily mandate cities, or they are planned but not yet implemented.

It is worth noting that the Kerbal Astronomical Society's description of Moho mentions 'Kerbal mythology'. This implies that Kerbals have, or once had, a mythology or form of religion.

Some theories state that Kerbals, if their anatomy and biology resembles plants, can be cloned. This idea could be supported by the fact that all Kerbals have the same surname, and that all of them look alike but have different personalities via artificial memories, meaning that all of them are clones of one original Kerbal with “Kerman” as the surname. This could possibly be Jebediah Kerman, since the "Selection Process" labeled him as #0001. Also, it could be supported more by the fact that at least some Kerbals, Jebediah, Bill and Bob, can respawn or un-die. In KSP 2, some randomly generated kerbal have Japanese and Italian names, suggesting that there may be a version or an analogue of these countries in Kerbin.


See also


  2. 2.0 2.1 Answer by C7 in Kerbal Polar Expedition - Day 5 - Part 1 (Charity Water Campaign) by HOCgaming at 1:14:13
  3. Poll, Do/Should Kerbal Genders exist?” in the forums
  4. POLL: Should SQUAD change the kerbal avatars for gender purposes.” in the forums
  5. A general address on Kerbal gender” in the forums
  6. Answer from @KerbalSpaceP on Twitter
  7. [ Kerbals talk reverse Spanish in the .16 trailer.