Each kerbonaut has a specialization as either a Pilot, Engineer, or Scientist. They gain Experience (XP) for completing a variety of achievements and reach higher levels in their specialization. Higher levels grant additional abilities, making veteran crew more capable as they attain more achievements.
Orbiting, planting flags, and escaping from the gravity of planets and moons grants various amounts of experience depending on the planet. Each Kerbal can only gain the experience once per planet, so planting multiple flags or repeatedly orbiting a planet do not add provide any further experience for the same Kerbal. Additionally, experience from a given planet or moon is only granted for the most valuable achievement, so orbiting the Mun (3 XP) and planting a flag on it (5 XP) will only grant 5 XP, not 8. Note that when planting flags, each Kerbal in the mission must plant a separate flag to gain the experience for doing so. If only one Kerbal in the mission plants a flag, only that Kerbal will gain experience for having done so. The kerbonaut gains the experience and reaches level only when returns to the Astronaut Complex by recovery.
|Order||Celestial body|| Fly by
| Plant flag
As Kerbals gain experience, they gain levels in their specialization. Kerbals start at level 0, and can reach level 5. The level of the kerbonaut represented by number of stars.
|Level||XP Required||Total XP|
As Kerbals level up, they gain new abilities. There are usually new abilities at every level, but some of the levels do not have new abilities, and none of the specializations gain new abilities when going from level 4 to level 5.
- Pilots - At level 0, pilots can stabilize a ship and allow SAS. At level 1, they can use the direction selector to aim a ship prograde or retrograde. At level 2, they can orient a ship to the normal, antinormal, radial in, and radial out vectors. At level 3, they can orient a ship towards a target, away from a target, or towards a maneuver. They gain no further abilities with additional levels.
- Engineers - Level 0 engineers have no special abilities. At level 1, they can repack parachutes. At level 2, they can repair lander legs. At level 3, they can repair wheels. They gain no further abilities with additional levels.
- Scientists - Scientists improve the amount of Science (⚛) gained from returned science parts and vessels. At level 0, there is no bonus. The bonus is 5% at level 1, 10% at level 2, 15% at level 3, 20% at level 4, and remains 20% at level 5.