The Science game mode is one of the three modes available in Kerbal Space Program. It is an intermediate choice between "freestyle" Sandbox mode, and the heavily resource dependent Career mode. The point of the Science game mode is the undertaking of various scientific activities without the burden of the contract, funds and reputation system present in career mode. This game mode was known as "Career" in all versions prior to the release of version 0.24, since its release in version 0.22.
Unlike the in the sandbox game mode, the Research and Development facility is open (as in career mode), allowing the use of environmental sensors and the collection of data. Recovering or transmitting the data from those experiments yields Science points, which can be used in the Research and Development facility to “research” new parts; this immediately unlocks all parts of that technology tree node, and allows access to the next node.
Because the player can use only parts which are already unlocked, every game begins with the Start node unlocked. Unlike career mode, the developed parts are free, as there is no monetary system, there are no contracts from different agencies, and there is no reputation. As a result of this, the Mission Control is closed. Due to there not being contracts, the player is unable to acquire the science points derived from completing them. Similarly, there is no entry to the Administration Facility, and there are no business strategies to choose to influence the financial (), scientific (⚛) and reputation (★) income.
The science and career modes have similar phases of gameplay. At the beginning of the game, the player will perform minor missions on and around Kerbin in order to acquire enough science points to unlock the parts needed for moon missions. The second phase is Mun and Minmus missions, with the intention of gaining enough science points to unlock the parts needed for interplanetary missions.