Now that you've quite certainly launched into space in Kerbal Space Program and almost definitely visited other worlds and absolutely don't explode your spaceships in terrible accidents anymore, it's time for science. Developer Squad yesterday released update 0.22 for the space sim, kicking off Career Mode with research and development experiments to unlock new parts.
Careed Mode starts the Kerbal Space Program with only a few parts to build with, just enough to perform a few experiments and earn a resource named, of course, Science. This unlocks more parts, which lets you build fancier ships, which let you go further and do more science. Science!
The grand goal of career mode is to task you with every aspect of running a space program, from hiring staff and performing R&D to taking contract jobs and building a reputation.
The hearty list of changes for version 0.22 also includes making Nose Cones actually useful, adding reusable subassemblies to the ship editor, expanding and tarting up your home space center on Kerbin, and starting to add biomes for celestial bodies.