The NASA Workbench is a specialized item assembly table which is used to craft a Tier 1 Rocket as well as other unlockable vehicles and items which require schematics in order to unlock them. Currently, the only other vehicle schematics available are the Moon Buggy, the Tier 2 Rocket, and the Cargo Rocket. It is 4 blocks tall so be sure to allow ample space when placing.
Right-clicking on the Workbench will pull up the interface. By default this will show the 'Tier 1 Rocket' as it is already unlocked. You can change tabs by pressing the 'next' or 'back' buttons on either side of the inventory. Schematics can be added via the Schematics tab, enabling you to create a broader range of vehicles (still a work-in-progress).