Virgin Galactic says its next passenger spaceship has reached a major construction milestone. The company says Wednesday that all major structural elements have been assembled and the rocket plane is standing on its own landing gear at Mojave Air & Space Port in California. Photos of the “Weight on Wheels" achievement show the craft in a hangar next to the Virgin Space Ship Unity spacecraft. It has already been to space in preparation for commercial operations based at Spaceport America in southern New Mexico. CEO George Whitesides says there has been making progress on the manufacture of a third craft. The company anticipates commercial flights this year.