The convention for orbital spacecraft is that the local coordinate system has +z facing whatever it is orbiting and +x facing travel direction. Then you can refer to directions relative to the spacecraft such as "+x", "-y", etc.
The space shuttle normally orbited with it's payload bay, opposite of the landing gear facing Earth. The payload bay was +z direction. From the layperson's point of view, the shuttle orbited upside down, but from an aerospace engineer's point of view it orbited right side up and landed upside down.
The space shuttle normally orbited with it's payload bay, opposite of the landing gear facing Earth. The payload bay was +z direction. From the layperson's point of view, the shuttle orbited upside down, but from an aerospace engineer's point of view it orbited right side up and landed upside down.