This might link with efforts you are making in meditation or exploring your inner world of experiences beyond your body senses. Sometimes it reflects states of mind in which you split off from your body, perhaps in an attempt to run away from or avoid direct life experience.
Useful questions:
What is it the astronaut or I am doing in this dream, and how might that relate to my waking activities?
Am I learning anything from the astronaut?
If I stand in the role of the astronaut what is my view of life and the world?
