Dreaming of being in outer space can symbolize feelings of isolation or being far removed from your usual environment and relationships. The presence of your mother in this dream may indicate a need for comfort and guidance during uncertain or challenging times in your life.

The empty container you dropped could represent a sense of loss or the feeling that you lack something important that you are trying to hold onto. The fact that it floated away rapidly might suggest that opportunities or emotions are slipping away from you, and you may feel powerless to stop it.

Your mother's warning about being careful suggests a protective instinct, perhaps reflecting your own awareness of the risks associated with your current situation or choices. It could be a reminder to be mindful of your actions and their potential consequences.

Overall, this dream could be highlighting feelings of vulnerability and the need for support as you navigate through uncertainties. Consider reflecting on areas in your life where you might feel stranded or overwhelmed, and think about how you can seek support or regain a sense of control.