I am also a pre-service elementary education teacher and enjoy Earth and Space Science very much, as well! I am currently in a workshop that has been utilizing multiple engaging activities that can be implemented for students at the elementary level. One activity was about creating a poster advertising a movie about a planet and when presenting you could discuss all the facts of the planet and why you would want to watch the movie about this planet or visit the planet. It was fun, engaging, and really got you thinking.
I highly recommend this article "The Many Levels of Inquiry" about inquiry-based learning. Creating lessons the are inquiry-based can be a fun, engaging way to get students thinking and curious about the topic they are learning.
Another option is informal learning, such as the Maryland Science Center, or other museums focuses on science, specifically space. A suggestion could be to try to see if they're websites offer any information about activities and what they're exhibits have to offer.
Hope this helps!