Classic public domain film, digitally preserved and free to stream forever.
Aelita: Queen of Mars (1924) is a landmark Soviet silent science fiction film in which a Moscow engineer becomes obsessed with radio signals he believes originate from Mars, eventually travelling there and falling for Aelita, the queen of the Martians, while helping to incite a workers' revolution on the red planet.
Starring Yuliya Solntseva, Nikolai Tsereteli, and Igor Ilyinsky. This film is in the public domain and free to watch, download, and share.