If you're looking for manga similar to The Voices of a Distant Star, you might like these titles. All recommendations are made by Anime-Planet users like you!
In the distant future, the human race is on the brink of destruction. Mankind, which now drifts in space aboard a massive, technologically-advanced base known as Avalon, is poised to launch one final, desperate attack against its enemy, the alien race Hideauze. It’s during this battle that Ledo, a mecha pilot, is thrown into a wormhole and sent to an unfamiliar place: Earth, the lost birthplace of humanity said to have turned to ice long ago. Having been saved by the inhabitants of the Gargantia, a fleet of ships that traverses the now-flooded planet, Ledo must come to terms with these primitive people with their backwards language and technology, learn to communicate, and try to find a way back home to his place in the sky.
Gargantia on the Verdurous Planet and The Voices of a Distant Star feature protagonists who pilot mechs and fight aliens in deep space. Both are interesting takes on human relationships and the reason for wars. In both series, humans fight against an alien enemy of which they don't know much about. The strange appearance and foreign culture of the aliens are met with fear, ignorance and hatred by the humans. However, the story is not really about the war but about the feeling of loneliness when you are galaxies away from your home and loved ones, the relationships of the people fighting it and the relationships between the soldiers and the civilians they protect.