If you're looking for manga similar to Starship Operators, you might like these titles.
This manga tells the story of a distant future within the Milky Way Galaxy, where the Galactic Empire and the Free Planets Alliance are constantly at war. The story begins with the young Reinhard von Müsel, a boy in the Galactic Empire that lives with his drunk father and his beautiful sister Annerose. He becomes close friends with the boy next door, Sigfried. After his sister is taken to become the Kaiser's concubine, young Reinhard is determined to take down the Empire in order to rescue her. He and his loyal friend Sigfried join the military academy together as the first step in Reinhard's plan.
Universal Century 0079. The original Duchy of Zeon end of the war a year dominated army, was starting to show color in the color of the border on the success of the federal military mobile suit development. In addition, the forced conscription of boys to girls in order to ensure personnel guileless yet lost the war.
The story takes place in U.C. 0084 in the form of a video documentary. It is based on interviews with soldiers and officers of the Earth Federation and the Principality of Zeon who participated in the final battle of A Baoa Qu during the end of the One Year War in U.C. 0079
Beginning four years after the one year war, 0083 starts with the arrival of two new Gundam units to be used for gravity testing. Things take a turn for the worse when members of Zeon steal Unit 2 and the nuclear warhead it that it has been armed with. Young test pilot-in-training Kou Uraki, piloting Gundam Unit 1, must now capture the stolen Gundam before it can be used to fulfill Zeon's mysterious "Operation Stardust".
Planet Martine is suddenly attacked! The alien invaders are known as the Abh. They are of human origin, but have been genetically modified so that each Abh has superior talent, skill, beauty, and longevity. Martine's president surrenders completely in the face of the Abh's awesome military power. Through a bizarre twist of fate, his son Jinto becomes a nobleman in the Abh's vast, intergalactic empire.
In the year 2199, unrelenting attacks from the planet Gamilus have forced all life on Earth into underground dwellings and raised radiation levels to near-toxic levels. The only way to clean up all this harmful radiation is by using the Cosmo Cleaner, which the Queen of the planet Iscandar has generously offered to humanity. Unfortunately, Iscandar is 148,000 light years away, but Earth only has one year before rising radiation levels make it uninhabitable! The only vessel capable of making the journey is the Yamato - a spaceship equipped with advanced technology and modeled after the famous WWII battleship. Can the crew of the Yamato make it to Iscandar and back before the extinction of all life on Earth?