Lunch Tubes are a reactionless spacecraft launching method, providing orbital entry for craft without powerful atmospheric engines.
The problem of launching spacecraft into orbit is that they need to attain a large velocity to break free from the planet's gravity well, or they will fall back to its surface. Reaching this velocity takes a large amount of energy and necessitates complex rocket engines and fuel storage compartments to be built into the starship's hull, further increasing its weight, thus completing a vicious circle of inefficiency.
The Launch Tubes were designed to remove this problem from the equation. Instead of having the ship's engines do all the work, the ship is accelerated by outside forces, namely an array of powerful electromagnetic coils, similar to a giant rail gun. In effect, a Launch Tube is like a giant magnetic cannon that shoots space vehicles into orbit like projectiles. After its mission, the spacecraft can then re-enter the atmosphere and be reused, with no need for expensive rocket engines.
The Launch Tubes became extremely popular on ancient Orceron, as they could be built near or inside densely populated urban areas for easy access. While their power requirements were extremely high, they were pollution free and were relatively inexpensive to build. For these reasons, the technology can still be found used on lesser colony worlds, where its use isn't made impossible by heavy aerospace traffic.