Understanding Space Launch vehicles
An important step towards making #space commercial has been to focus on making space launch vehicles cheaper and more efficient to increase accessibility to space. But what are space launch vehicles?
Space launch vehicles are designed to deliver spacecrafts or payloads (satellites, supplies etc.) to orbits in space — an endeavour that typically needs a large amount of energy to lift and carry load beyond the earth’s atmosphere. Broadly, the design of a launch vehicle needs to balance 3 critical aspects — maximise weight carrying capability, provide enough thrust while maintaining stability and provide this at optimal cost.
In order to put a payload in orbit, a launch vehicle needs to carry the payload through the Earth’s atmosphere — which needs large amounts of energy and fuel. Every launch vehicle has multiple stages, each of which propels it to a height before detaching from the launch vehicle. Most expendable launch vehicles have between 2–3 stages, however traditionally, launch vehicles had as many as 5 stages to take the spacecraft/ payload to space.
Stage 1: It is responsible for providing the initial thrust to lift the payload and vehicle off the earth. At the surface, the atmospheric pressure is the highest and as the rocket attempts to lift and accelerate such a heavy mass, it experiences a large amount of drag from the atmosphere. Hence first stages are the largest and need the most fuel.
Stage 2: Once the first stage has carried the payload to higher altitudes, it detaches from the vehicle and falls off. The second stage rocket and fuel combination are designed keeping in mind the reduced atmospheric pressure and allows the rocket to boost rocket towards the desired orbit. A core advantage of staging the rocket launch is to sequentially remove the mass of the lower stage rocket, which reduces the mass that needs to be carried further.
Stage 3 / Upper stages: Stage 3 and further stages contain the payload or further thrusters that propel it towards the final orbital destination. In the initial stages of the launch, the payload is enclosed in a fairing — this protects the payload from the initial force that is enacted as the launch vehicles powers through the Earth’s atmosphere. As the payload nears Orbit, the fairing breaks apart and falls back to the Earth, allowing the payload to then move ahead.
Traditional space launch vehicles cannot be reused and once the initial stages detach, they fall into the ocean and a new booster. This makes space launches very expensive. As the new space economy emerged at the start of the century, there was a growing focus on making space launches more affordable and easier, while also pushing reusability to increase launch frequency. In the next post, we’ll look at how reusable rockets are a critical endeavour to make space accessible and cheaper.
