Curved Rocket Trajectory

Rockets follow a curved trajectory when going into space because their objective is not only to reach space, but also to enter Earth orbit. In Earth orbit, rockets have enough speed to counter Earth’s gravity and do not require a lot of energy to stay up there. To enter Earth orbit, a rocket needs to attain a high enough horizontal speed.

Flat-Earthers claim the curved trajectory of any rocket launch tells us no rocket has ever reached space. They are wrong. The curved trajectory is a way for rockets to enter Earth orbit.

Space is not that far. Above 80 km or 100 km can be considered space. Reaching space is the easier part, but the primary objective of a rocket is to enter Earth orbit by having a high enough horizontal speed.

By orbiting the Earth, a spacecraft can shut off its thrusters, and remain up there for a very long time. Based on a simulation, an object of 100 kg with the cross-sectional area of 1 m², if placed on a 300 km orbit,  it will fall to the Earth only after 46 days, without using any fuel.

The most efficient way to reach orbit is to initially travel straight up to overcome air resistance, then tilt onto its side and gradually increases this tilt until the rocket is parallel to Earth’s surface.

If the rocket launches straight up, it will reach space faster with less energy. But it won’t have the required velocity to orbit. The rocket will have to continuously spend energy only to remain up there. Once ran out of fuel, the rocket will fall back to the Earth very fast.

It’s not rocket science.