China launches secretive TJS-27 pair, orbits next-gen Tianlian relay sat

Space Explainer: How Orbital Launches Work

Getting to orbit isn't just about going up — a rocket has to accelerate sideways to roughly 28,000 km/h to avoid falling back down, which is why launches burn most of their fuel gaining horizontal speed rather than altitude. Multi-stage rockets shed empty fuel tanks and engines as they climb, since carrying dead weight into orbit wastes enormous amounts of propellant.

Launch dates slip constantly, and it's rarely the rocket's fault: upper-level wind shear, lightning risk, ships or aircraft straying into the safety zone downrange, and last-minute technical holds during the countdown are all common causes. A 'static fire' — briefly igniting the engines while the rocket stays clamped to the pad — is a standard pre-launch test to catch problems before committing to flight.