Spacecraft Reach Orbit by Accelerating Sideways to 28,000 km/h, Not by Escaping Gravity
Updated
Updated · spacedaily.com · Aug 4
Spacecraft Reach Orbit by Accelerating Sideways to 28,000 km/h, Not by Escaping Gravity
1 articles · Updated · spacedaily.com · Aug 4
Summary
Roughly 28,000 km/h of mostly horizontal speed—not altitude alone—puts a spacecraft into low Earth orbit, where it keeps falling around Earth instead of dropping back.
At 148 km, gravity is still about 96% as strong as at the surface, so a vehicle that merely crosses into space without enough sideways velocity follows a suborbital path and returns.
Rockets rise vertically first to clear dense air and the launch site, then pitch toward the horizon as guidance systems trade height for speed and shed empty stages to cut dead weight.
Earth’s eastward rotation can add more than 1,650 km/h near the equator, but direction matters as much as speed because small errors can leave a payload in a drag-heavy or wrong-tilt orbit.
Once the right velocity is reached, engines usually shut down and gravity shapes the orbit; later burns are mainly for corrections, collision avoidance and transfers to higher or interplanetary trajectories.