Why do states like to develop launch sites as close as possible to the equator?

• A. Launching from on or near the equator maximizes the benefit of the Earth's rotation and reduces the magnitude of the plane change required to put the satellite in geostationary orbit.
• B. It facilitates direct insertion into a variety of retrograde orbits.
• C. It is easier to get into a polar orbit when starting from the equator because the rocket has more time to accelerate to orbital velocity before reaching the polar region.
• D. The real estate is cheaper in developing nations and southern U.S. states.

Answer: (A)

Launching near the equator leverages the Earth's rotation to give the rocket extra eastward speed right at liftoff. At the equator, the surface is moving about 465 meters per second eastward, so an eastward launch there adds this rotational velocity to the rocket’s initial boost. That means less propellant is needed to reach orbital velocity, which is especially helpful for reaching a geostationary orbit that sits directly above the equator and requires a near-zero inclination. If you start from higher latitudes, you’d have to spend energy to tilt the trajectory toward the equatorial plane, which is a large plane change. So the equator minimizes both the energy required and the plane-change effort, maximizing efficiency for GEO.

The other ideas don’t fit the physics: retrograde orbits don’t benefit from starting at the equator, polar orbits still demand a significant plane change or a different launch profile, and real estate prices don’t influence the orbital mechanics involved.