A Reason for Launching Artificial Satellite Eastward

In order to enter the artificial satellite into the target orbit, the launch speed must be above 7.9㎞/s.

However, this velocity is found assuming that the earth does not rotate. Therefore, in practice, the speed at which the earth rotates should be taken into account when launching an artificial satellite.

The rotational speed of the earth is 465m/s in the equatorial region, with the largest rotation speed and zero in both the North and South poles.

Thus, if an artificial satellite is launched toward the east, where the earth turns in the equatorial region, it is possible to achieve a minimum launch speed of 7.912-0.465 = 7.447 (km/s). However, if the earth is launched toward the west, as opposed to the direction of rotation, it should achieve a minimum launch speed of 7.912 + 0.465 = 8.377 (km/s).

Therefore, with less fuel, the artificial satellite is launched eastward to enter its orbit.