In Chinese legend, magpies took pity on two lovers separated by the Milky Way, so they created the Queqiao bridge, allowing the couple to be together for one day a year. Queqiao is also the name of a relay satellite which has entered on June 14 the Halo orbit in order to set up a communication link between the Earth and the future Chang’e 4 lunar probe on the back face of the moon. Getting a satellite into this orbit, circling the second Lagrange point (L2), where the centrifugal force is balanced with the Earth’s and Moon’s gravity, demanded to adjust orbit several times before the satellite could enter the correct orbit, and the time window for the satellite to brake near the moon lasted just 16 minutes.

CAS news release, June 25, 2018