NASA hopes to have a new leader for the agency’s human spaceflight directorate by the end of the year to replace Bill Gerstenmaier, who held the post for nearly 14 years before his reassignment in July amid the Trump administration’s push to land humans on the moon by 2024, a NASA official said Wednesday.

Four European navigation satellites fastened on top of an Ariane 5 rocket lifted off from Kourou, French Guiana, at 1836:07 GMT (1:36:07 p.m. EST) Tuesday to propel the Galileo navigation network closer to global service. The Ariane 5’s upper stage delivered the spacecraft to a circular orbit more than 14,000 miles above Earth around four hours after launch.

United Launch Alliance’s final Delta 2 rocket is now on display at the Kennedy Space Center Visitor Complex in Florida, a monument to an industry workhorse that helped build the GPS navigation satellite fleet and enabled a new era of Mars exploration.