Video: Press site view of Falcon 9’s launch with the Es’hail 2 satellite (members only)

European engineers test-fired the world’s most powerful present-day single-segment solid rocket booster Monday in French Guiana, clearing a major development hurdle for the Vega-C and Ariane 6 launchers set for debuts in 2019 and 2020.

United Launch Alliance called off the planned liftoff of a Delta 4-Heavy rocket and a classified National Reconnaissance Office spy satellite from Vandenberg Air Force Base in California on Wednesday after indications of elevated hydrogen concentrations around one of the launcher’s main engines. Three previous launch attempts were scrubbed by technical concerns and bad weather.

The Canadian telecom satellite operator Telesat plans to launch two multipurpose communications spacecraft aboard SpaceX Falcon rockets in 2018, the company disclosed this week in a quarterly earnings announcement.