Live coverage: Two satellites lift off aboard Ariane 5

A sharp-eyed French military surveillance spacecraft is set for launch aboard a Soyuz rocket Monday from French Guiana into a 300-mile-high orbit, where it will collect the highest-resolution imagery ever produced by a European reconnaissance satellite.

Arianespace has split its third order of Vega rockets from Italy’s Avio between old and new versions of the solid-fueled booster, as officials prepare to build a final batch of around 18 Ariane 5 rockets before switching to the next-generation Ariane 6 in the early 2020s.

Rocket Lab called off a launch attempt Tuesday, U.S. time, in New Zealand after encountering a technical problem during the countdown for the company’s first commercial satellite launch. Tuesday’s countdown came after a four-day delay to resolve problems with a downrange tracking station and wait for improved weather.