Live coverage: 400th Proton rocket takes off with Russian satellite

A Proton rocket and Block DM upper stage climbed into space Saturday from the Baikonur Cosmodrome in Kazakhstan with Spektr-RG, an astronomical observatory with dual X-ray telescopes developed by Russian and German scientists on the hunt for the signature of dark energy.

Citing medical reasons, Russia’s space agency announced Wednesday that it is replacing two cosmonauts who were scheduled to fly on the next Soyuz mission to the International Space Station in April with backup crew members.

A Soyuz-2.1b booster loaded with 34 satellites for OneWeb’s global Internet network rolled out of its assembly building Monday at the Baikonur Cosmodrome in Kazakhstan and rode a rail car to its launch pad for final preflight checks before liftoff Thursday.