The launch of a Soyuz rocket with a US astronaut and two cosmonauts from Russia and Belarus on board was unexpectedly aborted on Thursday. The Soyuz MS-25 spacecraft was due to take off on its mission to the International Space Station (ISS) from the Russian Baikonur Cosmodrome in the steppe of Kazakhstan at 1321 GMT. The Russian space agency Roscosmos later cited technical problems as the reason for the launch cancellation. Shortly before takeoff, a voltage drop in a power source was detected, Roscosmos boss Yury Borisov said, according to the Russian news agency Interfax. The crew was safely…