Video: NASA and SpaceX brief media on space station cargo flight

A United Launch Alliance Delta 4-Heavy rocket climbed into orbit Monday from a military base northwest of Los Angeles, delivering to space a classified U.S. government spy satellite as large as a school bus and leaving just three Delta rockets left to fly before retirement.

Russian engineers will replace rocket engines on two Soyuz rockets assigned to send a batch of supplies and the next crew to the International Space Station after an investigation revealed foreign objects or a manufacturing defect led to the crash of a Progress cargo craft on launch in December, according to Russian media reports and a statement from the Russian space agency.

Concern about a possible ammonia coolant leak Wednesday prompted astronauts on the International Space Station to evacuate the U.S. segment of the complex and shelter in the Russian portion of the outpost while flight controllers scrambled to untangle initially confusing telemetry.