Live coverage: Soyuz crew lands in Kazakhstan

Space station commander Chris Cassidy and Robert Behnken floated back outside Tuesday for their fourth spacewalk in less than a month, completing preparations for future upgrades including the eventual installation of an airlock that will allow commercial experiments to be moved into and out of vacuum as required.

NASA is sending into orbit Monday night a spacecraft to test a safer type of rocket fuel, an ultra-precise atomic clock that could change the way missions navigate in deep space, and an experiment to examine the resiliency of electronics to radiation.

Check out photos of a solid-fueled Vega launcher as it zipped away from its launch pad in Kourou, French Guiana, with Europe’s IXV mission Wednesday.