Live coverage: Space station crew back on Earth

After four years of brainstorming, custom tool development and training, two astronauts plan to venture outside the International Space Station Friday for the first of four spacewalks to repair a $2 billion cosmic ray detector. The excursions are considered the most challenging since work to service the Hubble Space Telescope.

NASA managers Thursday cleared the $1.5 billion Parker Solar Probe for launch early Saturday on a daring mission to “touch the sun,” repeatedly flying through its outer atmosphere to find out why the blazing corona is millions of degrees hotter than our star’s visible surface.

Spaceflight Industries has booked reservations for two commercial rideshare missions on Arianespace’s Vega rocket, officials announced Tuesday, beginning with a proof-of-concept flight in early 2019 of a new Italian-built multi-payload dispenser tailored to accommodate small satellites and CubeSats seeking a ride into orbit.