Live coverage: Ariane 5 lifts off on its first Galileo launch

After prepping their patient — a $2 billion cosmic ray detector — during two earlier spacewalks, two space station astronauts ventured back outside for a third outing Monday to carry out what amounted to transplant surgery, installing replacement coolant pumps in a bid to revive the costly instrument and extend its life.

Engineers working on the James Webb Space Telescope, which had its launch delayed to 2020 earlier this year, recently discovered another problem during testing at the observatory’s prime contractor Northrop Grumman in Southern California.

A new satellite joined Russia’s Glonass navigation fleet Saturday with a successful launch on top of a Soyuz rocket into an orbit nearly 12,000 miles above Earth.