Astronauts Randy Bresnik and Mark Vande Hei headed outside the International Space Station Thursday on a spacewalk to replace one end of the lab’s Canadian-built robotic arm, a changeout that engineers say will restore the device to full capability.

Space station commander Scott Kelly and flight engineer Kjell Lindgren are gearing up for their second spacewalk in nine days Friday, a planned six-and-a-half-hour excursion to reconfigure the ammonia cooling system used by one of the lab’s sets of solar arrays.

SpaceX has launched its fourth Falcon 9 rocket from Florida’s Space Coast in less than 16 days. A Falcon 9 rocket blasted off with 60 more Starlink internet satellites at 2:42 a.m. EDT (0642 GMT) Sunday. The reusable booster, making its 10th flight, landed on a drone ship parked in the Atlantic Ocean.