Live coverage: Two satellites lift off aboard Ariane 5

After several delays earlier this week, SpaceX conducted a hold-down test-firing of a Falcon 9 rocket at Cape Canaveral Friday evening in a key test before launch next week on a resupply mission to the International Space Station.

Two NASA astronauts and an Italian flight engineer are sheltering in the space station’s Russian segment as mission control analyzes a possible leak of toxic ammonia coolant aboard the complex.

Russian commander Oleg Kononenko, Canadian co-pilot David Saint-Jacques and NASA flight engineer Anne McClain closed out a 204-day mission in orbit Monday with an undocking from the International Space Station at 7:25 p.m. EDT (2325 GMT), followed by landing in Kazakhstan aboard their Soyuz MS-11 capsule at 10:47 p.m. EDT (0247 GMT Tuesday).