Watch live: Falcon 9 test-firing imminent at Cape Canaveral

SpaceX is counting down to a static fire test of a Falcon 9 rocket on pad 40 at Cape Canaveral Space Force Station in Florida. The test-firing of the booster’s nine engines is in preparation for a launch with 54 more Starlink internet satellites as soon as Sunday night at 10:53 p.m. EDT (0253 GMT Monday).

The launch of SpaceX’s Starlink 4-34 mission will be SpaceX’s 42nd Falcon 9 flight of the year. The launch, if it happens Sunday night, would come less than 26 hours after another Falcon 9 rocket is scheduled to take off a few miles to the north from pad 39 at the Kennedy Space Center. SpaceX is not performing a static fire test on pad 39A ahead of that mission.

The 229-foot-tall (70-meter) rocket on pad 40 is expected to fire up its nine Merlin 1D engines at 5:30 p.m. EDT (2130 GMT) Saturday. The engines will ignite for about seven seconds, ramping up to 1.7 million pounds of thrust as hold-down restraints keep the Falcon 9 firmly on the ground.

In preparation for the static fire, SpaceX is loading a million pounds of densified kerosene and liquid oxygen propellants into the Falcon 9 during the final 35 minutes of the mock countdown. The Falcon 9 was already stacked with its payload of 54 Starlink internet satellites ahead of the static fire test, and the rocket rolled out to the launch pad

Engineers will analyze data from the static fire test before clearing teams to continue with the countdown Sunday night.

SpaceX used to require a static firing every time an engine was removed between flights of one of its reusable Falcon 9 boosters. That requirement has changed to perform a pre-launch test-firing only when three or more engines are removed between missions, according to a report published earlier this year by Aviation Week & Space Technology.

The static firings were originally part of each SpaceX launch campaign to ensure engineers caught any problems with the rocket before launch day. But SpaceX has improved its performance launching on time as the test-firings have become less common.

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