https://www.wired.com/story/spacex-revs-its-engines-as-it-gets-closer-to-crewed-flight/

Last Thursday, a shiny new SpaceX Falcon 9 rocket sat perched atop NASA’s historic Pad 39A, at Florida’s Kennedy Space Center, waiting to briefly fire its engines. The exercise was part of a routine pre-launch test. What wasn’t routine was the presence of a Crew Dragon capsule atop the slick black-and-white Falcon. The domed capsule, which can accommodate up to seven passengers, represents the next big step in SpaceX’s evolution and in NASA’s dependency on a commercial space industry.

As the rocket’s nine Merlin engines roared to life for a few seconds, exhaust plumes billowed around the launch pad. The test simulated all of the events of an actual launch, though with the rocket secured to the pad. A static fire test typically occurs one to two weeks before a scheduled take-off. Although just a practice run, it is getting extra scrutiny because it signals the impending return of crewed space launches to American soil. And it means new hardware: the launch pad features a black-and-white astronaut walkway, called a crew access arm, which was installed last summer. A few hours after the test fire, SpaceX tweeted that it was a success.