SpaceX just let us peek behind the curtain as it preps for the second-ever launch of its powerful Falcon Heavy rocket on Tuesday (April 9).

The California-based company released on Twitter Saturday (April 6) a brief, sped-up video showing technicians mating the Falcon Heavy's three first-stage boosters inside a hangar at Launch Complex 39A, a historic pad at NASA's Kennedy Space Center (KSC) in Florida.

This "booster mate" was carried out ahead of the Falcon Heavy's Friday Falcon Heavy's static fire test on Friday (April 5). The test is a standard preflight check for SpaceX designed to ensure a rocket's engines are working properly.

Related: In Photos: SpaceX's 1st Falcon Heavy Rocket Test Launch Success!

SpaceX also tweeted out a photo showing the mated rocket and its 27 first-stage Merlin engines, which together produce more than 5 million lbs. of thrust.

Falcon Heavy’s 27 Merlin engines generate more than 5 million pounds of thrust at liftoff, making it the world’s most powerful operational rocket by a factor of two pic.twitter.com/0LGaLgdi13April 7, 2019

Also visible in the photo, SpaceX pointed out in another tweet, is the first stage of the Falcon 9 rocket that launched the company's Crew Dragon capsule on its first-ever spaceflight, an uncrewed test voyage to the International Space Station.

That mission, known as Demo-1, launched on March 2 and ended six days later when the capsule splashed down in the Atlantic Ocean. If all goes according to plan, Crew Dragon will launch astronauts to the orbiting lab soon — perhaps as early as this summer.

The Falcon Heavy's first stage consists of three modified, strapped-together Falcon 9 first stages. The central "core" booster is topped with the Heavy's single-engine second stage.

Falcon Heavy, the most powerful launcher flying today, has one space mission under its belt — a successful February 2018 test flight that lofted SpaceX founder and CEO Elon Musk's red Tesla Roadster (and its dummy driver, Starman) into orbit around the sun.

Tuesday's mission, however, is an operational one. The rocket will launch to Earth orbit the 13,200-lb. (6,000 kilograms) Arabsat-6A communications satellite for the Saudi Arabian company Arabsat.

Like the Falcon 9, the Heavy is designed to be reusable. During the February 2018 test flight, two of the rocket's three first-stage boosters came back to Earth for pinpoint landings at Cape Canaveral Air Force Station, which is next door to KSC.

The central core tried to land on one of SpaceX's robotic "drone ships" in the Atlantic but came up just short.