The pieces of NASA’s next-generation moon rocket are coming together — and firing up.

In a wrap-around video released on Tuesday, the space agency showed off the mighty thrust of its RS-25 rocket engine.

Four such engines will go on the bottom of NASA’s Space Launch System (SLS), a 321-foot-tall (70-meter-tall) rocket designed to rival the Saturn V rockets that launched Apollo astronauts to the moon.

A new bill passed by Congress asks NASA to launch its new rocket and Orion spaceship by 2018. It also calls on the agency to send astronauts to the moon by 2021, and reach Mars by 2033. However, the legislation won’t become law until President Trump signs it.

The new video by NASA’s Marshall Space Flight Center in Mississippi puts the viewer right in front of a test-firing rig, which rapidly cools down the fiery blast with water. Click and drag the video as it plays to look around the site:

Each RS-25 engine mixes liquid hydrogen and oxygen to produce up to 512,000 pounds of thrust, making for 2 million pounds of thrust total — enough to send more than 10 adult elephants into orbit around Earth.

The engines are 14 feet (4.3 meters) tall and weigh 3.9 short tons (3.5 metric tons).

To get a sense of scale, here’s an RS-25 engine being trucked out to the test-firing facility:

The RS-25 engine is a holdover from the Space Shuttle era.

It’s been through so many launches that Aerojet Rocketdyne, its maker, says it’s “the world’s most reliable rocket booster engine.”

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