After years of preparatory work, SpaceX plans to ignite all 33 of the main engines on its massive Super Heavy rocket booster today. This is the first stage of the company’s Starship rocket, which is intended to be fully reusable, to help power NASA’s return to the Moon and one day possibly help humans settle on Mars.

No rocket has ever used so many engines before. The closest comparison is the Soviet Union’s N1 rocket, which had a first stage powered by 30 NK-15 liquid-fueled engines. However, each of these engines was only about two-thirds as powerful as the Raptor 2 rocket engines bolted to the Super Heavy rocket.

And, oh yeah, the N1 was a massive failure. Intended to compete with NASA’s Saturn V rocket and form the backbone of a Soviet Moon program, the N1 rocket attempted four launches from 1969 to 1972. All were busts, including one—the second launch, just two weeks before the Apollo 11 Moon landing in July 1969—that destroyed its launch complex as the rocket failed shortly after liftoff.