SpaceX plans to make its most ambitious launch to date on Tuesday afternoon and send its Falcon Heavy rocket beyond Earth's atmosphere.
If its launch is successful, Falcon Heavy would become the most powerful rocket in use today — for a fraction of the cost of any comparable rocket ever built. Standing more than 21 stories tall, Falcon Heavy is a behemoth of engineering and will fly unmanned.
Such a complex machine has many people in the space industry anxious about whether the rocket will even get off the ground in one piece. SpaceX CEO Elon Musk has noted previously that failure is a possibility, saying there is a "lot that can go wrong" during a first attempt.
Here's what you need to know as SpaceX prepares to make history.