SpaceX on Wednesday disclosed its filing for an initial public offering, ahead of an expected stock market debut next month. Why it matters: This is expected to be the largest IPO ever, and could make Elon Musk the world's first trillionaire. Catch up quick: Musk launched SpaceX in 2002 with the goal of one day colonizing Mars. Since then, it has become the world's most successful commercial space company by far and inspired rival efforts by billionaires like Jeff Bezos and Richard Branson. It has also become a major partner to NASA and created the Starlink satellite internet network. More recently, SpaceX acquired xAI — Musk's frontier lab that itself had just merged with X (formerly Twitter) — with plans to focus on orbital data centers. SpaceX filed its IPO confidentially with the SEC on April 1. By the numbers: SpaceX financials are complicated, because of its recent merger with xAI (which itself recently merged with the company formerly known as Twitter).…