By Al Root

SpaceX is having a busy week. The release of its initial public offering filings was a big deal on Wednesday. Thursday's test of its huge rocket, Starship, matters more.

A launch window for the 12th test flight of Starship opens at 6:30 p.m. Eastern time. The launch can be watched at spacex.com and on X.

The test will debut the latest version of the huge launch system, which stands some 408 feet tall, with the booster and upper stage stacked on top of one another. The booster has 33 rocket engines, producing more than 8,000 tons of thrust.

The booster is slated to land on a drone ship off the coast of Texas. The upper stage has several test objectives, including cargo deployment and heat shield development.

The importance of Starship can't be overstated. The ship is designed to cut the cost of reaching orbit by 90% or more. SpaceX's Falcon 9 rocket has already cut the cost of reaching space by 95% relative to the space shuttle.

Starship is designed to be fully reusable, with both the upper and lower stages capable of multiple missions. SpaceX, of course, pioneered reusable rockets, but only the lower stage of the Falcon 9 is reused.

Reusing the upper stage enables new applications, such as orbital refueling of spacecraft, which will dramatically increase Starship's range. It's an important innovation for missions including exploring Mars.

Lower costs for the entire system enable new applications such as orbital AI data centers. CEO Elon Musk believes that orbital computing will be cost-competitive with Earth-based computing in a few years. Operating in space is difficult, but there won't be a power bill paid to a utility.

SpaceX is planning to raise tens of billions of dollars in a June IPO, valuing the company at $2 trillion or more. The money will help kickstart SpaceX's AI ambitions and provide additional funding for Starship development.

Hundreds of thousands of people typically watch Starship tests online. That number might go up on Thursday with the SpaceX IPO approaching.

Write to Al Root at allen.root@dowjones.com

This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.

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May 21, 2026 10:28 ET (14:28 GMT)