Key Points While SpaceX is best known for its work with NASA, the company's Starlink satellite internet unit is a key part of the overall business. Starlink provides global, high-speed internet coverage using a constellation of more than 10,200 satellites in low Earth orbit. SpaceX's connectivity business is its only profitable unit, while space launches and artificial intelligence are cost centers. A Starlink user terminal being set up. SpaceX Elon Musk's SpaceX is best known for its reusable rockets, and has been capturing headlines this year for its high-priced move into artificial intelligence through its merger with xAI. But as the company pitches investors ahead of its mammoth IPO, there's another part of its business that dwarfs the rest in terms of growth and profits: Starlink. In its long-awaited prospectus on Wednesday, SpaceX said its connectivity unit, which is primarily comprised of Starlink, generated $11.39 billion in revenue last year, accounting for 61% of total sales. That number went up to 69% in the first quarter of this year. Additionally, Starlink is the company's profit engine. It was the only profitable division last year, generating income of $4.42 billion, while the rocket launching unit, which includes contracts with NASA and the Department of Defense, lost $657 million, and the AI division had a deficit of $6.35 billion. Starlink provides global high-speed internet coverage using a constellation of more than 10,200 satellites in low Earth orbit, a region of space that's within 1,200 miles of Earth's surface. Since launching its first batch of satellites in 2019, Starlink has emerged as the leader among internet-from-space providers. It's now available on all seven continents and in over 160 countries. Musk, the world's richest person, has ambitions to colonize Mars, and even has a large incentive pay plan tied to his ability to do so. He also wants to build orbital data centers and has visions of being a key player in the AI race that's currently being led by OpenAI, Anthropic and Google . watch now Access Middle East Meanwhile Taiwan's government has ruled out deploying Starlink because SpaceX wouldn't agree to a joint venture with a local partner, the Financial Times reported. Taiwan officials have pointed out Musk's business ties in China, and his previous comments referring to Taiwan as an "integral part of China." Starlink has also been a contentious player in Ukraine, following Russia's invasion of its neighbor in 2022. That year, according to Reuters, Musk ordered SpaceX to actively shut off Starlink coverage over a battlefield in Kherson, hampering Ukraine's efforts to reclaim the territory. SpaceX and Musk denied the report. SpaceX took measures this year to stop Russia's unauthorized use of Starlink to guide some of its long-range drones to attack Ukraine. SpaceX said in its IPO filing that further expansion of its Starlink business, including satellite deployments and spectrum distribution, is dependent upon regulatory and licensing approvals. "There can be no assurance that our applications to renew, modify, or expand our authorizations will be granted on a timely basis, or at all, or without additional conditions," the company wrote. Starlink also faces challenges around retiring and replacing satellites in its megaconstellation. Satellites in geostationary orbit have a lifespan of around 15 years, but Starlink satellites are launched into lower orbit and last about three to five years. The upper stage of a Falcon 9 rocket deploys a stack of Starlink "V2 Mini" satellites in orbit. SpaceX SpaceX said in the risk factors section of its filing that space is "inherently hostile," and that Starlink satellites are subject to harsh conditions in orbit that could cause them to malfunction or fail. Excessive space debris could trigger what's known as the Kessler syndrome, a catastrophic chain reaction of collisions in space. Scientists have pointed to the increased risk of Kessler syndrome as one reason to object to SpaceX's proposal to launch 1 million satellites into orbit. Following SpaceX's FCC proposal, DarkSky, a nonprofit that advocates for reducing light pollution, wrote an open letter to the company urging it to commit to "true satellite invisibility standards," conduct an environmental assessment before it expands its constellation and to engage the astronomical and environmental communities about its plans. SpaceX's proposal would increase the number of satellites in the sky "by nearly 70 times," the group wrote. "Without meaningful oversight, this project could permanently alter the night sky as we know it," DarkSky said. Orbital data centers SpaceX has announced plans to build and launch orbital data centers, comprised of swarms of satellites equipped with graphics processing units and powered by solar photovoltaics. Earlier this year, Musk said data centers in space would be the cheapest way to train AI, "and that will be true within two years, maybe three at the latest." Experts say it will take much longer for orbital data centers to become feasible, if they ever do, in part because rocket launches remain capacity constrained and expensive. Orbital data centers would also require cooling systems and chips that can withstand extreme temperatures, as well as protection from radiation. SpaceX said in the prospectus that it expects to deploy space-based data centers as early as 2028. Its long-term vision would require thousands of rocket launches per year, according to the filing. The company has developed thermal control systems that disperse heat generated by data centers, and said in Wednesday's filing, "We have already solved the hardest part in the development of AI compute satellites."