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Portal Space Systems, Led by former SpaceX Propulsion VP, Targets In-Space Maneuverability 

By Rachel Jewett | May 6, 2024

Rendering of the Portal Space Systems Supernova spacecraft. Photo: Portal Space Systems

New startup Portal Space Systems, led by SpaceX’s former vice president of propulsion Jeff Thornburg, emerged from stealth mode last week with plans to build capabilities for in-space maneuverability. 

The company is developing the Supernova satellite bus, designed to maneuver from Low-Earth Orbit (LEO) to Geostationary Orbit (GEO) in hours, LEO to Medium-Earth Orbit (MEO) in minutes, and LEO to Cislunar space in days. 

The company’s founder and CTO Thornburg is the architect of SpaceX’s Raptor engine which powers Starship. He is also the former head of Mechanical Engineering & Manufacturing at Amazon’s Project Kuiper.

After working on the Raptor engines for Starship, Thornburg was thinking about the future demand for in-space mobility for when Starship is operational and further lowers the cost of reaching orbit. The company spent the last year and a half working with the U.S. Space Force and studying how mobility issues are evolving, to best design its solution to meet customer needs. 

“DoD legacy satellite systems and bus structures weren’t ever designed with any more [propulsive capability] than station-keeping to keep it in a particular position on orbit,” Thornburg tells Via Satellite. “Now we have looming threats to national security that make it more interesting to be able to move these assets in ways they weren’t originally designed to move.”

“Space is a contested domain now, or it will be soon. And like other forms of warfare that have evolved on Earth, logistics and mobility is what wins the day,” Thornburg added. “We need to increase the ability of U.S. assets to be able to maneuver and provide logistics services for those types of threats.” 

The company’s solution is Supernova, which Portal says provides a 50x improvement in current spacecraft mobility. It is a payload agnostic, 500 kg bus platform equipped with a solar thermal propulsion system that offers 6 km/s delta-v. The company is working toward a first launch in 2025 to demonstrate its capabilities. 

The company has received five DoD and Space Force awards to date, valuing more than $3 million. These include Small Business Innovation Research contracts, including a Tactically Responsive Space (TacRS) SBIR contract.

For commercial customers, the use cases for Supernova include relocation services, end-of-life services, or a faster way to reach GEO without purchasing an expensive direct-inject launch to GEO or spending time and on-orbit propellant on orbit-raising. 

Portal Space Systems currently has 25 employees and hopes to scale up to 200 over the next two years. 

Thornburg says that solar thermal propulsion technology is not new, but hasn’t been commercialized in this way before, similar to how an Air Force/NASA program informed the development of the Raptor engines. 

“This is my second round of trying to bring super great work that the government has pioneered but commercialize it and innovate it in a way that brings the cost down and commercializes it for the industry,” he said.