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The ex-Raptor engineer building a fighter jet for orbit just raised $50M — Starburst launches in October
Orig: Portal Space Systems raises $50M as it gets set to launch its first orbital vehicle made for rapid maneuvers
GeekWire reports Portal Space Systems' $50M Series A from Geodesic Capital and Mach33. CEO Jeff Thornburg describes the company's solar thermal HEX thruster as delivering performance comparable to nuclear without the reactor. Starburst-1 manifested on SpaceX Transporter-18 (Q4 2026). Key investor thesis from Mach33: a world of 1.2 million planned orbital assets needs propulsion architecture that delivers speed and endurance, and Portal fills a structural gap.
Solar thermal propulsion: the orbit-hopping tech NASA shelved in 2003 is finally commercializing
Orig: This founder helped build SpaceX's most powerful rocket engine. Now he's building a 'fighter jet for orbit.'
TechCrunch profiles Jeff Thornburg's path from SpaceX Raptor to Portal. Solar thermal propulsion was validated by NASA in the late 1990s but never commercialized due to lack of demand. Now orbital maneuvering is a national security imperative — Space Force Gen. Guetlein publicly cited China demonstrating "dogfighting" satellites. Portal also has a pathway to nuclear thermal propulsion: its HEX Thruster architecture needs only a reactor swap. Prior $45M government strategic investment confirms DoD sees the mission.