Portal Space Systems

Portal Space Systems is a spacecraft manufacturer headquartered in Bothell, Washington, that develops vehicles designed for sustained on-orbit maneuverability rather than fixed mission profiles. Its flagship vehicle, Supernova, is a payload-agnostic bus with a stated 500 kg mass and up to 6 km/s of delta-v, enabling repositioning across LEO, MEO, GEO and cislunar space, refuelability, and a multi-year operational life. Supernova is powered by a solar thermal propulsion (STP) system: deployable and re-stowable mirror concentrators focus sunlight onto a receiver, heating a thermal battery that surrounds the company's 3D-printed HEX thruster, which combines heat exchanger and nozzle into a single component with no internal interfaces or moving parts. A storable monopropellant passes through the thruster, absorbs the stored heat and expands out the nozzle. Company materials describe transfers of LEO to GEO in hours, LEO to MEO in minutes and LEO to cislunar in days, and taskability within minutes with payload swaps in under 24 hours.

Alongside Supernova, Portal has introduced Starburst, an ESPA-class rapid-maneuverability spacecraft that uses a more conventional thruster system but shares roughly 80-81% of its components with Supernova. Starburst-1 is manifested on SpaceX's Transporter-18 mission in Q4 2026 for a yearlong sun-synchronous-orbit mission demonstrating rendezvous and proximity operations, rapid retasking and orbital maneuverability, carrying TRL11's video camera and edge processing system and Zenno Space's superconducting magnetic actuator. An experimental payload nicknamed Mini-Nova was launched to test flight computer, control software and power systems for both vehicles. Supernova's debut mission is targeted for 2027.

Stated applications span national security (space domain awareness, cislunar logistics and tactical mobility, rapid response, non-kinetic ISR support, proximity operations), science and exploration (low-cost lunar insertion, experimental platform delivery, orbital repositioning to extend mission life, potential Artemis-related logistics), and commercial operations (constellation maintenance, life extension and servicing, and debris mitigation and removal).

Founding story

Portal Space Systems was founded in 2021 by Jeff Thornburg, who previously served as VP of Propulsion at SpaceX (where he was an architect of the Raptor engine), led mechanical engineering and manufacturing/engineering at Amazon's Project Kuiper, was Chief Engineer at Commonwealth Fusion, and served as an Air Force officer. He co-founded the company with Ian Vorbach (initially COO, later President and CRO; previously Stratolaunch propulsion engineer and an early BodyArmor employee) and Prashaanth Ravindran (VP of Engineering; previously senior propulsion analyst at Blue Origin and propulsion lead CFD engineer at Stratolaunch). The founders describe having repeatedly encountered the constraint that mission options vanish once a spacecraft reaches orbit.

Business model

Portal designs, manufactures and operates maneuverable spacecraft and offers their mobility and payload-hosting capability to customers, either by delivering and repositioning customer payloads or by performing on-orbit missions such as inspection, servicing, life extension and debris removal. Development has been part-funded by U.S. government programs, including Department of Defense/Space Force awards and a SpaceWERX STRATFI award, alongside venture capital.

Sources describe missions and services sold to defense, civil and commercial customers, including payload transport and deployment, on-orbit servicing and debris removal partnerships, supported by government development contracts; specific pricing or contract values beyond announced awards are not detailed.

Traction

Portal emerged from stealth in 2024 with over $3 million in Department of Defense and Space Force funding, subsequently earned STRATFI support including $45 million from the U.S. Space Force's SpaceWERX program, and raised a $17.5 million seed round in 2025 followed by a $50 million Series A in April 2026. Operational milestones include flight heritage on avionics via the Mini-Nova launch, completed HEX thruster ground testing at operational performance in thermal vacuum, Starburst-1 manifested on SpaceX Transporter-18 in Q4 2026, a Supernova debut mission targeted for 2027, growth to roughly 40 employees with plans for about 100 in 2026, and development of a 52,000-square-foot manufacturing facility in Bothell. Company materials also cite over $20 million in VC funding to date (as of the About page) and partnerships with Paladin Space and Starlab.

Latest developments

In April 2026 Portal announced a $50 million Series A co-led by Geodesic Capital and Mach33 with participation from Booz Allen Ventures, ARK Invest, AlleyCorp and FUSE. The company reported flight heritage on its flight computer and power system through Mini-Nova, completion of HEX thruster ground testing at operational performance in thermal vacuum, Starburst-1 manifested on SpaceX's Transporter-18 mission with a possible October 2026 launch, a Supernova-1 debut targeted for 2027, an expansion to a 52,000-square-foot Bothell manufacturing facility, plans to grow from about 40 employees toward 100 in 2026, and an ambition to build as many as four spacecraft per month by the end of 2027. It is also progressing a second Starburst build and the Paladin Space debris removal service, with Starlab having signed a letter of intent.