Portal Sets 2028 Supernova Launch as Starburst Nears Validation Flight

Portal Space Systems has set a 2028 Falcon 9 launch for its first Supernova spacecraft, but the company’s development sequence has a nearer checkpoint: getting the smaller Starburst-1 through an October 2026 flight. The spacecraft recently completed vibration testing in California and returned to Portal’s Bothell, Washington, lab for final software adjustments before its expected September shipment to Florida.

Starburst-1 is scheduled to lift off from Cape Canaveral Space Force Station on SpaceX’s Bandwagon-5 rideshare mission. Its primary job during a mission expected to last at least one year is to validate Portal’s spacecraft engineering, extending a test campaign that began with the much smaller Mini-Nova electronics and controls payload. “Until we get ready to fly, we’ll be constantly testing it and evaluating its health, and making any tweaks that we think we need to make,” CEO Jeff Thornburg said.

That makes Starburst-1 more than a technology side project. It is the intermediate hardware step between Mini-Nova and the substantially heavier Supernova, giving Portal an opportunity to assess an integrated spacecraft in orbit before moving to a different propulsion architecture and a larger production commitment. Starburst-1 has a stated mass of 600 pounds, compared with 1,100 pounds for Supernova.

Starburst-1 also carries secondary payloads: a TRL11 full-motion video system and a superconducting magnet experiment produced by Zenno. Those payloads broaden the mission, but they do not displace its central engineering objective. Thornburg said capability beyond the initial year would be residual, establishing a clear baseline for the validation campaign without presuming how long the spacecraft will ultimately operate.

Supernova changes how the ammonia receives heat

The propulsion distinction is central to Portal’s development plan. Starburst uses an electrothermal thruster that heats ammonia. Supernova’s Flare system is designed to concentrate sunlight onto a heat exchanger, where thermal energy heats the ammonia and produces thrust without chemical combustion.

That solar dependence creates an obvious operating boundary when the spacecraft passes into Earth’s shadow. Portal’s answer is a thermal battery integrated with the heat exchanger. According to Thornburg, its material is intended to heat up and retain thermal energy for as long as one hour, allowing propulsion operation during periods without direct sunlight.

The design therefore couples propulsion performance to thermal storage, heat-exchanger behavior and solar-energy collection. Starburst-1 cannot validate the complete Flare architecture because it uses a different heating method, but it can reduce risk elsewhere in the spacecraft stack: integrated controls, software, structural response and sustained on-orbit operation. That distinction matters when evaluating the October mission. It is a precursor to Supernova, not a full demonstration of Supernova’s propulsion system.

A dedicated launch adds integration work and schedule control

The first Supernova mission is named Motus Via Sol, Latin for “Movement With the Sun.” Portal has acquired a Falcon 9 launch for 2028 and plans to offer unused capacity to third-party payloads, according to the announced mission arrangement. Maverick Space Systems will handle payload accommodation, integration and manifest optimization while Portal manages its spacecraft mission and works with SpaceX.

This approach gives the Supernova demonstration a defined launch rather than requiring Portal to wait until it can fill a rocket with its own spacecraft. It also makes payload-stack design and rideshare integration part of the path to flight. Maverick says it is developing an optimized stack and bringing additional payloads onto the mission to distribute launch costs among participating customers.

Portal is also planning the physical capacity required to move beyond one-off development hardware. The company intends to relocate from its current 8,000-square-foot Bothell lab to a 65,000-square-foot facility roughly three miles away. Thornburg said the larger site is designed for annual capacity of 12 Supernova and 16 Starburst spacecraft.

Capacity, however, is not the same as demonstrated production rate. Before that factory plan can translate into recurring output, Portal still has to complete Starburst-1’s launch processing, operate the spacecraft through its validation mission and advance Flare from its thermal and propulsion design into a flight-ready integrated system. October’s Starburst-1 launch is the next concrete test; the 2028 Supernova flight is where the solar-thermal architecture itself is due to face its orbital examination.

By David Whitaker — Associate editor for AMI’s aerospace and drone systems desk, translating flight systems, aircraft programs, spaceflight, and UAV developments into accessible technical stories.