Portal Space Systems, a Bothell, Washington-based developer of highly maneuverable spacecraft using solar-thermal propulsion, has raised $50M in Series A funding led by Booz Allen Ventures. The company builds payload-agnostic satellite buses like Supernova and Starburst, enabling up to 6 km/s delta-v for multi-orbit operations from LEO to cislunar space. The capital will fund a new 52,000 sq ft production facility, Starburst-1 launch in Q4 2026, and team expansion from 40 to 100 employees.
Propulsion Funding Wave Builds
The raise follows a hot streak in in-space propulsion: PAVE Space secured $40M in March 2026, while Agile Space Industries raised $17M Series A in February. Portal's solar-thermal propulsion (STP) stands out by delivering chemical-like thrust with solar efficiency, unlike competitors' chemical or electric systems. This timing aligns with US Space Force budget proposals boosting space domain awareness (SDA) funding (per Federal News Network).
Congested Orbits Need Agility
Proliferating satellites and adversarial threats demand rapid on-orbit maneuvering for SDA, debris removal, and logistics. Current chemical propulsion limits delta-v due to fuel mass, while electric thrusters are too slow for dynamic responses. Portal targets national security operators facing these gaps in LEO and cislunar space.
Solar Thermal Delivers High Delta-V
Portal's STP uses deployable mirrors and 3D-printed HEX thrusters to achieve 50x delta-v gains over baselines, powering persistent operations without nuclear complexity. Supernova handles trans-orbital missions, while Starburst offers ESPA-class rapid maneuvers for defense and commercial tasks. Recent milestones include the first commercial STP hot-fire test in September 2025 and Mini-Nova's orbit on SpaceX Transporter-16.
As CEO Jeff Thornburg noted:
"It’s no longer acceptable to move slowly on orbit… China’s running circles around our spacecraft."
Defense Investors Signal Validation
Booz Allen Ventures led the round, joined by Geodesic Capital, Mach33, ARK, AlleyCorp, and FUSE, reflecting conviction in STP for national security. Prior $45M from SpaceWERX and $17.5M oversubscribed seed underscore DoD interest. These backers position Portal as a 'space mobility prime' for tier-one primes.
Jeff Thornburg continued:
"The strongest demand is in defense… more partnership opportunities with tier one and tier two primes."
$14B Market Eyes Multi-Orbit
The space propulsion market stands at $14.35B in 2025, projected to reach $16.84B by 2026 at 17.3% CAGR, driven by mega-constellations and ISAM. Competitors like Impulse Space ($525M raised) focus on chemical tugs, True Anomaly ($360M+) on defense interceptors, and Exotrail ($90M+) on electric propulsion. Portal's STP addresses speed-range tradeoffs amid rising orbital congestion.
SpaceX Vets Lead Propulsion Push
Co-founder and CEO Jeff Thornburg served as Senior Director of Propulsion Engineering at SpaceX, contributing to early methane engines. VP Engineering Prashaanth Ravindran, Ph.D., led BE-4 fluid dynamics at Blue Origin and co-invented Portal's thrusters. This ex-SpaceX, Blue Origin, and Stratolaunch team drives STP commercialization.
Starburst Launch Looms
Funds enable Starburst-1 on SpaceX Transporter-18 in Q4 2026 with TRL11 camera and Zenno actuators, followed by Supernova in 2027. Partnerships with Paladin Space for debris removal (Starlab LOI) and Momentus rideshares advance DRAAS missions. Production scales to 12 Supernova and 16 Starburst annually from the Bothell facility.