Portal Space Systems is a privately held spacecraft manufacturer based in Bothell, Washington, developing Supernova, a satellite designed to use solar thermal propulsion to move between orbital regimes in hours or days instead of weeks. The company aims to provide the mobility that the United States Space Force has requested for dynamic space operations. Supernova has not yet flown in space, and its published performance metrics remain engineering design targets.
Founded in 2021 by Jeffery Thornburg, Ian Vorbach, and Prashaanth Ravindran, Portal Space Systems targets a central limitation of satellite architecture: the tradeoff between the high thrust of chemical rockets and the fuel efficiency of electric thrusters. The company is developing hardware intended to give satellites maneuverability across Low Earth Orbit (LEO), Medium Earth Orbit (MEO), Geostationary Orbit (GEO), and cislunar space.
What Portal Space Systems Builds
Portal Space Systems builds maneuverable spacecraft designed to relocate rapidly across multiple orbits rather than remaining fixed in a single orbital slot. Its primary product line consists of two vehicles: Supernova and Starburst. Both platforms are designed around solar thermal propulsion, an architecture that uses concentrated sunlight to heat propellant rather than relying on combustion or electrostatic acceleration.
Supernova is Portal’s flagship spacecraft. The company describes Supernova as “a maneuverable, solar-thermal spacecraft engineered for persistent delta-v, on-demand autonomy, and real-time control.” Delta-v measures the total velocity change a spacecraft can generate, which determines how many orbital adjustments it can perform over its operational lifespan. Portal lists a published design target of 6 kilometers per second (km/s) of delta-v for Supernova. Payload reported in April 2024 that Supernova is a 500-kilogram, payload-agnostic platform, though Portal’s own site does not publish a vehicle mass figure. Portal has also not published a payload capacity figure in kilograms.
The company markets Supernova for missions requiring rapid redeployment. Portal states that the vehicle is designed to be “on-standby” and “taskable in minutes,” with software-defined payload integration allowing a payload swap in under 24 hours. The company advertises operations extending from LEO to cislunar space and back, paired with a multi-year operational lifetime.
Portal has made several specific maneuvering claims for Supernova that represent company design targets rather than demonstrated in-flight metrics. In its seed-round announcement, Portal claimed Supernova is engineered to move from LEO to MEO in minutes, from LEO to GEO in hours, and from LEO to cislunar space in days. CEO and CTO Jeffery Thornburg has referred to the vehicle as a “fighter jet for orbit,” asserting that “It’s no longer acceptable to move slowly on orbit.” In the company’s seed release, Thornburg stated that “Supernova delivers nuclear thermal propulsion capability without launching a reactor.” In the Series A release, Thornburg added that “Our customers don’t just need access to space. They need the ability to operate across it.”
Starburst is Portal’s second spacecraft product, unveiled on 5 November 2025. Described by the company as an Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA) class rapid-maneuverability spacecraft, Starburst shares roughly 80 percent of its systems with Supernova. The ESPA format matches standard secondary rideshare rings on launch vehicles, allowing the smaller bus to fly as a rideshare passenger while carrying similar maneuvering systems.
How Solar Thermal Propulsion Works
Solar thermal propulsion uses sunlight to heat a working fluid directly, bypassing both chemical combustion and electrical ionization. Portal frames the operational problem by stating: “Space has changed, but spacecraft haven’t. Static vehicles can’t meet the demands of a dynamic environment. Chemical propulsion can’t sustain maneuver, electric propulsion doesn’t have the speed.”
Conventional spacecraft rely on one of two propulsion methods. Chemical propulsion produces high thrust by burning fuel and oxidizer, allowing fast maneuvers, but its low fuel efficiency rapidly exhausts propellant tanks. Electric systems, such as ion propulsion, provide high fuel efficiency by accelerating ionized gas, but they produce tiny amounts of thrust. An electric satellite can take months of continuous firing to change its orbital altitude. Solar thermal propulsion is designed to bridge this divide by delivering moderate thrust at high efficiency, allowing orbital repositioning in hours or days without depleting all available propellant.
Portal explains its proprietary Flare propulsion system through three mechanical steps:
- Deployable and re-stowable mirror concentrators focus sunlight onto a compact receiver, generating thermal energy that Portal compares to a compact nuclear reactor.
- The concentrated solar energy heats a thermal battery that envelops the proprietary HEX Thruster, a 3D-printed unit that combines the heat exchanger and nozzle into a single component without internal interfaces or moving parts.
- A safe and storable monopropellant is pushed through the HEX Thruster, where it absorbs the stored heat, expands, and exhausts through the nozzle at high velocity, delivering up to 6 km/s of delta-v to sustain orbital maneuvers.
Portal describes its propellant strictly as “a safe and storable monopropellant” without specifying a chemical compound. The company positions the technology as an engineering upgrade to long-standing physics concepts: “Solar thermal propulsion isn’t new and it’s far from unproven. Backed by decades of research and now Portal has modernized it through advanced materials and additive manufacturing, it’s finally ready to move from the lab to orbit.” For an overview of alternative high-energy concepts, read our guide to nuclear propulsion in space.
Why the Space Force Wants Maneuverable Spacecraft
The United States Space Force has shifted its doctrine toward Dynamic Space Operations (DSO), creating demand for maneuverable spacecraft like Supernova. Dynamic Space Operations refers to the sustained maneuvering of satellites during peacetime, crisis, and conflict. The operational goal is to complicate an adversary’s tracking and targeting capabilities while preserving freedom of action for American assets.
Historically, military satellites flew predictable, unvarying orbital paths. Because adjusting an orbit consumes substantial fuel, operators rarely moved satellites except for small station-keeping burns. The Space Force Objective Force plan states that because competitors seek to degrade American space assets, successful orbital architectures must incorporate maneuverable and serviceable platforms. Further detail is at Breaking Defense and the US Space Force.
Senior officers have linked satellite mobility to national defense strategy. General Chance Saltzman, Chief of Space Operations, endorsed the approach: “When [Whiting] says ‘dynamic maneuvering’, I agree. We need a maneuver force.” General Saltzman has also cited orbital refueling as a “valuable contributor to that operational concept of maneuvering without regret.”
General Stephen Whiting, head of United States Space Command, described the objective in joint-warfare terms: “It is a strength of the United States Joint Force that we outmaneuver our adversaries, and that’s what we want to bring to the space domain.”
The Space Force Objective Force roadmap establishes three modernization windows:
- 2025 to 2030: demonstrating on-orbit refueling and fielding operational space tugs.
- 2030 to 2035: making refueling operational and demonstrating high-thrust reusable orbital transfer vehicles.
- 2035 to 2040: fielding an initial on-orbit logistics architecture.
Portal targets these mission requirements with marketing centered on national security: “Respond fast. Shadow threats. Extend reach across orbital regimes.” The company positions Supernova for cislunar logistics, tactical mobility, rapid-response deployments, and space domain awareness. Travis Bales of Booz Allen Ventures stated that the firm’s investment in Portal “will advance orbital warfare through rapidly maneuverable spacecraft.” For a broader look at defense platforms, see our guide on military satellites.
Portal’s Missions and Flight Schedule
Portal Space Systems has organized its development roadmap around three progressive flight demonstrations: Mini-Nova, Starburst-1, and Motus Via Sol.
Mini-Nova is an experimental risk-reduction payload rather than an independent spacecraft vehicle. Listed on Portal’s roadmap for the second quarter of 2026, Mini-Nova was designed to test multiple critical Supernova systems while flying aboard Momentus’ Vigoride 7 orbital service vehicle.
Starburst-1 is Portal’s first free-flying orbital demonstration mission. The spacecraft was originally manifested on SpaceX’s Transporter-18 rideshare mission for the fourth quarter of 2026 to evaluate rendezvous, proximity operations, and orbital maneuverability. As of late September 2026, KOMO News reported that Starburst-1 was scheduled to launch in October 2026 on a Falcon 9 rocket from Cape Canaveral. Readers should check the official Portal Space Systems site to verify the current flight status of the mission.
KOMO News reported that the Starburst-1 satellite weighs roughly 600 pounds, operates within a single orbital plane, and is designed for a five-year service life with one year dedicated to primary mission objectives. The spacecraft carries an advanced camera system, Atomic-6 “Space Armor” composite tiles for protection against micrometeoroids and orbital debris, and what KOMO described as “the world’s largest superconducting magnet that’s ever flown on orbit.” Thornburg characterized the magnetic payload by stating: “It’s really kind of like the Star Trek shields or the tractor beam of space. You can do a lot of cool things with that.”
Outside of government programs, Portal announced a commercial debris-removal partnership in March 2026 with Paladin Space, naming Starlab as an early partner. For more context on orbital cleanup challenges, read our explainer on space debris.
Portal’s third planned mission, Motus Via Sol, is scheduled for 2028. This mission will mark the maiden spaceflight of the full-scale Supernova spacecraft and the initial orbital test of the Flare solar thermal propulsion system.
Why Portal Bought an Entire Falcon 9
On 20 August 2026, Portal Space Systems announced that it had signed a contract with SpaceX to purchase an entire dedicated Falcon 9 rocket for its 2028 Motus Via Sol mission. Payload covered the transaction in its report on how Portal booked a dedicated Falcon 9 amid a constrained launch market.
The acquisition of a full rocket represents an unusual move for an early-stage satellite developer. Supernova will occupy roughly half of the Falcon 9 payload fairing. Rather than leaving the remaining volume empty, Portal contracted launch integrator Maverick Space Systems to sell the surplus capacity, which includes ESPA-class and “cake-topper” slots, to commercial and government rideshare customers. By doing so, Portal became a rideshare capacity broker for its own flight. For background on how secondary capacity is normally packaged, read our guide to the SpaceX rideshare program.
Thornburg explained the decision to purchase the rocket directly: “I needed to secure Portal’s launch future for the next couple of years. You’re very familiar with all of the angst over launch [availability].”
Broader launch-market constraints drove the purchase. The Wall Street Journal reported on 21 September 2026, in an article by Micah Maidenberg and Becky Peterson titled “A Rocket Supply Crunch Is Making It Harder to Hitch a Ride to Space,” that Portal “decided to guarantee it could get to orbit in 2028 by purchasing a dedicated Falcon 9 flight, something that wasn’t in its initial plans.” The Journal reported that the purchase occurred as SpaceX began winding down Falcon 9 operations, halted sales of shared Falcon 9 missions, and left several commercial satellite operators unable to secure launch slots beyond 2028. For details on vehicle transition timelines, read about the eventual Falcon 9 retirement.
How Portal Space Systems Is Funded
Portal Space Systems finances its spacecraft development through a combination of federal research contracts, state manufacturing grants, and private venture rounds.
The company has secured multiple research awards through the Department of Defense and United States Air Force Small Business Innovation Research (SBIR) programs. Award records listed on the federal SBIR portal document eight distinct contracts:
| Program Title | Agency | Award Year | Contract Amount |
|---|---|---|---|
| Scaled Supernova Spacecraft (STRATFI) | DOD / USAF | 2025 | $45,000,269 |
| High Delta-V Space Vehicle for Persistent Orbital Tracking | DOD / USAF | 2024 | $1,698,825 |
| Flare Propulsion Qualification Testing for Enhanced Dynamic Space Operations | DOD / USAF | 2024 | $1,249,177 |
| Solar Concentrator Development and Validation Testing | DOD / USAF | 2024 | $1,249,065 |
| Supernova Solar Energy Collection and Storage (SECS) | DOD / USAF | 2024 | $1,237,913 |
| Highly Mobile Space Vehicles (Phase I Award 1) | DOD / USAF | 2023 to 2024 | $74,942 |
| Highly Mobile Space Vehicles (Phase I Award 2) | DOD / USAF | 2023 to 2024 | $74,942 |
| Highly Mobile Space Vehicles (Phase I Award 3) | DOD / USAF | 2023 to 2024 | $74,942 |
The $45,000,269 STRATFI award in 2025, administered under SpaceWERX, represents Portal’s largest government contract. TechCrunch characterized this award as strategic military funding distinct from private equity capital. At the state level, Washington State awarded Portal $350,000 from its Strategic Reserve Fund on 10 December 2025 to accelerate manufacturing operations in Bothell.
In private financing, Portal has raised $67.5 million in equity across a 2025 seed round and a $50 million Series A announced in April 2026. For an analysis of the company’s capitalization and shares, see our guide on whether Portal Space Systems is publicly traded.
Public records and press releases provide conflicting figures regarding Portal’s facility square footage and workforce size:
- Headcount: The federal SBIR portal lists Portal with 25 employees based on an undated company registration entry. In its April 2026 Series A announcement, Portal stated it employed about 40 people and planned to expand the team to 100 during 2026.
- Facilities: Portal’s Series A release cited a 52,000-square-foot facility, whereas KOMO News and Payload reported a 65,000-square-foot footprint. An internal company news update referenced a second 50,000-square-foot facility, and Portal’s website lists an 8,000-square-foot research site in Washington for component validation and hot-fire tests. KOMO News reported in September 2026 that Portal expanded from an initial 6,000-square-foot site to 65,000 square feet in Bothell, with plans to produce roughly 30 spacecraft per year.
How a Maneuverable Spacecraft Differs From a Conventional Satellite Bus
A standard satellite bus provides structural housing, electrical power, thermal management, and communications for an attached payload. In conventional space missions, the bus is designed primarily for station-keeping. It holds just enough propellant to conduct minor thruster firings to counter atmospheric drag, solar radiation pressure, and gravitational variations, ensuring the vehicle stays within its assigned orbital slot.
Because conventional buses carry limited propellant supplies, making large orbital adjustments significantly reduces the satellite’s operating life. Relocating a satellite to an entirely different altitude or changing its inclination requires a major velocity change. Doing so repeatedly quickly exhausts the vehicle’s propellant, rendering the satellite uncontrollable and ending its mission. Consequently, conventional spacecraft operate along fixed, highly predictable flight paths.
Portal’s Supernova platform is built around sustained orbital maneuvering rather than passive station-keeping. The inclusion of the Flare solar thermal propulsion system and its targeted 6 km/s delta-v capability is intended to allow the vehicle to change orbits, transition across altitude regimes, or perform rendezvous operations without immediately ending its mission life. Instead of acting as a static sensor tied to one orbital path, a maneuverable spacecraft functions as an active platform capable of redeploying to new operational areas as mission priorities dictate.
What to Watch Next
The immediate milestone for Portal Space Systems is the flight demonstration of Starburst-1. While the smaller Starburst platform does not carry the full-scale Flare propulsion engine, its flight tests the company’s core avionics, structures, proximity operations software, and specialized payloads, including the superconducting magnet and composite armor tiles.
The critical long-term milestone remains the 2028 Motus Via Sol flight aboard the dedicated Falcon 9. That mission will provide the first on-orbit flight data for the 3D-printed HEX Thruster, the deployable mirror concentrators, and the thermal storage battery that underpin Portal’s performance claims.
Several factors could alter Portal’s trajectory. If ground testing or early orbital demonstrations reveal thermal storage inefficiencies or nozzle durability issues within the Flare engine, the company may struggle to achieve its advertised 6 km/s delta-v figure. Delays in Space Force procurement or shifts in military budget priorities could also lengthen the transition from prototype demonstrations to operational defense contracts. Conversely, if Starburst-1 validates Portal’s bus manufacturing and Motus Via Sol achieves rapid orbital transfers, solar thermal propulsion could establish itself as a practical propulsion category for military space logistics.
Readers can monitor flight status and development updates directly through the Portal Space Systems news page or review broader operational tracking via our guide to space domain awareness.