Editor’s word: This collection profiles six of the Seattle area’s “Unusual Thinkers”: inventors, scientists, technologists and entrepreneurs reworking industries and driving optimistic change on the earth. They are going to be acknowledged Dec. 11 on the GeekWire Gala. Unusual Thinkers is offered in partnership with Larger Seattle Companions.
BOTHELL, Wash. — Earlier than he turned the CEO of Portal Area Techniques, Jeff Thornburg labored for 2 of the world’s most progressive space-minded billionaires. Now he’s engaged on an concept these billionaires by no means thought to pursue: constructing a spacecraft powered by the warmth of centered daylight.
Thornburg and his teammates are aiming to make Bothell-based Portal the primary industrial enterprise to capitalize on photo voltaic thermal propulsion, a know-how studied many years in the past by NASA and the U.S. Air Power. The idea includes sending a propellant by means of a warmth exchanger, the place the warmth gathered up from daylight causes it to broaden and produce thrust, like steam whistling out of a teakettle.
The know-how is extra fuel-efficient than conventional chemical propulsion — and faster-acting than photo voltaic electrical propulsion, which makes use of photo voltaic arrays to show daylight into electrical energy to energy an ion drive. Photo voltaic thermal propulsion properly fills a distinct segment between these two strategies to maneuver a spacecraft between orbits. However neither NASA nor the Air Power adopted up on the idea.
“They didn’t abandon it for technical causes,” Thornburg mentioned. On the time, it simply didn’t make financial or strategic sense to take the idea any additional.
What’s modified?
“Decrease launch prices, coupled with additive manufacturing, are the most important unlocks to carry the tech to life, and make it inexpensive and consistent with industrial improvement,” Thornburg mentioned.
Thornburg argues that it’s the appropriate time for Portal’s spacecraft to fill a spot in America’s nationwide safety posture on the excessive frontier. “There was no crucial for fast motion on orbit within the Nineties,” he mentioned. “Solely just lately have the threats from our adversaries highlighted the weaknesses in present electrical propulsion techniques, in that they’ve so little thrust and may’t allow fast mobility.”
Portal’s imaginative and prescient has attracted curiosity — and monetary help — from buyers and potential prospects. Since its founding in 2021, the startup has raised greater than $20 million in enterprise capital. In 2024, Portal received a dedication for $45 million in public-private funding from SpaceWERX, the innovation arm of the U.S. Area Power. And subsequent yr, Portal is because of exhibit its {hardware} for the primary time in orbit.
So, how did Thornburg stumble on the thought of turning a decades-old concept into actuality?
The trail to propulsion
Thornburg, who’s now 52 years outdated, has centered on making issues fly for many of his profession. It began when he was a school scholar in Missouri within the early Nineties, incomes his aerospace engineering diploma with an ROTC scholarship from the Air Power. He recalled a dialog he had with an teacher who was an outdated F-4 fighter pilot.
“With my nearsightedness, I used to be out of the sport from a pilot standpoint,” Thornburg mentioned. “However he mentioned, ‘Thornburg, in case you can’t fly the planes, go be as near them as you may.’”
Thornburg signed up for a program that fast-tracked him into an plane upkeep function. He traveled all over the world with KC-135 cargo planes, supporting missions that included the NATO-led air marketing campaign towards Yugoslavia in 1999. Throughout his time as a flight commander and plane upkeep officer at MacDill Air Power Base in Florida, “I had a few hundred enlisted individuals who labored onerous to maintain me out of bother,” he mentioned.
The Air Power is the place he earned his grasp’s diploma in aerospace engineering. “My adviser had a good friend that labored on the Air Power Analysis Lab,” Thornburg recalled. “He referred to as him and mentioned, ‘The Air Power is about to ship this man to do one thing with airplanes, however I’m fairly certain he’s going to be upset if he can’t come out and work on rocket engines.’”
Certain sufficient, Thornburg was quickly engaged on rocket propulsion improvement, together with a mission to create what’s often known as a full-flow staged combustion cycle engine. “We made what folks thought was not potential potential with that program,” Thornburg mentioned.
In 2004, Thornburg left the Air Power to work on rocket propulsion techniques at Exquadrum, Aerojet and NASA. Then, in 2011, he took a telephone name from SpaceX’s billionaire founder, Elon Musk. “We talked for about an hour, hour and a half on the telephone — and he mentioned, ‘I’ve obtained a mission I need to speak to you about,’” Thornburg mentioned.
That mission led to the event of SpaceX’s methane-fueled Raptor rocket engine, which leveraged the know-how that Thornburg helped pioneer on the Air Power. “That was a wild journey, as a result of that felt like about 15 or 20 years of expertise in a five-year time interval,” he recalled.
After 5 years at SpaceX, Thornburg wanted to wind down. He determined to do some consulting at his residence base in Huntsville, Alabama, also referred to as Rocket Metropolis. “About six months in, I’m like, I would like an actual job once more,” he mentioned. “And a few mates of mine launched me to, in the end, Paul Allen. Paul referred to as me and mentioned, ‘Are you able to come out to my Seattle workplace?’”
The Microsoft co-founder and software program billionaire enlisted Thornburg to develop into the pinnacle of rocket propulsion improvement for Stratolaunch, Allen’s house enterprise. Thornburg led the hassle to create a liquid rocket engine often known as the PGA — which stood for “Paul G. Allen.”
Sadly, Allen handed away in 2018, only one month after the engine was unveiled. Underneath new possession, Stratolaunch pivoted to hypersonic testing, and the PGA mission fell by the wayside. As soon as once more, Thornburg and his household hunkered down in Huntsville.
Constructing a enterprise
“I made a decision to begin my first house firm after Paul died,” Thornburg mentioned. “I centered on hydrogen propulsion know-how and options, form of like what we had been engaged on for Paul.”
That first firm, Interstellar Applied sciences, began engaged on initiatives for NASA, Northrop Grumman and a few different prospects. Then the pandemic hit. “The buyers that had been about to supply funding disappeared,” Thornburg mentioned. “NASA went residence, Northrop Grumman went residence. And so I needed to discover my small workforce different jobs.”
Simply as Thornburg was about to resign himself to using out the pandemic in Alabama, Amazon’s recruiters referred to as. They requested him to maneuver to Seattle to run engineering and manufacturing for Mission Kuiper, the satellite tv for pc web mission that’s now often known as Amazon Leo. “That’s in the end what obtained us moved to Seattle,” Thornburg mentioned.
His yearlong stint at Amazon was lengthy sufficient to determine the method for constructing Mission Kuiper’s two prototypes and the production-grade satellites that got here after them. Then he took on engineering administration roles at Agility Robotics and Commonwealth Fusion Techniques.
That’s when Portal Area Techniques took form.
To be truthful, the seeds for Portal had been planted again in 2016, simply weeks after Thornburg left SpaceX. “Lawrence Livermore Lab had referred to as and mentioned, ‘We’re doing a seminar on the way forward for propulsion. Would you want to return be a speaker?’” he recalled. “I mentioned, ‘Sure, what would you like me to speak about?’ They mentioned, ‘We wish you to inform us what the way forward for propulsion appears to be like like.’ Oh my gosh, no stress on that!”
As he did the analysis for his speak, he got here throughout the thought of placing a nuclear reactor on a spacecraft, and utilizing the concentrated warmth from that reactor to blast a propellant by means of a thruster. The idea, often known as nuclear thermal propulsion, appeared like a stretch — however then Thornburg had an unusual thought.
“Are you able to focus photo voltaic power to warmth a thrust chamber and do the identical factor?” Thornburg mentioned. “You possibly can. It’s not fairly as efficient as a nuclear reactor, for apparent causes, nevertheless it’s all the identical items. … Now I don’t have to attend on a low-cost, low-weight, space-rated nuclear reactor that doesn’t exist but.”
Thornburg mulled over the thought for years. “I used to be excited about Portal, and I used to be beginning the beginnings of Portal in 2021, however I nonetheless needed to pay the payments,” he mentioned. For a few years, he labored through the day at Agility Robotics and Commonwealth Fusion — and spent nights and weekends laying the groundwork for the startup.
“When Portal may actually begin to stand by itself, as we began to win over the Protection Division, that’s after I made the swap with all of my time centered on what was happening in Portal,” Thornburg mentioned. In April 2024, the startup emerged from stealth and introduced it had acquired greater than $3 million in funding from the Protection Division and the Area Power.
The street forward
Portal’s flagship automobile is named Supernova. It’s a rapid-transorbital, multi-mission automobile that needs to be able to transferring itself and its payloads from one orbit to a different — even from low Earth orbit to geostationary Earth orbit, greater than 20,000 miles increased up. And it ought to be capable of do this inside hours or a day, fairly than the weeks or months which can be usually required.
The spacecraft itself will likely be concerning the measurement of a restaurant fridge. To pay attention daylight on its warmth exchanger and thruster system, Supernova will use sheets of reflective materials that may unfold to a width of roughly 55 ft. Ammonia will function the propellant. The 3D-printed warmth exchanger thruster, dubbed Flare, was efficiently examined earlier this yr.
Subsequent yr’s orbital demonstration will contain placing an instrument package deal often known as Mini-Nova, which is concerning the measurement of a tissue field, on a satellite tv for pc platform that’s due for launch on a SpaceX rideshare mission. The demonstration is supposed to validate Supernova’s system design.
In late 2026, Portal plans to ship up a free-flying spacecraft referred to as Starburst, which will likely be geared up with thrusters powered by an electrothermal heating system. Starburst received’t be as highly effective as Supernova, however it should present Portal’s prospects with an early choice for fast maneuverability in orbit. If subsequent yr’s check goes effectively, Starburst is anticipated to begin taking up buyer missions in 2027.
2027 can also be the yr when Supernova is scheduled to make its debut. The entire improvement work for Supernova and Starburst will likely be going down at Portal’s 8,000-square-foot lab and 50,000-square-foot manufacturing facility in Bothell.
All through Portal’s childhood, Thornburg has labored with fellow members of the “small workforce” he assembled at Interstellar Applied sciences. Each of Portal’s different co-founders — chief working officer Ian Vorbach and engineering vice chairman Prashaanth Ravindran — crossed paths with Thornburg at Interstellar, and at Stratolaunch earlier than that.
Vorbach, whose background consists of startup expertise in addition to engineering expertise, mentioned Portal’s enterprise mannequin has been fine-tuned to ensure it addresses the wants of its goal market. He and Thornburg recognized the U.S. navy’s want for tactical responsiveness in house as the highest precedence.
“What occurs loads within the house trade is that you’ve got extremely technical, proficient individuals who have a know-how that gives some very distinctive efficiency, after which they construct it, and it seems that efficiency isn’t wanted,” Vorbach mentioned. “There’s obtained to be a cause to carry that innovation to market.”
Vorbach is grateful for Thornburg’s management. “We work very lengthy hours, however I feel Jeff does an important job of creating certain folks know that they’re valued,” he mentioned. “I respect that, and I feel it’s why we, fortuitously, are in a position to rent nice expertise from the locations he’s come from, whether or not it’s SpaceX or Kuiper.”
Ravindran, who labored at Jeff Bezos’ Blue Origin house enterprise earlier than taking a founder’s function at Portal, agreed with that evaluation. “It’s at all times wonderful to have somebody like Jeff on the market, as a result of he’s come up the engineering street to appreciate our ache factors as effectively, and he doesn’t attempt to maintain us to unfair requirements,” he mentioned. “That means, we’re not arrange for failure.”
Stan Shull, an area trade analyst at Bellevue, Wash.-based Alliance Velocity, provides Portal excessive marks. “In house phrases, a extremely maneuverable satellite tv for pc is alleged to have excessive delta-V,” he informed GeekWire in an e-mail. “Portal, as an organization, feels excessive delta-V too.”
Thornburg’s expertise and experience are massive elements behind Portal’s fast progress, Shull mentioned. “He’s very educated about nationwide safety points and is a straight shooter concerning the rising risk surroundings in orbit,” he mentioned. “It’s no shock the Area Power is among the many many purchasers excited about what the corporate is as much as.”
What is going to Portal be as much as subsequent? Trying long-term, Thornburg is intrigued by the quantum frontier. “I feel there are some very attention-grabbing issues occurring in our understanding of quantum physics that may have propulsion functions, that received’t appear to be propulsion as we all know it proper now,” he mentioned. “If we may fold spacetime in intelligent methods … there’s been loads of writing about that.”
However when he takes a extra life like have a look at what may occur in his lifetime, Thornburg can’t cease excited about nuclear propulsion. “Our Supernova spacecraft can have a model that may leverage a nuclear reactor sooner or later. That was at all times the going-in place,” he mentioned.
The best way Thornburg sees it, the nuclear choice will revolutionize spacecraft — and broaden humanity’s attain on the ultimate frontier whereas we work out the best way to fold spacetime.
“Nuclear thermal will get us additional into the photo voltaic system, and this Earth-moon-Mars turns into our yard,” he mentioned. “However, you already know, for my 12-year-old model of myself, that’s not sufficient.”
