The New Space Race with Jeff Thornburg

with Jeff Thornburg

Published September 30, 2025
View Show Notes

About This Episode

Neil deGrasse Tyson and Chuck Nice interview aerospace engineer and Portal Space Systems CEO Jeff Thornburg about the emerging space industry, agile spacecraft propulsion, and the interplay between government and commercial space. Thornburg discusses his work on advanced rocket engines at the Air Force Research Lab and SpaceX, why rapid maneuverability in orbit is now strategically critical, and how his company is pursuing solar-thermal propulsion and modular spacecraft. They also examine the value of failure in engineering, the consequences of cutting U.S. R&D and NASA science budgets, the geopolitical competition in space-especially with China-and speculative future technologies like quantum-enabled warp-like drives.

Topics Covered

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Quick Takeaways

  • Jeff Thornburg's company Portal Space Systems is developing highly maneuverable spacecraft that can rapidly reposition between orbits, addressing a growing strategic need in space operations.
  • Thornburg helped pioneer full-flow staged combustion rocket engines at the Air Force Research Lab and later architected the Raptor engine for SpaceX's Starship.
  • He argues that government-funded labs and NASA are still essential for high-risk, no-immediate-business-case technologies that private venture capital will not finance.
  • Modern commercial space engineering cultures embrace visible hardware failures as critical learning tools, in contrast to legacy "failure is not an option" mindsets that drive cost and schedule bloat.
  • Thornburg distinguishes acceptable, documented risk from leadership incompetence that overrides engineering judgment, emphasizing rigorous risk management before flight.
  • He criticizes "vaporware" behavior in some startups that misrepresent technical progress to investors, positioning integrity and data-driven claims as core values at Portal.
  • Portal's Supernova platform uses concentrated solar energy and a thermal engine, avoiding combustion to increase efficiency, reduce part count, and enable flexible propellant use like ammonia and potentially methane or hydrogen.
  • The conversation highlights how U.S. dependence on GPS and satellite infrastructure creates national vulnerabilities that adversaries like China are actively exploiting with more massive, maneuverable spacecraft.
  • Thornburg believes advances in quantum physics may eventually unlock warp-drive-like propulsion by enabling manipulation of space-time, and he advocates for focused quantum R&D.
  • His long-term vision is for cislunar space-between Earth and the Moon-to become routine travel territory, while Neil imagines suborbital point-to-point trips that make any place on Earth reachable within about 45 minutes.

Podcast Notes

Show introduction and setup of the space industry theme

Need for more engineers and aerospace focus

Neil and Chuck emphasize wanting more aerospace engineers on the show[1:38]
Chuck jokes that aerospace engineers are the "best kind" because they will take humanity from where we are to where we want to go
Teasing Elon Musk and guest expectations[1:51]
Neil jokes about Elon Musk coming on, then clarifies the guest is someone else and not "a jerk"

Announcement of topic: future of the space industry

Neil frames the episode as about "Future of the Space Industry"[2:35]
Chuck expresses ambivalence about space travel, saying he wants to get off Earth but worries about who might be driving
Neil's quip about wanting pilots to "fly his mother first" before he flies[2:54]
This sets up the theme of safety and reliability in aerospace engineering

Guest introduction and career overview

Introducing Jeff Thornburg

Neil welcomes guest Jeff and confirms pronunciation of his last name as Thornburg[3:25]
Chuck references a TV soap opera called "The Thornbirds" and jokes about confusing it with Jeff's surname
Jeff's current role and background[4:04]
Jeff states he is CEO of Portal Space Systems and an aerospace engineer
Neil lists Jeff's background: Air Force, NASA, Aerojet, SpaceX, and more
They joke that Jeff has been around but "can't hold down a job"

Motivation behind Jeff's career moves

Jeff's dissatisfaction with slow progress[4:48]
Jeff says he grew up aspiring to a science-fiction-like future and kept finding organizations "not moving fast enough"
He implies this impatience with pace led him to move between organizations and eventually start his own company
Support from family[5:16]
Jeff notes he has a very loving and patient wife who has supported his 30-year career and risk-taking

Portal Space Systems and rapid maneuverability in space

What Portal Space Systems does

Jeff describes Portal's core product[5:24]
Portal is building "the most rapidly maneuverable spacecraft that's ever been built" with high payload flexibility
He emphasizes that this enables many missions for defense and commercial customers, done with speed
Current limitation: slow movement in space[5:40]
Jeff says "you can't get anywhere very fast right now" in space, especially with satellites and defense systems
He frames this as a "solvable engineering problem" that nobody was tackling aggressively enough, so he chose to

Performance specs of Portal's current spacecraft

Orbital maneuverability capabilities[6:10]
Jeff says their platform can move from medium Earth orbit (MEO) to low Earth orbit (LEO) in less than three hours
It can go from MEO to geostationary orbit (GEO) in less than a day, and from LEO to GEO in a day
He says such maneuvering is currently not routine unless using a rocket; existing satellites can't do this frequently
Customer value proposition[7:46]
Jeff stresses customers "don't care how cool the tech is"; they care about speed and responsiveness to events in the world
He mentions needs like quickly observing situations, checking on troubled spacecraft, and not agonizing over propellant use

Long-term propulsion vision: nuclear thermal propulsion

Jeff's vision of future propulsion[8:05]
Jeff states his long-term vision is nuclear thermal propulsion, and calls it a key technology in his lifetime
He and Chuck joke about nuclear thermal propulsion being an obsession since birth, using humorous exaggeration

Jeff's earlier work: rocket engines and Air Force Research Lab

Full-flow staged combustion engine development

Early-career project at Air Force Research Lab[8:40]
As a young engineer at Air Force Research Lab, Jeff worked on a new rocket engine type: a full-flow staged combustion engine
He describes it as "the highest-performing rocket engine ever made"
FFRDC explanation[9:07]
Neil asks if Air Force Research Lab is an FFRDC (Federally Funded Research and Development Center); Jeff clarifies it is a government lab, with contractors like Aerospace providing FFRDC-like support
Neil defines FFRDC as a way for government to support risky, non-business-case projects that corporations would not undertake

Seeding later engine programs including SpaceX Raptor

Air Force work as a kernel for future technologies[9:41]
Jeff says that program (1999-2004) seeded technologies for future engines like J-2X, Stoke's engine, and SpaceX's Raptor
He states he developed and architected the Raptor engine system for Starship at SpaceX

Being recruited to SpaceX

Elon Musk's personal phone call[10:37]
Jeff recounts Elon Musk calling him at home in Huntsville, saying he had a project Jeff might be interested in
Neil and Chuck interpret this as being "cherry-picked" by Elon, since the owner called him personally

Role of FFRDCs, NASA, and government vs private space

Are government research centers still necessary?

Chuck's question on continued relevance of FFRDCs[11:27]
Chuck asks whether government seeding of research is still needed now that commercial space and private capital are active
Jeff's defense of FFRDCs and government R&D[11:40]
Jeff contrasts venture capital, which chases profit and stock price, with government programs that fund necessary, non-profitable technologies
He argues FFRDCs should seed new technologies, including those Portal develops for rapid movement, because no one else will
He notes NASA and the Air Force have historically developed technologies that then sit unused "next to the Ark of the Covenant" in a proverbial warehouse, and says he's sometimes gone back to retrieve and apply them
He worries that budgets for such programs are shrinking due to misconceptions that private industry will handle everything

Engineering at Aerojet and the importance of reducing complexity

Jeff's work at Aerojet

Liquid rocket engine and turbopump development[17:47]
Jeff served as engineering manager and director on liquid rocket engine technology development, focusing heavily on turbopumps
Goals: weight reduction and additive manufacturing[18:13]
He emphasizes "every ounce matters" and that reducing weight and combining components were key objectives
He mentions bringing in additive manufacturing to reduce part count and the challenge of qualifying such systems
Reliability vs part count and shuttle complexity[18:28]
Jeff notes that reliability increases as part count decreases because there are fewer points of failure
Neil recalls the space shuttle being described as the "most complex rocket ever launched" and says that is not actually desirable
Jeff explains the shuttle couldn't be reused as often as planned because engines were harder to refurbish than expected and wiring and tiles presented additional issues

Russian vs American rocket philosophies and commercial launch shift

Soyuz reliability and design philosophy

Post-WWII divergence in rocket development[19:44]
After WWII, the U.S. and USSR each took groups of German rocket scientists; the U.S. got von Braun, while the Russian group focused differently
Jeff says Russian teams emphasized reliability, manufacturability, and part count, while von Braun and the U.S. emphasized performance and perfection
He notes the Soyuz has heritage back to the 1950s and is extremely reliable partly because they have "never changed it"
Buying Russian engines after the Cold War[20:53]
Jeff explains the U.S. bought Russian engines after the Cold War partly to keep Russian rocket scientists from going to countries like Iran and North Korea

Rise of commercial launch and Falcon 9 economics

Early skepticism of SpaceX and Blue Origin[21:34]
Jeff recalls that around the early 2000s, when SpaceX and Blue Origin were formed, NASA doubted they could achieve their performance and price claims
He says NASA "patted us on the head" and told them to come back when it worked
Cost comparison: Falcon 9 vs Shuttle[21:46]
Once Falcon 9 worked, he states NASA became interested because for about $60 million per launch they could do things the shuttle couldn't do economically
They mention that shuttle launches ended up effectively costing around a billion dollars each, partly due to low launch cadence and fixed overhead
Public perception of NASA vs SpaceX[22:49]
Jeff notes that during the transition, some people asked if NASA still existed because SpaceX seemed to be launching everything

Reusable vs expendable Falcon stages and business choices

Engineering for efficient reuse[22:55]
Jeff explains Falcon 9 was pushed to its operational limits so that when the first stage lands, it ideally has no excess fuel
Market choice between reusable and expendable[23:28]
SpaceX offered customers a choice: an expendable stage or a reusable one; the expendable uses all hardware once, while the reusable lands with remaining value
Jeff says customers overwhelmingly chose the reusable option because it made the most financial sense
He notes that a few missions, like those needing all possible delta-v (he references missions like going to Europa), require expendable stages

Engineering culture, mentorship, and value of failure

Learning from graybeards and the art of engineering

Mentorship from older engineers[24:56]
Jeff says he worked with "graybeards" at NASA and the Air Force and tried to be a good student of those who had seen more than he had
Neil's shout-out to engineers[26:42]
Neil emphasizes that scientists know what they want to do, but engineers build the hardware to make it possible, and often remain unnamed
He specifically notes that engineers enabled James Webb and Hubble but usually are not interviewed because the public hears only from scientists presenting results

Failure as a critical part of engineering

Contrasting "failure is not an option" with iterative testing[28:57]
Jeff criticizes legacy programs with a "failure is not an option" mantra, explaining that driving risk toward zero makes cost approach infinity
He says commercial startups instead design to break things intentionally, to learn design limits and unknowns
He attributes long timelines and high costs of traditional aerospace programs to trying to get everything right on the first attempt
Public failures at SpaceX as learning opportunities[29:47]
Neil notes Elon made early SpaceX failures highly visible and framed them as learning events with data, even calling an explosion an "experiment rich in data"
Jeff argues that when company culture accepts failure, teams can reach the final product much faster
NASA's historic experimentation vs later politics[30:29]
Jeff says Mercury, Gemini, and Apollo teams "blew up a ton of stuff" and were young and scrappy like modern startups
He claims politics later changed NASA's ability to operate this way, making them more risk-averse under public scrutiny
He believes NASA should focus on non-commercial, frontier technologies rather than big rocket programs

Risk management, leadership, and infamous engineering failures

How to handle warnings and memos before launches

Neil's question about ignored warnings[31:06]
Neil refers to infamous cases where an engineer warned not to launch and was ignored, and asks how to deal with such memos when failures occur
Active risk management and documentation[31:56]
Jeff describes using "active risk management" where all risks are reviewed and a single responsible person signs off on final risk posture
He says that if someone is strongly worried, he may explicitly take the risk from them, accept it himself, and document why it's acceptable
He stresses being able to explain his reasoning later if something goes wrong, and is willing to say "I was wrong" if necessary

Distinguishing acceptable risk from incompetence

Leadership failures vs engineering risk[33:59]
Jeff says there is incompetence and acceptable risk; companies get in trouble when management ignores engineers and proceeds regardless
He uses examples like doors blowing off or submarines failing as potential cases of leadership overriding engineering judgment
No absolute safety in space[35:13]
He states "there's no such thing as safe in space"; only risks you accept

Hubble mirror and systems engineering

Failure to test as a systems engineering problem[38:09]
Neil brings up Hubble's misfigured optics-components each perfect but not tested together-and asks if this is a leadership issue
Jeff calls it a failure of systems engineering due to an inadequate test program, implying they should have tested the integrated system

Metric vs imperial units and Mars orbiter loss

Legacy tools and mixed units[39:19]
Neil mentions the Mars reconnaissance orbiter-like failure due to mixed metric and imperial units between teams
Jeff says many engineering tools for spacecraft and launch vehicles were written in imperial units, and the community has been slow to convert them, leading to ongoing pockets of mixed-unit "dumbassery"

NASA budget cuts, brain drain, and long-term consequences

Scientists leaving the U.S. and R&D erosion

Jeff's concern about R&D cuts[41:01]
He says the U.S. has been "robbing R&D" for the 30 years of his career, and it's worse now than when he started
He predicts current events will have ramifications for America's leadership in science and technology for decades
Loss of scientists and engineers to other countries[41:32]
Neil notes scientists are leaving for other countries like France due to lack of funding and job security in the U.S.
Jeff frames this as plundering "intellectual treasure" and says you must fund many lines of research because you can't know in advance which ones will succeed

Intellectual property, integrity, and "vaporware" in space startups

Openness in science vs IP in business

Contrast between academic publishing and proprietary tech[44:08]
Neil explains that in academia, publishing ideas allows colleagues to judge them and build on them, with openness driving scientific progress
Jeff acknowledges that in competitive industry, there is a strong desire to hide unique innovations as intellectual property to add company value

Jeff's stance on integrity and benefiting humanity

Influence of Paul Allen and tech for humanity[45:19]
Jeff cites working for Paul Allen and absorbing the idea of "technology for the benefit of humanity" as a cultural touchstone at Portal
He says if Portal developed something truly beneficial to humanity, he would not want to hide it, framing this as a matter of integrity

Critique of misrepresentation and "vaporware"

Where lack of integrity shows up[46:33]
Jeff says he sees most integrity problems when startups lie about the progress of their products to get the next funding round
He claims some companies are essentially "vaporware," with ideas but no real underlying capability, and they "lie their asses off" to investors
He positions Portal's strategy as using data and government contracts (e.g., with Space Force and Air Force) to prove capability rather than relying purely on salesmanship

Funding dynamics, billionaire founders, and VCs in space

Difference between self-funded billionaires and VC-backed startups

Elon's financial head start[47:42]
Jeff notes Elon had about $100 million from PayPal proceeds to start Tesla and SpaceX, giving him a huge head start without diluting ownership
Typical fundraising path for space startups[47:39]
He contrasts this with typical startups that must raise a pre-seed of a few million, a seed of 10-20 million, and continue diluting with each round
VCs' limited technical understanding[48:05]
Jeff says investors typically don't know much about the technology, so the CEO must be a salesperson who can explain concepts like solar thermal propulsion in business terms
He describes using Small Business Innovative Research (SBIR) contracts with Space Force and Air Force to have technically informed customers validate Portal's work, which in turn builds investor confidence

Propulsion regimes, electric propulsion, and adversary capabilities

Different propulsion needs: launch vs on-orbit maneuvering

Chemical rockets for escaping Earth's gravity well[49:14]
Jeff says to leave Earth's gravity, you still want high thrust, and liquid rocket engines remain the best option
Alternative technologies once in orbit[51:07]
He argues that once in orbit, liquid engines are not the most efficient for moving around, and other technologies like electric propulsion and ion engines become attractive
Ion and Hall-effect thrusters are very efficient but low thrust, so they move spacecraft slowly, which satellites tolerated when only economic missions were at stake

Adversaries' rapid maneuvering and brute force

China's approach: massive satellites and tanks[52:17]
Jeff says China is using their growing Long March launch capability to put up larger spacecraft with bigger tanks and thrusters, effectively "brute forcing" maneuverability
He views this as a threat because it allows them to maneuver much faster than traditional U.S. satellites, changing the strategic landscape

Portal's Supernova platform, thermal propulsion, and payload flexibility

Naming inspiration and star-themed products

Rick and Morty and the "portal" concept[55:25]
Jeff says part of the inspiration for the company name "Portal" came from watching Rick and Morty and its "portal gun" with his daughter
He notes their products have a star theme, aligning with Neil's interests

Supernova: concentrated solar thermal propulsion

How Supernova works[56:10]
Jeff describes Supernova as using concentrated solar energy and an innovative heat exchanger to create a thermal engine cycle without combusting propellants
By not carrying oxidizer, the system can carry roughly twice as much fuel and use fewer parts, boosting efficiency and thrust while simplifying design
Choice of propellant and future versatility[56:55]
Supernova uses ammonia currently because it is storable and supports multi-year spacecraft life on orbit
Jeff says the same thermal engine architecture could later use methane, hydrogen, or other fuels, enabling more distant missions like to Mars
He likens it to "Mr. Fusion" from Back to the Future, suggesting flexible use of various propellants

Living off the land vs in-situ resource utilization

Live-off-the-land philosophy[58:09]
Jeff says he is a "live off the land" guy: if they must carry everything with them, they have failed as engineers
Neil suggests NASA should rebrand "in-situ resource utilization" as "living off the land" for better communication

Modular payloads and software-definable power

Lego-like spacecraft architecture[58:59]
Jeff explains Supernova offers software-definable power and a versatile payload deck, letting customers add cameras, telescopes, robot arms, etc., as Lego-like modules
He argues this avoids bespoke, one-off satellites where bus and payload are tightly coupled and not reusable if a business fails
His goal is a platform that can support multiple missions over multiple years, providing power and data while the customer defines the payload function

Geopolitics, Space Force, and protecting orbital infrastructure

Jeff's 2015 Congressional testimony and current message

Past argument: stop buying Russian engines[59:10]
Jeff recalls testifying to Congress in 2015, arguing that the U.S. should stop sending money to Russia for engines and instead train U.S. engineers and support commercial companies
Current warning: adversaries and R&D cuts[59:45]
He says if testifying today, he would emphasize that adversaries are "coming for us" while the U.S. cuts R&D, engineering, and science
He notes that China has openly stated a desire to be the preeminent superpower and questions why the U.S. has "its head in the sand" about this

Strategic importance of space assets and GPS dependence

Neil's explanation of Space Force's real mission[1:00:29]
Neil clarifies that Space Force is primarily about protecting satellites and infrastructure that underpin modern life, not about launching bombs into space
He lists GPS and communication satellites as foundational to things like military operations and daily civilian functions
Everyday systems that depend on space[1:01:01]
Jeff notes that gas pumps and ATMs rely on GPS for timing, and the U.S. has "selectively tied" financial systems to GPS
He points out that China did not do this and has other ways to handle timing, making the U.S. more vulnerable if GPS is disrupted

Harassment of satellites and need for maneuverability

Adversary satellites sidling up[1:02:02]
Neil describes reports of adversary satellites nestling close to U.S. satellites and harassing them, forcing U.S. satellites to move and expend fuel
Jeff calls this a "reasonable hypothesis" and does not directly confirm specifics, but implies such behavior is plausible
He argues current U.S. satellites generally cannot maneuver or defend themselves robustly when threatened, highlighting the need for new capabilities like Portal's

Future technologies: AI, robots, and warp-drive-like propulsion

AI and machine learning for space exploration

Jeff's priorities if he were "king" of space engineering[1:06:15]
Jeff says he would accelerate AI and machine learning and deploy more robots in space to do heavy lifting and exploration
He argues that keeping humans alive in space is extremely expensive and slows exploration, so robots and AI should scout and learn first

Ethics of robot treatment vs human survival

Ethical frontier of robotic exploration[1:07:21]
Neil mentions emerging ethical discussions about how we treat robots, especially if people form emotional attachments
Jeff responds that it's easier to keep robots alive than humans in space and implies that practical benefits should weigh heavily

Quantum physics and warp-drive-like concepts

Quantum understanding as a key to new propulsion[1:08:15]
Jeff says he reads extensively about quantum physics and believes aspects of the quantum world might unlock propulsion technologies resembling a warp drive
He suggests we need a better understanding of the fabric of space-time and ways to manipulate it, rather than just more powerful conventional propulsion
He proposes a quantum-focused FFRDC to concentrate research, noting there are many defense applications for quantum as well
Speculation on timeline and mechanism[1:09:09]
Referencing Star Trek, Jeff jokes that warp drive is invented in 2063 in that universe and treats it as a cultural reference point
He characterizes his view-that quantum physics will be the linchpin for warp-like drives-as "Thornburg's theory" and presents it as speculative

Visions for routine space travel and Neil's cosmic perspective on engineers

Holy grail of commercial space travel

Neil's dream: suborbital point-to-point travel on Earth[1:10:02]
Neil says he wants suborbital flights so any two points on Earth are at most 45 minutes apart, allowing lunch in Tokyo and return home for dinner
He compares this to how impossible such travel would have seemed to the U.S. founding fathers
Jeff's holy grail: routine cislunar access[1:10:44]
Jeff says his holy grail is for humans to go to any orbit between Earth and the Moon-or the Moon itself-without it being a "significant emotional event"
He imagines casually saying "I'll see you on Tuesday" about a trip to the Moon, making cislunar space like the local backyard

Neil's closing cosmic perspective on engineers

Difference between scientific and engineering mindsets[1:12:51]
Neil says as a scientist he asks what is possible and does not focus on how to build or pay for things; engineers instead live for figuring out how under constraints
He notes that engineers love well-defined constraints-limited time, money, and specs-because ingenuity comes from solving problems within those limits
Engineers as essential to civilization's future[1:13:00]
Neil argues there is no future civilization without "happy engineers" given challenging problems to solve in areas like energy, housing, and climate
He says society must provide engineers with the right problems to solve and concludes there is no civilization without them, framing this as his cosmic perspective

Lessons Learned

Actionable insights and wisdom you can apply to your business, career, and personal life.

1

In complex engineering and innovation, embracing controlled failure and rapid iteration is more effective than striving for zero risk, which drives costs and timelines to unsustainable extremes.

Reflection Questions:

  • Where in your work or projects are you clinging to a "failure is not an option" mindset that may be slowing real progress?
  • How could you design small, contained experiments that are allowed to fail so you can learn faster and refine your approach?
  • What is one current initiative where you could explicitly define an acceptable level of risk and move forward more boldly this month?
2

Rigorous, transparent risk management-where leaders explicitly accept and document risks rather than ignore engineering concerns-builds resilience and accountability when things go wrong.

Reflection Questions:

  • What important decisions in your role currently rely on undocumented assumptions rather than clearly articulated risk assessments?
  • How might your decision-making change if you had to sign your name to a one-page document explaining why each major risk you're taking is acceptable?
  • Which upcoming decision could benefit from a short, structured risk review with your team before you commit?
3

Public and private sectors play different but complementary roles: markets pursue near-term value, while governments must invest in foundational, high-risk R&D that has no immediate business case but underpins future breakthroughs.

Reflection Questions:

  • In your field, what kinds of long-term or high-risk work are least likely to attract private investment but most critical for future progress?
  • How could you advocate, even in small ways, for sustained investment in the "unprofitable" capabilities your organization or society will need in 10-20 years?
  • Where might you be over-relying on market forces to solve problems that actually require deliberate, collective investment?
4

Integrity in innovation-being honest about progress and limits instead of selling "vaporware"-builds durable trust with partners, customers, and investors, even if it slows short-term hype.

Reflection Questions:

  • Where might you be overstating certainty or maturity of your ideas, products, or skills to win approval or resources?
  • How could you shift toward showing real data, prototypes, or experiments instead of relying on promises or polished narratives?
  • What is one conversation this week where you could choose to be more candid about risks or unknowns, even if it feels uncomfortable?
5

Engineers and builders do their best work with clear constraints and well-defined problems; vague ambitions without boundaries paralyze creativity instead of enabling it.

Reflection Questions:

  • Which of your current goals feel fuzzy or open-ended, and how could you sharpen them with concrete constraints on time, budget, or performance?
  • How might you reframe a big, amorphous challenge you face into a specific engineering-style problem statement with measurable requirements?
  • What is one project where you could sit down this week and explicitly write out the constraints and success criteria so your team can innovate within them?

Episode Summary - Notes by Remy

The New Space Race with Jeff Thornburg
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