Specific Impulse

Hosted by Jason Carvalho & Jeff Thornburg

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Oct 2026

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About the show

Welcome to 'Specific Impulse,' the ultimate podcast for space technology enthusiasts and professionals. Join spacetech investor Jason Carvalho and legendary space engineer Jeff Thornburg as they dive deep into the latest advancements in rocket engines, propulsion systems, and the future of space exploration. Whether you're an aspiring aerospace professional or a passionate space enthusiast, tune in for expert insights and inspiring conversations that propel you towards the stars.

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5 recent

October 30, 2026Episode 547 min

One Launch Away: Can Maneuverable Spacecraft Change the Future of Space?

Spacecraft have traditionally been built to conserve fuel and avoid unnecessary movement. But as space becomes a more contested and commercially active domain, maneuverability is becoming a critical capability. In Episode 5 of Specific Impulse , spacetech investor Jason Carvalho and space engineer and Portal founder Jeff Thornburg revisit their January predictions and examine what the first half of 2026 revealed about the industry. They discuss Portal’s $50 million Series A, Mini Nova’s on-orbit mission, delays across the launch market, and the upcoming Starburst One mission. Jeff explains Portal’s solar thermal propulsion approach and why maneuverable, refuelable spacecraft could change how satellites operate. The conversation also explores launch capacity, orbital data centers, Golden Dome, and the role of allied partnerships in space. In this episode: Portal’s $50 million Series A and what changed after the funding round Mini Nova’s on-orbit mission and the tests still underway What Starburst One needs to prove after launch How solar thermal propulsion heats propellant without combustion Why maneuverable, refuelable spacecraft could change satellite operations How delays at New Glenn and Neutron affect launch availability The debate over orbital data centers and demand for space infrastructure The hosts’ predictions for the rest of 2026 Jason Carvalho is an early Portal investor, and Jeff Thornburg is Portal’s founder and CEO. They share their perspectives from those roles throughout the discussion. Follow Portal Systems at portalsystems.space .

January 3, 2026Episode 455 min

The Future of Space: Execution Over Ambition - A Recap of 2025

In this episode, Jason Carvalho and Jeff Thornburg discuss the evolving landscape of the space industry, highlighting the significant shift from ambition to execution that occurred in 2025. They explore the impact of defense spending on the sector, the importance of aligning products with customer needs, and the necessity of building strong, experienced teams in startups. The conversation also touches on emerging technologies, the role of venture capital and StratFi in funding, and the critical need for interconnectivity among space systems. As they look ahead to 2026, they emphasize the importance of execution and product-market fit for founders and investors in the space industry. Music Credit “Also sprach Zarathustra” (intro), composed by Richard Strauss (public domain). Recording used under Creative Commons Attribution 3.0 via Wikimedia Commons. Sound Bites "2025 marked a shift from ambition to execution." "Data centers in orbit are a growing topic." "2026 is the year of proof and execution." Chapters 00:00 The Evolving Space Industry Landscape 01:55 2025: A Year of Execution and Reality 05:45 Investment Trends and Market Dynamics 09:20 Navigating Capital: Venture vs. Strat-Fi 11:26 Building the Right Team for Success 20:33 Categories of Success and Failure in Space 26:16 Looking Ahead: Winners and Future Prospects 27:18 The Evolution of Space Industry Post-Pandemic 29:46 Defense Acquisition and Commercial Space Integration 32:43 Navigating Defense Timelines and Relationships 35:56 The Importance of In-Person Relationships 37:36 Innovation vs. Fragmentation in Space Systems 40:44 Preparing for Mini-Nova: Success and Learning 46:37 Identifying Hidden Risks for 2026

June 23, 2025Episode 32 hr 42 min

SPAC Fallout, Defense Dollars & the Real Space Economy

The SPAC wave promised liftoff—but reality hit hard. In this episode of Specific Impulse , hosts Jason Carvalho (Carvalho Capital) and Jeff Thornburg (CEO, Portal Space Systems) dissect the post-SPAC correction, the rise of defense-aligned investing, and why real space infrastructure—not hype—is finally having its moment. 🔍 In this episode, we cover: Why most space SPACs failed—and what comes next The myth of building “the next SpaceX” How defense funding is shaping the real space economy New blended capital models and secondary markets What space founders must do post-2024 to raise, build, and win 💬 “VCs are finally asking the right question: How does this space company actually become a business? ” — Jeff Thornburg Whether you're an investor, founder, or operator navigating the dual-use frontier, this is essential listening for understanding where space is really headed. 🎧 Listen on: SpecificImpulse.fm 🔗 Mentioned in This Episode: Creative Destruction Lab (CDL) US DoD & Space Force Budget Insights Palantir, Project Maven, SpaceX Silicon Valley Defense Group & SPAC trends 00:00 Introduction and Welcome 01:11 Setting the Stage: Space Economy 2.0 03:16 Segment One: The Tipping Point of 2024 04:04 Investment Trends and Market Corrections 08:25 The SPAC Era and Its Aftermath 11:14 Challenges and Opportunities in Space Tech 19:55 The Role of Defense in Space Investment 42:22 AI and Robotics: The Future of Space Exploration 46:14 Building Successful Space Tech Companies 50:43 Scaling a Business: The CEO's Role 52:24 Aligning Sales and Engineering 54:53 The Importance of Leadership and Mentorship 55:25 Fractional Executives and Pricing Strategies 56:52 Building a Strong Network 59:42 Recommended Reading for Executives 01:03:22 The Role of Vision in Space Tech 01:11:51 Manifest Destiny in Space 01:16:28 NASA's Future and Commercial Space 01:29:15 Global Space Ambitions and Cooperation 01:35:56 The Future of Space Companies 01:37:45 The Future of Telecom: Satellite-Based Internet 01:39:09 Leapfrogging Traditional Infrastructure: India and Africa 01:39:57 China's Independent Space Ambitions 01:40:27 The New Space Race: Infrastructure and Investment 01:40:54 Emerging Technologies and the Future 01:47:24 The Role of NASA and Government Policy 01:59:13 Global Space Collaboration and Challenges 02:04:26 The Impact of Leadership and Policy on Space Innovation

July 6, 2024Episode 22 hr 39 min

Mars-Bound: Engineering the Raptor Engine with Jeff Thornburg

Welcome to Episode 2 of 'Specific Impulse,' the podcast that propels you through the universe of space technology and exploration. I'm your co-host, Jason Carvalho, joined by my co-host Jeff Thornburg. Today, we take a deep dive into the engineering marvels and challenges behind the development of the Raptor Engine. In this episode, we explore: Engineering Hurdles : The major challenges faced during the Raptor Engine's initial development and how the team tackled them. Breakthroughs : Unexpected innovations that significantly impacted the engine's design and performance. Lessons Learned : Key takeaways from the Raptor Engine project that could benefit future rocket engine developments. Technical Perspective : An explanation of the key design principles behind the Raptor Engine and its importance for space exploration. Fuel and Combustion : The advantages and challenges of using methane as a fuel. Materials and Manufacturing : Critical material choices and the role of advanced manufacturing techniques like 3D printing. Testing and Validation : Significant hurdles during the testing phase and how they were overcome. Integration with SpaceX Missions : The role of the Raptor Engine in SpaceX's broader mission goals. Future of Rocket Propulsion : Trends and advancements in rocket propulsion technology. Join us as Jeff shares exclusive insights into SpaceX’s journey from 2011 to 2015, including the development of the Raptor engine and the transformative reusability of rockets. Whether you're an engineer, investor, or space enthusiast, this episode is packed with fascinating details you won't want to miss. Key Milestones Discussed: COTS Demonstration Flight (2011) First Commercial Cargo Flight to ISS (2012) Falcon 9 Upgrade and Reusability Milestones (2013-2014) First Successful Droneship Landing Attempt (2015) CRS-7 Failure and Redesign (2015) About Our Co-Host: Jeff Thornburg, co-host of 'Specific Impulse,' led the development of the groundbreaking Raptor engine at SpaceX, which became the world’s first methane-powered full-flow staged combustion cycle rocket engine. With a rich background at NASA, Aerojet, and the Air Force Research Laboratory, Jeff brings unparalleled expertise in propulsion engineering. Tune in as we ignite the engines and set course for the stars! Listen to the episode now and subscribe to 'Specific Impulse' for more deep dives into space technology and exploration.

April 17, 2024Episode 156 min

The New Space Economy: Opportunities and Challenges

Welcome to the inaugural episode of our series where we embark on an exploratory journey into the burgeoning NewSpace economy. This episode serves as your gateway into understanding the dynamic landscape of the space sector, unraveling the wealth of opportunities it presents for investors and engineers alike, alongside the formidable challenges that startups encounter. The NewSpace economy is rapidly reshaping our approach to space exploration and commercialization, moving beyond the confines of traditional space agencies to a more inclusive and innovative arena. Here, we'll dissect the current state of the industry, highlight key players, and provide insights into the technological advancements propelling us forward. But it's not all smooth sailing; the path to stellar success is fraught with obstacles. We'll delve deep into the hurdles startups face, from securing funding to navigating regulatory frameworks, and the resilience required to overcome them. This episode not only sets the stage for the season but also equips listeners with a comprehensive understanding of the space sector's potential and pitfalls. Join us as we explore the final frontier through the lens of the NewSpace economy, offering a blend of expert interviews, industry analysis, and forward-looking discussions. Whether you're an investor eyeing the next big opportunity, an engineer dreaming of the stars, or simply a space enthusiast, this episode is your launchpad into a universe of possibilities.