We’re excited to launch Valley of Depth, our new podcast taking the place of our beloved (formerly known as) Pathfinder (RIP) podcast.
Valley of Depth is about the technologies that matter—and the people building them. We talk to founders, investors, government officials, and military leaders shaping the future of national security and deep tech. From breakthrough science to strategic policy, we dive into the high-stakes decisions behind the world’s hardest technologies.
In our inaugural episode, EP 001, we’re joined by Bryon Hargis, co-founder and CEO of Castelion, a venture-backed defense startup building affordable, mass-producible hypersonic missile systems for the U.S. and allied militaries. Castelion, founded by former SpaceX engineers, is taking a vertically integrated, fast-iteration approach to strike weapons—redefining how complex defense hardware is built.
In this episode, we unpack the story behind Castelion’s formation, the rising hypersonic threat from China, how startups are challenging the dominance of traditional primes—and much, much more…
• Chapters •
00:00 Intro
00:52 What inspired Bryan to leave SpaceX and start Castelion?
03:06 Non-nuclear deterrence
05:15 How SpaceX's culture influenced Castelion
07:44 Current team size
08:07 Cultural shift in defense hiring
10:04 Hypersonic missile advantages
12:03 US vs China capabilities
13:32 Tradeoffs vs exquisite systems
16:08 What's behind Bryon
18:02 Recent test results
20:54 Iterating safely
24:27 Castelion's DoD buyer
26:56 Navigating defense acquisition
32:11 Championing innovation
35:17 The Golden Dome concept
37:10 Requirements for Golden Dome
39:21 Startups vs primes race
40:49 Scaling missile production timeline
42:48 European market potential
44:19 Competition with defense primes
45:49 Capital requirements
47:26 Company vision
49:13 World impact if successful
50:48 Next milestones
52:14 Story behind the name
• Show notes •
Castelion’s website — https://www.castelion.com/
Bryon’s socials — https://x.com/hargsb
Mo's socials — https://twitter.com/itsmoislam
Payload’s socials — https://twitter.com/payloadspace / https://www.linkedin.com/company/payloadspace
Ignition’s socials — https://twitter.com/ignitionnuclear /
https://www.linkedin.com/company/ignition-nuclear/
Tectonic’s socials — https://twitter.com/tectonicdefense / https://www.linkedin.com/company/tectonicdefense/
Valley of Depth archive — Listen: https://pod.payloadspace.com/
• About us •
Valley of Depth is a podcast about the technologies that matter — and the people building them. Brought to you by Arkaea Media, the team behind Payload (space), Ignition (nuclear energy), and Tectonic (defense tech), this show goes beyond headlines and hype. We talk to founders, investors, government officials, and military leaders shaping the future of national security and deep tech. From breakthrough science to strategic policy, we dive into the high-stakes decisions behind the world’s hardest technologies.
Tectonic: www.tectonicdefense.com
Valley of Depth 
