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My Independent Perspectives on Cislunar Depots

This week I had the opportunity to participate in a fun workshop hosted by AIAA and the Aerospace Corporation in Chantilly, VA on orbital propellant depots for supporting missions throughout cislunar space. This workshop built on a webinar they held earlier in the month, and lessons learned from the workshop will be briefed at a session of the AIAA ASCEND conference later this year in Las Vegas. The workshop was by invitation only, but had a great mix of government, industry, and academia participation.

All participants were invited to submit perspectives on propellant depots, and they asked me to brief my perspectives on the first day of the workshop. Given that depots are something that I’ve been working on for years across multiple companies, I wrote my own personal perspective, not speaking for Gravitics or Voyager/Altius. I was followed by a great talk by my former Masten colleague, Michael Mealling, who gave a perspective on depots coming from his role as a space-focused venture capitalist. I’ve updated this blog post to include a link to his presentation at the end.

In these perspectives we were asked to describe what we thought were valuable and useful about depots in cislunar space, what depot architectures we thought were most relevant, and what technology, use case, and policy developments could be most important in enabling bringing depots to market.

Main contributions

Based on the conversations at the workshop, I think the main thing I contributed in my presentation were that:

  • Depots for supporting Cislunar exploration did not just include depots physically located out in Cislunar space (e.g. EML-1 or 2, NRHO, etc), but also LEO multi-user depots, that can be a key part of how things get from LEO out to Cislunar space.
  • LEO depots aren’t just focused on supporting assets that want to stay in LEO. They can be used for refueling satellites and habitats/platforms in LEO, but one of their main roles is for refueling rockets for sending people, spacecraft, and cargo affordably beyond LEO.

If you haven’t had a chance to read them yet, I wrote a series of blog posts on my Selenian Boondocks space technology and policy blog laying out a taxonomy of different types of depots that some of this thinking was based on.

key lessons learned

I think the two main things I learned from the conference were:

  • When developing a business model, it’s critical to understand your customer’s business model, who their customers are, and what their value proposition is to their customer. This insight came from Mike’s presentation. His point was that if their value proposition to their customers don’t include your solution in some way, you’re easily substituteable, whereas if their customers really care about part of the value proposition that only can come through you, you have a much more “sticky” business that’s harder for competitors to just replace.
  • I’ve noticed for awhile that the DoD was warming to the idea of propellant depots, but they seemed to be almost entirely focused on hydrazine depots in GEO for refueling satellites. Some of the points at the workshop made me finally understand why this is the case — the DoD owns and operates satellites in GEO, so they’re a direct customer for depots. They have assets that they’re operating where refueling directly impacts the kind of operations they’re dealing with on a day-to-day basis, so the value of the depot is obvious. But when it comes to launch, the DoD doesn’t own or operate launch vehicles, they buy launch services. Which means that they’re an indirect customer for depots. They don’t care about refueling rockets per se, and don’t even really grok why it matters. They just care about getting spacecraft and supplies to a destination, on a specific schedule, as reliably and affordably as possible. If anything depots for refueling rockets have so far been an implementation detail for the launch providers.

Combining these two thoughts, I think that if you can point the DoD or NASA to certain launch capabilities they can get with depots that would be hard without (say affordable rapid smallsat delivery to MEO or GEO for the DoD or affordable dedicated interplanetary smallsat launch for NASA), that might get their attention. But it’s always going to be a more complicated story to them since they don’t actually operate the launchers.

my presentation

Anyhow, for those who want to read the actual presentation, here’s a copy of my presentation:

Here is a link to Mike Mealling’s investor’s perspectives presentation on his Medium page.

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