Hello, and welcome back to Beyond NERVA!
This week marks the one year anniversary of Beyond NERVA’s start as a blog. While I’ve been fascinated by nuclear powered spacecraft since I was a child, September 23, 2017 was the start of my outreach efforts in this incredibly diverse and fascinating area of research.
In the past year, I have had the extraordinary opportunity to speak with both amateurs and experts from all over the world about the use of nuclear power in space, and I can’t express how appreciative I am for all the insights and knowledge that they’ve willingly and eagerly shared with me. While I may be the (still mostly anonymous, since this isn’t about me AT ALL) author of the blog, almost every post I’ve ever written has not been solely my work. Most professionals are very wary of putting their name on anything as speculative as this (fairly hard nosed, in my opinion) blog, and I respect their privacy and professional reputation, but numerous Principle Investigators and holders of various advanced degrees in advanced propulsion have been instrumental in making this blog what it is, and I am incredibly grateful for their time, not only in helping me, but in developing the skillset to help humanity expand beyond our cradle, as Dr. Sagan so eloquently put it. My knowledge on this subject has blossomed thanks to their invaluable help.
What The Last Year Has Brought
In the past year, we’ve looked at the Kilopower program, from its’ inception as DUFF, through the design and modeling of the KRUSTY experiment, to the test of the first new nuclear reactor design to be tested in the US of any type since the 1970s (with special thanks to Dr. Patrick McClure for his invaluable help in our unique reporting on this design). These posts remain the most popular on the site, and in the coming months I’ll be rewriting them into a series of easier-to-read pages on the design, from conception to current form, as well as some about the future of this fascinating reactor.
We’ve looked at Project ROVER, and the testing that was done to enable humans to go to Mars in the 1980s, which was sadly cancelled with the massive defunding of NASA even as we were preparing to step foot on the Moon for the first time. Not only did we look at the basics of the designs used, but we delved into the testing that it takes to make a paper reactor into a real one, and the challenges that are faced when testing in real life.
We’ve looked at NASA’s Low Enriched Uranium Nuclear Thermal Rocket program, its’ predecessors, and the testing that’s needed to bring this to fruition. We glanced at the rocket that would need to be built in orbit to get humanity to Mars, and some of the challenges that must be overcome to make it a reality through real world testing. We also looked at the possibility of using carbide fuels, which the USSR, and now Russia, have pursued as their main focus, and which NASA has never abandoned as a possibility for getting even better efficiency out of these engines.
In the last couple months, we’ve begun looking at nuclear electric power supplies and propulsion in space. To be honest, I was hoping to be able to post the first of two posts on electric thrusters in the last few days, but this is a huge area to cover, with an incredible number of overlapping parts, and the post is taking longer than I hoped it would. I’m still hopeful to have it out either late this week or early next week, with the follow-on post shortly after, but… we’ll see how the writing and editing process goes.
In between, the website itself has started to develop. Not only have pages been written for the major subjects (except one, Kilopower remains the one I haven’t reworked into a proper website – ironic, since that’s my most popular set of blog posts, but there’s a lot there to unpack, rewrite, and add to), but other subjects have been expanded far beyond what’s available in this blog.
Many concepts that I haven’t had a chance to cover, or that simply wouldn’t fit in the blog posts, are covered on various sites on the webpage itself. For instance, the Nuclear Thermal Reactor page covers many designs that we will hopefully discuss over the next year, but haven’t had a chance to yet, such as liquid, vapor, and plasma fueled nuclear thermal rockets, bimodal thermal/electric systems, and others.
Fuel elements, a subject that we’ve covered in specific quite a bit in the blog, also have their own page, with a broader scope than what’s been covered on the blog. This is another area that I’m planning on expanding more widely as time is available, including with new information on both CERMET and carbide fuel elements.
I’m fairly proud of the Test Stands and Equipment page, since these are the actual nuts and bolts needed to make these designs a reality. This area of nuclear development has, to my knowledge, not been covered very well on any other website, and is an area that I hope to continue to expand in the future, including more information on both historical and current test stands, and expanding into proposals for future testing equipment and facilities. This is also the page that I’ve looked at the basics of reactor design, as well as the considerations that go into fuel element irradiation testing, a necessary early step in reactor development.
Finally, while we haven’t discussed nuclear pulse propulsion in the blog, there is a page covering it now, with some links to relevant articles. Next year will have many blog posts on this subject, I hope it won’t take the full year (my hope is to start the new year off with a bang, as it were).
What’s Been Going On Behind the Scenes
A lot has been going on that doesn’t make its’ way to the website or blog, mostly because it’s in the early stages of development. For those who are in the Facebook group, much of this won’t be new to you.
I’ve been doing a ton of research on various subjects that will be coming up in the future, and some that will only really be discussed when the YouTube channel gets started (when that will happen is still very much to be determined). This includes a lot of research into Project Rover, and the history of the various programs that weren’t discussed in the blog post for brevity’s sake, but will be a major part of the YouTube channel. My work with various other projects and organizations, especially Science and Futurism with Isaac Arthur, continues as well, bringing new ideas to various parts of this website.
I’ve also been honing my skills in Blender, to produce graphics for both the blog and the upcoming YouTube channel. This has been a very time consuming process, but I’m beginning to see much better results, and hope to be able to produce high-quality, original digital images and animations for the blog starting in the very near future.
As a glimpse into these efforts, here’s a selection of the work that I’ve been doing on the graphics side of things. Some models are more complete than others, and some animations are of better quality than others. Most are, in fact, test renders and animations, due to my lack of computer processing power (I’ve had offers from others for rendering capability, but as of yet have very few projects that are at the point where I consider them to the point of being ready to ask others to help).
One of the first projects was to develop a “baseline model” for a nuclear thermal rocket, in order to demonstrate the various strategies and techniques used to mitigate radiation exposure for the crew, among other things. This is that model (although more work remains to be done, especially on materials). I based it one half of Crouch’s “Coast Guard” cislunar craft from “Nuclear Power And Propulsion.” Here’s a short test render of the design:
Another early project is Boeing’s Integrated Manned Interplanetary Spacecraft concept, which was NASA’s preferred spacecraft to mount the NERVA engines to. Depending on mission profile, desired payload and other factors, anything from 5-10 engines would be discarded during the staging process. This will be another fairly-frequently used model during the YouTube channel. Work continues to be done on this model, this is just an early, low-poly render of the spacecraft:
As with the previous model, I also did a short animation about 6 or so months ago of this one leaving Earth orbit, although it does show that I’ve got a long way to go in terms of camera motion and other techniques.
During our discussion of Fission Power Systems, I was looking for a good illustration of a disc droplet radiator, and was only able to find a pen sketch from a NASA proposal, so I decided to do my own model.
Finally, while we haven’t covered Orion in this blog, it’s an iconic spacecraft, with a very complex and visible firing sequence. Because of this, I’ve begun to work on a number of models These are the variants of the 10 m Mars mission architectures. Each uses the same base, which I’m currently working on finishing the animation sequence of.
This sequence isn’t complete, there are a number of things that are still being done to make it more accurate, but the basic timing, as well as the compression of the two shock absorbers, is correct. The most glaringly obvious one is the oscillation of the structures surrounding the toroid shock absorbers are reversed: the pusher plate should smoothly go in and out, with the secondary plate (with the pistons attached) should be the one oscillating during the firing sequence. I’m rejiggering the armature to make this happen, and after that a small number of tweaks will be needed in order to be able to mount it to any of the 10 m models that I’ve already got at least partially modeled.
There are more models in various states of completion that I’m continuing to work on, and the process is definitely going to be improving over time. However, I figured that it would be nice for those that just follow my blog to be able to see that progress is also being made on the visuals side.
Where We’re Going
So what does the next year have in store for Beyond NERVA?
First, we’ll finish covering nuclear electric propulsion. The first post on the drive systems is close to complete, and the second is about half written, so hopefully there won’t be as big a gap between them as there has been between the last blog post and the one coming up. We will then look more deeply at power conversion systems in their own post, followed by heat rejection systems. Finally, we’ll look at designing NEP spacecraft, as well as the different types of missions that they offer for both crewed and uncrewed missions.
After we finish with NEP, we’ll return to thermal rockets… ish. Instead of looking at the purely thermal systems, though, we’ll be examining bimodal systems, starting with thermal/electric bimodal rockets. There have been many designs proposed over the years, but often (out side of technical papers) they’re often depicted as “bolt an ion drive on the side, and you’re good;” we’ll look at the actual challenges of designing these spacecraft. We’ll also look at thermal/chemical bimodal systems as well, with a look at Dr. Stanley Borowski’s LANTR design. We’ll look at a trimodal system, using thermal, chemical, and electric propulsion with a single reactor, the US Navy-funded TRITON concept. Finally, we’ll look at the implications for mission planning with these types of spacecraft, and other concepts that have variable thrust and specific impulse, such as VASIMR.
Then, it’s off to looking at nuclear pulse propulsion, starting with one of the most iconic nuclear powered ships ever, Project Orion. We’ll examine the later Marshall Spaceflight Center study of the concept, as well as more modern designs such as Mini-Mag Orion, and how they address some of the problems with the original design. Finally, we’ll look at fusion for the first time on this blog, with Project Medusa and Project Longshot, and even examine antimatter-catalyzed microfission and microfusion concepts.
We’ll look at designs that don’t really fit in anywhere in the grand scheme of common reactor types, starting with the fission fragment rocket engine. Two types have been designed, and one has undergone a significant amount of research and optimization in recent years. After this, we’ll look at fission sails, both with spontaneous fission (sometimes called Forward sails) as well as photofission concepts.
After we complete our grand tour of general nuclear rocket types, we’ll return to nuclear thermal rockets once again, to look at non-solid fuel elements. We’ll walk our way up the energy scale of the phases of matter, beginning with molten and liquid fueled designs. Vapor, gas, and plasma cores will follow, including a deep dive into the ever-popular open cycle gas core (which I prefer to call a plasma core) NTR. Finally, we’ll look at nuclear electric concepts that don’t use solid fuel elements, and the advantages and disadvantages they offer spacecraft designers.
My hope is to cover, at least in brief, all of the different fission-powered types of nuclear rocket in the next year, so in one years’ time I’m able to begin covering fusion concepts, as well as more exotic ideas, such as antimatter, beamed propulsion of both light and smart matter, and possibly even black hole propulsion.
Once covering the fission concepts is concluded, this blog will also slow down, unfortunately, because focus will shift onto the long-delayed YouTube channel, which will not only cover a lot of the basics in what is hopefully a more understandable way, but will also delve more deeply into the history of nuclear spacecraft and the technology behind them. I may bring on additional writers that I know and trust, perhaps even in the next year (but the two I have my eye on are both kneck-deep in their studies at the moment), but that’s a decision for the future.
Another concept that I’ll be beginning to cover in the next year, although on a sporadic basis, is rotating habitats, and their variants, the gravity-enhancing toroid habitats for low-gravity planets to make them more habitable. We’ll look at the basic concept, various proposed designs, and the limitations, both in engineering and in materials, that the different concepts have. We’ll look at the life support systems, including agriculture, volatiles recycling, and the mental health support systems as well, especially when it comes to not feeling like you’re stuck in a “tin can” all the time. Finally, we’ll look at the ecological concepts and models that have been developed over the last 50 years that could enable us to build an artificial ecosystem, as well as the limitations on our understanding of these systems. This is a subject that has been very sparsely covered, but one that I’m quite interested in, so expect to see posts from time to time on this concept as well.
The Adventure Continues!
This first year has definitely been a wonderful experience for me, and I hope that I’ve been able to provide a good resource for those that want to learn more about in-space nuclear power and propulsion. I’ve been very lucky to get assistance from a number of people in the astronuclear community, and I’ve also gained a couple of talented editors and technical experts that have been invaluable with their time and energy.
Thank you everyone for your encouragement and support in this first year. I’ll do my best to make the next year even better than this one has been!