The list of countries to achieve their own successful orbital space launch is a short one, almost as small as the exclusive club of states that possess nuclear weapons. The Soviet Union was first off the rank in 1957, with the United States close behind in 1958, and a gaggle of other aerospace-adept states followed in the 1960s, 1970s, and 1980s. Italy, Iran, North Korea and South Korea have all joined the list since the dawn of the new millennium.

Absent from the list stands Australia. The proud island nation has never stood out as a player in the field of space exploration, despite offering ground station assistance to many missions from other nations over the years. However, the country has continued to inch its way to the top of the atmosphere, establishing its own space agency in 2018. Since then, development has continued apace, and the country’s first orbital launch appears to be just around the corner.

Space, Down Under

The establishment of the Australian Space Agency (ASA) took place relatively recently. The matter was seen to be long overdue from an OECD member country; by 2008, Australia was the only one left without a national space agency since previous state authorities had been disbanded in 1996. This was despite many facilities across the country contributing to international missions, providing critical radio downlink services and even welcoming JAXA’s Hayabusa2 spacecraft back to Earth.

Eventually, a groundswell grew, pressuring the government to put Australia on the right footing to seize growing opportunities in the space arena. Things came to a head in 2018, when the government established ASA to “support the growth and transformation of Australia’s space industry.”

ASA would serve a somewhat different role compared to organizations like NASA (USA) and ESA (EU). Many space agencies in other nations focus on developing launch vehicles and missions in-house, collaborating with international partners and aerospace companies in turn to do so. However, for ASA, the agency is more focused on supporting and developing the local space industry rather than doing the engineering work of getting to space itself.

Orbital Upstarts

Just because the government isn’t building its own rockets, doesn’t mean that Australia isn’t trying to get to orbit. That goal is the diehard mission of Gilmour Space Technologies. The space startup was founded in 2013, and established its rocketry program in 2015, and has been marching towards orbit ever since. As is often the way, the journey has been challenging, but the payoff of genuine space flight is growing ever closer.

Gilmour Space moved fast, launching its first hybrid rocket back in 2016. The successful suborbital launch proved to be a useful demonstration of the company’s efforts to produce a rocket that used 3D-printed fuel. This early milestone aided the company to secure investment that would support its push to grander launches at greater scale. The company’s next major launch was planned for 2019, but frustration struck—when the larger One Vision rocket suffered a failure just 7 seconds prior to liftoff. Undeterred, the company continued development of a larger rocket, taking on further investment and signing contracts to launch payloads to orbit in the ensuing years.

Gilmour Space has worked hard to develop its hybrid rocket engines in-house. 

With orbital launches and commercial payload deliveries the ultimate goal, it wasn’t enough to just develop a rocket. Working with the Australian government, Gilmour Space established the Bowen Orbital Spaceport in early 2024—a launchpad suitable for the scale of its intended space missions. Located on Queensland’s Gold Coast, it’s just 20 degrees south of the equator—closer than Cape Canaveral, and useful for accessing low- to mid-inclination equatorial orbits. The hope was to gain approval to launch later that year, but thus far, no test flights have taken place. Licensing issues around the launch have meant the company has had to hold back on shooting for orbit.

The rocket with which Gilmour Space intends to get there is called Eris. In Block 1 configuration, it stands 25 meters tall, and is intended to launch payloads up to 300 kg into low-Earth orbits. It’s a three-stage design. It uses four of Gilmour’s Sirius hybrid rocket motors in the first stage, and just one in the second stage. The third stage has a smaller liquid rocket engine of Gilmour’s design, named Phoenix. The rocket was first staged vertically on the launch pad in early 2024, and a later “dress rehearsal” for launch was performed in September, with the rocket fully fueled. However, flight did not take place, as launch permits were still pending from Australia’s Civil Aviation Safety Authority (CASA).

The Eris rocket was first vertically erected on the launchpad in 2024, but progress towards launch has been slow since then. 

After a number of regulatory issues, the company’s first launch of Eris was slated for March 15, 2025. However, that day came and passed, even with CASA approval, as the required approvals were still not available from the Australian Space Agency. Delays have hurt the company’s finances, hampering its ability to raise further funds. As for the rocket itself, hopes for Eris’s performance at this stage remain limited, even if you ask those at Gilmour Space. Earlier this month, founder Adam Gilmour spoke to the Sydney Morning Herald on his expectations for the initial launch. Realistic about the proposition of hitting orbit on the company first attempt, he expects it to take several launches to achieve, with some teething problems to come. “It’s very hard to test an orbital rocket without just flying it,” he told the Herald. “We don’t have high expectations we’ll get to orbit… I’d personally be happy to get off the pad.”

Despite the trepidation, Eris stands as Australia’s closest shot at hitting the bigtime outside the atmosphere. Government approvals and technical hurdles will still need to be overcome, with the Australian Space Agency noting that the company still has licence conditions to meet before a full launch is approved. Still, before the year is out, Australia might join that vaunted list of nations that have leapt beyond the ground to circle the Earth from above. It will be a proud day when that comes to pass.

It’s rarely appreciated just how much more complicated nuclear fusion is than nuclear fission. Whereas the latter involves a process that happens all around us without any human involvement, and where the main challenge is to keep the nuclear chain reaction within safe bounds, nuclear fusion means making atoms do something that goes against their very nature, outside of a star’s interior.

Fusing helium isotopes can be done on Earth fairly readily these days, but doing it in a way that’s repeatable — bombs don’t count — and in a way that makes economical sense is trickier. As covered previously, plasma stability is a problem with the popular approach of tokamak-based magnetic confinement fusion (MCF). Although this core problem has now been largely addressed, and stellarators are mostly unbothered by this particular problem, a Canadian start-up figures that they can do even better, in the form of a nuclear fusion reactors based around the principle of magnetized target fusion (MTF).

Although General Fusion’s piston-based fusion reactor has people mostly very confused, MTF is based on real physics and with GF’s current LM26 prototype having recently achieved first plasma, this seems like an excellent time to ask the question of what MTF is, and whether it can truly compete billion-dollar tokamak-based projects.

Squishing Plasma Toroids

In general, to achieve nuclear fusion, the target atoms have to be pushed past the Coulomb barrier, which is an electrostatic interaction that normally prevents atoms from approaching each other and even spontaneously fusing. In stars, the process of nucleosynthesis is enabled by the intense pressures due to the star’s mass, which overcomes this electrostatic force.

Replicating the nuclear fusion process requires a similar way to overcome the Coulomb barrier, but in lieu of even a small-sized star like our Sun, we need alternate means such as much higher temperatures, alternative ways to provide pressure and longer confinement times. The efficiency of each approach was originally captured in the Lawson criterion, which was developed by John D. Lawson in a (then classified) 1955 paper (PDF on Archive.org).

In order to achieve a self-sustaining fusion reaction, the energy losses should be less than the energy produced by the reaction. The break-even point here is expressed as having a Q (energy gain factor) of 1, where the added energy and losses within the fusion process are in balance. For sustained fusion with excess energy generation, the Q value should be higher than 1, typically around 5 for contemporary fuels and fusion technology.

In the slow march towards ignition, we have seen many reports in the popular media that turn out to be rather meaningless, such as the horrendous inefficiency demonstrated by the laser-based inertial confinement fusion (ICF) at the National Ignition Facility (NIF). This makes it rather fascinating that what General Fusion is attempting is closer to ICF, just without the lasers and artisan Hohlraum-based fuel pellets.

Instead they use a plasma injector, a type of plasma railgun called a Marshall gun, that produces hydrogen isotope plasma, which is subsequently contained in a magnetic field as a self-stable compact toroid. This toroid is then squished by a mechanical system in a matter of milliseconds, with the resulting compression induces fusion. Creating this toroid is the feat that was recently demonstrated in the current Lawson Machine 26 (LM26) prototype reactor with its first plasma in the target chamber.

Magneto-Inertial Fusion

Whereas magnetic confinement fusion does effectively what it says on the tin, magnetic target fusion is pretty much a hybrid of magnetic confinement fusion and the laser-based intertial confinement fusion. Because the magnetic containment is only there to essentially keep the plasma in a nice stable toroid, it doesn’t have nearly the same requirements as in a tokamak or stellarator. Yet rather than using complex and power-hungry lasers, MCF applies mechanical energy using an impulse driver — the liner — that rapidly compresses the low-density plasma toroid.

The juiciest parts of General Fusion’s experimental setup can be found in the Research Library on the GF website. The above graphic was copied from the LM26 poster (PDF), which provides a lot of in-depth information on the components of the device and its operation, as well as the experiments that informed its construction.

The next step will be to test the ring compressor that is designed to collapse the lithium liner around the plasma toroid, compressing it and achieving fusion.

Long Road Ahead

As promising this may sound, there is still a lot of work to do before MTF can be considered a viable option for commercial fusion. As summarized on the Wikipedia entry for General Fusion, the goal is to have a liquid liner rather than the solid lithium liner of LM26. This liquid lithium liner will both breed new tritium fuel from neutron exposure, as well as provide the liner that compresses the deuterium-tritium fuel.

This liquid liner would also provide cooling, linked with a heat exchanger or steam generator to generate electricity. Because the liquid liner would be infinitely renewable, it should allow for about 1 cycle per second. To keep the liquid liner in place on the inside of the sphere, it would need to be constantly spun, further complicating the design.

Although getting plasma in the reaction chamber where it can be squished by the ring compressor’s lithium liner is a major step, the real challenge will be in moving from a one-cycle-a-day MTF prototype to something that can integrate not only the aforementioned features, but also run one cycle per second, while being more economical to run than tokamaks, stellarators, or even regular nuclear fission plants, especially Gen IV fast neutron reactors.

That said, there is a strong argument to be made that MTF is significantly more practical for commercial power generation than ICF. And regardless, it is just really cool science and engineering.

Top image: General Fusion’s Lawson Machine 26. (Credit: General Fusion)

An Instruction Set Architecture (ISA) defines the software interface through which for example a central processor unit (CPU) is controlled. Unlike early computer systems which didn’t define a standard ISA as such, over time the compatibility and portability benefits of having a standard ISA became obvious. But of course the best part about standards is that there are so many of them, and thus every CPU manufacturer came up with their own.

Throughout the 1980s and 1990s, the number of mainstream ISAs dropped sharply as the computer industry coalesced around a few major ones in each type of application. Intel’s x86 won out on desktop and smaller servers while ARM proclaimed victory in low-power and portable devices, and for Big Iron you always had IBM’s Power ISA. Since we last covered the ISA Wars in 2019, quite a lot of things have changed, including Apple shifting its desktop systems to ARM from x86 with Apple Silicon and finally MIPS experiencing an afterlife in  the form of LoongArch.

Meanwhile, six years after the aforementioned ISA Wars article in which newcomer RISC-V was covered, this ISA seems to have not made the splash some had expected. This raises questions about what we can expect from RISC-V and other ISAs in the future, as well as how relevant having different ISAs is when it comes to aspects like CPU performance and their microarchitecture.

RISC Everywhere

Unlike in the past when CPU microarchitectures were still rather in flux, these days they all seem to coalesce around a similar set of features, including out-of-order execution, prefetching, superscalar parallelism, speculative execution, branch prediction and multi-core designs. Most of the performance these days is gained from addressing specific bottlenecks and optimization for specific usage scenarios, which has resulted in such things like simultaneous multithreading  (SMT) and various pipelining and instruction decoder designs.

CPUs today are almost all what in the olden days would have been called RISC (reduced instruction set computer) architectures, with a relatively small number of heavily optimized instructions. Using approaches like register renaming, CPUs can handle many simultaneous threads of execution, which for the software side that talks to the ISA is completely invisible. For the software, there is just the one register file, and unless something breaks the illusion, like when speculative execution has a bad day, each thread of execution is only aware of its own context and nothing else.

So if CPU microarchitectures have pretty much merged at this point, what difference does the ISA make?

Instruction Set Nitpicking

Within the world of ISA flamewars, the battle lines have currently mostly coalesced around topics like the pros and cons of delay slots, as well as those of compressed instructions, and setting status flags versus checking results in a branch. It is incredibly hard to compare ISAs in an apple-vs-apples fashion, as the underlying microarchitecture of a commercially available ARMv8-based CPU will differ from a similar x86_64- or RV64I- or RV64IMAC-based CPU. Here the highly modular nature of RISC-V adds significant complications as well.

If we look at where RISC-V is being used today in a commercial setting, it is primarily as simple embedded controllers where this modularity is an advantage, and compatibility with the zillion other possible RISC-V extension combinations is of no concern. Here, using RISC-V has an obvious advantage over in-house proprietary ISAs, due to the savings from outsourcing it to an open standard project. This is however also one of the major weaknesses of this ISA, as the lack of a fixed ISA along the pattern of ARMv8 and x86_64 makes tasks like supporting a Linux kernel for it much more complicated than it should be.

This has led Google to pull initial RISC-V support from Android due to the ballooning support complexity. Since every RISC-V-based CPU is only required to support the base integer instruction set, and so many things are left optional, from integer multiplication (M), atomics (A), bit manipulation (B), and beyond, all software targeting RISC-V has to explicitly test that the required instructions and functionality is present, or use a fallback.

Tempers are also running hot when it comes to RISC-V’s lack of integer overflow traps and carry instructions. As for whether compressed instructions are a good idea, the ARMv8 camp does not see any need for them, while the RISC-V camp is happy to defend them, and meanwhile x86_64 still happily uses double the number of instruction lengths courtesy of its CISC legacy, which would make x86_64 twice as bad or twice as good as RISC-V depending on who you ask.

Meanwhile an engineer with strong experience on the ARM side of things wrote a lengthy dissertation a while back on the pros and cons of these three ISAs. Their conclusion is that RISC-V is ‘minimalist to a fault’, with overlapping instructions and no condition codes or flags, instead requiring compare-and-branch instructions. This latter point cascades into a number of compromises, which is one of the major reasons why RISC-V is seen as problematic by many.

In summary, in lieu of clear advantages of RISC-V against fields where other ISAs are already established, its strong points seem to be mostly where its extreme modularity and lack of licensing requirements are seen as convincing arguments, which should not keep anyone from enjoying a good flame war now and then.

The China Angle

Although everywhere that is not China has pretty much coalesced around the three ISAs already described, there are always exceptions. Unlike Russia’s ill-fated very-large-instruction-word Elbrus architecture, China’s CPU-related efforts have borne significantly more fruit. Starting with the Loongson CPUs, China’s home-grown microprocessor architecture scene began to take on real shape.

Originally these were MIPS-compatible CPUs. But starting with the 3A5000 in 2021, Chinese CPUs began to use the new LoongArch ISA. Described as being a ‘bit like MIPS or RISC-V’ in the Linux kernel documentation on this ISA, it features three variants, ranging from a reduced 32-bit version (LA32R) and standard 32-bit (LA32S) to a 64-bit version (LA64). In the current LS3A6000 CPU there are 16 cores with SMT support. In reviews these chips are shown to be rapidly catching up to modern x86_64 CPUs, including when it comes to overclocking.

Of course, these being China-only hardware, few Western reviewers have subjected the LS3A6000, or its upcoming successor the LS3A7000, to an independent test.

In addition to LoongArch, other Chinese companies are using RISC-V for their own microprocessors, such as SpacemiT, an AI-focused company, whose products also include more generic processors. This includes the K1 octa-core CPU which saw use in the MuseBook laptop. As with all commercial RISC-V-based cores out today, this is no speed monsters, and even the SiFive Premier P550 SoC gets soundly beaten by even a Raspberry Pi 4’s already rather long-in-the-tooth ARM-based SoC.

Perhaps the most successful use of RISC-V in China are the cores in Espressif’s popular ESP32-C range of MCUs, although here too they are the lower-end designs relative to the Xtensa Lx6 and Lx7 cores that power Espressif’s higher-end MCUs.

Considering all this, it wouldn’t be surprising if China’s ISA scene outside of embedded will feature mostly LoongArch, a lot of ARM, some x86_64 and a sprinkling of RISC-V to round it all out.

It’s All About The IP

The distinction between ISAs and microarchitecture can be clearly seen by contrasting Apple Silicon with other ARMv8-based CPUs. Although these all support a version of the same ARMv8 ISA, the magic sauce is in the intellectual property (IP) blocks that are integrated into the chip. These range from memory controllers, PCIe SerDes blocks, and integrated graphics (iGPU), to encryption and security features. Unless you are an Apple or Intel with your own GPU-solution, you will be licensing the iGPU block along with other IP blocks from IP vendors.

These IP blocks offer the benefit of being able to use off-the-shelf functionality with known performance characteristics, but they are also where much of the cost of a microprocessor design ends up going. Developing such functionality from scratch can pay for itself if you reuse the same blocks over and over like Apple or Qualcomm do. For a start-up hardware company this is one of the biggest investments, which is why they tend to license a fully manufacturable design from Arm.

The actual cost of the ISA in terms of licensing is effectively a rounding error, while the benefit of being able to leverage existing software and tooling is the main driver. This is why a new ISA like LoongArch may very well pose a real challenge to established ISAs in the long run, beacause it is being given a chance to develop in a very large market with guaranteed demand.

Spoiled For Choice

Meanwhile, the Power ISA is also freely available for anyone to use without licensing costs; the only major requirement is compliance with the Power ISA. The OpenPOWER Foundation is now also part of the Linux Foundation, with a range of IBM Power cores open sourced. These include the A2O core that’s based on the A2I core which powered the XBox 360 and Playstation 360’s Cell processor, as well as the Microwatt reference design that’s based on the much newer Power ISA 3.0.

Whatever your fancy is, and regardless of whether you’re just tinkering on a hobby or commercial project, it would seem that there is plenty of diversity in the ISA space to go around. Although it’s only human to pick a favorite and favor it, there’s something to be said for each ISA. Whether it’s a better teaching tool, more suitable for highly customized embedded designs, or simply because it runs decades worth of software without fuss, they all have their place.

In 2015, Tim Ellis and Jordan Noone founded Relativity Space around an ambitious goal: to be the first company to put a 3D printed rocket into orbit. While additive manufacturing was already becoming an increasingly important tool in the aerospace industry, the duo believed it could be pushed further than anyone had yet realized.

Rather than assembling a rocket out of smaller printed parts, they imagined the entire rocket being produced on a huge printer. Once the methodology was perfected, they believed rockets could be printed faster and cheaper than they could be traditionally assembled. What’s more, in the far future, Relativity might even be able to produce rockets off-world in fully automated factories. It was a bold idea, to be sure. But then, landing rockets on a barge in the middle of the ocean once seemed pretty far fetched as well.

Of course, printing something the size of an orbital rocket requires an exceptionally large 3D printer, so Relativity Space had to built one. It wasn’t long before the company had gotten to the point where they had successfully tested their printed rocket engine, and were scaling up their processes to print the vehicle’s propellant tanks. In 2018 Bryce Salmi, then an avionics hardware engineer at Relatively Space, gave a talk at Hackaday Supercon detailing the rapid progress the company had made so far.

Just a few years later, in March of 2023, the Relativity’s first completed rocket sat fueled and ready to fly on the launch pad. The Terran 1 rocket wasn’t the entirely printed vehicle that Ellis and Noone had imagined, but with approximately 85% of the booster’s mass being made up of printed parts, it was as close as anyone had ever gotten before.

The launch of Terran 1 was a huge milestone for the company, and even though a problem in the second stage engine prevented the rocket from reaching orbit, the flight proved to critics that a 3D printed rocket could fly and that their manufacturing techniques were sound. Almost immediately, Relativity Space announced they would begin work on a larger and more powerful successor to the Terran 1 which would be more competitive to SpaceX’s Falcon 9.

Now, after an administrative shakeup that saw Tim Ellis replaced as CEO, the company has released a nearly 45 minute long video detailing their plans for the next Terran rocket — and explaining why they won’t be 3D printing it.

Meet the New Boss

For the mainstream press, the biggest story has been that former Google chief Eric Schmidt would be taking over as Relativity’s CEO. Tim Ellis will remain on the company’s board, but likely won’t have much involvement in the day-to-day operation of the company. Similarly, co-founder Jordan Noone stepped down from chief technology officer to take on an advisory role back in 2020.

With the two founders of the company now sidelined, and despite the success of the largely 3D printed Terran 1, the video makes it clear that they’re pursuing a more traditional approach for the new Terran R rocket. At several points in the presentation, senior Relativity staffers explain the importance of remaining agile in the competitive launch market, and caution against letting the company’s historic goals hinder their path forward. They aren’t abandoning additive manufacturing, but it’s no longer the driving force behind the program.

For his part, The New York Times reports that Schmidt made a “significant investment” in Relativity Space to secure controlling interest in the company and his new position as CEO, although the details of the arrangement have so far not been made public. One could easily dismiss this move as Schmidt’s attempt to buy into the so-called “billionaire space race”, but it’s more likely he simply sees it as an investment in a rapidly growing industry.

Even before he came onboard, Relativity Space had amassed nearly $3 billion in launch contracts. Between his considerable contacts in Washington, and his time as the chair of the DoD’s Defense Innovation Advisory Board, it’s likely Schmidt will attempt to put Relativity the running for lucrative government launches as well.

All they need is a reliable rocket, and they’ll have a revenue stream for years.

Outsourcing Your Way to Space

In general, New Space companies like SpaceX and Rocket Lab have been far more open about their design and manufacturing processes than the legacy aerospace players. But even still, the video released by Relativity Space offers an incredibly transparent look at how the company is approaching the design of Terran R.

One of the most interesting aspects of the rocket’s construction is how many key components are being outsourced to vendors. According to the video, Relativity Space has contracted out the manufacturing of the aluminium “domes” that cap off the propellant tanks, the composite overwrapped pressure vessels (COPVs) that hold high pressure helium at cryogenic temperatures, and even the payload fairings.

This isn’t like handing the construction of some minor assemblies off to a local shop — these components are about as flight-critical as you can possibly get. In 2017, SpaceX famously lost one of their Falcon 9 rockets (and its payload) in an explosion on the launch pad due to a flaw in one of the booster’s COPVs. It’s believed the company ultimately brought production of COPVs in-house so they could have complete control of their design and fabrication.

Farming out key components of Terran R to other, more established, aerospace companies is a calculated risk. On one hand, it will allow Relativity Space to accelerate the booster’s development time, and in this case time is very literally money. The sooner Terran R is flying, the sooner it can start bringing in revenue. The trade-off is that their launch operations will become dependent on the performance of said companies. If the vendor producing their fairings runs into a production bottleneck, there’s little Relativity Space can do but wait. Similarly, if the company producing the propellant tank domes decides to raise their prices, that eats into profits.

For the long term security of the project, it would make the most sense for Relativity to produce all of Terran R’s major components themselves. But at least for now, the company is more concerned with getting the vehicle up and running in the most expedient manner possible.

Printing Where it Counts

In some cases, this is where Relativity is still banking on 3D printing in the long term. As explained in the video by Chief Technology Officer Kevin Wu, they initially planned on printing the propellant tank domes out of aluminum, but found that they couldn’t produce them at a fast enough rate to support their targeted launch cadence.

At the same time, the video notes that the state-of-the-art in metal printing is a moving target (in part thanks to their own research and development), and that they are continuing to improve their techniques in parallel to the development of Terran R. It’s not hard to imagine a point in the future where Relativity perfects printing the tank domes and no longer needs to outsource them.

While printing the structural components of the rocket hasn’t exactly worked out as Relativity hoped, they are still fully committed to printing the booster’s Aeon R engines. Printing the engine not only allows for rapid design iteration, but the nature of additive manufacturing makes it easy to implement features such as integrated fluid channels which would be difficult and expensive to produce traditionally.

Of course, Relativity isn’t alone in this regard. Nearly every modern rocket engine is using at least some 3D printed components for precisely the same reasons, and they have been for some time now.

Which in the end, is really the major takeaway from Relativity’s update video. Though the company started out with an audacious goal, and got very close to reaching it, in the end they’ve more or less ended up where everyone else in aerospace finds themselves in 2025. They’ll use additive manufacturing where it makes sense, partner with outside firms when necessary, and use traditional manufacturing methods where they’ve proven to be the most efficient.

It’s not as exciting as saying you’ll put the world’s first 3D printed rocket into space, to be sure. But it’s the path that’s the most likely to get Terran R on the launch pad within the next few years, which is where they desperately need to be if they’ll have any chance of catching up to the commercial launch providers that are already gobbling up large swaths of the market.