Elon Musk’s dream to make humanity a multi-planetary species and colonize Mars within a few decades goes right along with the dreams of most people involved in AM: seeing this technology change manufacturing. The two things are aligned and synergic. The relatively young commercial space industry relies significantly on AM technologies and AM industrialization has been driven by the needs of the aerospace industry.
But colonizing Mars is a whole new ballgame, one that will require AM technologies – many different types of AM technologies – to really step up and deliver. Most of the AM applications that will be needed for an interplanetary journey and colonization efforts have already been envisioned and described. Now, as Musk quantified the amount of equipment needed to start a self-sustaining Martian colony in 1 million tons of it, it’s time to put it all together and quantify exactly how much AM will be needed to go to and stay on Mars.
Making the rockets lo leave Earth
Musk plans on building 100 Starships, which will need Super Heavy rockets to launch them into space. Each combined vehicle will be capable of launching from Earth’s surface every six to eight hours. Super Heavy—which will return to Earth after giving Starship the initial push—will be able to do so roughly every hour, on missions that deliver up to 150 tons of payload to orbit, Musk said. The newest Super Heavy is fitted with 33 Raptor 2 engines and every Starship will now have 6.
The Raptor 2 is really a marvel of engineering: it is more powerful than the first Raptor and significantly smaller (and lighter). That is definitely thanks to the use of AM. It is no secret that SpaceX is a major adopter for rocket engine development and production. The company invested in Velo3D and has recently expanded its AM engineering division significantly. It’s not just that AM enabled SpaceX to make smaller and lighter engine parts, it’s that the ability to use AM to produce manifolds shaped exactly as they need to be, enables the development and production of much more efficient, smaller and lighter systems.
We have no idea how many 3D printed parts are present in a Raptor 2 engine but let’s say it’s as many as 100, representing one-tenth of the engine’s roughly 1,000 Kg weight. On 100 Starships (6 Raptors) and, let’s say, 35 Super Heavies (33 Raptors), that would be 175,500 additively manufactured parts for a total of 175.5 tons of materials. If SpaceX ever found it more convenient to 3D print the entire rocket engine nozzle (as has been done experimentally by NASA and Relativity), the weight of the 3D printed parts would change significantly and could even double or triple (up to 500 tons).
If, then, the company found it convenient to 3D print the entire Super Heavy booster rocket (like Relativity intends to do with its – much smaller – rockets), using metal DED technologies, the impact of AM would be even greater. With each one weighing roughly 3,000 tons that would drive the total up to over 100,000 tons of 3D printed parts just for the ships and boosters. By the way, SpaceX may leverage support from upcoming launch startups such as Relativity itself, RocketLab and Launcher, all major adopters of AM following in SpaceX’s footsteps.
According to Musk, the Starships will need to take 1 million tons of stuff up to orbit and transport it to colonize Mars. It seems logical that these 1 million tons should include several 3D printers and several thousand tons of 3D printable materials, including both metals and polymers/composites. Perhaps even some ceramics and cement (at least to get started with interplanetary construction). A lot of equipment will have been developed specifically for this voyage, including many accessories and tools that have to be customized for the astronauts and colonists. It seems safe to say that as much as 10% of these 1 million tons of things will have to do with 3D printing, including a few hundred 3D printers and lots of materials. That could be another 100,000. Some of these parts may need to be produced in orbit, on the upcoming new commercial space stations, or on the moon. It will be likely that any in-orbit manufacturing will be carried out by 3D printing, since it would often be much more costly to ship finished parts and components from Earth. Just shipping easily stocked packs of materials to in-space 3D printing facilities will keep the finished parts that have to be sent from Earth to the bare minimum.
Taking the trip to space and beyond
When all the Starships are lined up and ready to go, in-flight 3D printing will come in handy. We did not mention it earlier but we can imagine that many of the Starships’ cabin components will be 3D printed, using high-performance plastics to replace metal parts, to reduce both weight and costs. Examples of PEEK and PEKK 3D printing to replace structural metal parts have already demonstrated they can be a viable option for aerospace parts. It will also be possible to use strong biosourced materials such as nylon 11 or recycled polyesters, polycarbonates and polyurethanes to 3D print topologically optimized, generatively designed lightweight parts. Since Starship is going to be more like a spaceplane than just a rocket, many of the same lessons are going to apply.
Once the Starships get on their way to colonize Mars, 3D printing will be necessary for on-demand replacement parts. Not the kind of replacement parts that get 3D printed on Earth because it’s more convenient to do so (instead of keeping huge physical inventories or rebuilding old molds), but the kind of parts that get 3D printed in space, aboard the spaceship, because there is no other way in the entire universe to get that part. Deep space travel is not a possibility without onboard 3D printing. The idea of bringing along one or more of every part that could break on a six-month journey is preposterous.
However, the idea of bringing along large quantities of 3D printable polymer and metal materials and a few 3D printers is a sensible one. Some significant progress will need to happen in terms of making the 3D printing process (especially with metals) safer, lighter and more energy-efficient, but it can be done. A few years ago NASA, together with Redshift (the company that acquired Made in Space) demonstrated the use of a 3D printer to make polymer tools on the ISS. The printer (along with other printers) has been churning out replacement parts and tools since.
The advantage of using 3D printing is that the amount of materials that need to be carried along (and used to make the needed part using a weightless CAD design) is tiny, compared to the weight that every possible physical replacement part would have. So we can leave all these, for now, in the 100,000 tons total indicated above.
3D living on Mars
When the Starships will touch down on Mars they may do so on 3D printed landing sites. The astronauts and colonists will be able to head home to their 3D printed Mars habitats. NASA-run competitions to imagine new Mars habitats have often highlighted projects using 3D printing technologies. Even SpaceX itself recently experimented with the first 3D printed building at its Boca Chica site. The reason why it makes sense to use 3D printing is that it can build with locally sourced materials and it minimizes human labor (doing construction work in an astronaut suite does not seem the easiest nor the safest occupation).
With the proper mixtures of Martian regolith and water or other natural binders (that may be produced locally), it might be possible to build habitats that can shield the astronauts from radiation and combine them with inflatable structures to offer a complete solution that can be ready even before the bulk of the colonists get there. The 200,000 tons of 3D printers and 3D printing materials should also include at least a couple of construction 3D printing modules and material mixers, along with some binders and cement.
If the astronauts will bring along a few atomizers and equipment to extract minerals from the regolith, it may be possible to obtain structural materials such as iron and even titanium. By using natural ceramics, hydrogels and biocompatible polymers, along with a few bioprinters, the colonists will also need to be able to produce replacement tissues and organs. Although it has already been experimented with on the ISS, the technology to do this is still a few decades away but, then again, so is the trip to colonize Mars.
When colonial life on Mars commences, everything the colonists will need is going to have to be produced on site, 310 million kilometers away from Earth, for the ultimate distributed manufacturing effort. That’s where 3D printing excels. It takes is about 250,000 tons of 3D printing, starting now.