With the Mars 2020 mission now past the halfway point between Earth and its destination, NASA’s Jet Propulsion Lab recently released a couple of stories about the 3D-printed parts that made it aboard the Perseverance rover. Tucked into its aeroshell and ready for its high-stakes ride to the Martian surface, Perseverance sports eleven separate parts that we created with additive manufacturing. It’s not the first time a spacecraft has flown with parts made with additive manufacturing technique, but it is the first time JPL has created a vehicle with so many printed parts.
To take a closer look at what 3D-printing for spaceflight-qualified components looks like, and to probe a little into the rationale for additive versus traditional subtractive manufacturing techniques, I reached out to JPL and was put in touch with Andre Pate, Additive Manufacturing Group Lead, and Michael Schein, lead engineer on one of the mission’s main scientific instruments. They both graciously gave me time to ask questions and geek out on all the cool stuff going on at JPL in terms of additive manufacturing, and to find out what the future holds for 3D-printing and spaceflight.
Over the past decades, additive manufacturing (AM, also known as 3D printing) has become increasingly common in manufacturing processes. While immensely helpful in the prototyping of new products by allowing for rapid turn-around times between design and testing, these days additive manufacturing is used more and more often in the production of everything from small production runs of custom enclosures to hard to machine components for rocket engines.
The obvious advantage of additive manufacturing is that they use generic equipment and common materials as input, without requiring expensive molds as in the case of injection molding, or extensive, wasteful machining of raw materials on a lathe, mill, and similar equipment. All of the manufacturing gets reduced to a 3D model as input, one or more input materials, and the actual device that converts the 3D model into a physical component with very limited waste.
In the nuclear power industry, these benefits haven’t gone unnoticed, which has led to 3D printed parts being developed for everything from keeping existing plants running to streamlining spent fuel reprocessing and even the printing of entire nuclear reactors.
The first scramjet, an airbreathing jet engine capable of pushing an aircraft beyond Mach 5, was successfully flown in the early 1990s. But while pretty much any other technology you could imagine has progressed by leaps and bounds in the nearly 30 years that have passed, the state-of-the-art in hypersonic scramjets hasn’t moved much. We still don’t have practical hypersonic aircraft, military or otherwise, and any missiles that travel at those sort of speeds are rocket powered.
This is somewhat surprising since, at least on paper, the operating principle of the scramjet is simplicity itself. Air rushing into the engine is compressed by the geometry of the inlet, fuel is added, the mixture is ignited, and the resulting flow of expanded gases leaves the engine faster than it entered. There aren’t even any moving parts inside of a scramjet, it’s little more than a carefully shaped tube with fuel injectors and ignitors in it.
Unfortunately, pulling it off in practice is quite a bit harder. Part of the problem is that a scramjet doesn’t actually start working until the air entering the engine’s inlet is moving at around Mach 4, which makes testing them difficult and expensive. It’s possible to do it in a specially designed wind tunnel, but practically speaking, it ends up being easier to mount the engine to the front of a conventional rocket and get it up to speed that way. The downside is that such flights are one-way tickets, and end with the test article crashing into the ocean once it runs out of fuel.
But the bigger problem is that the core concept is deceptively simple. It’s easy to say you’ll just squirt some jet fuel into the stream of compressed air and light it up, but when that air is moving at thousands of miles per hour, keeping it burning is no small feat. Because of this, the operation of a scramjet has often been likened to trying to light a match in a hurricane; the challenge isn’t in the task, but in the environment you’re trying to perform it in.
Now, both Aerojet Rocketdyne and Northrop Grumman think they may have found the solution: additive manufacturing. By 3D printing their scramjet engines, they can not only iterate through design revisions faster, but produce them far cheaper than they’ve been able to in the past. Even more importantly, it enables complex internal engine geometries that would have been more difficult to produce via traditional manufacturing.
It’s been fifty years since man first landed on the Moon, but despite all the incredible advancements in technology since Armstrong made that iconic first small step, we’ve yet to reach any farther into deep space than we did during the Apollo program. The giant leap that many assumed would naturally follow the Moon landing, such as a manned flyby of Venus, never came. We’ve been stuck in low Earth orbit (LEO) ever since, with a return to deep space perpetually promised to be just a few years away.
But why? The short answer is, of course, that space travel is monstrously expensive. It’s also dangerous and complex, but those issues pale in comparison to the mind-boggling bill that would be incurred by any nation that dares to send humans more than a few hundred kilometers above the surface of the Earth. If we’re going to have any chance of getting off this rock, the cost of putting a kilogram into orbit needs to get dramatically cheaper.
Luckily, we’re finally starting to see some positive development on that front. Commercial launch providers are currently slashing the cost of putting a payload into space. In its heyday, the Space Shuttle could carry 27,500 kg (60,600 lb) to LEO, at a cost of approximately $500 million per launch. Today, SpaceX’s Falcon Heavy can put 63,800 kg (140,700 lb) into the same orbit for less than $100 million. It’s still not pocket change, but you wouldn’t be completely out of line to call it revolutionary, either.
Unfortunately there’s a catch. The rockets being produced by SpaceX and other commercial companies are relatively small. The Falcon Heavy might be able to lift more than twice the mass as the Space Shuttle, but it has considerably less internal volume. That wouldn’t be a problem if we were trying to hurl lead blocks into space, but any spacecraft designed for human occupants will by necessity be fairly large and contain a considerable amount of empty space. As an example, the largest module of the International Space Station would be too long to physically fit inside the Falcon Heavy fairing, and yet it had a mass of only 15,900 kg (35,100 lb) at liftoff.
To maximize the capabilities of volume constrained boosters, there needs to be a paradigm shift in how we approach the design and construction of crewed spacecraft. Especially ones intended for long-duration missions. As it so happens, exciting research is being conducted to do exactly that. Rather than sending an assembled spacecraft into orbit, the hope is that we can eventually just send the raw materials and print it in space.
[LudwigLabs] is creating PCBs using copper foil and a cutting plotter (vinyl cutter). In this approach, it’s an additive process where instead of removing copper from a copper-clad board, the traces are cut out of copper foil and transferred to a solid backing surface (cardboard, fiberglass, etc.).
While similar to the use of copper tape laid out by hand, as covered by us last year, the big advantage of using a cutting plotter is that it allows one to create much more complicated traces similar to those you would expect to see on a factory-made PCB. Since cutting plotters translate a 2D design into very precise movements of the cutting blade, this allows for sharp angles and significantly thinner traces, allows designs from EDA software like KiCad or Altium to be quickly translated to physical boards.
Enterprising hackers might consider the possibility of using this approach to make two-sided, and even multi-layered boards. The copper is produced separately from the substrate which opens up the potential for using uncommon materials like glass or paper to host the circuits. The main limitations are the transferring of (very delicate) copper structures and creating vias without damaging the traces.
As a comparison with traditional PCB fab processes, the photo exposure and etching (or laser exposure and etching) process requires the creation of masks, UV exposing a board, etching, cleaning and so on. The simplicity of copper foil traces has led to manyexperimenting with this approach. Would you want to use this additive process, or are there refinements or alterations you would make?
Sometimes there’s a lot of perks to working for a cutting edge tech company while also being a writer here at Hackaday. This week I had the opportunity to attend AMUG 2015 — the Additive Manufacturing User Group conference in Jacksonville, Florida.
I saw companies big and small, checked out the newest techniques like metal printing and mold making, and met a ton of interesting people. Join me after the break for the rundown and a video summary of my experience.