Harnessing the Sun & Wind to 3D Print Habitats on Mars

3D printing offers great potential for construction in space, as printers on the ISS, asteroids, or even the surface of the Moon could rely on materials from the local environment to fabricate structures, limiting the amount of resources that would need be launched from Earth, therefore reducing the valuable payload space and weight of outgoing spacecraft. Exactly how those printers would work, however, is still being sorted out.  On September 10th, NASA and America Makes announced 30 finalists for its 3D Printed Habitat Challenge, hoping to sift through the most viable proposals for 3D printing a habitat on Mars to award the winner with grants to take their project to the next level.  The first round of judging takes place at this year’s World Maker Faire in New York, with one of these 30 finalists taking home $50,000.

solar crafting 3D printed habitat mars

As this first big day approaches, a number of the finalists have reached out to us to introduce us to their unique approaches to space printing (we encourage the rest to do the same!).  All of the entries are unique, featuring everything from spiraled enclosures to novel composites, but Solar Crafting is the only firm that wants to 3D print on the Martian surface using a balloon.  Rather than relying on large gantry systems, such as those implemented by WinSun or D-Shape, Solar Crafting would make use of a NASA solar/hot air balloon as the central rig for housing the printer’s extruder.

I was able to learn more about the proposed process by team member Derek Mathers, a Business Development Manager at Worrell and Adjunct Professor of 3D printing at the University of Minnesota.  Not only did he tell me all about the methodology, but some of the exciting partners that may be involved, as well, including one very big name in the world of 3D printing.

solar crafting 3D printing robots on mars

As the Solar Crafting team envisions it, a team of robots – dubbed the R2RPs, the MissionBots, and the LassoBots – would be landed on the surface of the Red Planet via Entry-Descent-Landing Vehicle, where they would begin setting the stage for the larger 3D printing mission.  After debris is cleared from the construction site and telescoping LassoBot controllers are set up by the MissionBots, the LassBots can be set up to control the balloon gantry system.  Meanwhile, the MiningBots can get to work gathering the surrounding regolith (made up of a combination of mostly Iron and Quartz) to be converted into 3D printable resin by the R2RP (Regolith-to-Resin-Processor) machines.

solar crafting 3D printing on m ars

Up until now, this has been your run-of-the-mill terraforming job, with robots rolling around performing tasks to prep the actual building process, but, then, the Surface Habitat Printer (SHAB Printer) is actually inflated. Equipped with a solar array, based off of Markus Kayser’s Solar-Sinter 3D printer (video below), the SHAB would use the sun’s rays to concentrate a beam onto the regolith-turned-resin, as it’s continuously fed through the extruder, before it is instantly cooled by the low temperatures of Mars’s atmosphere.

In their concept, Solar Crafting is used primarily to construct an outer shell for the habitat, as well as an inner core structure, which is then filled with an inflatable, pressurized and uncontaminated living space.  The outer shell is essential to this habitat, Mathers says, “We have specifically designed our tough 3D-printed shell to be thick enough to protect against tempestuous Martian storms (a la Matt Damon) as well as the risks of direct solar radiation to the astronauts (due to Mars’ lack of an atmosphere).”

The Solar Crafting team sees a number of benefits for to their process, the biggest of which is the weight and cost savings of the balloon gantry system. Mathers tells me, “Traditional gantry cranes can weigh as much as 25,000 kilos; at $20,000/kilo to Low-Earth-Orbit, the cost of sending this system to Mars is simply not feasible, and certainly not scalable. Using our balloon-assisted gantry system, we are able to significantly reduce the transportation mass to Mars, and pave the way for large-scale colonization.”

If, like me, you wonder about the feasibility of balloons 3D printing on Mars, you can rest assured that the Solar Crafting crew has thought about it, too. The team believes that two months of clear weather will be needed to autonomously manufacture the outer shell. Two months of sunny, red skies is pretty unlikely, however, so the team has three proposals for mitigating the risk of weather interruption. Derek outlines them as follows:

  • solar crafting 3D printed martian habitat lockdown mode
    A rough sketch of “Lockdown Mode”

    Wind Power: “Just like we are directly harnessing sunlight to melt the sand, we will directly harness wind to help us cool the molten material quicker, and thus 3D print faster – this is because our TeraCraft print head has tungsten/carbide troweling arms will cover the molten iron-sand as it quickly cools behind it.”

  • Smart, Adjustable Cables: “Our robotic cable system will automatically adjust the tension of cables on the balloon, extrusion head, and the fresnel lens to remain printing during winds under a ‘Beaufort 4’, which is defined as a “Moderate Breeze” or anything under ~30 km/hr. Anything over this, and we will have to go in ‘lockdown mode’.”
  • Lockdown Mode: “Mars is notorious for crazy sandstorms, which can set-in in less than an hour and have been witnessed to increase from 2-3km/hr to over 61-94km/hr wind-speeds during that time. For that reason, we have built in a ‘lockdown mode’ feature where our cable system becomes completely tensioned and the balloon is pulled nearly flush to the ground.”

While Solar Crafting see Martian winds as a potential benefit for cooling the material, as it is extruded, the smart cable system will adjust the entire apparatus to respond to the atmosphere, like a righteous blonde dude maneuvering a windsurf board off the coast of Hawaii.  If you’ve still got any doubts about how well a balloon gantry might work, maybe some dense math will help? Jared, another Solar Crafting team member, compared the atmospheres, winds, and gravity on Earth and Mars to determine that the winds on Mars should not hinder the project:

Solar Crafting; 3D printed Construction GraphicThe pressure exerted by wind is dynamic pressure, or velocity pressure, and it is given by the formula q = 0.5ρv^2, where q is the pressure, ρ is the density of the atmosphere & v is the velocity (speed) of the wind. From the NASA Mars Fact Sheet, the density of air on Mars is about 0.020 kg/m3 and from Wikipedia the density of air on Earth, at sea level is 1.225 kg/m3. A significant difference of densities. Using wind speed of 60 mph (96.54 km/h, or 26.817 m/s.), a wind on Earth with this speed would exert a pressure of: q(earth) = 0.5(1.225)(26.817)2 = 440.480 Pa. The pressure from such a wind on Mars would be: q(mars) = 0.5(0.20)(26.817)2 = 7.192 Pa.

For a wind on Earth to exert the same pressure as that on Mars, its speed would need to be lower. By manipulating the dynamic pressure equation, the speed would be:

v = [2q/ρ]^(1/2)
v = [2(7.192)/1.225]^(1/2) = 3.427 m/s = 7.667 mph,

Wind on Earth, with a speed of 7.7 mph, exerting a wind pressure of 7.2 Pa will not blow over a landing vehicle thus, a wind on Mars with a speed of 60 mph, exerting the same pressure of 7.2 Pa would not blow over a landing vehicle.

Jared is a former geological researcher and geological lab manager at Indiana University who took part on the indigenous resource integration and materials science for the Solar Crafting proposal.  He is just one member, however, of an extensive group that consists of a 3D printing design team and a Martian Habitat design team. On the 3D printing side, in addition to Derek Mathers, is Leslie Oliver Karpas, the founder of 3D printing startup Metamason, and Charlie Wood, a leading industrial designer.

solar crafting 3D printed habitat floor 2 on mars copy
The top and bottom floors of the inflatable Martian habitat.

To create the Martian Habitat, they’ve got Leah Fett, an architect from Tushie Montgomery Architects in Minneapolis and Claire Cole, a former neuroscience researcher at Indiana University, as well as Jared on materials science.  Interestingly, Cole applied her neuroscience background to deal with the human factors design of the habitat, which you can see manifested in some beautiful renderings on the Solar Crafting site.

solar crafting 3D printed habitat on mars

Finally, Caleb Williams, a Business Consultant at Proficient, is the team’s project manager.  His leadership is augmented by two principal advisors, one of which many 3DPI readers will definitely recognize.  The first, Rich Baker, is the CTO of PaR Systems, which develops a huge range of robotics systems, and the other is Terry Wohlers, widely recognized as the leading analyst in the 3D printing industry. Of the two, Derek says, “[Terry Wohlers’] and Rich Baker’s guidance was essential in where we’ve gotten today!”

solar crafting 3D printed habitat food area on mars

The Solar Crafting proposal is clearly well-thought-out, and, with such advisors as Wohlers and Baker, it really seems as though they stand a chance to make it to the end of NASA’s challenge.  If so, the team may be able to take on some of its proposed industry partners, including 3M, DuPont Kevlar, Caterpillar, and Solartran. They’ve already obtained some industry support from Worrell and Stratasys to sponsor the 3D printing of their habitat model and, along with PaR Systems as a development partner, hope to bring 3M Optics on board for their microfilm fresnel technology. Then, all Solar Crafting will have to do is actually start building their system and, hopefully, get a working proof-of-concept constructed right here on Earth next year.