The Case for Orbital Industry
Adam Kall, Director of Technology
5 minute read
Imagine if scientists suddenly discovered a way to teleport to another dimension. This teleportation portal requires an immense amount of energy, the initial expeditions fraught with danger and tragedy, but eventually, the designs become standardized and the dangers are mitigated. Not long after this, any nation dedicated enough can construct and power their own portal to this alternate dimension or can contract passage through any number of privately owned portals. A significant distinction about this technology is that the portals become unstable the larger their surface area is, and as it has to be a circular shape, researchers can’t increase diameter without drastically increasing surface area. However, they can always increase the power going to the portal, allowing more mass to be passed through each time it is turned on, so long as that mass is packed into a cross-section smaller than the diameter of the portal ring. Because of this, many researchers focus initially on improving energy efficiency, but soon missions are planned with ever-larger cross-sections. This could be accommodated through deployable systems of ever-increasing complexity, but eventually, it would be necessary to enter a new phase of sending material and expertise through the portal to then assemble the final mission on the other side.
In case you haven’t guessed it, this portal is an analogy for traveling into space. Traveling to space has many difficulties and complexities that other experts have discussed, but I want to focus this column on the specific challenge of volume cross-section. This is the concept that even as rocket payload volumes increase, it is consistently because the volume is longer, while diameter has remained almost unchanged for decades. Two recent events have made launch volume cross-section a forefront issue: the launch and deployment of the James Webb Space Telescope (JWST) and the 2022 Starship Update. By first examining how the issue of launch volume cross-section is currently impacting space exploration, I’ll discuss how orbital industry could be a solution.
The JWST has a primary mirror diameter of 6.5 meters, compared to the Hubble Space Telescope mirror diameter of 2.4 meters. The Hubble mirror was this size because, once surrounded by necessary equipment, that was the largest size that would still fit in the docking bay of the Space Shuttle that delivered it to orbit. That cargo bay was 18.3 meters long and 4.6 meters wide when Hubble launched in 1990. With the launch of JWST in late 2021, one would expect the payload volume to have dramatically increased as the world built better and more powerful rockets. However, the Ariane 5 rocket that launched the JWST to space has a payload volume just 13 meters long and 5.4 meters wide, less than a meter wider than the cargo capacity three decades prior. This forced the JWST to utilize advanced deployable systems for the mirror and sunshield, folding them in for launch and then carefully and remotely deploying them once in orbit, adding to the 344 single points of failure, any one of which could have doomed the mission if it didn’t work perfectly. The solution also wouldn’t have been to just use a larger rocket, as even the SpaceX Starship (the largest rocket yet designed which wasn’t available anyway during the design of JWST and hasn’t yet completed a launch), has a diameter of just nine meters, big enough for the mirror but not the sunshield that protects it. At the 2022 Starship update, Elon Musk described how future versions of the Starship booster could be made taller and more powerful, but they can’t make them wider.
This represents a serious problem for the future of space exploration, but also a significant opportunity for the space industry. A major factor for launching things into space is the payload’s density. Some cargo missions to space have a very high density, like fuel or oxygen that is supercooled to fit as much mass in the available volume as possible. Other missions are just the opposite, like crewed spacecraft or space stations. These missions have the annoyingly necessary consideration of humans on board, who tend to enjoy things like space to stand up in. This means the very expensive rocket is going to launch a large volume that is just empty, and still can’t exceed the cross-section of the spacecraft, so a relatively small volume in human terms. High volume plus low mass equals low density. The solution is to stop constructing the entire mission on the ground first and instead start flat-packing the necessary materials to assemble the mission in space, making the cargo far more dense and allowing designs with cross-sections larger than 5 to 9 meters.
This all opens the door to a very important distinction between things that are better to assemble with terrestrial industry and things that are better to make in space. A precision computer chip is easier to manufacture on the ground, as the process is extensive, complicated, and the space environment is actively hostile to computers. It is also worthwhile to have computer chips as rocket cargo since they are very dense and can be reused in many applications. By comparison, an already existing example of the orbital industry is the 3D printing of tools on the ISS. The end product in this case is very simple, only consisting of one material and one machine to assemble it, and the purpose can be very specific where it is only used for one purpose. In this case, the material will be denser than the final product, and there is even an opportunity for recycling to turn obsolete tools into new material.
With these baseline examples laid out, I want to examine the very concept of structure in space. A structure, whether a satellite bus or a space station hull, is designed to be an empty rigid volume that has other components installed on both the inside and outside surfaces. Most of the time this structure is over-engineered for the space environment because it first must survive the forces of launching into space. By assembling the aluminum sheets and struts in space, each launch could pack many more components that are then assembled into the final spacecraft in orbit. In fact, several space companies are already pursuing missions with this type of function. One example of this dense packing within a launch fairing can be found from ThinkOrbital with the Orb2, illustrated in this conops video.
This efficiency in launch also increases the component utility in space, because it is akin to shipping the components of a chandelier to then assemble at the destination, rather than trying to ship the pre-assembled chandelier. Add to this the fact that processed aluminum is an abundant material in orbit, due to the large amount of space debris, then construction in space is eased by a lightweight, high-strength material not requiring its own launch. Organizations could capture and process debris in orbit, supplemented by ground-launched components like microchips, to create these otherwise unlaunchable constructs.
Until physics and launch constraints change, the future of the space industry will be built by the group of technologies known as On-orbit Servicing, Assembly, and Manufacturing (OSAM), with Active Debris Removal (ADR) providing a significant amount of material. OSAM needs industry to design and implement missions, with material from ADR. ADR needs industry to lead the development and demonstration of these new technologies, with OSAM as a viable and growing demand for captured materials. Without one, the other elements suffer, but utilized and coordinated together, humanity can continue and expand beyond Earth.
Recommended column to read next: Tragedy of the Commons