Over the last 50 years, astronauts have built up an extensive legacy in performing on-orbit inspection, servicing and assembly tasks. Unfortunately, such activities are very costly, time consuming, and require extensive pre-launch testing before launch.
Core technologies for on-orbit manufacturing and assembly are currently under development utilizing teleoperation, robotics and autonomy technologies. These approaches can enable several performance gains including science return on investment (SROI), cost reductions, asset reconfiguration and improved asset reuse capabilities.
Solar Panels
Solar panels convert sunlight to electrical energy that supplies spacecraft with energy. Constructed of multiple silicon cells connected together and wired together to produce a desired voltage and current output, these solar panels require a power regulation system in order to produce consistent power supply.
Flexible solar panels are essential to space exploration because of their lightweight and easy storage when not in use, enabling more payload to fit on each rocket launch. Furthermore, their production and launch costs are far cheaper than competing energy sources.
Solar panels can be degraded by radiation and other environmental factors, so they must be carefully designed and integrated into spacecraft. Furthermore, the arrays must produce sufficient power in space where the sun is farther away than on Earth; this poses unique challenges for missions spending extended amounts of time in GEO or LEO orbits. However, thin-film copper-indium-gallium-selenide (CIGS) solar cells offer lightweight yet long-term durability solutions for GEO or LEO space missions.
Metals
Nickel and titanium metals are essential in spacecraft manufacturing, as they combine well with other elements to form alloys which have the right properties for fabrication. Plus, these metals resist corrosion, heat radiation and other space conditions.
Spacecraft structures must meet several criteria when selecting their metals for construction; such as thermal expansion, ductility, fracture toughness and resistance to corrosion. Aluminum, stainless steel and titanium are popular choices.
Superalloys of these metals, commonly referred to as superalloys, are popularly used in jet engines due to their high temperature strength and corrosion and oxidation resistance. Spacecraft alloys such as Inconel are another important example; Inconel is a nickel-chromium alloy with additions of cobalt, molybdenum, tungsten and other elements for corrosion and oxidation resistance. New next-generation processing and casting systems on board the International Space Station could enable even more exotic alloys be created allowing for even greater metal AM opportunities within space.
3D Printing
3D printing allows engineers to design geometrically complex components that are optimized for performance, such as 3D-printed rocket engine nozzles that are lighter and more fuel-efficient than traditional versions, thus saving fuel and lowering launch costs.
Printers use directed energy deposition, in which a multi-axis robotic arm directs an energy source such as plasma arc or laser beam to melt and deposit materials onto a rotating build tray. They can produce parts up to 10 cm x 10 cm x 14 cm, roughly equivalent to softball size.
Astronauts on board the International Space Station have used a 3D printer to print various supplies, from tools to medical. Thanks to its versatility and a new recycling machine known as Refabricator that transforms single-use plastics into feedstock for printing, long-term missions may eventually no longer need resupplies of all items needed during long journeys – for instance astronauts could print replacement parts for their cabin or clothes, as well as produce spare rocket parts!
Habitats
Habitats are designed to keep humans alive and comfortable during long missions such as visiting Mars. These structures must provide shelter, water, food and space as well as provide research facilities with cutting-edge systems for environmental control, life support and regenerative healthcare.
Recyclers need to recycle air and water while simultaneously producing oxygen for combustion, as well as produce solar energy for powering their missions. They require massy radiation shielding measures that add mass. Furthermore, they must be flexible enough to meet ever-evolving mission needs and expand as required.
The best habitats are modular and scalable structures like the International Space Station; other examples, like Bigelow Expandable Activity Module or O’Neill Cylinder are spherical structures with adjustable mirrors to point towards the sun.