A futuristic company Tethers Unlimited Inc. is developing a revolutionary suite of technologies known as "SpiderFab" to enable on-orbit fabrication of large spacecraft components such as trusses, solar panels, antennas, and other multifunctional structures.
SpiderFab will manage spider robots as they construct these large structures, making the company's effort an alternate way of deploying space systems. The structures can be larger because they will be constructed in the microgravity of space and not subject to the high forces of gravity at liftoff.
Existing large space structures now have to be constructed on Earth first before they can be sent to space, making them very expensive and also limiting their size and weight, since the unit has to fit inside the rocket or what's referred to as a space shroud. With this new technology, spider robots could be controlled to build kilometer-scale radio antennas, solar arrays, and spacecraft booms among other components in outer space.
The vision that has motivated the effort to build things in space is that of creating a satellite "chrysalis," composed of raw material in a compact and durable form, "software DNA" assembly instructions, and the capability to transform itself on-orbit to form a high-performance operational space system, according to Tethers Ulimited CEO Bob Hoyt.
SpiderFab makes this work by adapting additive manufacturing techniques and robotic assembly technologies to fabricate and integrate large space systems on-orbit. The company outlined its SpiderFab project at NASA's Innovative Advanced Concepts (NIAC) program, which has a goal of promoting development of reliable and realistic space technologies.
Hoyt is a co-founder of the company that began in 1994 to develop robotics and communications products based upon space tether technologies. Hoyt told NASA's Future In-Space Operations (FISO) working group that he envisions space agencies using SpiderFab to construct things like radio antennas, solar panels arrays and telescope parts. He said he also is looking forward to spider robots in outer space "to construct the infrastructure in space needed to support humanity's expansion throughout the solar system."
"It's a very expensive and time-consuming process, and also, the size of systems is somewhat limited by the size of the deployable that are possible to fold up and fit within a launch shroud," added Hoyt. With this system, "we can deploy apertures and baselines that are much larger than we can currently fit into launch shrouds. The payoff of that will be higher power, higher resolution, higher sensitivity and higher bandwidth for a wide range of NASA, Department of Defense and commercial space missions."
Since 2005, NASA has been developing a space telescope called New Worlds Observer (NWO) that is projected for a grand launch in 2019, then followed by a "starshade" by 2020. The starshade, designed in a flower shape with from 12 to 16 petals, is intended to help obtain high-resolution pictures of planets by blocking out the bright light of their stars so the telescope can take images of Earth-like planets.
The starshade will be positioned between the telescope and the star that's being observed so it can block the starlight before it even reaches the telescope's mirrors. With the starlight suppressed, light coming from exoplanets orbiting the star would be visible. "Simply put," NASA says, "the starshade is analogous to holding your hand up to the sun to block it while taking a picture of somebody." The prototype starshade structure is a spacecraft that looks like a giant sunflower, equipped with thrusters so it can be moved. It is being developed by NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The width of this starshade that the manufacturers could put together would be an estimated 203 feet (62 meters) maximum, if created on Earth and then launched to space. However, if this starshade was built in orbit by the spider robots, its diameter could equal 406 feet (124 meters), which would enable the NWO space telescope to attain images that will be twice as near to its target stars, Hoyt believes.
Now imagine sending the starshade to outer space with raw materials only, not only would that decrease its volume 30 times, Hoyt says, it would also cost space agencies less money since smaller rockets could be launched to carry the supplies into space.