NASA and industry are expressing a growing interest in autonomous robotic in-space assembly and servicing of large aperture space telescopes in cislunar space and at Sun-Earth L2 (SEL2). The recently launched James Webb Space Telescope (JWST) will operate at SEL2 for about 5-10 years until fuel for station keeping and attitude maneuvers is depleted. At this point JWST will essentially become inoperable as it was not designed to be serviced or refueled. With a multi-billion-dollar price tag, it is essential that the technology is developed to enable future telescopes to be serviced autonomously in space. In addition to autonomous in-space servicing, autonomous in-space assembly of telescopes will allow for much larger telescopes that cannot be launched as a single payload. The probability of detecting Earth-like planets orbiting other stars is correlated to the size of the telescope aperture. To date, space telescopes such as JWST, have had to be designed to fit within the fairing of a particular launch vehicle and unfold after launch. This obviously presents numerous technical and programmatic challenges, which could be mitigated with advancements in technology for autonomous in-space assembly. Of course, autonomous in-space assembly also presents several challenges, some of which we will address in the proposed work. For the design reference mission, we consider autonomous assembly of a large aperture space telescope mirror that consists of multiple hexagonal components. We will use a distributed scheduler that tasks each agent in the system to retrieve a mirror component from a nearby cargo vehicle and place the mirror segment into a unique place within the primary mirror. Agents will plan their motion so as to reach their target goals while avoiding collisions. We will advance the start-of-the-art by developing a scalable interactive motion planner to ensure collision avoidance while satisfying constraints associated with the underlying dynamics.
The proposed work is applicable to many types of on-orbit servicing, assembly and manufacturing missions. For example, NASA’s Earth science orbiters, cislunar spacecraft and space telescopes operating at Lagrange points could all benefit directly from development of the proposed technology. In this particular proposal, we address technological challenges associated with autonomous in-space assembly of large aperture telescopes that are too large to be launched as a single payload. The technology is by no means limited to space applications.
The commercial sector has shown great interest in on-orbit satellite servicing missions to extend the lifetime of operational Earth orbiting assets. The proposed technology is applicable to commercial as well as military satellites. The technology is also applicable in other non-space scenarios that require decision making and path planning where human intervention is impractical or impossible.