Stranger Sats| Let's Connect
Let's Connect
StrangerSats Shepherd Orbital Assembly System
Summary
StrangerSats Shepherd is a set of tools that will assist orbital assembly of structures. It consists of the Shepherd Tug (a space drone - to bring the structures close together), a Structural Ring with attachment points (mounted on each of the structures being assembled ahead of time), and powered Turnbuckles which lock the structures together.
How We Addressed This Challenge
We developed a solution to the problem of assembling large structures in space. It consists of three elements: the Shepherd Tug, which brings the structures together, the Structural Ring with attachment points, which is integrated into each structure, and the powered Turnbuckles, which are used for the final locking together of the structures.
The system is designed to have as few requirements as possible for the structures being assembled, thus increasing the flexibility of design and lowering the cost of implementation. Our modular approach, with just a few simple standardized components, can be easily implemented by even the least technically advanced manufacturers. Nonetheless, structures with just the Ring built into them will be able to be assembled into large systems.
As you'll see in our presentation, the system works in four stages:
- The Arriving structure is delivered to orbit in the vicinity of the Base to which is it to be attached by a launch vehicle
- The Tug, normally berthed at the Base, flies out, meets and grapples the Arriving structure, and tows it close to the Base. Initially, this will be done under human control, but eventually, the AI autopilot built into it will be able to perform these maneuvers autonomously
- The Tug then installs the required number of Turnbuckles at minimum tension. The Rings can have 2, 3, 4, 6, or 12 attachment points. This enables the smaller structures, or those that are only temporarily attached to the Base, to have fewer attachment points, thus saving on the cost or manufacturing and assembly
- The Turnbuckles are tightened by remote command from a human Remote Operator
We hope that our system will not only save money for the builders, but that it will significantly expand their number and diversity, and will help democratize access to space.
How We Developed This Project
We've been working in the area of satellite design for several years, and have produced a number of innovative vehicle and robotics designs:
- LBCRV - a low ballistic coefficient re-entry vehicle experiment
- SpaceBuddy - a small autonomous space drone for safety and inspection missions near space stations or other large space vehicles
- FFCP - a large reusable free-flying camera platform for filming high quality cinematic footage near space stations and other large space vehicles and structures
- Mantis - a space-capable 6 or 7 DOF robotic arm
When we read the Create/Connect Challenge requirements, we realized that we have a lot of experience in designing solutions for related problems. So we put together FFCP and Mantis to form the core of the Shepherd system design. Starting with a clean sheet of paper, we then designed the powered Turnbuckle and the structural Ring with the attachment points. Finally, we defined the Concept Of Operations which brings it all together.
We used Autodesk Fusion 360 CAD tool to design and assemble all the system components. Because F360 is such a powerful tool, it requires very powerful desktop computers. Alas, the machines available to us were not quite up to par for the complexity and scope of our designs. It required a great deal of patience to coax good results from the machines we had. Hopefully, in the future, we'll be able to upgrade our infrastructure such that similarly complex projects can be executed faster and with less risk of missing the deadline.
How We Used Space Agency Data in This Project
We used the NASA Scientific and Technical Information (STI) document archive. In particular, we found the papers on the NASA Technical Reports Server to be very interesting and useful.
We also used CAD data from McMaster-Carr, SDP-SI, and VXB Bearings.
Additionally, we hope to receive direct feedback from spacecraft designers and operations engineers of the agencies participating in the Challenge to help us improve the designs and the Concept of Operations.
Project Demo
Here's a link to the slide presentation (as a PDF file): https://drive.google.com/file/d/1M6pzJQs3HdStyOYU_5y0aId8WUdYEtbn/view?usp=sharing
Data & Resources
- NTRS: "orbital assembly" section: https://ntrs.nasa.gov/search?q=orbital%20assembly
- McMaster-Carr: https://www.mcmaster.com/
- SDP-SI: https://sdp-si.com/
- VXB: https://www.vxb.com/