Therefore, if we start building satellites and space vehicles modularly like the ISS, we can make these tools as big as we need. If we automate the modular construction of these tools, we no longer need to risk the lives of astronauts on dangerous space-walks. This will limit the risk of modular construction of space craft and improve their feasibility.
MIT Space Systems Laboratory (SSL) researcher Lennon Rodgers explored this concept, designing an automated universal docking port (UDP) for his master’s thesis.
Rodgers worked on small test satellites, called SPHERES (Synchronized Position Hold, Engage, Reorient Experimental Satellites), which are currently being tested on the ISS with his UDPs.
“We were initially exploring the feasibility of modular spacecraft, which is the idea that a spacecraft could be composed of multiple modules assembled in orbit,” said Rodgers. “One application is the primary mirror of a large, space-based telescope. Instead of being limited by the size of the rocket, the mirror could be composed of multiple module segments and assembled in orbit.”
“So we set out to build a mechanism for connecting multiple SPHERES together autonomously and rigidly,” Rodgers added. “A key requirement was that identical ports needed to connect to each other, which we referred to as ‘universal.’”
To build the UDPs, Rodgers enlisted the help of students from the Department of Aeronautics and Astronautics. The senior students helped to design and fabricate the mechanical components of the UDPs in their AeroAstro machine shop. The team also helped to create the camera sensors of the mechanisms.
The SPHERES are able to rotate and translate in all directions using twelve carbon diode thrusters and determine their positions using ultrasound beacons and receivers in the test area and on the satellites. NASA astronauts have been able to control the SPHERES with an impressive amount of precision in zero gravity.
Watch NASA astronauts make the SPHERES dance in this test video below:
The ISS experiment will be assessing the UDP’s and their autonomous, vision-based algorithms to dock the SPHERES. This will test the feasibility of modular spacecraft as well as the ability to dock with a tumbling spacecraft in cases of emergencies.
Once the UDP’s are installed onto the SPHERES on the ISS, a team of graduate students from the SSL will perform remote tests. These tests will assess the models created to automatically dock while in orbit in various potential situations. For instance, some tests will involve assessing how thruster or sensor failures can be overcome.
“The ultimate goal for the SPHERES docking port system is to provide an open testing platform for autonomous satellite assembly in zero gravity,” described Rodger. “The flight of the UDPs will be followed by a launch of [systems that] will enable a larger range of docking formations and autonomous satellite reconfiguration. This technology has applications to many next-generation space systems, including satellite servicing and assembly, large telescopes, space debris removal, and asteroid sampling.”
As for the future of the SPHERES, they will be used in a high school STEM program called Zero Robotics. The students will compete to see who can program the satellites to meet various goals.
Let’s just hope that this universal docking technology doesn’t redesign the ports as much as the universal serial buses, or USBs, if they do then NASA will be making conversion ports forever.